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Kepler: A Love Story

2011-12-12T09:45:00.000-07:00

Last week NASA announced the discovery of an Earth-like planet in a 290-day orbit, placing it firmly in the habitable zone of its Sun. I was attending the Kepler Science Conference where the announcement was made, and I was part of the team that determined the absolute size of the planet in the discovery paper using a technique known as asteroseismology to characterize the host star. Ironically, NASA recently rejected my proposal to perform this type of analysis in the future -- but they are willing to let me do it for free.

Last February, I submitted a proposal to do "Precision Asteroseismology of Kepler Exoplanet Host Stars". I did not have access to the Kepler data on these targets, but the methods that I had developed for asteroseismic analysis were yielding very exciting results for other solar-type stars in the Kepler field, including precise values of the stellar radius, mass, and age. Becoming a Kepler Participating Scientist would give me access to the exoplanet data and allow the mission to benefit from these developments. In early May, I was contacted by members of the Kepler science team and asked to sign a non-disclosure agreement to become part of a small team doing asteroseismology of exoplanet host stars. Previously, all such analysis was done by just three people on the science team and they were quickly finding that they could not keep up with the demand. The expanded team included about a dozen people recruited from the Kepler Asteroseismic Science Consortium -- a large collaboration of primarily European scientists who were providing their expertise in exchange for early access to the data (without funding from NASA). Before signing the agreement, I contacted the Participating Scientist program officer to express my concern that doing so may influence the selection process. He assured me that there was a "firewall" between the science team and the panel review. I signed the agreement and became part of the new team.

As promised, the science team did not influence the ranking of proposals by a panel of experts, and my proposal was ranked high enough to be funded by the program. However, the selection of proposals for funding was based not only on the panel rankings but also on a "programmatic evaluation" by the program officer in consultation with several members of the Kepler team, including the Science PI, Project Scientist, Deputy Project Scientist, Science Team Lead, and Deputy Science Team Lead. This evaluation occurred several weeks after I had signed the agreement to become part of the team that would do for free the analysis that I was asking NASA to support in my proposal. In other words, the same people who asked me to become part of the team doing asteroseismology of exoplanet host stars in early May told the program officer several weeks later that "the need for a Participating Scientist in the area of asteroseismology was not as pressing as it was in other areas". The experts determined that the science was worthy of funding, but the Kepler team passed over my proposal to fund several others that were judged inferior based on the science. They were happy to have me do the work for free, they just didn't want to pay for it.

This was not the first time that the Kepler team had rejected my asteroseismology proposal due to a "programmatic" evaluation that trumped the rankings based on science. In 2007, I submitted a Participating Scientist proposal to develop the method that I am now using to do asteroseismology of the stars observed by Kepler. That proposal was also ranked in the top tier, high enough to be funded by the program but again passed over to fund lower-ranked proposals. As a direct consequence of that decision, in early 2008 I started the Pale Blue Dot project -- an attempt to raise private funding by putting the Kepler target stars up for adoption for $10 each through a non-profit website. This program has provided enough funding to help sponsor two international workshops of the Kepler Asteroseismic Science Consortium, waiving the registration fee for all of the students and early career scientists. Even so, the available funds are meager compared to the grant support that I was requesting from NASA. To make things even more difficult, due to federal budget cuts my current position as a research scientist will be eliminated next year -- so I am faced with a decision to either contribute the analysis for free, or be left out of the team doing this exciting work.

It is understandable that NASA wants to apply its scarce resources to areas where it will have the most impact. But with a large team in Europe doing asteroseismology for free, the few U.S. scientists who are working in this field are facing an uphill battle for funding. The science will certainly push forward, but without support the U.S. asteroseismology community will ultimately disappear.

Slow Motion Disaster

2011-11-14T10:05:00.001-07:00

Last week an asteroid known as 2005 YU55 zoomed past the Earth at a distance closer than the Moon. Imagine if astronomers knew about a similar asteroid that would actually impact the Earth sometime in the next few decades, but they decided not to discuss it with the people of the world. The public would understandably be outraged at such a cover-up -- they would demand to know the details of when and where the asteroid would strike our planet, and the likely consequences for the survival of the human race. Although this example is fictional, it is precisely the situation faced by climate scientists who are currently not talking about the unavoidable consequences of climate change during the next 50 years.

The release of too much heat-trapping pollution into the Earth's atmosphere is like an ecological deficit that we pass to future generations, and the gradual accumulation of this pollution is our climate debt. The choices of our parents and grandparents resulted in the release of so much carbon-dioxide that it exceeded the capacity of the Earth's natural systems -- primarily the oceans and forests -- to absorb it. The surplus pollution from each year remains in the atmosphere, and commits us to some amount of climate change for as long as it takes the planet to work through the accumulated excess. Even if we eliminated all human-induced sources of this pollution right now -- like coal-burning power plants and gasoline-powered automobiles -- the globe would continue to warm significantly for at least the next 50 years. This fact is not a secret, but the implications are so devastating that climate scientists generally prefer to discuss what we can do to "avoid the worst consequences of climate change" so that people will be less likely to feel overwhelmed.

Since the industrial revolution, the average temperature on the surface of the Earth has increased by about 1 degree centigrade. Knowing how much extra heat-trapping pollution is already in the atmosphere, and looking at the geological record of how temperature and carbon-dioxide empirically change together, scientists know that we are already committed to additional warming of 1-2 degrees centigrade over the next 50 years. Our decisions now about how to respond to the threat of climate change will only affect how much warmer the planet will get, and how long it will take to return to its normal temperature during the lives of our children and grandchildren. There is a significant moral difference between our actions and those of previous generations, because we now know with certainty what our choices are doing to the atmosphere and we are collectively making a conscious decision that will determine the type of world we will leave for our progeny. Considering the extreme weather events that have already resulted from 1 degree of warming -- hurricanes, tornadoes, drought and flooding -- the prospects for the next 50 years already look bleak, even if we manage to stop digging the hole deeper within our lifetimes.

Although it can be depressing to focus on the unavoidable consequences of climate change, it is important to remember that we still have the power to save the future. Our generation will certainly need to adapt to a warmer world, but we can also take steps in the short term to minimize the impact of the current climate debt. There are a variety of options for countering the warming effect of the excess carbon-dioxide in the atmosphere, from simple actions like planting more trees to more aggressive responses like artificially enhancing the capacity of the ocean to absorb heat-trapping gases, or injecting sulfates into the upper atmosphere to reduce the amount of energy the Earth's surface receives from the Sun. These are just short term strategies -- even if we can temporarily regulate the temperature of the planet, the excess carbon-dioxide will still acidify the oceans and disrupt fragile ecosystems -- but they could potentially help us make the transition to a clean-energy future at a lower financial and ecological cost.

Scientists should level with the public about the climate change we will experience over the next 50 years. Just like an asteroid on an impact trajectory, the longer we wait to respond to the problem the harder it becomes to avoid a disaster. Unlike an asteroid, part of the climate disaster is unavoidable. With a better understanding of the impacts we are already facing, the citizens of the world can demand a response.

Faster than Light?

2011-10-15T12:09:00.001-06:00

Last month a team of physicists from the European Center for Nuclear Research (CERN) in Switzerland announced that they had sent a burst of particles across 450 miles to collaborators in Italy -- and they appeared to complete the journey faster than light. According to Einstein's theory of relativity, light establishes the ultimate speed limit for the Universe, and nothing can move faster. My thesis adviser Ed Nather at the University of Texas had a simple rule of thumb for such situations: "Never bet against Einstein".

The experiment itself was conceptually simple. The scientists used the huge accelerator at CERN to produce a bunch of sub-atomic particles called neutrinos, and then beamed them toward a laboratory in Italy where they could be detected. Neutrinos do not interact very much with other matter, so most of them would be expected to complete the journey -- and with something like a large vat of cleaning fluid surrounded by light-sensitive detectors, a small fraction of them could be measured at the finish line. If the distance between the two locations could be determined accurately, the time required to make the trip would reveal the speed of the neutrinos. After repeating the experiment many times, the physicists came to a startling conclusion: the particles took 60 billionths of a second (60 ns) less than it would take light to travel between the laboratories. Light moves about 1 foot (30 cm) in a billionth of a second, so a 60 ns discrepancy corresponds to an error of about 60 feet (18 meters) on the distance between the two locations. Using GPS satellites, they actually knew the distance to within about 8 inches (20 cm), and they also had very precise measurements of the time. So they announced the result and asked for other explanations.

Astronomers were quick to point out a serious problem with the result. If neutrinos really moved slightly faster than light, then those produced in the most recent nearby explosion of a massive star should have been detected about 4 years before we saw the star grow brighter in 1987. In fact, the neutrinos from that "supernova" explosion were detected just a few hours before the light, which is consistent with what we understand about how stars end their lives. So something had to be wrong with the experiment -- and the culprit was probably identified this week by a Dutch mathematician. It turns out that the GPS satellites are moving fast enough in their orbits around the Earth that corrections are needed to the times that they record for the production of the neutrinos in Switzerland, and their subsequent detection in Italy. Ironically, these corrections come from Einstein's theory of relativity and amount to 32 ns on each event, for a total difference of 64 ns -- within the uncertainty of the 60 ns discrepancy observed by the CERN team.

Einstein has stood the test of time. In his one mistake of failing to predict the expansion of the Universe discovered by Vesto Slipher and Edwin Hubble (which he described as the "greatest blunder" of his career), he ended up predicting the "dark energy" that was discovered more than half a century later. So the next time you hear a claim about faster-than-light travel, just remember Ed's rule of thumb.

Changing Priorities

2011-09-08T08:30:00.003-06:00

If you are an astronomer who doesn't work at a university, the chances are good that you work at one of the many federally funded research facilities or observatories (e.g. STScI, NOAO). There are several types of positions at such institutions, including some supported by grants (soft money) and others supported by base funding from the sponsor (hard money). Some hard money positions can even be on a tenure track, with the usual disclaimer about being "contingent on the availability of funding". These jobs generally involve some combination of research and service in support of the mission of the organization. Such positions are ideal for scientists who want to spend most of their time doing research rather than teaching -- the only catch is that your research must be relevant to the strategic goals of the institution.

My first experience working in a federally funded research laboratory came during the summer before I finished my PhD. One of the external members of my thesis committee was a hard money scientist at the High Altitude Observatory (HAO) in Boulder, Colorado -- part of the National Center for Atmospheric Research (NCAR), which is sponsored directly by the National Science Foundation. Growing up professionally in an academic environment, I was surrounded by scientists who decided that being a university professor was the best career choice. This was my first exposure to an institution filled with people who had made a different evaluation. It was a powerful experience that really resonated with my vision of the ideal job, and by the end of the summer I was convinced that a hard money career path was right for me.

After finishing my thesis, I spent several years as a postdoc before landing an NSF fellowship that brought me back to HAO. About a year later, I was hired as a tenure track hard money scientist. As the name suggests, the primary research focus at NCAR is the Earth's atmosphere -- but because the Sun is responsible for the energy input at the top of the atmosphere and for the particle flux underlying disruptive "space weather" events, HAO is the NCAR laboratory devoted to solar physics. My job was to maintain a connection between this group of several dozen solar physicists and the wider astrophysics community -- using stars to provide a broader context for our understanding of the Sun, and ensuring that stellar research could benefit from the laboratory's detailed knowledge of our local star.

Life as a hard money scientist was good. In addition to having access to a 12-month salary without the requirement of writing grant proposals, each scientist was allocated a modest annual travel stipend while internal funds also paid for journal page charges and even helped bring in scientific visitors. In return, we worked on large-scale and long-term projects that were not amenable to funding through standard three-year grants, often with a focus on serving the scientific community with new modeling capabilities or public data. The primary disadvantage of being an astronomer in a solar physics laboratory was the difficulty of finding students and postdocs. Unlike a university environment where students are the lifeblood, only a few students could be supported by internal fellowships at HAO. Postdocs were also hard to find, since most of the fellowship applicants were interested in solar physics, not astronomy. Consequently, like many hard money scientists I still wrote grant proposals to help recruit students and postdocs, and to provide part of my salary.

Perhaps the greatest source of anxiety for a hard money scientist is the annual drama of the federal budget cycle. Flat budgets at the federal level generally translate into a flat budget for the NSF and all of its programs. As everyone knows, a flat budget in the face of rising operating costs really means a cut. When the budgets do get increased for inflation, salary levels within each laboratory are supposed to be adjusted according to merit -- but in reality the extra funds either disappear entirely to offset a previous budget shortfall, or they are distributed evenly among the staff to compensate for the years without a cost of living adjustment. The leadership in Washington certainly recognizes the importance of scientific research as an engine of economic growth and innovation (read the America COMPETES Act), but these lofty pronouncements rarely seem to be reflected in national budget priorities.

Nobody needs to be reminded of the chaos surrounding the most recent federal budget cycles. A series of short-term "continuing resolutions" to fund the government at 2010 levels ultimately led to a budget for 2011 that finally passed more than halfway through the fiscal year. By this time the NSF and its programs were already preparing budget scenarios for 2012, and the partisan rancor in Washington made it clear that difficult decisions were unavoidable. It was in this atmosphere that HAO concluded it could no longer support stellar research, and I was given 12 months notice that my position would be eliminated. Despite outstanding annual performance reviews and wide ranging contributions to programs across the organization, changing priorities motivated by federal budget cuts ended my career as a hard money scientist.

Fortunately there are other ways to survive as a research scientist. After my final year on hard money, I hope to continue working at NCAR for another year or so on soft money. In the longer term, I will probably need to seek an environment with lower overhead expenses to continue funding myself on grants. As a graduate student I formed a non-profit organization dedicated to scientific research and public education, thinking that it could always be my backup plan in case a hard money position didn't materialize. This unexpected career transition may be just the impetus I needed to build on this foundation, and hopefully make a soft landing on soft money. Wish me luck.

Seeds of Life from Space

2011-08-16T10:15:00.006-06:00

Last week, just in time for the annual Perseid meteor shower, NASA scientists announced new evidence that the building blocks of life may have been manufactured in outer space and delivered to our planet on a meteorite. The implications of the discovery are profound: if the chemicals that make up DNA can be formed anywhere in the cosmos, the universe is most likely teeming with life.

Every year in early August, the Earth passes through a cloud of debris in space left behind by comet 109P/Swift-Tuttle, which last came through the solar system in 1992. Some of the ice and dust shed by the comet on its 135 year journey around the Sun is pulled in each year by the gravity of the Earth and burns up in the atmosphere, creating a "shooting star" for anyone who happens to be watching. At the peak of the shower, observers far from the city lights can see about 100 meteors every hour. Meteorites -- chunks of space rock that are large enough to make it all the way to the ground -- are much less common than meteors. Even when they don't disintegrate entirely from the friction of entering the atmosphere at 100,000 miles per hour, most of them fall in the ocean or are quickly eroded on land. The exception is Antarctica, where meteorites are preserved in the ice -- and this is where the space rocks with DNA were found.

Over the past 50 years, evidence of life has turned up in many space rocks. It has been clear since the 1960's that amino acids (chemicals that build proteins) can be formed in space, and a recent examination of a dozen Antarctic meteorites led NASA scientists to suggest that adenine and guanine -- two of the four "nucleobases" that link up to form DNA -- can also come from the sky. We know that the meteorites came from space, but the difficulty has always been establishing the source of the organic molecules: they are much more likely to come from contamination after they reach the surface of the Earth. In this case, the scientists did not find any other molecules that should have accompanied the nucleobases if they had come from contamination. Instead they found additional non-biological molecules that were not present in samples of the soil and ice where the meteorites were found. The properties of the samples, along with simple experiments to show how nucleobases can be manufactured naturally in space, support the idea that these space rocks contain some of the building blocks of life.

Over the past two decades we have learned that planets are much more common than we ever imagined, and this latest research suggests that a lifeless planet can be seeded with organic molecules from outer space. If rocks from the sky contain some of the ingredients of DNA, it is not a stretch to believe that life must be common in the universe.

Rethinking Space Exploration

2011-07-25T08:09:00.008-06:00

When the shuttle Atlantis touched down in Florida last week, it marked the end of an era for space exploration. Thousands of NASA engineers found themselves unemployed after three decades of a largely successful program. Astronauts scheduled to visit the International Space Station will now be forced to hitch a ride with the Russians. The human space flight program in the United States will soon be handed over to private companies, and anyone willing to pay a few hundred thousand dollars can buy their 15 minutes of space. Is this the beginning of a new era of discovery, or the end of exploration as we know it?

In a 1962 address at Rice University, President John F. Kennedy said "we choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard". Less than 7 years later, the Apollo 11 mission delivered astronauts to the moon and returned them safely to the Earth. There were certainly some scientific contributions of the Apollo program -- astronauts returned samples of the lunar surface, and they set up a reflector that allowed astronomers to measure the distance to the moon with unprecedented accuracy -- but it was driven more by the arms race with the Soviet Union than by science. After all, if the United States could launch a rocket and deliver astronauts to a target nearly 240,000 miles away, that same technology could also be used to deliver a nuclear warhead to Red Square in Moscow. If we accomplished some science along the way -- well, great.

With the cold war now a fading memory, our current leaders have struggled to identify a generational goal for NASA, let alone one that can be accomplished in less than a decade. From the least ambitious circles there have been calls to return to the moon, as if the United States can somehow save itself from imperial decline by reliving the glory days of the past. More ambitious, though arguably suicidal, are the calls to send astronauts to the planet Mars -- apparently for no other reason than to continue providing large subsidies to aerospace contractors. Once outside the protection of the Earth's magnetic field, it would be difficult to avoid a fatal dose of radiation from solar flares during the 450-day round trip. With the Sun gradually becoming more active in its 11-year cycle, such a mission cannot be scheduled for the coming decade. So the two sides struck a compromise: let's send astronauts to an asteroid.

Right on cue, last week NASA's Dawn probe beamed back images of Vesta, one of the largest asteroids in the solar system. No, this is not one of the asteroids on a collision course with our planet, and there are no plans to revive the shuttle program and send retired astronauts on a mission to blow it up. Vesta is much smaller than the moon, but much closer than Mars, so by sending people there we can relive our glory days and continue to provide large subsidies to aerospace contractors, probably without killing any astronauts and almost certainly without making any accidental contributions to science. All of this at a time when funding for the National Science Foundation has been declining in real terms for years, NASA's next generation space telescope is on the chopping block, and the nation is about to go bankrupt.

At the end of the shuttle program, the future of space exploration is up in the air. There are more harmful ways to spend money than using it to send people into space, but there are also more productive ways to spend that money. If science is the purpose, there is much more we can do without ever leaving the surface of our planet.

Understanding the Sun

2011-06-30T09:27:00.007-06:00

Earlier this month, reports emerged from the Solar Physics Division meeting of the American Astronomical Society that the Sun may be headed into magnetic hibernation, pushing the Earth into a "Little Ice Age" and resulting in a "sharp decrease in global warming". The historical record of sunspots can only take us back a few hundred years. To understand the Sun on longer time scales, it helps to study other stars that are older and younger. Without this broader context, we have no way of knowing whether the Sun is typical or peculiar.

Consider the Gallup Organization, which regularly conducts telephone polling around the world to track public opinion. Each poll typically includes interviews with more than 1000 people, representing the full range of demographics within a given region. Imagine how different the Gallup poll results might be if instead of contacting a broad cross-section of society, they only interviewed one person in the town of Gallup, New Mexico. Depending on the topic of the poll and the person they happened to choose, we might get a very biased view of "public opinion" from this single interview. That's the whole point of sampling opinion more broadly: the responses from the population provide context for those of any individual. When scientists study the Sun, observations of other stars provide this context. So what can other stars tell us about the solar magnetic cycle and the possibility of the Earth entering a "Little Ice Age"?

Observations of sunspots show that the Sun goes through a magnetically active phase every 11 years, causing it to brighten by about 0.1% and bombard the Earth's upper atmosphere with high-energy radiation and charged particles. For a 70-year stretch beginning around 1645, this magnetic cycle disappeared from the surface of the Sun. Historians note that the absence of sunspots during this time coincided with a period of unusually cold winters in Europe -- a time known as the "Little Ice Age". There were several volcanic eruptions during the same period that thrust large quantities of sulfates into the Earth's upper atmosphere, which is known to have a cooling effect on climate -- so it is unclear whether, or to what extent, this so-called "Maunder minimum" in the Sun actually influenced global temperatures.

Studies of large populations of stars like the Sun reveal two particularly interesting facts: (1) Stars typically spend about 15% of their lifetimes in magnetic hibernation like the "Maunder minimum", and (2) There is a clear set of relationships between a star's rotation period and the length of its magnetic cycle -- that is, for all stars except the Sun. In other words, studies of other stars tell us that the Sun is in a peculiar phase of its evolution. If we want to understand the general problem of how magnetic cycles are created and sustained in stars -- including why they occasionally go into hibernation -- a good place to start is with stars that are more typical. Otherwise, we risk fine-tuning our understanding to explain a special case (our Sun) that turns out to be peculiar.

The broader context provided by other stars suggests that the Sun may very well be entering magnetic hibernation -- with the last one starting more than 350 years ago, we are nearly due for another. But the logical jump from expecting another "Maunder minimum" to creating a new "Little Ice Age" is much more speculative. In fact, the latest research suggests that "the change in climate radiative forcing since the Maunder minimum is about one tenth of the change caused by man-made trace greenhouse gases". So whatever happens with the Sun in the coming decades, the planet is certainly going to get warmer.

Kepler's Multi-planet Bonanza

2011-05-31T08:39:00.007-06:00

Last week at a meeting of the American Astronomical Society in Boston, scientists working with NASA's Kepler mission announced the confirmation of an additional planet in a previously identified planetary system. The abundance of systems showing multiple planets has been one of the early surprises to emerge from the stellar census being conducted by the space telescope.

"We didn't anticipate that we would find so many multiple-transit systems," said astronomer David Latham from the Harvard-Smithsonian Center for Astrophysics. "We thought we might see two or three. Instead, we found more than 100." In a survey of 156,000 stars during just the first four months of the mission, the Kepler team identified more than 700 stars that appeared to host planets. This relatively small fraction (0.5%) was expected, since the technique that is being used to discover the planets is only sensitive to those that pass directly in front of their host star. The orbits of the planetary systems are randomly oriented in the sky, so simple geometry can be used to convert the fraction of stars with observed planets into the fraction of stars that actually host planets. In addition, since the experiment must observe several consecutive orbits to trigger a detection, only planets with the shortest orbital periods have already been identified -- so the number of planets is expected to grow as the mission continues. The big surprise was the relatively large fraction of these stars that appear to have more than one planet (~15%). The planetary orbits within our own solar system are in roughly the same plane, but the slight misalignment would prevent a distant observer from seeing many planets with the technique used by the Kepler mission.

It is exciting enough to learn that multi-planet systems like ours may be more common than we anticipated -- but these systems can also help us measure the masses of the planets, and teach us about how planetary systems form and evolve. In multi-planet systems, not only do the individual planets gravitationally tug on their host star, they also pull on each other and change their orbits over time. Larger planets pull more strongly on other bodies in the system, so the changes in the orbits can be used to measure the masses of the individual planets. The masses are usually determined by measuring the tiny reflex motion of the host star, but many of the planets being discovered by Kepler are far too small -- approaching the size of the Earth -- to make such measurements with currently available technology. So the ability to measure interactions between planets in these distant solar systems represents a huge opportunity to characterize our stellar neighbors. Looking at the multi-planet systems discovered by Kepler so far, one striking fact is that none of them seem to contain planets much larger than Neptune. The gravity of larger planets like Jupiter tend to scatter smaller planets into tilted orbits -- or even eject the planets from the system entirely. So the absence of large planets in the systems that have so far been discovered appears to make sense.

If there is one recurring lesson in the history of astronomy, it is that we have always been conservative about how common other solar systems like ours might be. Kepler has already taught us that tiny planets like ours are even more plentiful around other stars than the big planets that have been discovered over the past two decades. In the coming years, perhaps we will also find that habitable planets -- those that may support life -- are also far more abundant than we ever imagined.

Space Shuttle Triple Finale

2011-04-28T09:00:00.006-06:00

NASA's space shuttle program will soon be coming to an end, after 30 years and 135 missions to low-Earth orbit. The "final" launch tomorrow of the shuttle Endeavor will mark the second "final" launch this year (after the "final" launch of Discovery in February), with the third and final "final" launch of Atlantis planned for June. The retirement homes for the aging shuttles have already been selected, and flocks of tourists are gathering in Florida to witness the penultimate launch. Like the history of the shuttle program itself, the event is driven more by public relations than by science.

Consider the Hubble Space Telescope, one of the landmark public relations achievements of the space shuttle program. Released into low-Earth orbit from the cargo bay of the shuttle Discovery in April 1990, it was soon determined to have blurry vision which was subsequently corrected during the first servicing mission in December 1993. Various shuttles returned for additional servicing missions in February 1997, December 1999, March 2002, and finally in May 2009. It made great television. Heroic astronauts performed difficult tasks while floating 350 miles above our stunning blue planet. I don't mean to marginalize their achievements. It's just that low-Earth orbit is a lousy place to do science.

The only scientific advantage of low-Earth orbit is safety. A telescope that flies well within the protective magnetic field of the Earth is less vulnerable to charged particles from the Sun that could damage sensitive scientific instruments. The price for this safety is an endless 96-minute loop around the planet punctuated by enormous temperature variations between daylight and darkness, staggering levels of scattered light from the surface of the globe, and occasional journeys through the South Atlantic Anomaly -- a distortion in the Earth's magnetic field over South America that disrupts the normal functioning of crucial electronics. It is far better to put a telescope in an Earth-trailing orbit around the Sun like the Kepler mission, or near one of the Sun-Earth Lagrange points like the SoHO and Planck missions.

This isn't rocket science -- NASA knows that there are better places to do science than low-Earth orbit, which is why the James Webb Space Telescope will be parked at the outer Lagrange (L2) point. With the shuttles retiring and Hubble in the final phase of its mission, will the public relations gravy train come to a halt? Don't worry NASA, you still have the International Space Station.

The Inner Lives of Red Giants

2011-03-30T11:00:00.001-06:00

Just as in Hollywood, the age of a star is not always obvious if you look only at the surface. During certain phases in a star's life, its size and brightness are remarkably constant, even while profound transformations are taking place deep inside. For most of their existence, stars shine from the energy released by nuclear reactions that convert hydrogen into helium, but eventually they begin to burn the helium in their cores to synthesize heavier elements, such as carbon and oxygen. In the latest issue of Nature, astronomer Tim Bedding and his collaborators demonstrate a new technique for distinguishing between these life stages, using continuous 'starquakes' to probe the deepest regions, where the changes are most dramatic.

The objects examined by Bedding and colleagues are known as red giants, the bloated fate of stars such as our Sun as they begin to exhaust their primary source of energy -- the hydrogen near the center that powers nuclear fusion. The resulting helium accumulates in the core, forcing hydrogen in a surrounding shell to burn more vigorously than before. About 5 billion years from now, these processes will gradually cause our own star to expand to more than 100 times its present size, becoming a red giant and destroying some of the inner planets in our Solar System. Stars that were born before the Sun, as well as heavier stars (which evolve more quickly), have already reached this phase of stellar evolution.

Like the Sun, the surface of a red giant seems to boil as convection brings heat up from the interior and radiates it into the coldness of outer space. These turbulent motions act like continuous starquakes, creating sound waves that travel down through the interior and back to the surface. Some of the sounds have just the right tone -- a million times lower than the audible range for humans -- to set up standing waves (known as solar-like oscillations) that cause the entire star to change its brightness regularly over hours and days, depending on its size. Inferring the properties of stars from these periodic brightness changes is a technique known as asteroseismology. The sound waves generated near the surface of a red giant can interact with buoyancy waves (rather like the waves in the ocean) that are trapped inside the helium core. Under the right conditions, the two types of waves can couple to each other, changing the regularity of the brightness changes at the surface. These 'mixed' oscillation modes are much more sensitive to structure in the core than are the uncoupled sound waves that sample only the stellar envelope.

The innovation that allowed Bedding and colleagues to distinguish between red giants at different life stages emerged from precise observations by the Kepler space telescope. Launched in March 2009, Kepler stares at a large patch of sky near the constellation Cygnus, monitoring the brightness of more than 156,000 stars with the goal of detecting habitable planets like Earth. The mission has been extremely successful at finding alien worlds, but it is also revolutionizing the study of stellar oscillations by providing many months of continuous data for thousands of stars. Earlier efforts to study red giants from ground-based telescopes were hampered by both the daily interruptions of sunlight and the limited duration of the monitoring.

As mentioned before, the trouble with red giants is that they all look nearly the same on the outside, regardless of their mass and age. Bedding and colleagues sought to determine these properties for the hundreds of red giants observed by the Kepler satellite, to measure precisely when stars of a given mass would shift from burning hydrogen in a shell to helium in the core. The regular pattern of standing waves is insufficient to pinpoint which energy source makes a particular red giant shine, but the mixed oscillation modes exhibit a unique pattern. By deciphering this pattern, Bedding and collaborators demonstrate how the two life stages of red giants can be separated using asteroseismology.

The life story of a red giant theoretically depends not only on its age but also on its mass, with stars smaller than about twice the mass of the Sun experiencing a sudden ignition known as a helium flash. The temperature required to fuse helium is significantly higher than that needed for hydrogen, and in low-mass stars the helium accumulates in the core at very high density until it reaches a critical size and ignites almost instantaneously. In more massive stars, the transition to helium core burning is gradual, so the stars exhibit a wider range of core sizes and never experience a helium flash. Bedding and colleagues show how these two populations can be distinguished observationally using their oscillation modes, providing new data to validate a previously untested prediction of stellar evolution theory.

This extraordinary peek into the inner lives of red giants was made possible by just the first year of observations from the Kepler mission, which is scheduled to operate for at least 3.5 years and might be extended by NASA for a further 2.5 years. The picture that emerges from asteroseismology will steadily improve as the observations continue, so we can expect even better results for the stars examined by Bedding and colleagues, as well as similar measurements for other red giants, in the near future.

James Hansen's Climate Future

2011-02-09T14:51:00.010-07:00

In his global warming memoir "Storms of my Grandchildren", NASA scientist James Hansen describes his role over the last decade trying to inform policy decisions about climate change. Hansen has been working tirelessly on the science for more than 30 years, and I was most impressed with his reflections on the empirical certainty of climate change, his baseline for any serious attempt to address the problem, and his proposal to reconsider advanced nuclear power as part of the response.

One of the greatest criticisms of climate change theory is its reliance on computer models to make uncertain predictions about the future. According to Dr. Hansen, a better approach is to rely on the empirical evidence from the geological climate record. The layers of ice deposited in Antarctica over the past 425,000 years contain a detailed record of both the relative temperature (from the properties of the ice) and the concentration of heat-trapping gases in the atmosphere (from air bubbles trapped in the ice). This record includes information spanning the last four ice ages, which are caused by natural variations in the orbit and rotation axis of the Earth, and it demonstrates a precise relationship between the average temperature and the concentration of heat-trapping gases. The conclusion is unambiguous: we can expect the globe to warm by 3°C from a doubling of carbon-dioxide.

It may surprise readers of Hansen's book that he is opposed to cap-and-trade legislation as a policy response to climate change. Looking at the results of the relatively modest Kyoto Protocol, he concludes that even legally binding international agreements are simply not effective in practice. Instead, he favors a gradually increasing carbon tax, with the dividends redistributed uniformly to the public to help offset the resulting price increases. According to Hansen, this approach is the only way to ensure that much of the remaining coal and unconventional fossil fuels (such as tar sands and shale oil) stays in the ground and is never burned. His litmus test for any politician who is truly serious about addressing climate change is to call for an immediate moratorium on the construction of new coal-burning power plants that will not capture and store the carbon.

Rather than leave us with a big problem and no way to solve it, Hansen presents a thorough and honest assessment of the potential of nuclear power. If you thought that all nuclear power produces a mountain of radioactive waste that remains dangerous for ten thousand years, then you've never heard of a "liquid-metal fast breeder reactor". The concept for this 4th generation nuclear power (currently operating reactors use 2nd generation technology) has been around since the 1940's, and in 1994 a full scale demonstration reactor was on track to be constructed by Argonne National Laboratory. In that year, the program was canceled by Bill Clinton and Al Gore -- possibly without much thought, as a nod to anti-nuclear activists that helped them get elected. Hansen claims that such reactors are 100 times more efficient than conventional nuclear power plants, and that there is enough of the required nuclear fuel (uranium hexafluoride, a byproduct of nuclear weapons production) in U.S. stockpiles to power the country for the next thousand years. The only waste products can be stored safely on-site for just a few hundred years.

Hansen believes that we have not yet reached a tipping point, and that we have the power to save the future for our grandchildren if we choose to do so. He understandably remains skeptical that we will actually make that choice, and this book is his final attempt to make his message heard. If we don't listen, we have nobody to blame but ourselves.

Essential Astronomy Research

2011-01-17T08:55:00.013-07:00

Last week I attended the annual winter meeting of the American Astronomical Society. After hearing such a broad range of scientific presentations, I always wonder what research would survive the drastic funding cuts that might be required to balance the federal budget. Some astronomy research has very obvious practical applications, while other topics have nearly universal public appeal or transformative spin-off potential. Below are my "top 5" essential research areas, starting close to home and moving outward.

1. Killer Asteroids: Few people would seriously argue against the idea of finding all of the asteroids that cross the Earth's orbit and could pose an impact risk. Astronomers believe there are tens of thousands of potentially hazardous asteroids in our solar system, of which the 1200 largest have already been found. It is widely believed that the dinosaurs met their demise from a comet impact in the Gulf of Mexico, and there's no reason it couldn't also happen to us.

2. Space Weather: The Sun is constantly spewing radiation and charged particles towards the Earth that can harm orbiting satellites, interfere with communications systems, and damage electrical grids. Scientists monitor our nearest star for such activity, and try to understand the basic physical processes that drive this "space weather" by comparing the Sun to other nearby stars. With our growing reliance on GPS and cell phones, this work is more important than ever.

3. Alien Worlds: Over the past 15 years, more than 500 planets have been discovered around distant stars. With better technology and larger telescopes, astronomers are now finding planets nearly as small as the Earth that may be in the "habitable zones" of their stars. It is virtually certain that in the next few years we will identify dozens of Earth-like planets around other stars. Are we alone in the universe? We will soon answer this 1000-year-old question.

4. Dark Energy: Edwin Hubble discovered that the universe is expanding, but recent studies of distant supernova explosions have shown that the expansion is accelerating -- the tell-tale sign of "dark energy" in the fabric of space-time itself. The origin and nature of this energy is still unknown, but it accounts for nearly 3/4 of all the mass-energy in the universe. If we could somehow tap into this cosmic battery, we would have a limitless supply of renewable energy.

5. Cosmic Fate: Observations of the cosmic microwave background confirm that the universe began with a "big bang" more than 13.7 billion years ago. There is no way to see beyond this original cosmic fireball, so astronomers study the most distant galaxies to try to determine the ultimate fate of our universe. Will gravity pull everything back together in a spectacular "big crunch", or will the cosmos expand forever into an icy darkness? Stay tuned.

Much of the basic research in astronomy can be related to one or more of these grand themes. The curiosity-driven research that falls outside of these areas can be considered like art -- a luxury that any civilized society can afford. The government is now more than a quarter through the current fiscal year and still doesn't have a budget. When the time comes to make hard decisions, let's hope our representatives in Washington can see beyond the next election and invest in the future through science.

Communicating Climate Change

2010-12-08T09:42:00.017-07:00

In an effort to combat misinformation about climate change during the UN negotiations in Cancun this week, the American Geophysical Union (AGU) -- a non-profit scientific organization with more than 58,000 members -- launched a Climate Question & Answer Service for journalists. The program is part of a recent effort by scientists to be more proactive in communicating the science of climate change to the public, but it draws a line at questions of policy. In reality the line between science and policy is slightly fuzzy, and scientists need to formulate a coherent strategy to have any chance of success.

Climate scientists have come a long way in their thinking about public relations since the release of the last report by the UN Intergovernmental Panel on Climate Change (IPCC) in 2007. At a press conference in Paris associated with that release, lead author Susan Solomon of the National Oceanic and Atmospheric Administration declined to comment on how society should respond to the climate crisis. "I honestly believe that it would be a much better service for me to keep my personal opinions separate," she said. Her response is now regarded as one of the greatest missed opportunities to frame the public debate about climate policy. Solomon and the IPCC team went on to receive the Nobel Peace Prize for their work, along with Al Gore.

Given the persistent misinformation and outright falsehoods perpetuated by some media outlets and politicians, the new question and answer service is a step in the right direction. Journalists who are unsure about how to report on some technical issue -- or who are confronted with unsubstantiated claims from global warming skeptics -- now have the ability to fact check. As part of the pilot program, more than 700 PhD climate scientists volunteered to answer questions from a shared email box over a period of 10 weeks around the UN negotiations in Cancun. But the "AGU explicitly requests participating scientists not to comment on policy", and questions "relating to policy, ethics, and economics will be returned to sender". In other words "just the facts". Unlike these scientists, politicians and media pundits are not constrained by the facts -- so ultimately this approach may still be a losing strategy.

I have several ideas for a more successful media strategy by scientists. First, the answer to a question about policy does not need to be political to be useful. For example: "Over the next several decades society must dramatically reduce its emissions of heat-trapping pollution into the atmosphere. How this is accomplished, and on what timeline, are questions that must be answered by policy makers." Second, scientists should try to frame climate change as a form of debt being left to future generations. The same conservatives who are concerned about passing a $14 trillion national debt to their grandchildren are also opposed to any action on climate change. Finally, rather than talk about "avoiding the worst impacts of climate change", it's time to focus on the inescapable impacts that we will see in our lifetimes. For example: "No matter what we do now, by the middle of the century the global climate will warm by at least 4 degrees Fahrenheit. The only thing we can control now is the sort of planet that our grandchildren will inherit from us."

By re-framing the debate about climate change policy, and by shifting the focus to the immediate impacts that are both certain and unavoidable, scientists can jump start the necessary response by society. When people understand that it is "too late" to avoid severe impacts during their lifetime, they just might skip over the denial, focus their anger, and begin bargaining.

The Cost of Science

2010-11-24T10:42:00.011-07:00

With so many recent discussions about reducing the federal budget deficit and gradually paying down the nearly $14 trillion national debt, the government agencies that fund science appear to be easy targets. Looking for solutions to narrow this budget gap, a recent opinion column in my own local newspaper characterized NASA's budget as "a luxury we can't afford". But the numbers tell a different story -- the sum total of all non-defense discretionary spending is less than half the current budget deficit, and funding for science amounts to pocket change buried under a mountain of cash.

The 2010 federal budget totals $3.55 trillion. When you compare this to the $2.38 trillion in revenue from taxes, you get a $1.17 trillion deficit -- the gap between what the government spends, and what it collects from taxpayers. Similar deficits since the 1970's have gradually increased the U.S. government debt, like running a balance on the nation's credit card. The interest payments alone on this national debt will amount to $168 billion in 2010, enough to give every taxpayer in America a $1000 refund. To fix the problem, the government needs to cut spending and/or raise taxes to balance the budget and slowly begin paying down the national debt. It's been done before -- Bill Clinton inherited a $255 billion deficit from George H.W. Bush, and he transformed the federal budget to yield a $236 billion surplus by the time he left office. But this episode of fiscal responsibility was short-lived, and the nation has been spending hundreds of billions of dollars more than it collects ever since.

So, how does science funding compare to this enormous imbalance between taxes and spending? Suppose lawmakers decided to completely eliminate the National Science Foundation -- how much money would it save? The 2010 NSF budget is just $7 billion, about 0.6% of the current federal deficit. By contrast, the Department of Defense spends the annual budget of the NSF every few days. If lawmakers wanted to be more selective in their cuts to science, they might decide that Mathematics and Physical Sciences are "a luxury we can't afford". The MPS budget in 2010 is $1.38 billion, a potential savings of about $8 for every taxpayer. If this sort of cut seems too draconian, maybe congress would just target Astronomical Sciences with an annual budget of $250 million, the equivalent of a round-off error in the federal budget. You get the picture -- there isn't a lot of savings to be realized by forcing the nation's scientists into the unemployment lines.

What about NASA? Surely the potential savings from the space program could make a significant impact on the deficit -- right? At $18.7 billion, the annual budget of NASA is larger than the NSF, but it still represents just 1.6% of the deficit or about 10 days of military spending. NASA launches astronauts into space to repair a 20-year-old telescope that continues to make ground-breaking discoveries on a weekly basis -- it captures the imaginations of children around the world and inspires them to study science. But much of NASA's budget is actually devoted to spaceflight -- the Science Mission Directorate has an annual budget of $4.5 billion, with about $1.1 billion for Astrophysics. It's a good deal of funding compared to the NSF, but it barely registers in the context of total government spending.

Congress has some difficult decisions to make in the coming years. It's clear that as a nation we cannot continue to spend more than we are willing to pay. Returning tax rates to the levels of the 1990's is certainly part of the solution, but spending cuts will also be necessary. Our investments in science can be sustained by trimming the defense budget just a few percent. Let's hope our lawmakers arrive at the right conclusions.

NASA Outsourcing Science

2010-10-22T08:32:00.008-06:00

Next week NASA will issue a press release and hold a media event in Denmark to announce the first results from the study of pulsating stars with the Kepler satellite. Kepler was designed to find distant Earth-like planets, but part of the mission is devoted to characterizing the target stars. When NASA holds a press conference, the media usually report on whatever they say -- so this is a great opportunity for a group of scientists who have been working in relative obscurity. Unfortunately, the public may never hear about the most significant results.

Like many NASA projects, the history of the Kepler mission has been riddled with delays and cost overruns. In 2006 NASA approved a 20% increase in the price tag for Kepler, bringing the total cost of the satellite to $550 million and pushing the launch date from 2007 to 2008. A year later the team asked for another $42 million -- but this time the request came to the desk of Dr. Alan Stern, the new associate administrator for NASA's Science Mission Directorate. "Four times they came for more money, and four times we told them no," said Dr. Stern. With threats of NASA turning the project over to new management, it was widely reported that the team cut costs by reducing the mission duration from 4 to 3.5 years and scaling back on preflight tests of the hardware. It is less well known that they also reduced the budget by outsourcing one of the major scientific programs to Europe, where they could externalize the data analysis costs to international partners.

In addition to the primary mission of discovering habitable Earth-like planets around distant stars, the Kepler satellite also has the capability of studying the stars themselves in great detail. The giant digital camera inside the space telescope monitors the brightness of more than 150,000 stars every 30 minutes. This is enough to detect the tiny drops in brightness caused by planets that pass in front of their host stars -- events that typically last for a fraction of a day. But at any given time, the brightness of 512 of those stars is measured 30 times more often. This 1-minute sampling is enough to document the subtle pulsations of starlight caused by continuous "star-quakes" that reveal the properties of the star itself. Thousands of stars have been monitored for one month each during the first year of the mission, and the entire program has been coordinated from headquarters in Denmark at no cost to NASA. Some of the world's leading experts in the study of pulsating stars are based in Europe, so they traded their labor for early access to Kepler data -- effectively extracting a subsidy to NASA from their home countries.

After the first year of the mission, the initial results from these studies were about to be published, so NASA asked the largely-European team to draft a press release. With the help of one of their local media offices (another hidden subsidy), the team pitched a story about Kepler "taking the pulse of distant stars" to learn about their properties -- while developing techniques that could also be used to characterize the host stars of the many planets discovered by the mission. After receiving the draft press release, NASA delayed the target date for the media event by two weeks and asked for additional information from the lead authors of the studies, essentially trashing the draft and starting the process from scratch. This week NASA circulated their "final" version of the press release to the scientists, which largely ignores many of the results and gets the science wrong in what remains -- leaving the scientists to wonder why they agreed to embargo their results for two months.

Kepler Program Scientist Douglas Hudgins was positively giddy about the scientists "quite literally revolutionizing our understanding of stars ... at no cost to the American taxpayer". He's absolutely right about the quality of the work being done by these world-class researchers -- but because of continued mismanagement at NASA, you might never hear about it. I guess you get what you pay for.

Astronomical Events

2010-09-20T11:01:00.003-06:00

One of my astronomy professors had a cartoon on her door labeled "a beginner's guide to star gazing". The first panel showed a person looking downward shielding his eyes with his hand, and the caption said "wrong". The second panel showed the same person looking upward, and the caption said "right". Star gazing isn't rocket science -- anyone can do it. Even so, last month many people were fooled by an Internet hoax claiming that Mars would appear in the night sky as large as the Earth's moon, for one night only! While astronomers might lament the inability of the general public to recognize this claim as a hoax instantly, it may have been credible precisely because of the way astronomers and the media typically report celestial events.

For example, it has been widely reported that Jupiter will be closer tonight than it has been since 1963 or will be again until 2022. This is technically true, but it makes the opportunity of viewing Jupiter tonight seem like an all-or-nothing proposition -- if you miss it tonight, you'll have to wait 12 years before you can see it this good again. The reality is not nearly as urgent. Tomorrow night, Jupiter will be 0.003% further away than it will be tonight. Next week it will be 0.2% further away, and when the Earth swings by Jupiter again next year (28 October 2011), it will be 0.4% further away than it was this year. Even a trained eye would have a hard time detecting differences this small. Despite this reality, public observatories will be jam packed tonight while almost nobody will show up tomorrow.

Maybe we can understand this tendency of the media to hype astronomical events by considering another recent example -- the "International Observe the Moon Night" that took place over the weekend. This event was not fabricated by the media, it was created by astronomers to generate increased public interest in the Moon. For one night, several NASA centers partnered with local amateur astronomers to set up telescopes and open their doors to public viewings of the Moon. Prominent scientists gave lectures about the Moon that were streamed live online. There was nothing urgent happening on the Moon over the weekend. It was just a concerted effort by lunar scientists to engage the public, and it worked. Meanwhile, anyone can observe craters on the Moon at any time from their own back yard with a cheap pair of binoculars.

Maybe the lesson here is that the media understandably tends to focus on what is new or unique, so astronomers pitch celestial events as if they were Valentine's day or Mother's day -- a social construct reminding people to do what they could be doing all of the time (appreciating their partner/mother, or looking at the sky instead of watching reality television).

Forcing the Climate

2010-08-23T14:49:00.009-06:00

In an editorial for the Houston Chronicle earlier this month, Walter Cunningham (a geophysicist and former Apollo astronaut) claimed that global warming is a natural phenomenon that is unrelated to human activities. "Scientists have long known that the sun, oceans and variations in the Earth's orbit are the principal drivers of climate change", he wrote. It is actually true that changes in the Earth's orbit can explain the periodic ice ages and warm periods of the past. But all of the known sources of natural variation cannot account for the warming observed in the last few decades.

Three properties of the Earth's orbit are known to change on long timescales, from 26,000 to about 100,000 years. These include how non-circular the orbit is (the eccentricity), how titled the rotation axis is compared to the orbital plane (the obliquity), and the direction of that tilt at a given point in the orbit (precession). The effect of these variations on the length of the seasons and the amount of sunlight received by the Earth throughout the year was worked out in the 1930's by a Serbian mathematician. Comparing the predictions of this natural variation in solar energy received by the Earth with the reconstructed surface temperature over the past 250,000 years shows a clear correlation, at least until recently.

What about the Sun itself? Could variations in its energy output be responsible for recent changes in the Earth's climate? In fact, the magnetic field of the Sun flips every 11 years and during this time the total energy output changes by about 0.1 percent -- the Sun emits more energy during periods of high magnetic activity. However, the change in energy output from one magnetic cycle to the next can only account for about 10 percent of the warming over the past century, and it has actually been going down since the 1960's while the temperature of the planet has continued to rise dramatically.

Climate scientists have tried to account for global warming using only these natural contributions, but they can only match the recent increases in temperature when they also consider human activities. The most significant of these activities is the release of heat-trapping pollution like carbon dioxide and methane, but the scientists also consider the cooling effects of aerosols and modern changes in land use patterns. On balance, considering all of the natural and human-induced contributions to climate change, the conclusion is unambiguous. The planet is warming because of us.

It is human nature to prefer a reassuring lie over an inconvenient truth. We want an easy way to escape the difficult situation we have created for ourselves. In a rebuttal to Cunningham's editorial, Nobel prize winner Robert Curl put it simply. "How much does the present owe to the future? This is a hard philosophical question. Neither Cunningham nor I will live to see how this turns out, but I expect my grandchildren to. I prefer that the planet they inherit is not a world in distress."

Cycles in the Sun

2010-07-13T15:37:00.002-06:00

In a classic Far Side cartoon by Gary Larson, we see a man sitting at a desk surrounded by fans, reading a newspaper. On the wall beside him is a large lever with two positions labeled "rise" and "set", and the caption reads: "Inside the Sun". Our nearest star is actually much more dynamic than it might first appear, and a short paper published this week has revealed fresh evidence of something very interesting beneath the surface.

To anyone who has ever seen the Sun through a telescope (equipped with a special filter to protect your eyes!), the most obvious features are sunspots -- small dark patches about the size of the Earth that are strongly magnetic and cooler than their surroundings. If you recorded the position of the spots every day for weeks, you would see them come and go tracing the fluid rotation of the Sun -- moving faster near the equator and more slowly towards the poles. If you kept careful records of the sunspots over decades, you would notice a regular rise and fall in the number of spots every 11 years. This is the most visible manifestation of an underlying magnetic cycle in the Sun, where the magnetic bubbles that appear as sunspots are periodically stretched out, reorganized and recycled by the rotation and other motions deeper in the interior.

Although we cannot see spots on other stars directly, long-term studies of stars like the Sun show similar magnetic cycles. All other things being equal, stars that rotate faster generally have shorter cycles, since they are more efficient at recycling their magnetic bubbles. However, when astronomers examine in detail the relationship between rotation and the length of the magnetic cycle, there seem to be two different types of stars -- "active" stars that spin faster than the Sun and have magnetic cycles every 400 rotations, and "inactive" stars that spin more slowly and exhibit magnetic cycles every 90 rotations. Some of the "active" stars show both types of magnetic cycles simultaneously, suggesting that the two types of cycles might actually just be operating in different regions of the star.

The paper published this week by a team of mostly British astronomers used an innovative tool to study the magnetic cycle of the Sun -- they peered beneath the surface with the help of sound waves that bounce around inside and set up standing waves with specific frequencies, a technique known as helio-seismology. As the Sun moves through its magnetic cycle, the frequencies of these standing waves change slightly. Looking at the changes in these frequencies over 25 years the team noticed not only the expected 11-year variation, but also a regular 2-year variation that appeared to be operating independently. Although the Sun itself seems to be peculiar, other stars that show an "active" magnetic cycle every 11 years also show a secondary "inactive" magnetic cycle -- every 2 years. This is the most direct evidence to date that the Sun might actually have two different magnetic cycles operating simultaneously on the inside.

Although the Sun does not seem to be a typical star, astronomers can study it in much more detail to understand how stars work in general. As this new observation suggests, it is equally important to study a variety of other stars to identify what is peculiar --- and what is normal -- about our nearest star.

Exoplanet in Action

2010-06-11T13:08:00.007-06:00

Yesterday the European Southern Observatory issued a press release containing an incredible image of an alien planet moving from one side of its host star to the other in just 6 years. The star, known as beta Pictoris, has been studied for several decades after the early discovery that it was surrounded by a debris disk. With new technologies that now enable high-resolution imaging from large ground-based telescopes, we can actually watch an exoplanet as it moves around in orbit.

In 1983, beta Pictoris was one of four hot stars (including also Vega, Fomalhaut, and epsilon Eridani) that were discovered to be surrounded by disks of gas and dust using the IRAS satellite. The classic image of beta Pictoris at the center of a cross-hair with the debris disk shooting out diagonally in 1980's graphics instantly became an icon -- symbolic of the quest for extra-terrestrial life. If we could see an alien solar system being formed before our eyes, then the chances seemed good that we are not alone in the Universe. It was just 18 months ago that NASA released the first direct image of an exoplanet from the Hubble Space Telescope, in orbit around one of the other IRAS stars, Fomalhaut. But in that case the orbit of the planet was 10 times the size of Saturn's orbit around the Sun -- so the planet only moved a tiny fraction of its orbit in the two years between the sets of observations. The planet around beta Pictoris is much closer to its star, at a distance between the orbits of Saturn and Uranus in our solar system.

Soon after the Hubble announcement in 2008, a team of French scientists released their first image of a faint object close to the star beta Pictoris, from observations made at the Very Large Telescope in 2003. The telescope has a computer-controlled mirror that can actively deform itself to compensate for the distortions caused by turbulence in the Earth's atmosphere. Using this technology, the scientists were able to cleanly separate the image of the faint object from the image of the bright star, just one ten-thousandth of a degree apart in the sky (roughly the size of a mosquito viewed from a mile away). The trouble was, they couldn't rule out the possibility that the faint object was a distant background star -- so they had to wait several years to see if the object would move. In late 2009 they obtained a second high-resolution image, and sure enough the faint object had moved to the other side of beta Pictoris. It was a true planet, about 9 times as big as Jupiter.

The astronomers estimate that they should be able to see the planet go all the way around beta Pictoris in less than 20 years. By then this type of observation should be routine, and it would be surprising if we weren't monitoring the movements of hundreds of such exoplanets.

The Ages of Stars

2010-05-28T16:01:00.005-06:00

Astronomers have used many tricks to try and measure the ages of stars, but most methods are not very precise. A star like the Sun has a lifetime of around 10 billion years, so knowing the age to within a few billion years is about the best we can expect from conventional techniques. Using new observations from the Kepler space telescope, this week I finished a project that measured the age of a star to within just 50 million years, a precision that has only been achieved for one other star: the Sun.

We can set a lower limit on the age of the Sun just by measuring the age of the Earth. This is usually established by finding rocks containing elements (like Uranium) that radioactively decay, and determining what fraction of the material has been converted into the stable byproducts. The oldest rocks on the Earth are found to have an age around 4.4 billion years, while similar methods applied to meteorites give an age just over 4.5 billion years. This is a good first guess for the age of the Sun, but there are also more direct methods. As a star gets older, it converts hydrogen into helium and energy through nuclear fusion -- this is what makes a star shine. Sound waves generated by the boiling motions of the hot gas near the surface travel through the center of the Sun and reveal the composition deep inside. This technique, known as helio-seismology, implies an age for the Sun of 4.68 billion years.

The Kepler space telescope is observing thousands of other stars like the Sun, and we can also use seismic techniques to measure their ages. For a typical star, astero-seismology can determine the age to within about 1 billion years. However, during certain phases of a star's life we can see an interaction between the sound waves generated at the surface and buoyancy waves (similar to the waves in the ocean) that are trapped deep inside. Essentially the two types of waves couple to one another briefly and influence the tiny changes in brightness that we can measure at the surface. The net effect is like a very precise clock -- by measuring the frequency of the brightness variations, we can tell the age of the star to better than 100 million years. To make such measurements, we rely on computer models of the star -- so any imperfections in our models carry over into uncertainties about the absolute age. It's as if we have a watch that keeps very good time, but we still don't know whether it is set to the correct time zone.

It is difficult to measure the ages of individual stars, since the visible changes throughout their lifetimes are fairly subtle. Whatever the limitations of seismology for determining the absolute ages of stars, this technique can certainly place stars into a precise chronological sequence. By applying the method to many other stars like the Sun we can get a better understanding of what our own star was like in the past, and how it will be in the future.

Life in the Universe

2010-04-27T10:46:00.010-06:00

Legendary physicist Stephen Hawking made headlines this week when he suggested that "if aliens ever visit us...the outcome would be much as when Christopher Columbus first landed in America, which didn't turn out very well for the Native Americans." Most people are surprised to learn that many astronomers actually believe in extraterrestrial life, though few scientists tend to speculate about how the aliens might relate to our civilization. But what we know about the size and composition of the universe -- and what we've learned about the stars in our own Galaxy over the past 20 years -- make it unthinkable that we could possibly be alone.

The scientific argument for extraterrestrial life can be traced back to the 1960's, when astronomer Frank Drake first formulated what has come to be known as the "Drake Equation". Essentially, this is just a simple method to estimate the number of intelligent civilizations in our Galaxy. It starts with the number of stars (a very big number) and then multiplies by reasonable estimates of the fraction of stars that have planets, the fraction of those that are habitable, that form life, where the life becomes intelligent, that develop the technology to emit signals into space (like radio communication), and finally how long those civilizations exist before becoming extinct or destroying themselves. The main conclusion is that even if you make very pessimistic assumptions for all of these fractions, the number of stars is so large that there will still be a handful of intelligent civilizations like ours in the Galaxy. In Hawking's words, "To my mathematical brain, the numbers alone make thinking about aliens perfectly rational."

It was just 15 years ago that the first planet outside of our solar system was discovered around a star like the Sun. As of this week, more than 450 "exoplanets" have been discovered around other stars. Many of these planets do not resemble those in our own solar system at all. The methods that have been used to discover them are biased towards large planets like Jupiter that orbit relatively close to their suns like Mercury (and in most cases even closer), but a few of the known exoplanet systems include up to five planets. The diversity of planetary systems that astronomers are finding around other stars suggests that planets are much more common than we originally thought, and it's a first step towards actually measuring the fractions in Drake's equation.

Despite our progress in detecting planets around other stars, we still don't know of any habitable planets other than the Earth. However, within the next few years NASA's Kepler mission will tell us exactly how common habitable planets are in our Galaxy. Launched just over a year ago, the Kepler space telescope is performing a detailed census of planets around stars in our Galactic neighborhood. Its enormous digital camera has the sensitivity to detect the tiny eclipse of a planet the size of the Earth passing in front of its host star, and the mission is monitoring more than 150,000 stars like the Sun for such signals. Since a habitable planet like the Earth takes a full year to complete an orbit, Kepler needs to search for several of these "transits" over the course of a few years to identify the distant Earths reliably. If such planets are as common as we believe, Kepler should find a dozen or so within the first few years -- but in any case, it will measure another fraction in Drake's equation.

Throughout human history whenever we have believed ourselves to be special in some way, we turned out to be wrong. We now know that the Earth is just one planet among many in our Galaxy, and we will soon know how common planets are that might also be habitable. With a short list of distant Earths, we can begin to search for alien radio signals. It may take some time, but the conclusion is inevitable -- we are almost certainly not alone.

Comet Crash

2010-03-16T10:56:00.008-06:00

Last week, astronomers watched in awe as several anonymous comets plunged into the Sun. Many people are surprised to learn that similar events happen almost every day, but the icy fragments are typically too small to be seen. A string of comet fragments struck Jupiter in 1994, causing quite a splash. Should we worry that the Earth might be next?

Comets are generally believed to be leftover debris from the formation of our solar system more than 4 billion years ago. A distant icy halo surrounding the Sun, known as the "Oort cloud", is the source of nearly all of the comets that have been observed throughout history. Some of these comets return regularly (like Halley's comet in its 75.3 year orbit), while others pass through once and head back to the cloud, never to be seen again. Astronomers believe that comets are like "dirty snowballs", containing a loosely packed mixture of ice and dust. As they approach the Sun they warm up and begin to evaporate, spawning a long bright tail that generally makes them much more visible.

There is a population of comets known as the "Sun grazers", which appear to be the leftover fragments of a much larger comet that probably broke up more than 2000 years ago. The orbits of these comets are extremely elongated, and in some cases shoot them directly into the Sun, a fiery demise that is barely noticed by the enormous boiling mass. Most of the fragments are so small that they are nearly invisible until they begin their plunge, where satellites that are always watching the Sun for signs of hazardous space weather can finally see them brighten and abruptly disappear.

In the summer of 1994, the planet Jupiter had a similar encounter with a train of comet fragments known as "Shoemaker-Levy 9". About two years earlier a large comet passed so close to Jupiter that it was broken into many pieces by tidal forces and thrust into an orbit that would strike the giant planet like a string of pearls on the next pass. I was an undergraduate student at the time, working with a group known as SpaceWatch at the University of Arizona. Over the months leading up to the collision, we carefully measured the positions of each fragment to calculate the individual orbits and make predictions of the precise impact times. For the nine largest pieces, we calculated times that were correct to within a few minutes.

As for something similar happening to the Earth -- don't worry! Jupiter is a huge target with significant gravitational pull, and the Sun is over 1000 times more massive. Nothing as large as a comet has struck the Earth since the disappearance of the dinosaurs, 65 million years ago.

Red Giant Groove

2010-02-26T14:39:00.013-07:00

Earlier this month I attended a scientific conference on a small Spanish island called Lanzarote, just off the coast of Morocco. The meeting was for scientists who study the insides of the Sun and other stars using a technique similar to seismology. Without a doubt, the coolest result presented at the meeting came from Italian astronomer Andrea Miglio and his colleagues in Belgium. For the first time in any star other than the Sun, they measured an abrupt variation in the internal structure -- like the boundary between the crust and the core of the Earth, but in a red giant star more than 350 light years away.

A red giant star is what our Sun will become when it begins to run out of hydrogen fuel, about 5 billion years in the future. As the hydrogen begins to burn faster in a shell around the helium core, our star will slowly bloat and cool -- eventually engulfing the inner planets, including the Earth. Like the Sun, the surface of a red giant seems to boil as convection brings heat from below and radiates it into the coldness of outer space. The boiling churns more slowly in a red giant, but the turbulent motions still create sound waves that travel down through the star and then back toward the surface. Some of these sounds have just the right pitch, a million times lower than we can hear with the human ear, and they set up standing waves that cause the entire star to slowly change its brightness over hours and days.

Like the standing waves on a vibrating string, the brightness changes that we can see in a red giant have very specific frequencies. The fundamental frequency of a vibrating string is sort of like a jump rope, with the entire length moving up and down together. If the people at the ends of the rope move their hands up and down at twice the fundamental frequency, the standing wave will have two lobes with a stationary point in the middle -- one side will move up while the other moves down. At three times the fundamental frequency you get three lobes, and so on to create a whole series of evenly spaced frequencies. Now imagine that somewhere along the jump rope you attach a small lump of clay -- the extra weight at this position will change the way that waves travel along the rope, and the frequencies of the standing waves will change slightly from the evenly spaced pattern. Here's the cool part -- by looking at the deviations from uniform spacing, you can actually figure out where along the rope you have attached the clay!

This is essentially what Andrea and his friends did for the red giant. Using measurements taken over 5 months from a French space telescope called COROT, they identified a series of almost evenly spaced frequencies of brightness variation in a red giant known as "HR 7349". By looking at how the frequencies they observed differed from perfectly uniform spacing, they determined the position of a boundary layer on the inside of the star. Comparing this prediction with theoretical models of the star, they identified this layer as the depth below the surface where the temperature was just high enough to strip both of the electrons from every helium atom. From a distance of more than 350 light years, the team had pinpointed the position of a subtle change in the composition and density of the star -- just by measuring its regular changes in brightness over time.

This beautiful result promises to be just the first demonstration of the types of measurements that are possible using stellar seismology. The same basic techniques will allow us to measure the size of the boiling layer on the surface of a star like the Sun, providing new ways to test our understanding of how stars are actually built.

Kepler's First Planets

2010-01-27T11:20:00.003-07:00

This month the Kepler mission announced its first batch of extrasolar planet discoveries. Many people were surprised that only five new planets were announced, since the mission is monitoring more than 150,000 stars. But there are very sensible reasons why the initial catch was limited.

The first thing to understand about the newly discovered planets is that all of them were found in just the first 43 days of Kepler observations. The satellite was launched in early March, but the first two months were spent largely on engineering to ensure that the instrument was operating as expected. This was followed by a 10-day "commissioning" run in early May, and then a 33-day initial science run before the spacecraft made its first quarterly roll in mid-June to keep the solar panels facing the Sun. Because the search method requires a minimum of three transits, only planets with orbital periods shorter than about 14 days were detectable from the initial 43 days of observations. In fact, all of the planets that were announced had orbital periods between 3.2 and 4.9 days.

Fair enough, but shouldn't Kepler have discovered hundreds of such planets during the first 43 days? It probably did, but the mission requires detailed follow-up observations from ground-based telescopes to confirm each planet discovery. This is necessary to weed out "false positives" -- stars that look like they may host planets, but are actually something else. A simple example is an eclipsing binary star, where one star periodically passes in front of the other just like a transit. If there is a bright star close to the binary, or just along the line of sight, it dilutes the eclipses so they look like they are caused by a smaller object like a planet. The follow-up observations involve measuring the wobble of the host star caused by the orbiting object -- the traditional method of detecting planets around other stars. If the orbiting object is a star, the wobble is enormous; If it's a planet, the wobble is tiny.

Kepler is searching for planets in a large patch of the sky in the constellations Cygnus and Lyra. This area of the sky is well placed for ground-based telescopes during the summer months, but by the time the early data from Kepler was processed it was already August. The season for these follow-up observations was very short, so the team could only confirm a limited number of the planet candidates. In the end, they decided to announce only five of the more than 70 candidates that emerged from the initial analysis. By next summer, the mission will have many more candidates in longer orbits -- but they will also have a full summer season to confirm the discoveries.

By next January, expect to hear about hundreds of new planets. It will still be too early for the Earth-like planets, since that requires three 1-year orbits. But planets as tiny as the Earth may be found in faster orbits, and if they are hosted by smaller stars they might even be habitable. Stay tuned.

Climate and Altruism

2009-12-15T10:42:00.006-07:00

Writing from the floor of the climate summit in Copenhagen this week, Danish economist Bjorn Lomborg suggested that a singular focus on reducing greenhouse gas emissions was misguided. Such cuts, he argues, would be "breathtakingly expensive and woefully ineffective" and the money would be better spent on more immediate problems like global health and education in developing countries. Is his suggestion realistic, or just a diversion?

In his 1970 book "The Possibility of Altruism", philosopher Thomas Nagel tried to understand why people make sacrifices -- sometimes even give their lives -- to save others. He argued that the notion of altruism is similar to the notion of prudence. Just as a prudent individual must extend their concept of self to another time, an altruistic individual must extend their concept of self to a different space, in another person. Thus, if we believe it is important to plan for our own future (prudence), it is possible to act on an analogous belief in the value of other people's lives (altruism). It was an assertion of the commutability of space and time that would have made Einstein proud. This is relevant to Lomborg's suggestion because the arguments for taking action on climate change invoke both prudence and altruism: we should reduce our carbon emissions to secure our own future, but also to improve the future of our children and the citizens of developing nations who will be most affected.

Richard Dawkins promotes a different view of altruism in his 1976 book "The Selfish Gene". He suggests that it is useful to think of altruism from the perspective of the individual genes inside of a person. Instead of attaching a survival instinct to the individual, Dawkins ascribes this trait to the genes themselves. In this view, a gene does not care where it survives -- only that it survives. As a consequence, if I have two children who are in danger of being eaten by a lion it is rational from the perspective of my genes to risk my life to save them. Since each of my children shares half of my genes, my complete DNA may have a better chance of continuing to survive in the two kids than in me. Brothers and sisters are even more likely to share my genes, while more distant relatives share less and citizens of developing countries share almost none. According to Dawkins, any act of altruism must be justified by this sort of detailed calculus. This naturally explains why the average person feels very little obligation to ease the suffering of people in distant lands, whether caused by climate change or more immediate problems.

Lomborg is a former Greenpeace member, and author of the 2001 book "The Skeptical Environmentalist" where he applies the economic principle of cost-benefit analysis to world problems. Whatever your understanding of altruism, his suggestion that the world should address the more immediate problems in developing countries rather than fight climate change is a false dichotomy. If the international community had the will to improve human health and education in the third world, it would have done so already. On the other hand, climate change is a problem that will affect the entire planet -- not just developing nations -- so the motivation to avoid the worst consequences is a personal imperative whether Nagel or Dawkins is right about altruism. Whether we cap our emissions because we recognize the humanity of others or because we simply want our genes to survive in our children, the outcome will be the same.

The worst thing that could happen at the climate summit in Copenhagen is nothing. If the delegates fail to reach a consensus on carbon reductions, there is at least one good idea promoted by Lomborg. "Instead of making far-fetched promises about greenhouse gases," he writes, "how about a concrete commitment to green energy research and development?" Now there's something we can all support.

Stimulus for Science

2009-11-19T12:37:00.011-07:00

This week the $787 billion in economic stimulus funding approved earlier this year came under intense scrutiny, as reporters and citizens examined preliminary data posted on a government website. The primary focus in the news has been whether the estimate of 640,000 "jobs saved or created" is accurate, and on a few typographical errors in the database such as non-existent congressional districts that supposedly received funding from the stimulus. I looked at the data to see how the stimulus was supporting astronomy research, and how well the funding agencies were doing at getting that money into the economy.

Although NASA's larger budget normally provides much more support for astronomy research than the National Science Foundation (NSF), the opposite was true for stimulus funding. The NSF has so far received more than $2.4 billion dollars from the American Recovery & Reinvestment Act that was signed into law last February. By the end of October the agency reported spending only $50 million of these stimulus funds. Most of the allocated funds (about $2 billion) are for "Research & Related Activities", which supports individual researchers through various grants and fellowship programs. Typically, the proposals to such programs require 6-9 months for review prior to being awarded -- so maybe the low level of spending so far is not surprising. Another $254 million has been allocated to support "Major Research Equipment and Facilities Construction" including the Advanced Technology Solar Telescope, which is scheduled to begin construction in 2010. None of these funds have yet been spent.

NASA has done a better job of pumping stimulus funds into the economy, having already spent $68 million of the $572 million it has received. In fact, most of this spending (about $66 million) has been to support NASA's "Astronomy & Astrophysics Research Recovery" plan, a $212 million program that primarily supports development of the James Webb Space Telescope, which will supersede the Hubble Space Telescope in 2014. NASA has actually been promised more than $1 billion in stimulus funding, so part of the delay in spending seems to arise from the slow allocation of funds by the government. The NSF has received a larger fraction of the funding it was promised under the stimulus ($2.4 billion allocated out of $3 billion total), but it has spent a much lower fraction of what it has received. It was not immediately obvious how many jobs were "saved or created" due to the funding at either agency.

Overall, the data posted to recovery.gov represents a valiant attempt by the Obama administration to ensure the transparency of stimulus spending. The deployment hasn't been flawless, but it's a step in the right direction in terms of trying to establish a more open government. The relatively slow spending at the agencies that support astronomy research reflects the careful consideration that must go into their funding decisions. This is certainly preferable to the alternative -- more rapid funding of projects with questionable or unknown merit. Hopefully, we can expect more of this research funding to enter the economy soon.

NASA at the Crossroads

2009-10-27T10:37:00.006-06:00

When I was in college, many of my astronomy classmates joined a group called "Students for the Exploration and Development of Space". Although I strongly support exploration, I didn't join the group because I felt uneasy about the "development" of space -- to some people this means glowing billboards in low-earth orbit, or inflatable space hotels for wealthy clients. In an era of dwindling support for the space program, NASA is wrestling with similar questions about the future.

This week NASA is scheduled to launch the new Ares I-X, an experimental version of the rocket that is supposed to replace the space shuttle. Unfortunately the Ares is unlikely to be ready by the time the space shuttles are retired at the end of 2010, leaving at least a 5-year gap in the ability of NASA to send astronauts to the International Space Station (ISS). NASA is hesitant to extend the life of the shuttle program, since the accidents in 1986 and 2003 raised fundamental questions about safety. The other immediate option is to hitch a ride to the ISS with the Russians for a few years until the Ares rocket is finished. But a committee appointed by the Obama administration earlier this year would like to see a different solution. Led by a former aerospace executive, the panel concluded that NASA should turn over the business of putting astronauts in orbit to private companies.

The notion of a "public-private" partnership for space exploration involves large public subsidies to aerospace companies, who will then take over the business when it is mature and collect the profits. Of course the risks would continue to be insured by the government, not the private sector. Former NASA administrator Michael Griffin is skeptical about the safety of commercial space travel, commenting that the plan "will work right up until there is the first accident." But Elon Musk, founder of the private launch company SpaceX, disagrees. "It's incredibly bad business to kill your customers", he said. There are other private launch companies with a longer track record, but none have any experience putting people into orbit. So the problem remains.

Perhaps the most sensible thing for NASA to do is once again rethink its long-term objectives. The "Vision for Space Exploration" set forth by the Bush administration will only funnel more money to aerospace companies -- fueling the "development" of space at the expense of "exploration" that would provide real scientific advancement.

Personalizing Climate Impacts

2009-09-15T10:12:00.005-06:00

A report released today by the World Bank includes a simple observation about the failure of humanity to act against the dangers of a warming planet. "The slow pace of climate change as well as the delayed, intangible and statistical natures of its risks simply do not move us." Scientists must strike a careful balance between communicating the seriousness of the problems we face, without using scare tactics. How can we bring the future impacts home to the citizens of the world?

A few weeks ago I had a conversation with a young woman at the birthday party of a mutual friend. When she learned that I work at the National Center for Atmospheric Research, she asked, "is climate change real, or is it just a scam to get more funding from the government?" I was floored. I explained that when our parents were our age there was still some uncertainty about the exact causes of global warming. There have always been natural changes in climate caused by a slight wobble in the Earth's orbit around the Sun, leading to ice ages and warm periods that alternate over tens of thousands of years. During the past century the changes have been much faster than ever before, and less than a quarter of the recent warming can be explained by natural cycles. The rest is from heat-trapping gases released by human activities. Whatever we do now, the globe will continue to warm for the next several decades as the Earth slowly absorbs the excesses of earlier generations. We can't blame them, because they didn't know what they were doing. But now we know, and our actions will determine the kind of world our children will live in. I told her that the necessary changes wouldn't be as dramatic as everyone imagines. If we all adopt a lifestyle more like our parents in the 1960's, with smaller houses and one car per family, it would go a long way toward solving the problem. At the same time it will improve our real quality of life, allowing us to spend less time working and commuting with more time for the things that truly matter.

The evidence for climate change is all around us. Here in Colorado, recent warming has expanded the population of parasitic pine beetles that have decimated our national forests. One campground in Rocky Mountain National Park now resembles a clear-cut logging operation, with all of the "beetle kill" removed for the safety of visitors and the surrounding trees that are still healthy. As dramatic as it seems, the connection to climate change is not obvious to the casual observer. The park staff do not distribute pamphlets that explain the cause of the beetle problem, and there are no signs to proclaim "global warming in action". But the Nature Conservancy recently announced a website that tries to convey the impacts of climate change on a local level. Their Climate Wizard is a science-based website that allows anyone to select their state or country and see the temperature and precipitation projections over the next 50 to 100 years from the most recent report of the UN Intergovernmental Panel on Climate Change. Users can zoom in on their state and then switch between alternate futures with high, medium or low heat-trapping emissions. The default is to view the temperature changes over the next 100 years across the U.S., since the next 50 years are dominated by the emissions of the past. The main lesson is that the future is typically hotter and drier, but some regions are bigger losers than others -- like the area of the U.S. where most of the food is produced.

Although it's hard to get people motivated to make lifestyle changes now that will affect the temperature of the world inhabited by their children and grandchildren, it's helpful to frame it as a moral issue. Many citizens are concerned about passing trillions of dollars in national debt to the future, and climate change is really just another kind of debt. Somebody will eventually have to pay. The sooner we address the problem, the smaller the burden will be for future generations.

Waiting for Colbert

2009-08-21T12:49:00.003-06:00

This week I finally succeeded at getting some media attention for a fundraising project that I have volunteered for during the past two years. The basic idea is to take the 100,000 stars that NASA's Kepler satellite will search for planets, and allow anyone to adopt one of them for a $10 donation. Donors receive a certificate of adoption by email, and updates when any planets are discovered around the star they adopted. Unlike the many "name a star" scams on the Internet, no two people can select the same star and all of the proceeds go to support scientific research on the target stars. The program hasn't been without its challenges, and the exposure this week has certainly pushed it forward -- but to meet our fundraising goal, we need a Colbert bump.

After all of the news about the first science results from Kepler two weeks ago, I decided to try and ride the tail of the wave of coverage by issuing my own press release. I had tried press releases before without success, but this time it sparked the interest of reporters at both Space.com and New Scientist. From there, the story was picked up and translated for articles in Russia, China, and Brazil. By the end of the week the coverage had driven more than 4000 visitors to our website, and inspired star adoptions by more than 250 new donors. It generated as much funding in a few days as the website normally attracts in 5 months! But we are still far from attracting the millions of visitors that we need to adopt thousands of stars.

Along the road, there have been additional challenges aside from the difficulty of getting our message heard. Last summer, after the first successful fundraising from a short post to slashdot, NASA became aware of the program. They expressed some concern that donors might mistakenly believe the project was sponsored by NASA, or maybe they would think that the donor name would be officially assigned to the Kepler target stars. To appease NASA, we added a disclaimer at the bottom of every page. After the news coverage this week we were contacted by the estate of Carl Sagan, who believed that calling our adopt-a-star program the "Pale Blue Dot" project constituted unauthorized use of their copyright from his 1994 book. They were concerned that the name might lead donors to assume some kind of endorsement by Carl Sagan. Whatever the legal status of their copyright, our non-profit educational use of the phrase clearly falls within the "fair use" exception -- but to alleviate their concerns we added "the estate of Carl Sagan" to our disclaimer. Who knew there could be such a disconnect between the good intentions of scientists and the nervous deliberations of managers and lawyers?

The biggest lesson of the week is that we will need exposure to a much larger audience than we can possibly reach on the web or in print. We need television, and who would be better than Comedy Central host Stephen Colbert? He loves outer space, and his character is obsessed with having things named after him. Although our program doesn't actually name the stars, we did reserve the few stars with previously known planets just for such an opportunity. So we adopted a planet-hosting star for Stephen Colbert, and we even set up a special page for his fans. He's our first genuine pale blue dot! Best of all, one of our early adopters has a connection at the show, and offered to pitch the idea for us. Now we're just waiting for Colbert. Will he invite me to come on the show and present him with a Certificate of Adoption? If so, I'm certain that the "Pale Blue Dot" project will finally reach its goal.

Cap and Trade

2009-07-29T12:43:00.009-06:00

Last month the U.S. House of Representatives narrowly passed the "American Clean Energy and Security" (ACES) Act, which would regulate the pollution that is responsible for global warming. The centerpiece of the bill is the establishment of a "cap and trade" system -- a market-based approach that was successfully used during the last two decades to reduce acid rain. Of course all markets have winners and losers, and how the rules are written determines which side you end up on.

The basic idea of a cap and trade system is simple. First you determine how much pollution can be allowed, and you limit or "cap" total emissions at that level. The cap is initially set slightly below current levels, and it is lowered slowly over time to the final goal. Polluting is no longer free -- every polluter must have permits to cover their emissions. Those who figure out how to reduce their emissions can sell or "trade" their permits to polluters who have more trouble meeting the new requirements. As the number of permits is reduced over time the market price goes up, creating an incentive to reduce your emissions and sell the permits for a profit. In 1990 a cap and trade system was established for sulfur, a common pollutant from coal burning that produces acid rain. Congress mandated a 50% cut in sulfur emissions over 20 years, but the cap and trade system worked so well that it only took 15 years to achieve the goal. Initial worries about the possible economic impact were revealed to be entirely wrong.

The ACES Act would establish a similar system for carbon, which arises primarily from burning fossil fuels and contributes to global warming. The bill requires carbon emissions to be 17% below 2005 levels by 2020, and 83% below 2005 levels by 2050. The long-term goal is based on a scientific assessment of what will be required to avoid the worst consequences of climate change. The short-term goal is somewhat disappointing, since emissions cuts are similar to compound interest -- the more we do early, the greater the long-term impact. The other important feature is how pollution rights are distributed -- the bill initially gives away 85% of the emission permits to energy companies and electric utilities for free! This fraction is gradually reduced to only 30% by 2030, but it still means huge potential profits for these businesses -- even though some of the revenue is required to be given to customers as rebates. The remaining permits are sold in an auction with most of the proceeds divided equally among all citizens and a small fraction reserved just for low-income families. The idea is to help offset the potential increase in energy prices.

An alternative vision for the carbon cap and trade system was outlined in the 2001 book "Who Owns the Sky?" by Peter Barnes. He believed that every American should get an equal share of the emission permits, and the energy companies should be required to buy them from us! The extra costs that the energy companies would inevitably pass on to consumers would be perfectly offset for the average customer by the extra income from selling the permits. Customers who found ways to decrease their energy consumption would end up making money -- providing a strong personal incentive for conservation and efficiency, which is one of the least expensive ways to reduce global warming emissions quickly.

This bill isn't perfect, but it's a step in the right direction. The Senate is expected to consider similar legislation sometime this fall. With luck a compromise bill can be signed into law before the international climate negotiations in Copenhagen this December.

Earth as an Exoplanet

2009-06-23T13:19:00.002-06:00

Last week a group of Spanish scientists published some unique observations of the Earth's atmosphere, as it might be seen by an alien civilization looking for signs of life. The idea was to see what they could learn about our home from the type of data that may soon be available for distant Earth-like planets orbiting other stars. The results were impressive. The researchers identified several of the dominant molecules in the Earth's atmosphere -- and they could even tell that the sunsets are red, and the skies are blue.

More than 350 planets have now been discovered around other stars, with nearly 60 of them passing directly in front of their Suns from our vantage point on Earth. These "transiting" planets provide a special opportunity to study the atmospheres of alien worlds. As they pass in front of their host star, they block some of the starlight from reaching us. Just from the amount of missing light, we can determine the relative size of the planet compared to the star. So far, most of the planets we know about from such measurements are big -- like the outer planets in our solar system: Jupiter, Saturn, Uranus and Neptune. But with more precise measurements from satellites, we will soon be able to find smaller ones. During the transit a small fraction of the starlight passes through the planet's atmosphere, and we can use this light to learn about its composition and other properties.

Something similar happens during a lunar eclipse. As our Moon passes into the shadow of the Earth, the only sunlight that reaches it passes through our planet's atmosphere. By measuring the light on the Moon during an eclipse, we can see what a transit of the Earth would look like to a distant observer. The Spanish scientists measured a lunar eclipse last August, passing the moonlight through a prism to separate it into its spectrum of colors. Individual molecules in the Earth's atmosphere absorb specific colors of light, creating dark lines in the spectrum like a fingerprint that identifies the molecule. The lunar eclipse spectrum revealed signatures of oxygen, water vapor, carbon dioxide and methane -- as well as traces of many other molecules. But the most dramatic feature of the spectrum was immediately obvious -- nearly all of the blue light was missing.

As sunlight passes through the Earth's atmosphere, some of the light that isn't absorbed by the individual molecules is scattered by them instead. The typical size of air molecules makes this process, known as "Rayleigh scattering", much more effective for blue light than it is for red light. As a consequence mostly the red light makes it through the atmosphere to the Moon during a lunar eclipse, while the blue light is scattered and makes the sky appear blue. This is also why sunsets look red, since the sunlight passes through much more atmosphere when it is near the horizon than when it is high in the sky.

The most amazing thing about these new observations is that nobody had ever thought to look at the Earth in this way before. In the near future, after NASA has discovered transiting Earth-like planets around other stars, satellites such as the James Webb Space Telescope will be able to obtain spectra if their atmospheres. And now we know what it might see... blue skies.

Lifeline for Hubble

2009-05-20T10:33:00.005-06:00

A long drama finally came to a close this week, as the crew of the space shuttle Atlantis released the Hubble Space Telescope back into orbit after 8 days of grueling repairs. Headlines have understandably been dominated by the overwhelming success of the servicing mission -- but behind the scenes there was another story, with a more human dimension, that most people never knew about.

After the tragic loss of the space shuttle Columbia and its crew in February 2003, everything in orbit that relied on the shuttle program came to a grinding halt. The future of the final Hubble servicing mission was suddenly very uncertain. It took nearly 29 months before the shuttle returned to the skies in July 2005, and another year before it continued regular operations in July 2006. During these three and a half years, the primary concern was whether NASA could ensure the safety of shuttle crews -- so in August 2004, administrator Sean O'Keefe commissioned a study to determine the viability of a robotic servicing mission to Hubble. This idea was ultimately rejected in April 2005 by the next administrator, Michael Griffin, who finally approved the servicing mission in October 2006. In the meantime, Hubble was gradually losing many of its scientific functions.

Throughout this period, the life of Hubble was extended again and again by the heroic efforts of the scientists and operators at the Space Telescope Science Institute in Baltimore. Every time a component of Hubble failed, these men and women figured out a way to continue limited science operations on whatever was left. For many, their jobs literally depended on it -- without Hubble they would have nothing to do until the launch of the James Webb Space Telescope in June 2013 (at the earliest). So they were determined to keep Hubble working, and they did. The servicing mission was finally scheduled for October 2008, but Hubble's on-board computer system failed just two weeks before launch. It took weeks for engineers to design a short-term fix, and months for astronauts to incorporate the replacement computer into their long-rehearsed training routine.

Which brings us to this week -- when all of that training was finally put to good use, and the long-anticipated repair mission has come to a successful conclusion. The main digital camera on Hubble was replaced with a newer model, and the old corrective lenses it received in 1993 to fix its fuzzy vision were replaced by a new light-splitting spectrograph that will peer to the very edge of the observable universe. Two of the other scientific instruments, STIS and ACS which have been dead or crippled since power supply failures in 2004 and 2007, have now been restored. These science upgrades were complemented by a host of routine repairs including: the installation of new gyroscopes for the telescope's pointing system, new batteries which are charged by Hubble's solar panels for 60 minutes of each orbit and supply all of the power during the remaining 36 minutes on the dark side of the Earth, and a new insulating outer blanket that helps protect the satellite from harmful radiation and space junk. With the installation of a replacement on-board computer system and an external dock to support the future robotic capture of the telescope for disposal at the end of its life, the servicing mission was complete.

Hubble is now expected to continue its marathon of ground-breaking discoveries well into the next decade -- and most importantly, until the next space telescope is operational. The dozens of people at the Space Telescope Science Institute whose jobs depend on this mission can now breath a collective sigh of relief.

Colbert Station

2009-04-16T08:49:00.002-06:00

This week, the name of the next module to be added to the International Space Station was announced by NASA on Comedy Central's show "The Colbert Report". While it may seem an odd venue for such an announcement, NASA's online poll to name the new module had an unambiguous winner: "Colbert". The question on everyone's mind: would NASA honor the results of the web vote?

The poll was initiated by NASA earlier in the year, and the voting ended on March 20. In addition to four suggested options -- "Serenity", "Legacy", "Earthrise" and "Venture" -- NASA also allowed write-in votes. When space enthusiast and host of a popular Comedy Central show Stephen Colbert learned of this opportunity, he encouraged his viewers to write-in "Colbert" to help him win the contest. They responded in droves. Nearly 1.2 million votes were cast, and "Colbert" topped the list. "Serenity" was the most popular of NASA's options, but the voting was dominated by write-ins.

On Tuesday, astronaut Sunita Williams appeared on "The Colbert Report" to announce NASA's final decision for the name of the new station module. And the winner is: "Tranquility"? Since this year marks the 40th anniversary of the Apollo 11 mission that landed the first humans on the Moon, NASA selected one of the other suggestions among the top 10 write-in votes -- a reference to the Apollo 11 landing site, in the Sea of Tranquility. The contest rules were clear that NASA reserved the right to make the final decision, regardless of the outcome of the online poll. But one can imagine that many Colbert fans were disappointed.

As a compromise, NASA decided to honor the Comedy Central host in a slightly different way. Among the contents of the new station module will be a sophisticated zero-gravity exercise device that will now be known as the "Combined Operational Load Bearing External Resistance Treadmill," or COLBERT. They even designed a "mission patch" for the unit, and offered to let Colbert try it out for himself at one of NASA's facilities in Houston. His response on the show was classic Colbert: "I think a treadmill is better than a node … because the node is just a box for the treadmill. Nobody says, 'Hey, my mom bought me a Nike box.' They want the shoes that are inside."

It was a boost of publicity for the International Space Station that NASA would never have enjoyed without the help of Colbert. Now, if I could just get him to lend the "Colbert bump" to my project...

SONG of the Stars

2009-03-19T03:29:00.002-06:00

In the region of Canada that is now Quebec and Ontario, a Native American tribe known as the Algonquin developed a detailed myth about the annual path of the Big Dipper around the north celestial pole, which they chanted in their Song of the Stars: "We are the stars which sing, / we sing with our light; / We are the birds of fire, / we fly over the sky". Next week an international team of astronomers known as the SONG collaboration will gather in Denmark to discuss future plans for studying "stars which sing with their light".

The SONG collaboration is a Danish-led initiative to establish a global network of small telescopes to observe the subtle signatures of star-quakes that probe the interiors of distant Suns. The idea for SONG -- an acronym for Stellar Oscillations Network Group -- is based on the successful implementation of a similar concept deployed in the 1990's for observations of the Sun. The continuous oscillations that can be detected on the surfaces of the Sun and other stars require uninterrupted observations for long periods of time. The rotation of the Earth prevents a single telescope from being able to observe for such long periods without interruption. This limitation can be overcome by coordinating the observations of telescopes that are strategically located around the planet -- the star under investigation is always visible from somewhere, so a suitable network of telescopes can monitor any given star 24/7.

The Danish astronomers are among the world's leading experts on the observation and interpretation of star-quakes to deduce the internal structure and composition of stars like the Sun. Their motivation for establishing a global network of dedicated telescopes was driven by their frustration trying to conduct such observations with existing facilities. Obtaining time to use the telescopes at most observatories is a competitive process. Proposals are normally submitted 6 months to a year ahead of time, including a detailed scientific justification, and a typical allocation usually does not exceed 1 or 2 weeks. Since the proposals at different observatories are evaluated by independent time allocation committees, coordinating the observations from many telescopes is difficult to say the least. In the end, these logistical constraints were compromising the quality of the resulting observations -- so the Danes started looking for a better way to proceed.

With an initial grant from the Carlsberg Foundation, funded by the Danish beer company, they formulated a conceptual design that could accomplish their scientific objectives. Subsequent grants from public and private sources in Denmark will fund the construction of the prototype, which is scheduled to begin operating at an observatory in the Canary Islands by 2012. The purpose of the meeting next week is to coordinate with international partners who will seek their own funding to replicate the prototype and operate one of the telescopes in the network at their local observatory.

The Danes can't do it alone, but they have made it considerably easier to establish the network by doing much of the difficult work up front. This will certainly make it an easier sell to funding agencies and private foundations around the planet.

Launching Kepler

2009-02-27T15:45:00.002-07:00

Next Friday NASA is scheduled to launch a satellite known as "Kepler", on a several year mission to find planets like the Earth around distant stars like the Sun. As a member of the committee that leads an international collaboration of astronomers who will be analyzing some of the data from this mission, I received an invitation from NASA to attend the launch in person.

Kepler is an enormous science-grade digital camera with nearly 95 megapixels (compare that to your digital camera at home). The giant camera is attached to a telescope with a mirror more than 55 inches across, which will stare at a large patch of the sky just above the Milky Way for at least the next few years. The diameter of each image on the sky will be as wide as 24 full moons lined up side by side, and the camera will normally take 30-minute long exposures. The images will be processed on board the spacecraft to measure the brightness of more than 100,000 stars, and these measurements will be saved and transmitted to the Earth every few months.

Some fraction of the stars that Kepler monitors will have planets, and some fraction of those planetary systems will be oriented in such a way that the alien worlds pass directly in front of their host star from the vantage point of the telescope. It's sort of like an eclipse, except the planet will only cover a small fraction of the surface of the star for up to a few hours, causing a small dip in the amount of light recorded by Kepler's camera. Astronomers are particularly interested in finding planets similar to the Earth, which are far enough from their stars that water exists in liquid form, but not so far that the water becomes mostly frozen. Like the Earth, such planets will go around their stars only about once a year -- so scientists will be looking for stars that show several tiny dips in light, each separated by about a year. By looking at more than 100,000 stars, Kepler should be able to find at least a few planets like the Earth if they are at all common. If not, that will also be a very interesting thing to know!

The satellite will be launched on a Delta II rocket next Friday evening from Cape Canaveral, Florida. The Delta II is the same vehicle used by NASA to put GPS satellites into orbit, and night launches are particularly spectacular since you can easily see the rocket ascend all the way to the edge of the Earth's atmosphere. Kepler will be placed in orbit around the Sun, just behind the Earth, and will slowly drift further away over the next few years. By then its mission should be finished, and we will know exactly how special the Earth really is -- or how common it is to find planets just like ours in the neighborhood.

Although I'm not part of the official science team, I've been preparing for the Kepler mission for the past several years. I just got a grant from NASA to continue this work for the next few years. Cross your fingers that everything goes well!

Penguins in Peril

2009-01-29T10:40:00.005-07:00

Emperor penguins -- the stars of the 2005 documentary March of the Penguins -- may be headed for a population collapse brought on by global warming, according to a study published this week in the Proceedings of the National Academy of Sciences. The impact of climate change on the extent of sea ice in Antarctica, where the penguins live and breed, is projected to reduce the penguin population by nearly 95% by the end of this century.

The authors of the report developed a sophisticated computer model to predict the population size over time for a specific colony of emperor penguins that currently contains about 6000 breeding pairs. The model was tuned to fit actual observations of a smaller population collapse that occurred during a warm period in the 1970's, and then it was coupled to the predictions of future climate from the Nobel prize-winning report of the Intergovernmental Panel on Climate Change (IPCC). The key factor that determines whether the penguin population will decline over time is how often such warm periods occur -- if they happen too often, the sea ice does not have a chance to recover between events and the penguins suffer a loss of habitat that reduces their chances of survival and corrodes their ability to reproduce.

The population model was coupled to a wide variety of individual climate predictions from the IPCC report, but all of them assumed a "business as usual" scenario in which humans continued to burn fossil fuels sufficient to double the atmospheric concentration of carbon dioxide (CO2) from pre-industrial levels by the end of the century (from 360 to 720 ppm). While this does not represent the worst case scenario for the future climate of our planet, humanity can certainly choose to avoid such a path. For example, most scientists agree that we can avoid the worst consequences of global warming by stabilizing CO2 concentrations no higher than 450 ppm, and the successor to the Kyoto climate treaty is likely to specify this target.

The results of the study suggest that the emperor penguin population could decline by 95% to only 400 breeding pairs by 2100 -- an event that would qualify as a "quasi-extinction". The chances of this happening varied from near certainty (84%) to about 1-in-3 (36%) depending on which specific climate projection was used, but all of them predicted a population in steep decline after 2080. Unlike other Antarctic species, emperor penguin behavior -- such as the timing of their migration and egg laying -- does not appear to have changed much in response to the warming that has already occurred. The authors speculate that the long lives of the penguins may prevent them from adapting to these relatively fast environmental changes, so it is unlikely that they will be able to save themselves.

The good news is that our planet is not yet committed to the amount of warming represented by these projections. We can choose to alter our behavior now, and reduce the future increases in greenhouse gas concentrations below those assumed in this report. If we do, perhaps our grandchildren will one day be able to enjoy March of the Penguins 2.

Blast from the Past

2008-12-04T10:43:00.003-07:00

More than 400 years ago, a nearby star in our Galaxy exploded with a flash of light so bright that we can still see echoes of the event from the surrounding dust clouds. The event is known as "Tycho's supernova", after the Danish astronomer who published detailed observations of it in 1572. In today's issue of the journal Nature, astronomers announced new observations that have for the first time established the exact cause of the explosion.

When a new star appeared in the sky in 1572 -- bright enough to be visible in full daylight -- it instantly attracted public attention. At the time the "sphere of the stars" was believed to be unchanging and eternal, so the event challenged the prevailing view of the universe. Tycho Brahe was one of the first astronomers to make precise observations of the positions of stars and planets, before he famously died of a urinary infection after straining his bladder at a royal banquet as a courtesy to the host. Tycho's observations of the 1572 event were published in a book titled "Stella Nova" (Latin for "new star"), which demonstrated that the object was far beyond the orbit of the moon.

Modern analysis of the historical record suggests that the event was actually an exploding star, now commonly referred to as a "supernova". There are several types of supernova explosions, arising either from the detonation of a white dwarf star (the ember that is left at the end of the life of a regular star like our Sun), or from the gravitational collapse of a very massive star at the end of its life. The available evidence suggested that Tycho's supernova was probably the first type, but it could not distinguish between two possible scenarios that can trigger such an event. In one scenario the white dwarf is in a close orbit with a regular star -- so close that its gravity slowly consumes the mass from its companion until the white dwarf exceeds a critical size and collapses under its own weight. In the other scenario the companion is also a white dwarf, and the two white dwarfs slowly draw closer together until they merge and similarly collapse in a spectacular explosion.

The usual way of deciding what triggered the supernova explosion requires evidence that was not available in 1572. The light from the event is passed through a prism to separate it into its constituent colors (a spectrum), where dark lines appear at specific colors that reveal what the object is made of and how it is moving. For the observations that were announced today, astronomers used the interstellar dust that surrounds Tycho's supernova as a sort of time machine to record the spectrum of the event. Here's how it works: the explosion created a sudden flash that moved out in all directions at the speed of light and reached the Earth in 1572. Now imagine that there was a cloud of dust 200 light years behind the supernova that reflects some of the light of the original flash back toward the Earth. This dust cloud would not be lit up until 200 years after the explosion, and the reflected light would then have to travel another 200 years just to get back to the supernova itself -- so the flash from the dust cloud would arrive 400 years after the original explosion. Using this basic idea, astronomers recorded the spectrum of an illuminated dust cloud near Tycho's supernova and discovered that it looked exactly like an explosion caused by the first scenario -- from a white dwarf consuming a regular star.

It's a wonderful piece of detective work, and by repeating the experiment on dust clouds in every direction around the remnant of Tycho's supernova, scientists hope to eventually measure the three dimensional shape of a 400 year old explosion. Tycho would surely be impressed by our ability to study this blast from the past.

Science under Obama

2008-11-05T15:07:00.005-07:00

The decisive presidential victory of Barack Obama last night has given millions of ordinary people hope for the future, but it also represents a symbolic end to the "war on science" that has been waged by the current administration. Scientists across the country now share the hope that the newly-elected administration will not only reverse the politicization of science that has taken place over the past eight years, but also demonstrate a renewed commitment to maintaining the competitiveness of the United States in science and technology by expanding our investment in basic research.

The abuses of the Bush administration -- distorting and suppressing scientific research for political purposes -- has been well documented within several federal agencies. Much of this information has come from a series of surveys conducted by the Union of Concerned Scientists over the past few years, and their efforts to restore scientific integrity now represent one of the top priorities of the organization. Scientists are consistently ranked by the public as more credible than politicians or even journalists, so it's important that their research is free from government interference and that their conclusions are released to the taxpayer-sponsors without political censorship. One indication that Barack Obama intends to use science to craft policy -- rather than the other way around -- can be seen in his proposal for addressing climate change, which aims to "reduce greenhouse gas emissions 80 percent by 2050". This target is not arbitrary, but was taken directly from the recommendations of the UN Intergovernmental Panel on Climate Change, representing the consensus of thousands of scientists from around the world.

With the rampant international aggression and reckless fiscal policies of the Bush administration, funding for non-military programs has stagnated even as deficit spending has soared and the national debt has more than doubled. The Bush strategy of using irresponsible tax cuts for the ultra-wealthy coupled with massive increases in military spending to justify a shrinking domestic budget has been disastrous for the basic government services that millions of people depend on. But it has also had a corrosive effect on our nation's scientific research facilities -- leaving some of the most promising technologies undeveloped, and stunting the bold new discoveries that attract the brightest young people to pursue careers in science. The newly-elected administration understands that a federal commitment to basic research provides the raw material for future economic growth and prosperity, and ensures our nation’s competitive position in the world. That's why Barack Obama co-sponsored legislation in the Senate in 2007 that tried to boost support for NASA and double the funding for basic research through the National Science Foundation by 2015. Though it sounds ambitious, the annual research budget of the NSF could be doubled for the current cost of about one week of military operations in Iraq.

The global financial crisis has created some uncertainty about what sort of economy the next administration will inherit from George W. Bush, and this has understandably led to a reflection on the nation's priorities. With the right leadership -- one that uses sound science to craft effective policy, and that understands the importance of an investment in basic research -- scientists can help turn this economy around. With Barack Obama at the helm, it just might happen.

Climate Conservatives

2008-10-06T12:55:00.004-06:00

Over the weekend, I attended a high school reunion with my wife. One of the great things about reunions is that you get to talk with people from all walks of life, who typically have a wider variety of opinions than your co-workers or neighbors. One of my wife's classmates, after hearing that I work at a federal laboratory that does climate change research, asked whether or not I believed in global warming. The question really took me by surprise because, to me, global warming is like gravity: it doesn't really matter whether you "believe in" it -- it just is.

I responded that her question made me wonder whether or not she believed in climate change. She explained that the issue made her very upset because of how political the debate had been, and that she didn't believe in global warming at all. She said she didn't trust Al Gore, and she thought he was a hypocrite for making so much money from his film and for flying his private jet between stops on his "climate crisis" tour. If the facts in the film had been presented by a scientist, she said, it probably would have done more to persuade her about the problem. The central issue seemed to be about credibility, not about facts. I tried to imagine my own response to claims about a crisis coming from a source that I didn't trust.

In situations like these, it's important to try to communicate with people using arguments that will not instantly be rejected by their conservative viewpoint. I tried to explain that when our parents were our age there were still significant uncertainties about climate change, so we couldn't really blame them for not acting. While scientists were establishing the root causes of global warming, the greenhouse gas emissions of humanity had exceeded the capacity of the natural world to absorb them -- and there was so much surplus carbon-dioxide in the atmosphere that even if we stopped the emissions now, the planet would still continue to warm for nearly the rest of our lives. So the debate about climate change was really about what (if anything) we should do to influence the kind of world our children and grandchildren would live in.

I also pointed out that politicians were no longer arguing about the reality of climate change. The real debate was about how much we should do to mitigate the problem. Look at the proposals of the two major presidential candidates in this election year: the Democratic candidate is proposing to cut greenhouse gas emissions 80% by 2050 (a target drawn directly from the scientific recommendations of the UN Intergovernmental Panel on Climate Change) while the Republican candidate is proposing a 60% cut. Furthermore, only the Republican candidate for vice-president has expressed skepticism that climate change is primarily caused by human activity. Everyone else agrees with the scientific consensus.

I may not have convinced my wife's classmate to reconsider her position on global warming, but I'm fairly sure that I presented the issue in a manner that she could identify with. If conservatives continue to resist efforts to mitigate climate change, they are the ones who will have to explain to their grandchildren why they failed to take action even after the science was clear.

Grassroots Astronomy

2008-09-09T07:59:00.004-06:00

A catalog of stars that a NASA satellite will search for distant solar systems over the next few years is scheduled to be released today through the Space Telescope Science Institute. In an unconventional approach to funding their research on the project, a team of astronomers is working with a non-profit organization to put the stars up for adoption on the Internet.

"NASA's budget is heavily earmarked, and research funding has been stagnant in recent years," said astronomer Travis Metcalfe, who leads the fundraising project. "We decided to engage the public directly for some grassroots financial support of this crucial element of the program."

The scientists are preparing for the launch of NASA's Kepler satellite, which will monitor more than 100,000 stars beginning in April of next year. To bring the catalog to life, the likely target stars were marked in Google Sky, where potential sponsors can browse them through the project website before selecting a star to adopt for a modest $10 donation. All contributions are used to support the analysis that will determine the physical sizes of any planets discovered by the mission.

The adopt-a-star service, named the "Pale Blue Dot" project after a phrase coined by popular astronomer Carl Sagan, has already attracted donations from hundreds of people who signed up early to get their first choice of stars. Donors receive a certificate of adoption by email, and updates when any planets are discovered around their adopted stars. Each star is tagged with the name of the sponsor, both in Google Sky and in a text version of the catalog, so no two people can adopt the same star. The final targets will not be decided until later this fall, but if an adopted star does not end up on the list, the associated donor will make a new selection.

"This is a creative way of involving the community," said Danish professor Joergen Christensen-Dalsgaard, who organized the international team that is conducting the research. "The present list of adopters is already fairly impressive, and of course the funding that it brings in is useful."

The outreach and fundraising effort is being coordinated by White Dwarf Research Corporation, a non-profit located in Boulder, Colorado. Dedicated to scientific research and public education, the organization hosts the project web pages and accepts donations on behalf of the research team free of charge. If most of the Kepler target stars are ultimately adopted, the resulting endowment is expected to provide significant support to the research project throughout the lifetime of the mission.

"This program educates the public about the Kepler satellite, but it also makes them stakeholders in its success by allowing anyone to adopt a star that NASA will search for planets," said Metcalfe. "How cool is that?"

Arctic Meltdown

2008-08-28T09:33:00.003-06:00

This week, scientists at the National Snow and Ice Data Center (NSIDC) announced that the amount of unmelted sea ice in the Arctic has reached the second lowest level since satellite monitoring began 30 years ago, and it may be on a trajectory in the coming weeks to break the record melting that occurred just last year. The revelation comes on the heels of reports earlier this month of polar bears swimming in the open waters off the northwest coast of Alaska. It has long been known that the effects of global warming appear first near the north and south poles, so this news provides a glimpse of what's in store for the rest of the world if we don't begin to change course soon.

On the summer solstice this year, I was on an airplane returning from a two week visit to Denmark -- I purchased carbon offsets for the trip, but the irony of the situation is still tangible. In the middle of the day, I peered out the window to discover that we were flying over the east coast of Greenland. I was encouraged to see that there still seemed to be plenty of sea ice floating around, but the land was littered with cobalt blue melt ponds and the dramatic retreat of the surrounding glaciers was readily apparent from above. Little did I know at the time that only about a third of that sea ice would still be around by the annual low point in mid-September.

Through most of the melting season this year, the total area covered by sea ice in the Arctic has followed roughly the same pattern as observed in 2005, which was previously the second greatest melt in recorded history. But in early August this year, the melting seemed to accelerate -- maybe from all of those flights to China for the Olympics. "We could very well be in that quick slide downwards in terms of passing a tipping point," said Mark Serreze, a senior scientist at the Colorado-based NSIDC. Within the next few weeks as the melting bottoms out, we'll know whether this year's melt breaks the all time record from last year.

Nothing seems to bring this crisis into clearer focus for most people than the plight of the polar bears. Last week an aerial survey of wildlife off the northwest coast of Alaska reported observing 9 polar bears swimming in open waters between 15 and 65 miles offshore. Ironically, the survey was being conducted to prepare for future offshore oil development. Satellite data from the time of the survey showed that the nearest pack ice was about 100 miles from the coast. Polar bears are good swimmers, but they typically only swim distances of 10 to 15 miles. "We have some observations of bears swimming into shore when the sea ice was not visible on the horizon. In some of these cases, the bears arrive so spent energetically, that they literally don't move for a couple days after hitting shore" said Steven Amstrup, senior polar bear scientist for the U.S. Geological Survey in Anchorage. If the changes in Arctic melting were happening more gradually, the polar bears might have time to adapt over many generations. But the unprecedented pace of Arctic warming makes the outlook fairly grim.

The inconvenient truth of the matter is that these events give us a sneak preview of the types of changes we are likely to see at lower latitudes in the coming decades. Only it won't be the polar bears who are struggling to adapt to the new circumstances -- it will be us.

Secrets of the Aurora

2008-07-29T13:20:00.003-06:00

Anyone who has ever witnessed the northern or southern lights would certainly attest to their beauty, but few would imagine that the mysteries of the aurora are still being uncovered. Last week, scientists announced a fundamental discovery about the physical mechanism that converts a stream of charged particles from the Sun into a stunning display of color and light in the Earth's upper atmosphere. The work represents a significant step forward in efforts to predict such events, which can damage satellites in orbit and disrupt power grids on the ground.

The basic mechanism that drives the aurora has been known for a long time. Our Sun is constantly shedding a "wind" of charged particles, primarily electrons and protons, which slams into the Earth's magnetic field. Since charged particles in motion create their own magnetism (the underlying concept of an electromagnet), the solar wind spirals towards the Earth's north and south magnetic poles. There, it slams into the upper atmosphere and interacts with the oxygen and nitrogen atoms to produce shimmering curtains of green and red light in the sky.

The researchers used observations of the aurora from detectors on the ground, as well as measurements from a network of five NASA satellites that orbit at different heights within the Earth's magnetic field. By combining the data from these different sources, the scientists determined the detailed series of electro-magnetic events that precede and follow an auroral display. During times of relatively mild solar wind, the Earth's magnetic field works a bit like a capacitor -- accumulating charge for several hours and then quickly releasing it. The process is accompanied by a sudden disruption of the current in the upper atmosphere (something like blowing an electric fuse), as well as a snapping of the Earth's magnetic field lines far above (a process known as magnetic reconnection). The standard model for aurora suggested that the magnetic reconnection caused a disruption in the current, which then produced the aurora. The new observations show that the aurora are produced directly by the snapping field lines, and the disruption of the current occurs later.

Although the discovery is unlikely to change the way most people view the northern and southern lights, it may improve scientist's ability to predict the potentially harmful consequences of the storms. This could ultimately allow us to avoid regional electric blackouts and service outages from satellites that provide navigation services and communications -- the dark side of the auroral lights.

Communicating with Mars

2008-06-20T01:32:00.003-06:00

In a landmark discovery this week, NASA's Phoenix lander dug a trench in the Martian soil and watched as small chunks of water ice slowly evaporated. Scientists have known about the existence of water ice in the polar cap of Mars for a long time, but it was only in 2002 that the Odyssey spacecraft found evidence of much more ice just below the surface. This is what motivated the experiment on Phoenix that directly confirmed this vast reservoir of frozen sub-surface water. It's not easy to control an experiment from a hundred million miles away. Have you ever wondered how NASA actually does it?

Even when the Earth and Mars are as close as they can come to each other in their orbits they are separated by more than 30 million miles, and sometimes they are nearly 250 million miles apart. How do we communicate across such enormous distances? It's similar to how we do it on Earth: we encode our signals into radio waves and send them from one antenna to another. Radio waves travel at the speed of light, more than 186000 miles or eight times around the Earth in a single second. This is very practical for communicating across the planet, but it's fairly slow to communicate between planets. When it is closest, a radio signal to the Mars lander takes several minutes to get there -- and its response takes several minutes to return to Earth. More typically, the trip takes 10 minutes each way. Imagine playing a video game where any move you make with the controller doesn't show up on the screen for 20 minutes!

With such slow communication, scientists do not control the Phoenix lander the same way you might play a video game. Many of the functions of the experiment need to be automated and programmed ahead of time. So they simply tell the lander to "dig a trench" then "take a picture" and wait for the image to be sent back. This led to the discovery earlier this week of some "white stuff" beneath the soil. To test whether it might be water ice they waited for a day, asked the lander to take another picture, and compared the second picture to the first one. This showed that some of the crumbs from the digging actually disappeared in the second picture -- suggesting that they were made from ice and had evaporated.

If you think playing a video game with a 20 minute lag time might be frustrating, imagine what it would be like with people on both ends of the line. This is one of the many challenges of sending astronauts to Mars, but it's something that most people don't think about.

WorldWide Worthless

2008-05-14T16:21:00.003-06:00

This morning I received an email from my mother-in-law with the subject line: "Travel to the Stars!' Naturally, I was intrigued. She wanted to know whether I had heard about the new free program from Microsoft called WorldWide Telescope, just released yesterday. I had actually seen some of the headlines and my impression was: oh, Microsoft is trying to compete with Google Sky, which came out last August. But to be fair, I decided to download the new software and try it out.

My first complaint is that WorldWide Telescope only runs under Windows (surprise!). Google Sky also runs on Mac and Linux machines. I decided to install it on a laptop I use for presentations, where I had successfully installed Google Sky several months ago. I went to the website at WorldWideTelescope.org, which looked very nice, and downloaded the 20 MB install application. No problem. When I ran this application, it downloaded an additional 90 MB of Microsoft software that WorldWide Telescope depends on. Everything seemed to install just fine, so I clicked the new shortcut that had been placed on my desktop. The program loaded and a dialog box appeared with instructions about what to do with my mouse to control the interface. Looks a lot like Google Sky. So I started to pan around the sky -- and within a few seconds the program crashed. I rebooted the machine for a fresh start, launched the program and tried to pan again -- another crash. And a third. And a fourth.

At this point, I decided to uninstall the software and everything that came with it. I also decided to check that my copy of Google Sky was still working -- and thankfully, it was. In the process I also discovered that Google now has a version of Sky that runs in the maps interface through a web browser. If you go to the WorldWide Telescope website you can watch flash movies of children's reactions as they explore the sky through the software. Microsoft is great at public relations, but not so great at writing software that actually works. As for me, I'm sticking with Google Sky.

Ozone and Climate

2008-04-25T11:52:00.002-06:00

Many people confuse the issue of climate change (or global warming) with the other major influence of humanity on the Earth's atmosphere: the hole in the ozone layer. These phenomena are actually caused by two very different aspects of atmospheric chemistry, and they have distinct consequences for the environment. But this week, climate scientists announced a surprising connection between the ozone layer and climate change: if we adopt one approach to cooling the planet, it could make the ozone problem worse.

Ozone is just another form of oxygen. The oxygen that we breath is really a molecule consisting of two oxygen atoms bound together. Ozone is similar, but it has three oxygen atoms. High in the Earth's atmosphere there is a relatively thin layer of ozone, and because of its specific structure it acts like sunblock -- filtering out much of the harmful ultraviolet radiation coming from the Sun before it ever reaches the ground. Back in the 1980's, scientists discovered that large holes were developing in the ozone layer, particularly over the polar regions of the planet. Further study linked this depletion to widespread use of chlorofluorocarbons (CFCs), particularly as refrigerants and as propellants in spray cans for consumer products. Alternative gases were quickly identified for these uses, and CFCs were phased out in most industrialized countries. The results were dramatic -- further monitoring of the ozone holes showed them begin to recover as the widespread use of CFCs was discontinued. It was a landmark achievement for climate science and its influence on public policy.

More recently it has become clear that the global climate is getting warmer and that, like ozone depletion, a substantial fraction of the effect can be attributed to human activities. In this case the underlying cause is the release of so-called greenhouse gases -- molecules like carbon dioxide (CO2) and methane (CH4) that trap the Sun's infrared radiation or heat from being released back into outer space. Large volumes of these gases are produced from burning fossil fuels like coal in power plants or gasoline in automobiles -- and as humanity releases more greenhouse gases than the environment can naturally absorb, it builds up in the atmosphere, traps more heat, and gradually warms the planet. This has been happening dramatically since the industrial revolution in the late 1800's, and unless we find suitable alternatives for our energy needs we risk a major disruption of our climate system later in this century.

Since this is a much bigger problem than finding substitute refrigerants and propellants -- and because the consequences are potentially much more severe -- some climate scientists are considering how to cool the planet without reducing greenhouse gas emissions. In the long term climate record that has been reconstructed from ice cores drilled in Antarctica, scientists noticed that historical periods of global cooling often follow major volcanic eruptions. The cooling was traced to large quantities of sulfates that were hurled into the Earth's upper atmosphere during the eruptions. The sulfates block some of the incoming sunlight from ever reaching the surface, which can counteract the warming effects of increased greenhouse gas concentrations (though other problems like ocean acidification still remain). So if global warming gets really out of control, the scientists reasoned that we could manually inject sulfates into the upper atmosphere like an artificial volcanic eruption to cool the planet.

Working from this premise, the study released this week examined the other possible consequences of engineering the climate with massive injections of sulfates -- and this is where ozone returns to the picture. It turns out that sulfates also deplete the ozone layer, and if enough of them were injected into the upper atmosphere to offset the expected warming in the coming decades it would destroy between 1/4 and 3/4 of the Arctic ozone layer and delay the expected recovery of the ozone hole over the Antarctic by between 30 and 70 years. So if we want a reasonable climate and an ozone layer, sulfates might not be the best answer.

Personal Space Telescope

2008-03-19T10:39:00.004-06:00

The beautiful images produced by the Hubble Space Telescope have probably done more to capture the public imagination than any other NASA project since the Apollo moon missions. As you might expect, not just anyone can use Hubble. The allocation of observing time is extremely competitive, and even most professional astronomers have never used it. Few people realize that Canada also has a space telescope -- and now, a team of Canadian astronomers wants to help any Canadian citizen use it for their own projects.

In June 2003, Canada launched its first space telescope called "MOST" for Microvariability & Oscillations of STars (or Microvariabilité & Oscillations STellaires for those in Quebec). It's quite a bit smaller than Hubble, roughly the size of a large suitcase, earning it the nickname "Humble Space Telescope". Because of its modest size, MOST was lifted into orbit on a decommissioned nuclear missile from Russia. Under an international peace treaty the missile was required to be destroyed anyway -- so they decided to use it for science! Inside MOST there is a 6-inch diameter reflecting telescope and a high quality digital camera. Scientists use the camera to take a series of images of pulsating stars, and record the amount of light emitted by the stars over time. They use this information to learn about the insides of the stars -- a cutting-edge technique known as asteroseismology.

After four years of very successful science operations, MOST had reached the end of its expected life, but it was still running. Rather than keeping the telescope for themselves, the MOST science team decided to do something unprecedented: they announced that any Canadian citizen could submit a proposal to use it. Young, old, scientist, amateur -- it didn't matter. The process was open to all. They called this new phase of the project "MOST: My Own Space Telescope". No word yet on whether any citizen projects have been selected, or announcements of their results. But the concept certainly reflects the best of the Canadian spirit.

Lunar Eclipse Demystified

2008-02-19T09:37:00.007-07:00

Tomorrow night the Moon will once again plunge into the shadow of the Earth, marking the third lunar eclipse in the past 12 months. Despite the recent frequency of such events, your next chance to see a total lunar eclipse won't come for nearly three years, in December 2010. While not as spectacular (or rare) as a solar eclipse, watching the Moon turn dark red (but not invisible) has its own rewards. And this time, it will be joined by Saturn and the bright star Regulus -- both within a few degrees on the sky.

People often wonder why lunar eclipses are so much more common than solar eclipses, and why the Moon doesn't pass through the shadow of the Earth every month. Since both events involve the alignment of the Sun, Earth, and Moon it seems like they would both occur with similar frequency. But the dark shadow of the Earth (the umbra) is roughly three times the diameter of the full Moon, so the alignment doesn't have to be perfect as with a solar eclipse -- where the Sun and Moon appear almost the same size in the sky. This also makes lunar eclipses last much longer (about an hour, compared to just a few minutes) and allows half of the planet to see them each time (since you just need to be on the night side of the planet when they happen, not a special location where the alignment is perfect). Despite these advantages, the Moon doesn't pass through the Earth's shadow every month because its orbit is actually inclined by 11 degrees relative to the plane of the Earth's orbit around the Sun. So we only see a lunar eclipse when the full Moon occurs near the intersection of these two orbital planes (the so-called "line of nodes").

One of the interesting features of a lunar eclipse is that the Moon doesn't go completely black. Instead, it usually turns some shade of red when it passes through the darkest part of the Earth's shadow. We know that the Moon normally just reflects the light of the Sun -- so where does this red light come from? During a lunar eclipse, the light that reaches the Moon is just sunlight that has been diverted towards the Moon through the Earth's atmosphere. Why is it red? The answer turns out to be the same as "why is the sky blue?". The molecules in the Earth's atmosphere are similar in size to the wavelength of blue light, so they interact and scatter the blue light (making the sky blue) while letting most of the red light through (making the Moon look red). This is also why sunsets often look red.

If you've never seen Saturn through a telescope, this event will offer a good chance, since the ringed planet will appear within a few degrees (5 or 6 Moon diameters) of the lunar eclipse. The bright blue star Regulus (in the constellation Leo) will also appear nearby -- but it should be easy to distinguish from yellowish Saturn. Viewed with high power binoculars or a small telescope, the rings of Saturn are fairly easy to see, even for a pea-sized image.

Mars Asteroid Uncertainty

2008-01-30T10:41:00.000-07:00

Earlier today, an asteroid as wide as a football field cruised past Mars at a distance just over three times the diameter of the red planet. By cosmic standards, this was a very near miss. The asteroid was discovered in late November, and in mid-December astronomers placed the odds of an impact at 1-in-75. Additional observations just before the new year increased these odds to nearly 1-in-25, but within two weeks the probability of an impact sank dramatically to just 1-in-10,000. All of the attention given to the developing story led a satire website to release an article headlined: "NASA plans to blow up Mars if asteroid misses".

With such wildly oscillating predictions, it would be easy to imagine that scientists simply don't know what they're doing. But predicting the path of an asteroid in space is a little like predicting the path of a hurricane over the ocean -- natural uncertainties in the observations that are used for the calculations lead to a range of possible positions as we predict further into the future. In the case of an asteroid, astronomers use the observed positions of the space rock over time to define an orbit from Kepler's laws. With positions observed over a reasonable fraction of the asteroid's path around the Sun, the orbit can be calculated very accurately. But with data spanning only a few weeks, the orbit is harder to define and each new observation can lead to significant changes when estimating the future path of the asteroid.

This is exactly what happened in the case of the Martian asteroid, officially named "2007WD5". While routine calculations of asteroid trajectories typically lead to one-in-a-million odds for any planet impacts, the early observations of 2007WD5 gave a better than 1% chance of striking Mars. This got the attention of many astronomers, and new observations came pouring in from around the globe, leading to a better estimate of the orbit and a new calculation of the impact probability, by then up to 4%. This led to even more excitement, and many new observations -- defining the orbit so well that an impact was effectively ruled out.

As cool as it would have been to watch a big rock punch a fresh crater into Mars, we should be comforted by the fact that astronomers are conducting their census of the asteroid belt. After all, the next near miss could belong to the Earth...

Reflecting on StarStuff

2007-12-17T14:49:00.000-07:00

It's now been more than a year since I started this blog. I've had a great time with it, and I hope that I've been able to entertain and inform a few people along the way. A few months after I started, I began tracking visits using Google Analytics to help me get some sense of my audience -- and I discovered that I didn't have much of an audience. Even so, I decided to continue posting for at least a year.

I'm glad I did. If I hadn't continued, I would have missed the one remarkable event in the first year of this blog. On August 22, newspapers around the world carried an announcement by Google that the latest version of its popular "Earth" application also included the Sky -- turning any computer into a virtual telescope. One of my early posts to this blog speculated that such a feature might be coming soon, and during the final week of August that post attracted hundreds of users who were looking for the new software. In fact, about half of the visitors to this blog over the last 9 months came during those few days. Most didn't stay long. They were looking for something else.

Aside from that week in August, Google Analytics tells me that during a typical week about 15 unique visitors view this blog. Roughly 80 percent are new visitors, meaning that only 3 visitors per week are coming back for another look -- and the average time spent browsing the site is less than a minute, suggesting that most visitors aren't even reading a post. At this point, I have to ask myself whether I can justify the time I spend on this blog, even if it isn't much time.

Six months ago, I disabled the comments feature since I was essentially the only one making any comments (sometimes following up on the topics raised in the original post). Today, I'm turning the comments back on -- and I'm asking for your feedback: Should I continue posting to starstuff.blogspot.com? After the new year, based on the comments you leave or email, I'll either continue for another year or hang up my blogging hat. In either case, it's been a great experience, and the archive is here for everyone to enjoy.

Telescope Philanthropy

2007-12-11T09:38:00.000-07:00

In the early history of astronomy, pioneers like Tycho Brahe depended on the generosity of kings to fund their science. Since the mid-20th century, this role has largely been supplanted by the government, through agencies like the National Science Foundation and NASA. Recently, with the federal budget slumping under the weight of excessive military expenditures and declining tax revenues, government funding for science has stagnated. But at the same time, a new class of philanthropists has emerged to help fill the gap.

Last week, Intel founder Gordon Moore announced that his foundation would donate $200 million to help build an enormous telescope with a mirror thirty meters (100 feet) in diameter. Imaginatively called the "Thirty Meter Telescope" (TMT), the California-led project is one of several competing efforts to build the next generation of large telescopes for astronomy research -- including the "Giant Magellan Telescope" (GMT) and an even larger European project called the "OverWhelmingly Large" (OWL) telescope, with a 100-meter mirror. All of these projects seek to produce the sharpest images ever obtained from a ground-based observatory (10 times sharper than images from the Hubble Space Telescope), offering new insights into the history and fate of the universe.

Moore's grant to the TMT project is just one example of a growing trend toward private funding for astronomy research. Last January, Google announced a partnership with the Large Synoptic Survey Telescope (LSST), which plans to image the entire sky every three nights beginning in 2013, and Microsoft co-founder Paul Allen is funding the latest efforts by the Search for Extra-Terrestrial Intelligence (SETI). Several global telescope networks have also received private funding, including the Whole Earth Telescope (from the DuPont Foundation), the Stellar Oscillations Network Group (from Danish beer giant, the Carlsberg Foundation) -- as well as the Las Cumbres Observatory Global Telescope Network, which was recently endowed by a retired silicon valley technology guru.

While most funding for science continues to come from government sources, it is encouraging to see the entrepreneurial spirit blossom among astronomers -- and to see it rewarded with the patronage of new donors who hold a special place in their hearts for the stars.

Adopting a Star

2007-11-29T09:38:00.000-07:00

Whenever the holiday shopping season rolls around, I consider the idea of setting up an "Adopt a Star" website to help fund scientific research. A quick Google search persuades me to abandon the idea -- the Internet is already full of such sites, and most of them are far more sophisticated than anything I would have time to create. Anyone who cares to fork out $19.95 can name a star "Lula", after their cute Bichon Frise puppy -- they even get a certificate with a star map and the vital statistics of their stellar namesake. But what are they really buying?

The International Astronomical Union (IAU) is the only "internationally recognized authority for naming celestial bodies... and names are not sold". In fact, with the exception of a few bright stars that have ancient traditional names, most of the stars in the sky only have boring old catalog numbers. The IAU does name comets after the discoverers, and astronomers who find new planets or asteroids in our solar system are allowed to suggest names for them (though they can only be named after people who have been dead for more than 100 years, which obviously limits the commercial possibilities). None of the websites that allow you to "buy" or "adopt" a star are affiliated with, or endorsed by, the IAU. So what are these businesses selling?

It's important to distinguish between companies that allow you to "adopt a star" and those that say you can "buy a star name". Although both are engaged in essentially the same business, the representation of the transaction as an "adoption" is more intellectually honest. When you "adopt a highway" it's understood that you do not thereby own a section of a public road. Instead, you agree to keep the adopted stretch free from garbage in exchange for a blue sign on the roadside acknowledging your effort (and possibly persuading drivers to stop at your coffee shop). In the case of stars, your only responsibility is to pay the $19.95 -- the company then lists your name beside the chosen star on their website, and maybe sends you a glossy certificate. One of the best operations I discovered recently is actually run by scientists to support their research. The website resembles the vision I had for "Google Sky", which I wrote about last December, and cleanly separates the commercial portion of the site from the main section that is meant to be a tool for astronomers and the general public.

Allowing anyone to adopt a star is fairly harmless, and most people probably realize that astronomers around the world do not subsequently publish scholarly articles detailing their in-depth decades-long study of "Lula" the puppy star. For those who don't realize that it's just a novelty gift, I have some very nice real estate on the Moon that promises to be really hot property in a few years...

Alien Solar Systems

2007-11-13T15:35:00.000-07:00

Last week a team of scientists in California announced the discovery of the fifth planet orbiting a distant star similar to our sun. The star is known as "55 Cancri", and is located 41 light years away in the constellation Cancer. This star now holds the record for hosting the largest known planetary system outside of our own. Only one other star (called mu Arae) is known to host four planets, while triple-planet systems have been documented around another half-dozen stars.

Since 1995, more than 220 planets have been discovered in orbit around other stars. The overwhelming majority of these planets have been found by their gravitational influence on the star that they orbit. We tend to think of a planet as simply moving around its star -- but even small planets exert a gravitational tug on the star that causes it to wobble around slightly in space. Astronomers can measure this wobble, essentially by passing the light from the star through a prism to spread it out into all of its colors (think of the famous Pink Floyd album cover) and then carefully measuring the positions of dark lines that appear where different chemical elements like hydrogen and helium absorb light near the surface of the star. The color corresponding to the position of these dark lines moves around as the star wobbles -- basically for the same reason that the pitch of an ambulance siren sounds different when it is moving towards you or speeding away (the effect is known as the Doppler shift).

The team has been monitoring 55 Cancri for more than 18 years. Since the wobbles caused by the five planets are all happening at the same time, and with different orbital periods, it took a long time to isolate the wobbles caused by each planet individually. The outermost planet in the system is about four times the size of Jupiter, and it takes 14 years to orbit the star. The other previously known planets are similar in size to Neptune, Jupiter, and Saturn, but they orbit the star relatively close in -- circling every 3, 15, and 44 days (all much faster than Mercury orbits the Sun). The newly discovered planet falls somewhere in between, orbiting the star in about 260 days. Since 55 Cancri is a little fainter than the Sun, this places the new planet inside an Earth-like "habitable zone" where liquid water can theoretically exist. Although the planet is roughly the size of Saturn, it could have large Earth-like moons where water and potentially life could survive (Saturn's largest moon "Titan" is bigger than the planet Mercury).

It's only a question of time before astronomers discover more and larger planetary systems around distant stars. The longest running surveys have been operating for less than 20 years, so even in the best case we would not be able to detect Saturn, Uranus, or Neptune if we were watching the Sun from a distance. As the technology improves we should also begin finding smaller planets, closer to the size of the Earth. In the future, people might wonder what all the fuss was about over this little five-planet system around 55 Cancri.

Splitting the Sky

2007-10-26T07:11:00.000-06:00

Now that the Intergovernmental Panel on Climate Change (IPCC) and Al Gore have been awarded the Nobel Peace prize, the debate about global warming can shift from whether or not the human population is primarily responsible, to how we should design a solution. The idea that is currently most popular with politicians involves setting a cap on carbon emissions, distributing free permits to corporate polluters, and then allowing them to trade the permits amongst themselves. Since it establishes a free market for pollution rights, this "cap and trade" system is supposed to lead to the most efficient reduction in carbon emissions -- allowing the companies that learn how to reduce their pollution to profit by selling their permits to companies that have more trouble.

It sounds like a reasonable system, and it has even been used successfully in the past to reduce sulphur-dioxide emissions -- the leading cause of acid rain. But it suffers from a fatal flaw: the polluters do not pay the costs of the efficiency improvements, but instead transfer the burden to consumers. A slight modification of this system, popularized by the book "Who Owns the Sky?", divides the pollution permits equally among the population and forces the polluters to purchase them from us! Again the costs are eventually transferred back to us through products and services -- but the average person comes out about even. This has the advantage that it also establishes an incentive for individuals to reduce their pollution-generating consumption: if you drive an efficient car or reduce your overall energy use, you can can earn more from selling your carbon permits than you pay back to the polluters.

On a national level, this modified system seems pretty workable -- but how do we divide pollution rights between countries? The most obvious answer would be to split the sky evenly among the entire population of the planet -- every person gets an equal share. But the obvious answer may not be the best answer, because it effectively rewards countries with large populations -- and population is a major factor in the growth of global warming emissions. What really matters for each country is the relationship between its biocapacity (the natural resources within its borders, and how they are used) and the product of population and consumption (the total drain on those resources). Some countries have more biocapacity than their population consumes, while others have ecological deficits. If the global distribution of carbon permits were based on biocapacity, it would force countries that are far out of balance (whether due to consumption, population, or both) to purchase permits from countries that manage their resources more responsibly. This establishes the right incentives for both consumption and population.

With the right system, we can transform our societies and bring them back towards a balance with the resources of the planet. If we start reasonably soon, we might even avoid the most unpleasant consequences of pushing the limits of nature.

Science and Politics

2007-10-05T11:35:00.000-06:00

During the U.S. election season, which seems to stretch on forever compared to most modern democracies, it's more difficult than usual to find science in the headlines. I'm fairly certain that good science continues to be produced, with press releases diligently prepared, while presidential hopefuls give stump speeches along the campaign trail. But most of the time, science just doesn't seem to make the cut. The exception to this general rule occurs when science and politics collide -- when the candidates begin to address the issue of government interference in research, where policymakers lose access to unbiased information.

This week, on the 50th anniversary of the launch of the Russian sputnik satellite, one high-profile candidate delivered a speech blasting the current administration's "war on science", and outlined strategies to shield government scientists from political pressure. Recent examples of scientific research being either suppressed or distorted by government managers -- many of whom were appointed more for their loyalty to an ideological agenda than for any expertise in the relevant discipline -- are most obvious in the area of climate change research. But other research areas have also been politicized, including the science of food safety, air quality, and forest management, to name just a few.

As with many issues, politicians are following rather than leading public opinion. The campaign to restore "scientific integrity" to decision making has recently been championed by the Union of Concerned Scientists. This grassroots organization has sponsored surveys of government scientists and circulated a petition, now with more than 12000 signers, to keep politics out of science. On the specific issue of embryonic stem cell research, which has had limited federal funding imposed by the current administration since August 2001, several prominent celebrities have also played an active role. One of the current group of candidates promises a return to "evidence-based decision-making" in the next administration, something most scientists would undoubtedly welcome.

Like oil and water, science and politics simply do not mix. The government might shake things up for awhile, but -- honoring the finest traditions -- science will eventually rise to the top.

Astronomy Career Paths

2007-09-28T10:33:00.000-06:00

The American Astronomical Society (AAS) and the American Institute of Physics (AIP) recently sent out the first survey of a planned 10 year “longitudinal study” that will follow astronomy and astrophysics graduate students registered in 2006-2007 throughout their early careers. The idea is to better understand not only the wide variety of career outcomes, but also the motivations underlying the decisions that lead to each path. This will hopefully allow the study to identify any factors in the culture of astronomy that might discourage some sectors of the initial student population from pursuing long-term careers in the field. Although certainly not as scientific as a formal survey, individual graduate programs could get a sort of “sneak preview” of this longitudinal study by finding everyone from their incoming class of 1996-1997 and asking what they are doing now. I performed an informal survey for one such class, which began with eleven incoming students in a large astronomy graduate program at a major public university. The sample consisted of seven males and four females, including seven domestic and four international students (one of them female).

At the end of the first year of graduate study, one female domestic student was asked to leave the program for academic reasons, and one male international student left the program to pursue a graduate degree in computer science at another university. The current status of these two students is not known, although the absence of recent scientific publications suggests that neither of them are presently doing astronomy research. After finishing coursework in the second year, four students ultimately decided to leave the program with a Master's degree, including three males (one of them international) and one female. The male international student transferred into the computer science graduate program at the same university and went on to work as a software developer for a local company. One male domestic student immediately obtained a software engineering and management job at a local startup, and eventually took a similar position out of state, closer to his family. Another male domestic student began teaching astronomy at a nearby community college, where he continued working on the tenure track for 6 years while also earning a Master's degree in a related science. He was recently given tenure and became chair of the department. The female domestic student stayed in the program for 2 more years before becoming a high school teacher. She took some graduate courses in mathematics prior to leaving, allowing her to obtain certification in math and physics through an alternative program that ran concurrently with her first year of teaching. She taught math in nearby public high schools for 4 years, and is now teaching physics at a private high school where she eventually expects to teach an astronomy course as well.

Only five of the eleven incoming students ultimately earned a Ph.D. through the program: three males and two females with one international student of each gender. One male domestic student took a series of postdoctoral fellowships over nearly 5 years before obtaining a tenure-track research position at a national laboratory. The female international student was awarded prestigious back-to-back postdoctoral fellowships, providing a total of 7 years of support, and is currently beginning her sixth year as a postdoc. The female domestic student worked as an associate editor for a popular astronomy magazine and in an instructional support position for an undergraduate program at a private university before recently accepting a non-tenure-track position at a small teaching college. Another male domestic student worked for several years through a postdoctoral fellowship at an international observatory before being hired as a tenure-track instrument scientist with both research and support responsibilities. The male international student worked in a postdoctoral position at a public university for almost 3 years before becoming a faculty member at a university in his home country, with a continuing adjunct appointment at his postdoctoral institution.

This “anecdotal” longitudinal study suggests that it might be difficult to define a “standard career path” in astronomy, if such a thing even exists. The wide variety of outcomes for this one small sample of students certainly did not reveal any systemic problems in the culture of the field, since both male and female as well as domestic and international students were proportionally represented along each major career path. More than a decade after entering a graduate program in astronomy, the experience appears to have led most of these students to interesting and fulfilling careers that they each shaped through their personal choices. Future students can take comfort in knowing that graduate study in astronomy only seems to multiply their possible career options.

Extreme Exoplanet

2007-09-13T10:31:00.000-06:00

About 5 billion years from now, the Sun will begin to exhaust its primary source of energy -- the hydrogen near the center that fuels nuclear fusion. The remnant helium core will begin to contract, and the surrounding shell of hydrogen will start to burn hotter. Our star will slowly bloat to 100 times its former size, becoming a "red giant" and possibly destroying some of the inner planets of our solar system. An unsettled question among astronomers is: could the Earth make it through such a catastrophic event?

New evidence in this longstanding debate surfaced this week, when an Italian-led group of scientists announced the discovery of the first planet around a distant star that appears to have survived this phase of stellar evolution. "The future of the Earth is to die with the Sun boiling up the oceans, but the hot rock will survive", said Don Kurtz, one of the coauthors of the investigation. The study focused on a star called V391 Pegasi, which is estimated to be about 10 billion years old and appears to have already gone through the red giant phase. This particular star is special: the light coming from its surface exhibits very regular pulsations, a kind of continuous "star-quake" that provides a window into its interior structure. The astronomers have been monitoring these pulsations for more than 6 years, and they noticed something interesting.

As expected, the period of the pulsations are increasing slightly over time -- a consequence of the continuing evolution of the star, which slowly modifies the interior conditions that determine the regularity of the pulsations. But in addition to the expected changes, the pulsations sometimes arrived a few seconds sooner or a few seconds later than predicted, in a pattern that suggests the star is wobbling around in space from the gravitational pull of an orbiting planet. This is the same technique that led to the discovery of the very first planets detected outside of our solar system in 1992, which were orbiting a distant pulsar. As it turns out, the planet around V391 Pegasi is close enough to the star right now that its orbit was probably the same size as the Earth's orbit around the Sun at the time the star became a red giant. The fact that the planet is still there suggests that close planets can, at least in some circumstances, survive this phase of stellar evolution.

Of course, more research is needed to determine whether or not V391 Pegasi represents a typical outcome for close planets. But, as Kurtz succinctly stated, "It is psychologically interesting to think that the Earth will survive." Even if all that's left is a hot rock.

Teachers in Space

2007-08-28T10:34:00.000-06:00

I will never forget the morning I entered my seventh grade science class and our teacher, Mr. Harshfield, quietly played a video recording of that morning's launch of the Space Shuttle Challenger. It was the 28th of January 1986, and 73 seconds after liftoff the classroom fell into a stunned silence as we witnessed the disaster that claimed the lives of seven astronauts, including Christa McAuliffe who would have been the first teacher launched into orbit under a new NASA program. The tragedy was later traced to a design flaw in the "O-ring" seal on one of the solid rocket boosters, leading to a fuel leak which ultimately broke up the entire shuttle.

The dream of sending a teacher safely into space was finally realized last week, when the Space Shuttle Endeavour successfully returned home after 13 days in orbit. Former elementary school teacher Barbara Morgan, who served as NASA's backup astronaut to McAuliffe for the ill-fated Challenger mission in 1986, said "the flight was absolutely wonderful" and "the shuttle program gets an A-plus". There were initially some concerns about the safety of the crew after a small gouge was discovered in the protective heat shield on the underside of the shuttle. The gash was apparently caused by a collision during liftoff with a baseball-sized chunk of insulating foam from the external fuel tank, similar to the damage that caused the Space Shuttle Columbia to disintegrate during re-entry in February 2003, but considerably less severe and in a less vulnerable location on the spacecraft.

Engineers from NASA determined that the risk posed by the gouge was not significant enough to justify an unrehearsed spacewalk to repair the damage from the International Space Station, where the shuttle was docked for most of the mission. Given the tragic potential of the damage, as exemplified by the Columbia disaster, it must have been a difficult decision for the engineers to make and for the astronauts to accept. But knowing the extreme risks of an impromptu spacewalk to the underside of the shuttle -- a procedure that has never been attempted before, and one that would normally require extensive training and practice in enormous dive tanks to simulate the weightless environment -- and considering the unknown effectiveness of the proposed repair work, NASA's decision is understandable.

Thankfully, it all worked out in the end. The space agency is now planning to implement several modifications to the foam-covered fuel tanks to prevent future damage to the shuttle's heat shield. These modifications are expected to be complete in time for the next mission to the International Space Station, in April 2008.

Cosmic Fireworks

2007-08-10T14:14:00.000-06:00

This weekend, one of the best annual displays of shooting stars will light up the night sky. The Perseid meteor shower has its peak activity during August 11-12 every year, but it promises to be a particularly good show this year since it coincides with new moon -- ensuring dark skies if you're away from the city lights.

Contrary to their name, "shooting stars" aren't stars at all -- they are tiny pieces of dust from outer space that run into the Earth's atmosphere and burn up from the friction of moving at thousands of miles per hour. Most of the streaks of light that we see are caused by particles no larger than a grain of sand. When they burn up in the atmosphere, somewhere between 30 and 80 miles above the surface of the Earth, scientists call them "meteoroids". Only the very rare chunks of rock that are larger than a car have any chance of striking the ground, and these so-called "meteorites" are typically no bigger than your fist by the time they hit the surface. On average, only about 8000 meteorites weighing more than a few ounces make it to the ground every year (with another 16000 falling into the oceans). That's a little more than 1 per day for an area the size of the continental United States.

Meteors are streaking through the sky all the time, but sometimes the Earth moves through a dense cloud of dust that was left behind by a comet and we have a "meteor shower". Meteor showers are named for the constellation where all of the streaks of light appear to originate, which is roughly the direction that the Earth is moving in its orbit around the Sun as we intersect a particular cloud of comet dust. During the Perseid meteor shower you can trace most of the shooting stars back to the constellation Perseus, which rises in the northeast sky after sunset. Comet Swift-Tuttle, named after the astronomers who discovered it in 1862, is the source of the Perseid meteor shower. It orbits the Sun every 130 years, and most recently crossed the orbit of the Earth in 1992 -- leaving behind fresh debris for our viewing pleasure every August.

So find a spot away from the city lights, spread out a blanket or set up your reclining lawn chairs facing the northeast, and just look up. Give your eyes about 30 minutes to adjust to the dark, and keep your flashlights off or covered in red plastic. You can expect to see a Perseid meteor shoot across the sky about once or twice minute, with the show getting better and better after midnight when you are on the side of the Earth that is blasting through the dust cloud. Happy skywatching!

Water Worlds

2007-07-23T13:02:00.000-06:00

Earlier this month, astronomers announced the first clear detection of water in the atmosphere of an alien world orbiting a distant star in the constellation Vulpecula, "the Fox". The star is formally known as HD 189733, and the planet -- which is slightly larger than the planet Jupiter in our solar system -- is affectionately called HD 189733b. Like the detection earlier this year of an extrasolar planet not much larger than the Earth, finding evidence of water from a distance of 63 light years is a landmark in the search for habitable worlds outside of our solar system.

This particular planet is special -- the alignment of its orbit causes it to pass directly in front of its parent star as seen from the Earth. As a consequence, the planet causes a tiny eclipse during each orbit as it blocks a few percent of the starlight from reaching us. How much starlight it blocks depends on the size of the planet, including its atmosphere. That atmosphere acts as a kind of filter -- allowing some colors of light through easily, while blocking some others. The scientists exploited this fact, along with the known absorption properties of water, to measure the size of the planet in several different colors of infrared light. The pattern of absorption in these colors matched the pattern expected for water, and could not be explained by any other common atmospheric molecule.

After the planet stops blocking any starlight, it swings around to the back side of the star. During this segment of its orbit, the planet exhibits phases just like the moon -- showing a crescent until it reaches the largest separation, and then gradually becoming fully illuminated before it slides out of view behind the star. Although astronomers cannot observe the phases directly, they can monitor the tiny changes in reflected light during this part of the orbit. In this way, it was also recently possible to reconstruct a map of the temperature difference between the day and night sides of HD 189733b. The day side of the atmosphere turned out to be more than 200 C degrees hotter than the night side, and the hottest spot actually occurred slightly before noon local time on the planet.

The ultimate goal of such research is to find water and other possible signs of life on a distant Earth-like planet, motivated by the age old question: "Are we alone in the Universe?". With the demonstration of these powerful techniques to study the atmospheres of alien worlds, we are on our way to finding the answer.

The Would-Be 10th Planet

2007-06-15T09:47:00.000-06:00

Today, astronomers at the California Institute of Technology announced new measurements of a Pluto-like object in the outer solar system, which under different circumstances could have been identified as the 10th planet. The object, officially named Eris, belongs to the new class of "dwarf planets" that now includes Pluto. Earlier measurements had securely determined that Eris was physically larger than Pluto, which was one factor in the decision to demote Pluto from planethood and create the new category. The new observations show that Eris is also 27 percent more massive than Pluto -- making the would-be 10th planet the currently undisputed king of the dwarf planets.

In 2005, a tiny moon called Dysnomia was discovered in orbit around Eris. Using both the Hubble Space Telescope and the largest telescope in the world on top of Mauna Kea in Hawaii, the scientists measured the position of Dysnomia on six different nights as it traveled around Eris in a 15-day orbit. There is a simple relation between the size of a moon's orbit and the mass of the planet it circles, formulated in the 16th century by Johannes Kepler. This allowed the CalTech astronomers to calculate the mass of Eris directly from the observations.

This discovery adds further support to the reclassification of objects like Pluto and Eris as "dwarf planets" instead of traditional planets like the other 8 in our solar system. Without the new definitions, there would probably already be 8 Pluto-like planets for school children to memorize in the sequence after Neptune, with hundreds of others likely to be discovered in the coming years. Pluto has made its mark in history, but 50 years from now it will be as anonymous as a random chunk of rock in the asteroid belt.

Images of Distant Stars

2007-06-05T14:51:00.000-06:00

Last week, astronomers from the University of Michigan announced that they have successfully obtained the first image of a distant Sun-like star. Using a technique known as optical interferometry, the scientists combined the light from a group of four small telescopes scattered across the top of a mountain in California -- effectively creating one huge telescope more than 200 meters across. The resulting image is about 100 times sharper than the view from the Hubble Space Telescope.

Astronomers have been making images of the nearest star (our Sun) since the time of Galileo, but other stars are so far away that even the most powerful telescopes see them as single points of light. In 1995, the Hubble Space Telescope obtained the first direct image of a distant star -- the supergiant Betelgeuse in the constellation Orion, which is so enormous that it would span the orbit of Jupiter in our solar system. The technique of interferometry -- combining the signals from many individual telescopes to produce a sharper image -- has been used in radio astronomy for a long time, most famously in New Mexico at the Very Large Array that was featured in the movie Contact, with Jodie Foster. Recent advances in technology have now made it possible to do a similar thing with optical telescopes.

The target of the University of Michigan study was Altair, the brightest star in the constellation Aquila, which is about 80% more massive than the Sun and spins about 60 times faster. It's rotation is so fast -- more than 600,000 miles per hour at the equator -- that Altair bulges out around the middle. The new image not only reveals this flattened shape, it also shows that the star is much cooler around the equator than near the pole. Although this feature was expected, the predictions do not match the observations exactly -- suggesting that astronomers may need to improve the theory.

There are several arrays of telescopes around the world that are designed for this type of imaging. As the technology continues to improve, imaging of distant Sun-like stars will become routine. This is just the beginning of an exciting era for interferometry.

Book Review

2007-05-25T14:50:00.000-06:00

"Survival Skills for Scientists" by Federico Rosei and Tudor Johnston is the best career guide to be published since Peter Feibelman's "A Ph.D. Is Not Enough!". Because the authors work in an academic environment, as opposed to a government laboratory, they offer a different perspective of the optimal career path. By co-authoring the work, they combine the time-tested wisdom of a senior researcher (Johnston) with the more recent experience of a junior faculty member (Rosei) who has direct knowledge of the current job climate. Drawing from their own interactions in Europe, North America, and Asia, they also provide a more international outlook.

The authors begin with the First Law of Scientific Survival, which is "Know thyself". Their simple recommendation is that you figure out what kind of scientist you want to be by carefully considering the kind of person you actually are. Obviously this includes an assessment of your strengths and weaknesses, but it also means understanding what role you want to play in research, and how you want to spend your time on a day to day basis. They don't try to conceal their preference for an academic career, and this could slightly alienate the reader who prefers another path. But everyone can benefit from the self-reflection that the authors promote by asking the right questions.

The bulk of the book is devoted to the Second Law: "Know your tradecraft". This begins with a very honest and pragmatic critique of postdoctoral experience, and outlines the essential factors to consider when choosing a position at various stages of your career. While admitting that intelligence and hard work are the foundation of a successful career in science, they go on to summarize other advantageous character traits that anyone can develop over time. They continue with a broad overview of the landscape of the science profession, and the metrics that will be used throughout your career to judge your productivity. Among the many unique themes that emerge from the text is the concept of being your own "agent", boosting your prospects for a successful career. The authors point out that publications in scholarly journals are the primary way other scientists learn about your research, and that generously citing the work of others will help get their attention. They finish by detailing all of the ways you communicate your work to others, including specific advice about journal papers, your thesis and curriculum vitae, as well as conference talks and posters.

The book closes with the Third Law: "Know thy neighbor". Unlike Feibelman's book, which begins with a series of anecdotes to illustrate how a scientific career can be derailed, Rosei and Johnston place this section in the back of their book. The authors also try to keep it positive by including success stories in addition to the failures.

Overall, this book fills a niche that nicely complements the material contained in other popular career guides. It is logically organized, and is filled to the brim with candid advice that you are unlikely to find anywhere else. Some readers may be frustrated by the many parenthetical remarks, footnotes, and clearly labeled "diversions" that make the text less concise than it could be. To others, these features will simply add humor, depth, and humanity to an otherwise serious discussion. "Survival Skills for Scientists" may not replace your copy of Feibelman's "A Ph.D. Is Not Enough!", but it certainly deserves to sit alongside it on your bookshelf.

Sister Earth?

2007-05-02T12:38:00.000-06:00

Last week, a group of European astronomers announced that they had discovered the "most Earth-like planet yet" around a star in the constellation Libra. The planet, known as GL581c, is the first of more than 200 planets discovered outside our solar system that is apparently in the so-called "habitable zone" of its star -- the range of orbital distances where liquid water can theoretically exist. In this sense, the discovery is a landmark in the search for life elsewhere in the Universe.

But if you examine the details more closely, you will discover a planet that is very different from the Earth. First of all, it is at least 5 times the mass of the Earth -- and it orbits the star every 13 days (instead of our leisurely 365 days), at less than 1/5 the distance from the Sun to the sweltering planet Mercury. The only reason the planet isn't burnt to a crisp is that its parent star is much cooler than the Sun -- a tiny red dwarf. As a consequence, it is likely that the surface of this planet has the right temperature for liquid water to exist.

But I wouldn't want to live there, even if I could breath whatever atmosphere might exist. Red dwarf stars give off most of their radiation in the form of infrared light -- basically heat, like what you see with night vision goggles -- and almost no visible light. So it might be warm, but it would always be dark to human eyes. Finally, although it is among the 100 nearest stars to the Sun, even the fastest spacecraft ever built by humans would take more than 90,000 years to get there. So don't count on this planet offering us a safe haven in case we wreck our own.

It's an exciting discovery -- and one that we will undoubtedly see more of in the near future. As technology improves and allows astronomers to find ever-smaller planets around other stars, we will eventually find a true Sister Earth, and maybe even life. But we're not there yet.

Sustainable Planet

2007-04-09T13:37:00.000-06:00

A report issued Friday from the UN-sponsored Intergovernmental Panel on Climate Change (IPCC) has once again prompted debate about how to respond to global warming. Perhaps one of the biggest obstacles to meaningful progress on this issue comes from the perception that changing our consumption levels will drastically reduce our standard of living. This kind of hysteria is fueled by the commonly quoted phrase: "if everyone consumed like North Americans, we'd need five planets to support us". But if you consider the natural resources, population, and consumption patterns of the U.S. by itself, how unsustainable are we, really?

This is similar to the question raised by popular "ecological footprint" calculators, but it takes into account the fact that our nation has more natural resources and a lower population density than most of the rest of the world. So in a sense, it's more fair. Basically, "sustainability" is a careful balance of three factors: (1) the available natural resources, often lumped into a quantity called "biocapacity", (2) the average consumption level of those natural resources, known as our "footprint", and (3) the total size of the population. Since total biocapacity is fairly constant, any increase in population erodes the available footprint per person. So if we want to maintain a certain standard of living, we need to either control population growth or decrease our footprint over time.

As you can imagine, the average footprint in the U.S. is actually growing slowly over time, mostly from energy use (the inability of the environment to absorb all of the carbon dioxide we release). The last time we were in balance with the available resources was around 1969. As it stands today, the average footprint is about twice the available biocapacity per person. So we only need two planets to be sustainable as a nation, not five. The reason is simple: it's harder for Africa to be locally sustainable because they don't have enough arable land, and it's harder for China because they have too many people. We should certainly help them address these problems, but those challenges are distinct from the challenge of sustainability at home.

Even so, the average footprint in the U.S. is still twice as high as it needs to be if we want to live a sustainable lifestyle. So you might ask: when in history was the standard of living in the U.S. half of what it is today? Even if you use a traditional economic measure of the standard of living, like "real GDP per capita" (which is adjusted for inflation and population growth), you find that to be sustainable we would need to adopt the lifestyle of the mid-1960's. That doesn't seem like such a sacrifice, and it's close to the "1969" balance mentioned above because improvements in (agricultural and energy) efficiency have basically made up for all of the population growth since then.

The average U.S. footprint is currently about 24 acres, while the locally sustainable level is around 12. Something to shoot for.

Blaming the Sun for Global Warming

2007-04-02T09:46:00.000-06:00

In recent weeks, skeptics of the notion that global warming is caused by humans have been promoting alternative theories. One of the most plausible explanations asserts that global warming is part of a natural cycle caused by changes in the temperature of the Sun. It's undeniable that the Earth experiences natural variations in climate due to the Sun and other factors, but the warming over the past 100 years has a fundamentally different character, and is unprecedented in the 600,000 year climate history that scientists have reconstructed from ice cores and tree rings.

One way to quantify the relative importance of natural variations compared to those caused by people is to calculate the climate "forcing" of each factor individually. In this way, scientists have shown that changes in the concentration of carbon dioxide (CO2) in the Earth's atmosphere are at least 5 times more important to global warming than any changes in the Sun. The skeptics argue that the atmospheric CO2 concentration is changing because of temperature changes on the Earth, rather than the other way around. In fact, scientists have shown that changes in the Earth's orbit over thousands of years lead to natural changes in global temperature (periodic ice ages) that also cause natural changes in the CO2 concentration. But this predictable effect cannot explain the extraordinary warming that the Earth has experienced in recent times.

Another point raised by skeptics is that for several decades after 1945, global temperatures were falling even though the atmospheric CO2 concentration was rising. This is true, but there is a very simple explanation: in addition to the warming effect of CO2, common pollution in the form of particulate matter called "aerosols" has a cooling effect on the climate. Prior to the clean-air legislation enacted in the 1960's and 1970's, the cooling from aerosols overwhelmed the warming from additional CO2. As developing countries such as China and India adopt similar clean-air measures, this may actually accelerate global warming in the future.

By raising plausible doubts about the responsibility of humans for global warming in modern times, skeptics are trying to confuse the public into inaction. If climate scientists successfully communicate these subtle effects to the public, the skeptics will ultimately fail.

The Magnetic Sun

2007-03-23T13:24:00.000-06:00

This week, the recently launched "Hinode" satellite returned some stunning new photos and video of our Sun. Focusing near the edge of our star, the space telescope documents the turbulent boiling of the solar surface in exquisite detail. But look a little closer and you will notice that as the hot material flows away from the surface, it does not simply stream off in any direction. It follows the invisible lines of a pervasive and dynamic magnetic field.

Galileo was the first to point a telescope at the Sun, revealing the dark spots that litter the surface. We now know that these "sunspots" are areas where the magnetic field is stronger, inhibiting the boiling motion and keeping the surface cooler -- and thus darker -- than its surroundings. Each spot is enormous, typically the size of our entire planet. But sunspots are only the beginning of the story of our magnetic Sun.

If you watched the Sun closely over many years, and you counted the total number of sunspots regularly, you might notice an interesting pattern. Every 11 years, the Sun seems to show a few sunspots, then many more, and then fewer again. What's more, when there are only a few spots they seem to show up in two bands, about halfway between the Sun's equator and poles. Over the course of this 11 year "solar cycle" they increase in number, migrate toward equator, and gradually fade away.

As the decades go by, you would notice that some of the cycles are stronger than others -- generating far more sunspots during the peak. Best of all, you would undoubtedly notice the huge explosions on the Sun's surface that eject hot gas out into space, sometimes directly at the Earth. When there are many sunspots, these explosions are more frequent and more dangerous. They are powerful enough to threaten astronauts and orbiting satellites, disrupt our communications systems, and occasionally bring down electricity grids.

With this new eye in the sky, astronomers will study the underlying order in these patterns -- eventually helping us predict the explosions and protect ourselves from the boiling magnetic Sun.

Astronomer Surplus

2007-03-09T13:43:00.000-07:00

This week, as part of my work with the American Astronomical Society's Committee on Employment, I've been digging up statistics on the relative rates of training and employment of young astronomers. As in many sciences, the production rate of new Ph.D. astronomers by universities is completely decoupled from the global demand for trained scientists. This has created a huge surplus of young astronomers -- there are now about 3 new Ph.D. recipients annually for every new tenure-track job in astronomy.

The job market has responded by creating more and more temporary (2-3 year) "postdoctoral" positions -- a sort of holding pattern for young scientists who are seeking an academic or research career. In the long term, there appears to be no easy solution to the problem, since the incentive of the university system is to use as many graduate students as possible for cheap skilled labor, without regard to their long-term job prospects. Essentially, overproduction appears to be built into the system -- making the mathematical formulation of surplus production of astronomers similar to that for industrial pollution models, an unintended side-effect of the production process.

What I found in the numbers surprised me. Although the current situation is clearly unsustainable, it was much worse a decade ago -- with nearly 7 times as many Ph.D. recipients in 1995 than new tenure-track jobs. While the number of new "permanent" positions steadily increased throughout the late-1990's, the number of new Ph.D. astronomers gradually declined. After the turn of the century, something else happened. The number of new astronomers being produced by the system leveled off, but new postdoctoral positions grew dramatically. With fewer graduate students around, all of those new university professors had to hire postdocs to get the work done.

Of course this only tells part of the story. There has also been recent growth in the number of non-tenure-track lecturer, research, and support positions. This is just one example of the larger cultural shift to temporary employment that is happening throughout society -- it is not unique to astronomy. It may not be in the best interests of science, but there it is.

Pluto and Planethood

2007-02-28T10:08:00.000-07:00

Today NASA's "New Horizons" mission, launched just over 13 months ago, will fly past Jupiter on its way to Pluto. The giant planet will provide a gravitational boost to the spacecraft, helping it reach the edge of our solar system by 2015. Over the past few decades, NASA satellites have visited Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune -- but this is the first mission ever to visit Pluto. Meanwhile, astronomers have decided that Pluto should no longer be considered a planet.

To the average person, it probably seemed ridiculous when the International Astronomical Union announced last August that Pluto would henceforth be known as a "dwarf planet" -- the prototype of a new class of objects in the outer solar system. It even led to a satirical headline reading "NASA Launches Probe To Inform Pluto Of Demotion". However, there were legitimate scientific developments that compelled astronomers to adopt a new definition of planet -- it was just unfortunate that this new definition removed Pluto from the list.

Starting in 1992, astronomers began to discover many small icy objects outside the orbit of Neptune that appeared similar to comets, but which never came close enough to the Sun to evaporate and develop tails. As time went by and the technologies for detecting these objects improved, surveys began to identify some larger examples. In the last few years, astronomers found several that are comparable in size to Pluto -- and even one that is larger! Theories suggested that there were likely to be hundreds or thousands of such objects in the outer solar system, so classifying them all as new planets could create real problems for school children trying to remember them all.

Since Pluto appeared to be just one of the larger members of this class of objects, it fell victim to the new classification scheme. Like many political decisions, the available choices were limited to bad (define planet in a way that excludes Pluto) or worse (bestow the title of planet on hundreds of new objects). Conspicuously absent was an alternative proposal to adopt a new definition of planet that would avoid such proliferation, while honoring the historical status of Pluto as an exception to the new rule. When the IAU meets again 3 years from now, I suspect that such an alternative will be considered by the astronomers -- with plenty of time to spare before "New Horizons" reaches its final destination.

Killer Asteroid Politics

2007-02-20T10:50:00.000-07:00

This past weekend, a group of scientists and former astronauts met in San Francisco to discuss the possibilities for averting disaster if one of the hundreds of known potentially hazardous asteroids were found to be on a collision course with the Earth. They were motivated, in part, by the recent discovery that one such asteroid -- known as "99942 Apophis" -- will skim very close to the Earth in 2029, and has a significant chance of actually hitting the Earth seven years later. The central question is: if precise observations during the 2029 passage reveal that Apophis will hit in 2036, what should we do about it?

You might think that these astronomers are just being alarmist. After all, there have been several recent occasions when the news media report on an asteroid that might hit the Earth -- only to retract the claim a few days later, after additional observations rule out a collision. The primary source of these reports is a list maintained by the Minor Planet Center at the Harvard- Smithsonian Center for Astrophysics. Consider the position of the scientists. They are certainly aware that additional observations will often rule out a future impact -- but if they withhold the early predictions they are accused of a cover-up. So instead they update their predictions continuously, the newspapers report on an uncertain impact, and the astronomers are accused of fear-mongering. It's a no-win situation.

Considering the possible consequences of an asteroid impact, I would rather know about it as far ahead of time as possible. It's similar to the early predictions by meteorologists tracking the path of a hurricane. The uncertainties grow larger as they extrapolate the observations further from the storm's current location -- but the advance warning helps residents of the potentially affected areas to begin preparing for the worst. In the case of Apophis, this might mean placing the entire planet on alert, but at least we would have seven years to devise and execute a plan for avoiding doomsday.

The age of the dinosaurs came to a sudden end when a large asteroid struck near the Yucatan peninsula in the Gulf of Mexico. If humans are smart enough, we can avoid a similar fate.

Budget Uncertainties

2007-02-07T17:49:00.000-07:00

More than 4 months into the current fiscal year, the U.S. government still hasn't passed a budget. The administration has already released its budget request for the next fiscal year, which begins in October. This is not the first time we've seen such long delays in the funding of government programs -- including scientific research and development -- and it probably won't be the last. But these annual delays undermine the ability of federal agencies to engage in the long-term planning that could improve the overall efficiency of government.

After the elections in November, the lame-duck Congress passed only 2 of the 11 appropriations bills needed to keep the government running. So, while the Departments of Defense and Homeland Security were fully funded, all other federal programs were asked to continue operating at last year's budget levels through mid-February. The idea was to force the newly elected Congress to spend its first weeks debating the unfinished business of the outgoing Congress. But it didn't work, and in late January the incoming Congress was poised to extend last year's funding levels through the end of this year.

This was a particularly unpleasant prospect for science funding, since several federal agencies (including the National Science Foundation) had been promised significant budget increases this year as part of the American Competitiveness Initiative announced in the State of the Union address in 2006. Without an appropriations bill, this extra funding would simply disappear. Fortunately, last week Congress included a last-minute provision to restore the promised budget increases for several agencies that support scientific research.

A typical grant from the NSF to an individual researcher lasts for 3-5 years, so this effectively sets a minimum planning timescale for the agency. Long annual budget delays create serious inefficiencies in the system -- inflation erodes the value of last year's budget dollar, forcing program cuts to make up any gap, and budget increases that arrive late need to be spent on a shorter timescale. There must be a better way to fund science.

Engineering the Climate

2007-01-31T08:25:00.000-07:00

This week the media got a sneak preview of the most recent 5-year study from the Intergovernmental Panel on Climate Change -- a United Nations group of more than 500 scientists from around the globe. The report, which will officially be released this Friday, concludes that "humans have already caused so much damage to the atmosphere that the effects of global warming will last for more than 1,000 years." The good news is: we haven't reached the tipping point yet -- there's still time to reverse the damage we've done and avoid the most severe consequences of climate change.

But some scientists have already started to think about the worst case scenario. What if we don't have the political will to break our addiction to fossil fuels and overconsumption before it's too late? In this case, we might want to consider more drastic measures -- like devising a technological fix, as a last ditch effort to save ourselves.

One such idea, soon to be published in the Journal of the British Interplanetary Society, is to shade the Earth slightly for several decades by creating huge dust clouds in semi-stable orbits near the Moon. The dust could be obtained by deflecting a nearby comet to this region of space and then grinding it up -- but this has the disadvantage of possibly causing the comet to strike the Earth itself and destroy all life as we know it. The other potential source of dust is the Moon. There's plenty of dust there, but we would need to launch it into orbit. This is somewhat easier on the Moon, since the gravity is weaker and there is no atmospheric drag, but it is still a formidable challenge.

To obtain the necessary amount of lunar dust, the author estimates that we would need to launch "about 300 metric tons/s for 10 years" and that "the energy can be derived directly from the Sun". The amount of energy required is about 2% of the current global demand for energy, hundreds of times more solar power capacity than we currently have on Earth -- and we need it on the Moon! If we cannot manufacture solar panels on the Moon, then we would need to launch them from the Earth -- and this would cost about 300 times the current U.S. national debt. This is much more expensive than simply blanketing the Earth with solar panels now -- a technological fix to the climate problem before it gets out of hand.

The Earth from Space

2007-01-11T11:11:00.000-07:00

In a live conversation from the International Space Station last night, Indian-American astronaut Sunita Williams told a group of school children in India that "Space is an amazing place for all. Here there are no borders, and the world is very peaceful". Sunita traveled to the ISS aboard the space shuttle Discovery, and plans to work there for the next six months.

The view of a world without borders may be the greatest benefit of making space tourism more accessible to the people of Earth in the future. But with a current price tag of about $20 million, few people can afford the trip. Several entrepreneurs are developing concepts for bringing space travel to the masses, and they are already busy building "spaceports" in places like New Mexico and west Texas. Competition between these companies will help push the price down by a factor of 100, but there are still relatively few people who will be able to afford a $200,000 seat.

Fortunately, an ongoing project by NASA is bringing the view of our planet without borders (or even clouds!) to computer screens around the globe. No doubt you have already seen the impressive composite image of the Earth, pieced together from satellite data obtained at different times and places when there were no clouds to block the view. NASA's "Blue Marble" project is now generating such images every month, so we can watch the surface of the Earth changing over time. At the highest resolution, each pixel in these new images spans just 500 meters on the ground.

Maybe if more people see these images and begin to think of the Earth as a place without borders, we can all live in the peaceful world that Sunita was talking about.

Selling Stellar Seismology

2006-12-27T10:17:00.000-07:00

After the successful launch of the French COROT satellite from Kazakhstan, news reports from around the world described the new space telescope as a "planet-seeker" designed to "search for new Earths". These headlines may have surprised some of the European scientists who plan to use observations from COROT to study the interiors of distant stars -- a technique known as asteroseismology. Beyond the headlines, only about 1 in 10 articles even mentioned that COROT would also "probe the mysteries of stellar interiors".

The COROT website features both scientific objectives prominently. In fact, the name COROT is an acronym for "COnvection ROtation and planetary Transits". If you think using only the T from "planetary Transits" is a bit of a cheat, you're right. The mission was originally given its name when it was only designed to do asteroseismology (studying COnvection and ROTation in stars similar to our Sun). Mission scientists added the planet-hunting capability later, since it exploited the same type of observations and attracted political support from a broader cross-section of the scientific community.

The fact that planet-hunting garners more support than asteroseismology is a reflection of its greater appeal among the general public. It also helps explain why the media chose to focus on the search for distant worlds rather than the more abstract goal of probing stellar interiors. About 2 years from now, NASA will launch a slightly larger telescope called Kepler, which is also designed to do both asteroseismology and planet-hunting. Unless stellar seismologists become a bit more media savvy in the meantime, you can count on more headlines about the search for distant Earths.

"Google Sky" coming soon?

2006-12-18T12:36:00.000-07:00

This week, NASA announced a strategic partnership with Google to make the agency's massive archive of data more accessible to the public. In the initial phases of the project, the Internet search giant will integrate 3D maps of the moon and Mars into an interface similar to its popular "Google Earth" software, allowing anyone "to experience a virtual flight over the surface of the moon or through the canyons of Mars".

As a simple demonstration of how Google can collaborate fruitfully with space scientists, take a look at the "Google Mars" project, on the web since last March. Working with a group of NASA researchers at Arizona State University, Google adapted their intuitive Maps interface to display optical, infrared and radar data of the red planet. In place of local businesses, the Mars maps include information bubbles marking the locations of major craters, mountains, and the landing sites of robotic spacecraft.

NASA has numerous archives of astronomical data that are already available to the general public, but even some astronomers have a difficult time finding and navigating these websites. For example the Multi-mission Archive, hosted by the Space Telescope Science Institute in Baltimore, allows anyone to download images and other data from the Hubble Space Telescope and many other NASA missions dating back to the 1970's. While the concept is useful (it beats trying to get the data from each mission website individually), the search interface is needlessly complicated and the query results are almost inscrutable. It's not hard to see how Google could make a significant contribution to making these data more accessible.

My own model for a search-friendly archive of astronomical data would be called "Google Sky". Imagine the Google Maps interface populated with the high resolution color images generated by the Sloan Digital Sky Survey (supplemented by the old Palomar Sky Survey to include the entire southern sky). Now imagine that when you search for a specific star or galaxy, the map would zoom into that location and allow you to switch to an infrared or ultraviolet view, just as you can turn on satellite imagery with Google Maps. Finally, the "Find Businesses" feature in the Maps interface would be replaced with "Find Data" -- allowing seamless access to complete archives of ground-based and satellite data that are ready to download and use. It may sound like a dream, but with Google and NASA on the same team, it could soon be a reality.

Misguided Moon Base

2006-12-11T14:09:00.000-07:00

Last week NASA announced plans to establish a permanent base on the Moon by the year 2024. You might think astronomers would be among the biggest cheerleaders of such an idea. I can't pretend to speak for all astronomers, but a little history might help you understand the lack of enthusiasm among at least some of my colleagues.

The whole idea of NASA going to the moon again is part of a new vision for space exploration outlined in a speech given by George W. Bush on January 14, 2004. This vision called for a return to the Moon as part of a longer-term plan to prepare for human exploration of Mars. At the time, the scientific community was stunned -- in part because the announcement seemed to come out of nowhere. It certainly wasn't the result of a grassroots effort by the astronomy community. In fact, astronomers had completed their own scientific vision of the future just a few years earlier, and it made no mention of a Moon base.

So where did the President get the idea? The consensus seems to be that, since NASA was planning to decommission the Space Shuttle and end its support of the International Space Station by the end of the decade, aerospace contractors began to wonder where that generous slice of NASA's $15-billion budget would end up. The new vision provided a definite answer, and NASA began to implement it almost immediately.

In its 2005 budget plan, NASA earmarked $12-billion in funding over five years to support the new vision for space exploration, but $11-billion of this total was "reallocated" from existing programs. To astronomers, this means a likely budget cut for research funding (the Office of Space Science, NASA's main source of basic research funding for astronomers, had a $4-billion budget in 2005).

Of course, now that NASA intends to build a base on the Moon there are many scientists with ideas for how to exploit it scientifically. But this is not a good recipe for getting the most science from the taxpayer's dollar -- it is a bunch of astronomers scrambling to recover from the new source of funding what they have lost from the old one.

Welcome to the New Media

2006-12-06T11:49:00.000-07:00

Several years ago, a friend of mine from graduate school started a website called starstuff.org, which was designed to bring astronomy news directly from astronomers to interested journalists and members of the general public. The name was motivated by a famous quote from astronomer Carl Sagan on the popular PBS television series, "Cosmos". He said, "we are, all of us, made of star-stuff". This unfiltered news website was a great idea, and I contributed several articles to it. But, for a variety of reasons, it eventually shut down.

It is in the spirit of starstuff.org that I am starting this new blog. I will try to make new posts about once a week, giving an astronomer's perspective on current news from the world of astronomy and about science in general.

My thanks go out to Sara "Star" Johnson of Bloomington, Indiana for letting me take over this blog name. Her blog is now hosted at star.qnarf.com