My Surprising and Exciting Journey from Scientist to Science Writer

I’ve been drawn to science since I was a kid. I had many excellent and creative teachers along the way, including one who taught us students to be more observant and to think critically and another who smashed bowling balls into desks and who ran into a wall (while wearing pads and a helmet, of course) to demonstrate momentum conservation. I grew up in Colorado, and I enjoyed gaping at the Milky Way and the beautiful night sky while in the Rockies, even if I couldn’t name many constellations. Carl Sagan’s Cosmos program and the Star Trek TV shows also inspired me to explore astrophysics later in life.

Milky Way over Great Sand Dunes National Park, Colorado. (Photo by Carl Fredrickson)

Milky Way over Great Sand Dunes National Park, Colorado. (Photo by Carl Fredrickson)

But my head isn’t always in the stars. I have many other interests too, including sociology, political science and philosophy of science, and I’ve always enjoyed literature and poetry too. I’m not just interested in doing science and analyzing datasets and phenomena; that, by itself, is not enough. I also desire to use science and critical thinking to help people and connect with them. Since science plays such an important role in human society, I’d like to communicate scientists’ research and debates and the scientific process as well as I can. While the behavior of neutrinos, ice sheets and red pandas might sound interesting, for example, we always have to ask, why are they important? What do scientists claim to have learned about them and how did they learn it? What are the broader implications and context for the research?

Ever the lifetime student, a couple years ago I thought I might become an absent-minded, nerdy, activist professor, maybe widening my scope beyond astronomy and physics into interdisciplinary research and public outreach. But then I realized that I wanted to do more. I examined many interconnections between science and policy—often posting about them on this blog—and I investigated ways I could utilize and develop my science writing skills. I earned fellowship opportunities in both science writing and science policy, and I considered going on both directions. As the head of our astrophysics and space sciences department told me while I mulled over the options, “Those aren’t actually that different. They both involve communicating science to people who might not understand it well.”

In the end, after fifteen years working as a Ph.D. student, teaching and research assistant, postdoctoral researcher, research scientist and lecturer, I decided that I would make the shift and become a science writer! It’s a big step, and I felt a bit nervous about it. Now that I’ve made the decision, I am happy and excited to be trying something new, and I look forward to improving my skills and working on it full-time.

For those of you considering working in science writing or science policy, or for those of you just interested in learning more, I am happy to help. In any case, here are a few suggestions and pieces of advice, which will be particularly relevant for you if you’re coming from a science background as I did.

First, I recommend becoming involved in public outreach and education programs. You may even decide to organize your own events. Just connect to people in whatever ways work well for you, such as speaking in local school classrooms, making demonstrations for students at your university, mentoring prospective students, interacting with members of the public at museums and planetaria, talking to people at cafes and pubs (such as Two Scientists Walk into a Bar, Astronomy on Tap, and other programs), etc.

Second, become more involved in and volunteer for the relevant professional scientific societies, such as the American Astronomical Society, American Physical Society, American Geophysical Union, etc. Be more than just a card-carrying member. All of these societies, and especially the American Association for the Advancement of Science (AAAS), have many useful resources, scholarships and internships at your disposal.

Third, it is crucially important to talk to a variety of people who work in science writing or science policy (or whatever you might be interested in), get involved and try it yourself. Make sure that you don’t merely like the concept of it but that you actually enjoy and excel at doing it. You will need to make the time to do this. You may find new people in your own college, university or community working in these professions who have much to teach you. Try a variety of media and styles too, possibly including social media, blogs, podcasts, news articles, feature stories, videos, etc. If you’re curious about what I’ve done over the past year or so, look here.

Fourth, check out professional science writing organizations. In particular, I recommend looking up the National Association of Science Writers, the Society of Environmental Journalists and the Association of Healthcare Journalists. Furthermore, you might find useful local organizations too. (We have the San Diego Press Club here, for example). Science writing workshops, such as those in Santa Fe, New Mexico and in Banff, Alberta, could be beneficial for you and could introduce you to others like yourself who are also just starting to venture into the profession. Finally, if you are interested, the AAAS has mass media and science policy fellowships, and the University of California, Santa Cruz, MIT, NYU, and other universities have graduate programs you may consider, though these involve an investment of time and money.

Before diving in, consider the job prospects. Although we have our ideals, we also want to work for a livable salary with sufficient job security. Staff writers, editors, freelancers and public information officers (PIOs) all have pros and cons to their jobs, and it’s important to understand them well.

I’ll make it official: I decided to head to the UC Santa Cruz science communication program, and I’m looking forward to it! In a few days I will be on my way north to Santa Cruz. I plan to try my hand working with a local newspaper, magazine, and an online news outlet, and this fall I will be working with PIOs at Stanford Engineering. Stay tuned for my new articles!

Coming from a science background, I have many challenging things to learn, but I think I’m up to it. I’m trying to learn to write more creatively and evocatively, while identifying compelling characters. I’m learning to assess which scientific discoveries and developments make for the most intriguing stories. Moreover, scientists and science writers have different ways of thinking, and bridging the gap between them involves more steps than you might think it does. Perhaps most importantly, after thinking of myself as a scientist for so many years, it’s hard to craft a new identity. It turns out that while I am an astronomer and a physicist, I am many other things too. I’m continuing to explore the universe, just in a myriad different ways than before. I’m boldly going where I haven’t gone before, and the sky’s the limit!

Why do we engage in space exploration?

A review of diverse perspectives on space exploration and extraterrestrial life reveal fundamentally human hopes, fears and flaws

Since the dawn of civilization thousands of years ago, humans have looked to the skies. Archaeologists have found evidence of people from China, India, and Persia to Europe and Mesoamerica observing and contemplating the many stars and planets that fascinated them. We humans have also wondered about—and often hoped for—the existence of other intelligent life out there. Considering the large number of planets in the Milky Way and in billions of other galaxies, perhaps we are not alone, and maybe even while you are reading this, extraterrestrials could be looking in our direction through their telescopes or sending us interstellar telegrams. But if our galaxy teems with aliens, following Italian physicist Enrico Fermi’s persistent question, we must ask, “Where are they?”

Artist's depiction of a travel poster for a "Tatooine-like" planet orbiting two suns, recently discovered by NASA's Kepler spacecraft. (Courtesy: NASA)

Artist’s depiction of a travel poster for a “Tatooine-like” planet orbiting two suns, recently discovered by NASA’s Kepler spacecraft. (Courtesy: NASA)

Two recent pieces in the New Yorker and New York Times, as well as numerous books over the past couple years, motivate me to consider this and related questions too. Astronomers and astrophysicists around the world, including scientists working with NASA, the European Space Agency (ESA), the Japanese Space Agency (JAXA) and many others, have many varieties of telescopes and observatories on Earth and in space, just because we want to investigate and learn about our galactic neighborhood and beyond. We also attempt to communicate, like sending a message in a bottle, with the Golden Records aboard the Voyager spacecrafts, and we listen for alien attempts to contact us. In our lifetime, we have dreams of sending humans to Mars and to more distant planets. Why do we do this? We do it for many reasons, but especially because humans are explorers: we’re driven to see what’s out there and to “boldly go where no one has gone before.” As Carl Sagan put it in Cosmos, “Exploration is in our nature. We began as wanderers, and we are wanderers still.”

Views of human space exploration

Elizabeth Kolbert reviews three recently published and forthcoming books by Chris Impey, an astronomer at the University of Arizona (where I used to work three years ago), Stephen Petranek, a journalist at Discover, and Erik Conway, a historian of science at Jet Propulsion Laboratory. (She did not mention an award-winning book by Lee Billings, Five Billion Years of Solitude, which I will review in a later post.) She fault finds with the overoptimistic and possibly naïve “boosterism” of Impey and Petranek. “The notion that we could…hurl [humans]…into space, and that this would, to use Petranek’s formulation, constitute ‘our best hope,’ is either fantastically far-fetched or deeply depressing.” She asks, “Why is it that the same people who believe we can live off-Earth tend to believe we can’t live on it?”

Kolbert’s assessment has some merit. Astrophiles and space enthusiasts, of which I am one, sometimes seem to neglect Earth (and Earthlings) in all its wonder, marvels, complexity, brutality and messiness. But is the primary reason for exploring the universe that we can’t take care of ourselves on Earth? Mars should not be viewed as a backup plan but rather as one of many important steps toward better understanding our little corner of the galaxy. Furthermore, we should be clear that sending humans to Mars and more distant worlds is an incredibly complicated and dangerous prospect, with no guarantee of success. Even if the long distances could be traversed—at its closest, Mars comes by at least a staggering 50 million miles (80 million km) away, and then the nearest star, Alpha Centauri, is about 25 trillion miles from us—future human outposts would face many obstacles. The popular novel by Andy Weir, The Martian, demonstrates only some of the extraordinary challenges of living beyond our home planet.

Overview of components of NASA's Journey to Mars program, which seeks to send humans to the red planet in the 2030s. (Credit: NASA)

Overview of components of NASA’s Journey to Mars program, which seeks to send humans to the red planet in the 2030s. (Credit: NASA)

Though Kolbert criticizes Conway’s dry writing style, she clearly sympathizes with his views. “If people ever do get to the red planet—an event that Conway…considers ‘unlikely’ in his lifetime—they’ll immediately wreck the place just by showing up…If people start rejiggering the atmosphere and thawing the [planet’s soil], so much the worse.” This line of criticism refers to flaws of geoengineering and of the human species itself. Many times in history, humans ventured out acting like explorers, and then became colonists and then colonialists, exploiting every region’s environment and inhabitants.

Note that Kolbert is a journalist with considerable experience writing about climate, ecology and biology, while astrophysics and space sciences require a stretch of her expertise. In her excellent Pulitzer Prize-winning book, The Sixth Extinction, Kolbert argues provocatively that humans could be viewed as invasive species transforming the planet faster than other species can adapt, thereby constituting a danger to them. “As soon as humans started using [language], they pushed beyond the limits of [the] world.” I agree that humans must radically improve their relationship with nature and Earth itself, but this does not preclude space travel; on the contrary, the goal of exploring other worlds should be one aspect of our longer-term and larger-scale perspective of humanity’s place in the universe.

Views of extraterrestrial intelligence

Dennis Overbye, a science writer specializing in physics and astronomy, covers similar ground, but focuses more on the search for extraterrestrial intelligence (SETI). He mentions the Drake Equation, named after the American astronomer Frank Drake, which quantifies our understanding of the likelihood of intelligent life on other planets with whom we might communicate. Both Drake and Sagan “stressed that a key unknown element in their equations was the average lifetime of technological civilizations.” If advanced species don’t survive very long, then the possibility of contact between overlapping civilizations becomes highly improbable. It would be unfortunate if similarly advanced civilizations, like Earthlings and Klingons, could never meet.

Overbye introduces the controversial University of Oxford philosopher, Nick Bostrom, who is rooting for us to fail in our search for ETs! “It would be good news if we find Mars to be sterile. Dead rocks and lifeless sands would lift my spirit.”

Bostrom bases his argument on a concept he refers to as the Great Filter. Considering the likelihood of advanced civilizations, many conditions and criteria must be satisfied and steps must be taken before a planet in the “habitable zone” has a chance of harboring intelligent life. The planet probably must have the right kind of atmosphere and a significant amount of liquid water and some kind of possibly carbon-based building blocks of life, and after that, the alien species’ evolutionary developments could go in any direction, not necessarily in a direction that facilitates intelligence. In addition, asteroids, pandemics, or volcanic eruptions could wipe out this alien life before it got anywhere. In other words, myriad perils and difficulties filter out the planets, such that only a few might have species that survive and reach a level of social and technological advancement comparable to those of humans.

On the other hand, if we do find life on other planets and if intelligent extraterrestrial life is relatively ubiquitous, our lack of contact with them could mean that advanced civilizations have a short lifetime. Perhaps the Great Filter is ahead of us, “since there is no reason to think that we will be any luckier than other species.” Maybe nuclear war, climate change, or killer robots might wipe us out before we have the chance to explore the galaxy.

I am not convinced by Bostrom’s pessimism. Even if the Great Filter is ahead of us, implying that humans face more existential threats in the future than have been overcome in the past, this doesn’t mean that we are doomed. Humanity does have major problems with acknowledging large-scale impacts and long-term outlooks, but I hope we could learn to change before it is too late.

A more positive outlook

We have learned a lot about planets, stars, galaxies, black holes and the distant universe from our tiny vantage point. But we would be immodest and mistaken to brazenly presume that we’ve already figured out the rest of the universe. We really don’t know how many other “intelligent” species might be out there, and if so, how far they are, what level of evolution they’re at (if evolution is a linear process), or whether or how they might communicate with us. We should continue to discuss and examine these questions though.

While traveling to other planets will take a long time, in the meantime astronomers continue to make exciting discoveries of possibly “Earth-like” planets, such as Kepler-452b, an older bigger cousin to our world. It seems likely that the Earth has a very big family, with many cousins in the Milky Way alone.

So why do we engage in space exploration and why do we seek out extraterrestrial life? This question seems to transform into questions about who we are and how we view our role in the universe. I believe that humans are fundamentally explorers, not only in a scientific sense, and we have boundless curiosity and wonder about our planet and the universe we live in. Humans also explore the depths of the oceans and dense rainforests and they scour remote regions in arid deserts and frigid glaciers (while they still remain), just to see what they’re like and to look for and observe different lifeforms.

More importantly, even after tens of thousands of years of human existence, we are still exploring who we are, not just with scientific work by psychologists and sociologists but also with novelists, poets and philosophers. We still have much to learn. To quote from Q, a capricious yet occasionally wise Star Trek character, “That is the exploration that awaits you: not mapping stars and studying nebulae, but charting the unknown possibilities of existence!”

As Galaxies’ Light Gradually Fades, the Universe is Slowly Dying!

The Universe, long past retirement at an age of 13.8 billion years, appears to be gradually “dying.” New observations strongly indicate that galaxies, vast collections of billions of stars such as our Milky Way and neighbors Andromeda and Triangulum, generate much less energy than they used to across the wavelength spectrum, a clear trend revealing the fading cosmos.

This composite picture shows how a typical galaxy appears at different wavelengths in the GAMA survey. The energy produced by galaxies today is about half what it was two billion years ago, and this fading occurs across all wavelengths. (Credit: ICRAR/GAMA and ESO.)

This composite picture shows how a typical galaxy appears at different wavelengths in the GAMA survey. The energy produced by galaxies today is about half what it was two billion years ago, and this fading occurs across all wavelengths. (Credit: ICRAR/GAMA and ESO.)

Scientists with the Galaxy and Mass Assembly (GAMA) survey, led by Simon Driver of the International Centre for Radio Astronomy Research in Australia, extensively and thoroughly examined more than 200,000 galaxies. Driver and his colleagues presented the results of their analysis at the general assembly of the International Astronomical Union (IAU) in Honolulu, Hawaii, which came to a close last weekend. Their announcement coincided with their data release and the submission of their paper to the journal, Monthly Notices of the Royal Astronomical Society. The paper has not yet been peer-reviewed or published, but the authors’ main conclusions are unlikely to change.

“While most of the energy sloshing around in the Universe arose in the aftermath of the Big Bang, additional energy is constantly being generated by stars as they fuse elements like hydrogen and helium together,” Driver said. “This new energy is either absorbed by dust as it travels through the host galaxy, or escapes into intergalactic space and travels until it hits something, such as another star, a planet, or, very occasionally, a telescope mirror.”

Stars of all ages throughout this multitude of galaxies convert matter into energy (remember E=mc2?) in the form of radiation ranging from ultraviolet to optical to infrared wavelengths, and astronomers have long known that the total energy production of the universe has dropped by more than a factor of 1.5 since its peak about 2.25 billion years ago. But GAMA scientists, utilizing the Anglo-Australian Telescope at Siding Spring Observatory in eastern Australia, were the first to document the declining energy output so comprehensively over 21 wavebands.

Check out this fly-through of the volume mapped out by the GAMA survey, which is expected to be approximately representative of the rest of the “nearby” universe, with the galaxies’ images enlarged (video courtesy of ICRAR/GAMA/Will Parr, Mark Swinbank and Peder Norberg (Durham University) and Luke Davies (ICRAR)):

The GAMA astronomers’ results point toward the universe’s continued “gentle slide into old age,” as Driver put it, but there is no need to panic! The time-scales involve billions of years, and we humans have only been around for about 100,000th of the universe’s lifespan so far. (That’s like the incredibly short lifetime of mayflies relative to ours.) We should be careful to note that the scientists’ conclusions come from a statistical assessment of numerous and diverse galaxies, similar to the way pollsters or census takers evaluate a population by studying a large number of its members. Individual galaxies and their stars may be young or old, but the general population continues to age with no indication of deviations from the demographic trend, much like the gradual aging of people in Japan.

Filled with galaxies and much more dark matter and much much more empty space, the universe rapidly expands and pulls objects away from each other, countering gravitational forces. Old stars within galaxies provide the fuel for new stars to form, but eventually it becomes harder and harder to scrape enough fuel together to make those new stars and galaxies, and on average the aging universe becomes fainter and fainter. It’s as if potential parents become increasingly unlikely to meet with random encounters and many ultimately die alone.

The universe will eventually pass away, but long after our sun has exploded in its red giant phase and destroyed the Earth and long after the Milky Way and Andromeda collide. I think the universe—and humans—has many more good years left though.

High-Definition Space Telescope: Our Giant Glimpse of the Future?

Where do you see yourself in a decade? What is your vision for two decades from now? What could you accomplish if you had billions of dollars and infrastructure at your disposal? A consortium of astrophysicists attempt to answer these questions as they put forward their bold proposal for a giant high-resolution telescope for the next generation, which would observe numerous exoplanets, stars, galaxies and the distant universe in stunning detail.

Artist’s conception of proposed proposed High-Definition Space Telescope, which would have a giant segmented mirror and unprecedented resolution at optical and UV wavelengths. (NASA/GSFC)

Artist’s conception of proposed proposed High-Definition Space Telescope, which would have a giant segmented mirror and unprecedented resolution at optical and UV wavelengths. (NASA/GSFC)

The Association of Universities for Research in Astronomy (AURA), an influential organization of astronomers from 39 mostly US-based institutions, which operates telescopes and observatories for NASA and the National Science Foundation, lays out its vision of High-Definition Space Telescope (HDST) in a new report this month. Julianne Dalcanton of the University of Washington and Sara Seager of the Massachusetts Institute of Technology—veteran astronomers with impressive knowledge and experience with galactic and planetary science—led the committee who researched and wrote the 172-page report.

As the HDST’s name suggests, its wide segmented mirror would give it much much higher resolution than any current or upcoming telescopes, allowing astronomers to focus on exoplanets up to 100 light-years away, resolve stars even in the Andromeda Galaxy, and image faraway galaxies dating back 10 billion years of cosmic time into our universe’s past.

A simulated spiral galaxy as viewed by Hubble and the proposed High Definition Space Telescope at a lookback time of approximately 10 billion years. Image credit: D. Ceverino, C. Moody, G. Snyder, and Z. Levay (STScI)

A simulated spiral galaxy as viewed by Hubble and the proposed High Definition Space Telescope at a lookback time of approximately 10 billion years. Image credit: D. Ceverino, C. Moody, G. Snyder, and Z. Levay (STScI)

In the more recent past, the popular and outstandingly successful Hubble Space Telescope celebrated its 25th birthday a few months ago. Astronomers utilized Hubble and its instruments over the years to obtain the now iconic images of the Crab Nebula, the Sombrero Galaxy, the Ultra Deep Field, and many many others that captured the public imagination. Hubble continues to merrily float by in low-earth orbit and enables cutting-edge science. But the telescope required 20 years of planning, technological development, and budget allocations before it was launched in 1990.

For the newly proposed space telescope, some headlines describe it as NASA’s successor to Hubble, but it really constitutes a successor to a successor of Hubble, with other telescopes in between (such as the Wide-Field InfraRed Survey Telescope, WFIRST). If the astronomical community comes on board and if astronomers convince NASA and Congressional committees to fund it—two big “ifs” for big projects like this—it likely would be designed and constructed in the 2020s and then launched in the 2030s.

The James Webb Space Telescope (JWST), proposed two decades ago by AURA and now finally reaching fruition and set for launching in 2018, could be considered the HDST’s predecessor. All of these major projects require many years of planning and research; Rome wasn’t built in a day, as they say. James Webb scientists and engineers hope that, like Hubble, it will produce spectacular images with its infrared cameras, become a household name, and expand our understanding of the universe. Nevertheless, JWST has been plagued by a ballooning budget and numerous delays, and Congress nearly terminated it in 2011. When a few large-scale programs cost so many billions of dollars and years to develop, how do people weigh them against many smaller-scale ones that sometimes get sacrificed?

Approximately every ten years, members of the astronomical community get together and determine their set of priorities for the next decade, balancing large-, medium- and small-scale programs and ground- and space-based telescopes, given the budget realities and outlook. Back in 2001, they prioritized James Webb, and then a decade later they put WFIRST at the top of the list. For the next generation though, in the 2010 Decadal Survey (named “New Worlds, New Horizons”), they highlighted the need for a habitable (exo)planet imaging mission. Everyone loves planets, even dwarf planets, as revealed by the popularity of NASA’s missions exploring Pluto and Ceres this year.

Building on that report, NASA’s 2014 Astrophysics Roadmap (named “Enduring Quests, Daring Visons”) argued that much could be gained from a UV/optical/infrared surveyor with improved resolution, which could probe stars and galaxies with more precision than ever before. According to the AURA committee, the High-Definition Space Telescope would achieve both of these goals, taking planetary, stellar and galactic astronomy to the next level. Importantly, they also argued that astronomers should prioritize the telescope in the 2020 Decadal Survey, for which planning has already commenced.

How do scientists balance the need for different kinds and sizes of projects and missions, knowing that every good idea can’t be funded? Astronomers frequently disagree about how to best allocate funding—hence the need for periodic surveys of the community. They hope that what is best for science and the public will emerge, even if some scientists’ favorite projects ultimately aren’t successful. James Webb Space Telescope’s budget has been set to $8 billion, while the High-Definition Space Telescope would cost $10 billion or more, according to Alan Dressler of the Carnegie Observatories. This is big money, but it’s small compared to the cost of bank bailouts and military expenditures, for example. While the scientific community assesses which programs to focus on, we as a society need to determine our own priorities and how space exploration, astrophysics research as well as education and outreach are important to us. In the meantime, HDST scientists will continue to make their case, including in an upcoming event at the SPIE Optics & Photonics conference in San Diego, which I will try to attend.

Scientists and journalists alike frequently talk about Big Science these days. The recently published and much reviewed book by Michael Hiltzik about the physicist Ernest Lawrence describes its history since the Manhattan Project and the advent of ever-bigger particle accelerators. Big Science is here to stay and we clearly have much to gain from it. Only some Big Science ideas can be prioritized and successfully make the most of the effort and investment people put in them. Hubble exceeded all expectations; the High-Definition Space Telescope has astronomical shoes to fill.

Happy Birthday to Vera Rubin, Discoverer of Dark Matter

Peering through their powerful telescopes, scientists observe a stunningly diverse array of phenomena, including comets, planets, stars, gaseous nebulae, novae, quasars, galaxies, and numerous other exciting things. But astrophysicists argue that these light-emitting objects only amount to a tiny fraction of the universe. According to the latest measurements from the European Space Agency’s Planck telescope earlier this year, they account for less than 5% of the universe’s matter and energy, while mysterious-sounding “dark matter” accounts for nearly six times as much. Nevertheless, dark matter cannot be seen and does not interact with normal matter, so how did astronomers figure out that so much invisible, intangible stuff exists out there?

Vera Rubin measuring spectra, circa 1970. (Credit: American Institute of Physics)

Vera Rubin measuring spectra, circa 1970. (Credit: American Institute of Physics)

As I recently wrote in a post for the International Year of Light, the story of scientists’ discovery and exploration of dark matter began many decades ago. Physicists had long utilized Newton’s and Einstein’s gravitational laws to estimate our sun’s mass by measuring planets’ distances from it and examining how fast they travel around it. For example, Mercury is very close to the sun and orbits it much faster than Pluto, which takes 248 Earth-years to complete an orbit. (If you’re wondering, the sun has a mass larger than a trillion billion billion kilograms. That’s a lot!) Similarly, it turns out that one can make such calculations for stars within galaxies and infer the enclosed mass, but the results of the analysis are not so simple to understand.

Detailed image of the Andromeda Galaxy, recently surveyed by the Panchromatic Hubble Andromeda Treasury
. (Credit: NASA, ESA, J. Dalcanton et al.)

Detailed image of the Andromeda Galaxy, recently surveyed by the Panchromatic Hubble Andromeda Treasury
. (Credit: NASA, ESA, J. Dalcanton et al.)

In the 1960s and 1970s, American astronomer Vera Rubin measured and analyzed the precise velocities of stars in spiral galaxies and came to a startling conclusion. Most stars at outer radii orbit the center at surprisingly large speeds, much faster than they should be based on the mass of the stars themselves, but the galaxies do not tear themselves apart or fling their stars hurtling away. Studying galaxies, such as Andromeda, as a whole, she found that they rotate too quickly for their stars’ gravity to keep them intact. It was as if the galaxies contain and are surrounded by much more unseen dark matter, which gravitationally binds the galaxies together. Rubin’s crucial discovery has not yet received the recognition it deserves.

This critically important area of research came to be known as galaxy “rotation curves,” in which Rubin became an influential figure. Rotation curve measurements of spiral galaxies from two of her many highly-cited publications appear in the reference, Galactic Astronomy, which every respectable astrophysicist has on their bookshelf. Her measurements from hundreds of galaxies constitute strong evidence for the existence of massive clumps of dark matter extending to many thousands of light-years beyond the edge of the galaxies themselves. Astrophysicists also considered the alternative hypothesis that Newton’s gravitational laws need to be modified for objects separated by large distances, but that approach has been less successful and lacks support among the community.

Rotation curves of three spiral galaxies of varying brightness, adapted from an influential 1985 paper by Rubin. (Credit: Binney & Merrifield, "Galactic Astronomy," Princeton, 1998.)

Rotation curves of three spiral galaxies of varying brightness, adapted from an influential 1985 paper by Rubin. (Credit: Binney & Merrifield, “Galactic Astronomy,” Princeton, 1998.)

Vera Rubin turns 87 years old today. She continues her work at the Department of Terrestrial Magnetism at the Carnegie Institution of Washington, and she still publishes research in galactic astronomy. In addition, she writes popularly such as in Scientific American and Physics Today. Moreover, she inspires, supports, and encourages young people, especially women, in science. This includes her four children, all of whom have earned Ph.D. degrees in the natural sciences or mathematics.

In 1965, Vera Rubin was the first woman permitted to observe at Palomar Observatory. When she applied to graduate schools, she was told that “Princeton does not accept women” in the astronomy program; she went to Cornell instead. As she put it in a recent astronomical memoir, “Women generally required more luck and perseverance than men did.” In her 1996 book, Bright Galaxies, Dark Matters, she wrote

Since the 1950s, opportunities for women in astronomy have increased, but serious problems have not disappeared…The saddest part, of course, is that only about one-fifth of the women who enter college intend to study science. Lack of support and encouragement at an early age has by then taken its toll. A young woman who enters graduate school to study science is a rare creature indeed…but the colleges are often a part of the problem rather than part of the solution.

Now with many years of hard work and persistence, people are making gradual progress. For example, Meg Urry leads the American Astronomical Society, France Córdova is the director of the National Science Foundation, and Marcia McNutt now heads the National Academy of sciences. But much more work needs to be done to reduce gender inequality and underrepresentation throughout science research and education.

Many people argue that Vera Rubin would be a strong contender for a Nobel Prize in Physics, and I join that call. She has already won many other awards, including the National Medal of Science, but the Nobel would officially recognize her enormous contributions to astrophysics and her critical role in illuminating the way to dark matter. Considering that the 2011 Nobel Prize went to Saul Perlmutter, Brian Schmidt, and Adam Riess for discovering dark energy, it’s time for dark matter to have its day.

New Discoveries as New Horizons Flies by Pluto!

You may be wondering, what’s the deal with Pluto? First, astronomers demote Pluto’s planetary status in a controversial move, to say the least, and then NASA sends a spacecraft on a mission to observe it in detail? Why is this important, and what could we learn about Pluto that we didn’t know already?

Image from the Long Range Reconnaissance Imager (LORRI) aboard NASA's New Horizons spacecraft, taken on 13 July 2015. Pluto is dominated by the feature informally named the "Heart." (Image Credit: NASA/APL/SwRI)

Image from the Long Range Reconnaissance Imager (LORRI) aboard NASA’s New Horizons spacecraft, taken on 13 July 2015. Pluto is dominated by the feature informally named the “Heart.” (Image Credit: NASA/APL/SwRI)

Of course, we have quite a bit to learn. Moreover, as one of the least studied objects in the outer regions of our solar system, Pluto is ripe for exploration and investigation. Within a few days, NASA’s New Horizons probe already produced detailed and exquisite photos of Pluto, much better than has been done with Hubble or any other telescope. Its mission is far from over, but it’s already an amazing success and has inspired public interest in space exploration once again.

Back in 1930, 85 years ago, a young astronomer by the name of Clyde Tombaugh at Lowell Observatory in Flagstaff, Arizona noticed a distant possibly planet-like object moving across photographic plates. When other astronomers confirmed the discovery, thousands of people suggested names for the planet. In the end, the name that caught on in the community came from an 11-year-old girl in Oxford, Venetia Burney, and the Lowell astronomers approved “Pluto” unanimously. (Contrary to some rumors, she did not name it after the cartoon dog.) Burney (later Phair) lived to witness the launching of New Horizons, but she passed away in 2009. Some of Tombaugh’s ashes are aboard the spacecraft, and his children and grandchildren were present for the events of New Horizons.

NASA's New Horizons spacecraft.  (Artist's impression.)

NASA’s New Horizons spacecraft.
(Artist’s impression.)

NASA’s New Horizons spacecraft launched from Cape Canaveral in January 2006. Its journey took it 3 billion miles (about 5 billion km) from Earth, including a slingshot around Jupiter—covering nearly 1 million miles per day!—to reach Pluto. To paraphrase Douglas Adams, you may think it’s a long way to the chemist’s, but that’s just peanuts compared to the distance New Horizons traveled. Principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado leads the mission, which also includes a relatively large fraction of women on the team. In another important point, the mission had a relatively small cost ($700M) considering its huge impact on planetary physics, space exploration, and science outreach.

Once Pluto was demoted (or even dissed) by the astronomical community back in 2006, it’s never been more popular! New Horizons’ flyby only rekindled interest in Pluto in popular culture. I’ve seen many comics, memes and jokes about it, including XKCD, a cartoon showing Neil deGrasse Tyson and Pluto giving each other the finger, a cartoon with a sad Pluto as New Horizons flies by while saying “HEYWHATSUPGOTTAGOBYE!,” and another cartoon with Pluto saying, “So you dumped me years ago, but now you’re driving by my house real slow?”

As I wrote in a previous post, Pluto has many characteristics, including its small size and mass, that give it a questionable planetary status. It is one of many objects hurtling about the edge of our solar system called the Kuiper Belt, named after Dutch-American astronomer Gerard Kuiper. According to the International Astronomical Union (IAU), these are some of the solar system’s non-planets, ranked by size: Ganymede (Jupiter moon), Titan (Saturn moon), Callisto (Jupiter moon), Io (Jupiter moon), Earth’s moon, Europa (Jupiter moon), Triton (Neptune moon), Pluto, and Eris. Much further down the list comes Ceres (in the asteroid belt between Mars and Jupiter), which is actually smaller than Charon, one of Pluto’s moons. Eris, which was previously known as 2003 UB313 (and also as Planet X, and then Xena, as in the Warrior Princess) is slightly more massive than Pluto. In addition to Pluto, Eris, and Ceres, Haumea (a trans-Neptunian object) and Makemake (another Kuiper Belt object) are the other two dwarf planets the IAU recognizes. In any case, Pluto may be small and may be less unique than we thought and may have an abnormally elliptical orbit, but we all love it anyway.

New Horizons made its closest approach on 14 July, Tuesday morning, about 50 years after the first spacecraft landed on Mars, Mariner 4. It will take many months for New Horizons to transmit all of the Pluto flyby data back to Earth, but what has the probe discovered so far? First, New Horizons already obtained the most detailed images of Pluto ever. Second, based on the imagery, astronomers calculated that Pluto is slightly larger than previously thought: it turns out to have a radius 1.9% larger than Eris’s, making it the largest dwarf planet.

New Horizons scientists also found that Pluto is icier than previously thought, with its polar ice cap and with icy mountains nearly as high as the Rockies. The ice consists of a frozen mixture of methane, ethane, carbon monoxide and nitrogen—not the sort of thing you’d want to put in a drink. Pluto’s mountains likely formed less than 100 million years ago, which is a relatively short time in the history of a (dwarf) planet. At least some of Pluto’s surface might still be geologically active today—some scientists think they have spotted potential geysers as well—but planetary physicists are not sure about what could have caused this activity. Furthermore, Pluto exhibits very few impact craters from Kuiper belt objects (KBOs), which would also be consistent with recent geological activity.

Charon also lacks such craters—a surprising observation considering that it appears to have no atmosphere. Charon’s diameter is over half of Pluto’s, which makes it big enough to cause Pluto to wobble as it orbits. Scientists believe that Charon likely formed from a huge collision with a young Pluto, and debris also settled into Pluto’s four other moons: Nix, Hydra, Kerberos, and Styx. Alternatively, Pluto could have gravitationally captured Charon a few hundred million years ago, which could explain the “tidal interactions” between them.

Finally, New Horizons astronomers discovered vast frozen craterless plains in the center of Pluto’s “heart,” which they have informally named the “Tombaugh Regio.” The plains region has a broken surface of irregularly-shaped segments that either may be due to the contraction of surface materials, like when mud dries, or may be the result of convection. The New Horizons team released the following zoom-in images at a press conference today, and we expect more to come.

What’s next for New Horizons? The probe continues to send more valuable data from its seven instruments in our general direction. Project scientists will sift through these data to try to learn more about Pluto and Charon’s surface, geology, and atmosphere, and therefore to infer how these interesting objects formed and evolved. In the meantime, New Horizons continues on its merry way throughout the Kuiper Belt. Assuming NASA approves funding for its extended mission, in a couple years it will use its limited fuel to investigate much smaller and newly discovered KBOs, such as 2014 MT69. In any case, we shall keep in touch with New Horizons as it follows the Voyager spacecrafts into the outskirts of our solar system and boldly ventures beyond.

[For further reading, you can find great coverage about these exciting discoveries in many places. For example, take a look at Nature (Alexandra Witze), Science, Scientific American, National Geographic (Nadia Drake), Wired, NBC (Alan Boyle), as well as New York Times, Los Angeles Times, Guardian, BBC, etc… For the most up-to-date information, I suggest taking a look at NASA’s website and the Planetary Society (Emily Lakdawalla).]

Dispute Continues between Astronomers and Native Hawaiians about Thirty Meter Telescope

The conflict over Mauna Kea, where astronomers seek to build one of the world’s largest telescopes and where Native Hawaiians consider sacred ground, continues. The situation escalated in early April when protesters, defending their land and angry about their concerns being ignored, managed to stop construction on the Thirty Meter Telescope (TMT), which was planned to be built by 2024 and begin detailed observations of distant galaxies and other objects at optical-infrared wavelengths.

Native Hawaiians protesting the Thirty Meter Telescope. (Credit: AP Photo/Anne Keala Kelly)

Native Hawaiians protesting the Thirty Meter Telescope. (Credit: AP Photo/Anne Keala Kelly)

After police arrested 31 peaceful protesters for blocking the road to the summit, the new Hawaii governor, David Ige, called for a temporary halt to construction of the telescope on 7 April. “This will give us some time to engage in further conversations with the various stakeholders that have an interest in Mauna Kea and its sacredness and its importance in scientific research and discovery going forward,” Ige said. The situation remains at an impasse, and he extended the construction moratorium multiple times since then.

Artist's rendition of the planned Thirty Meter Telescope. (Credit: TMT/Associated Press)

Artist’s rendition of the planned Thirty Meter Telescope. (Credit: TMT/Associated Press)

This is only the latest battle in an ongoing dispute. (See my previous post on the TMT and protests last fall.) Astronomers have found that Mauna Kea, on Hawaii’s Big Island, is an ideal place to build ground-based telescopes because of its “seeing” statistics. Optical and infrared images are less distorted by light traveling through the atmosphere here than in many other places. Although many indigenous Hawaiians have allowed smaller telescopes to be built on the mountain, it becomes more controversial as astronomers try to construct more and larger telescopes on these protected lands which hold a great cultural importance for them. The TMT also drew opposition from celebrities of Native Hawaiian descent, including Jason Mamoa (Khal Drogo on Game of Thrones), who encouraged others to join the protests.

In addition, the protests drew more media attention than the last time, during the ground-breaking. For example, see these excellent articles by Azeen Ghorayshi on Buzzfeed and Alexandra Witze in Nature, as well as other articles in Science, New Scientist, and NPR. George Johnson also discussed the protests in the New York Times, though his column clearly sides with the TMT.

Supported by US and international universities as well as the National Science Foundation (in the form of “partnership-planning activities”), the TMT is the primary 30-meter-class telescope given priority by the US astronomical community in the 2010 Decadal Survey and highlighted in a recent National Research Council report. The other two planned telescopes in that class include the European-Extremely Large Telescope (E-ELT) led by the European Southern Observatory and the Giant Magellan Telescope (GMT) led by an international consortium of universities, both of which are under construction in northern Chile. All three telescopes are scheduled to have “first light” in the early 2020s. During the planning phase of the TMT, in addition to Mauna Kea, astronomers considered other possible locations as well, also including northern Chile and Baja California, Mexico.

The Native Hawaiian position is not monolithic, but some groups oppose the construction of the TMT and others would support it if negotiations took place in good faith and with respect and not only in Western spaces. The protesters are not a small minority, and they don’t believe that their voices have been heard. Many Hawaiians make it clear that they are not against science or astronomy; for example, the Mauna Kea Protectors “[take] a stand specifically against scientific practices that do a lot of damage—to our planet, to traditional native cultures, and to public health and safety.”

They and others make arguments on cultural, environmental, and legal grounds. If built, the TMT would dominate the landscape as it would rise 18 stories above the mountain, at an elevation of 4200m, and would disturb a large area of its slope. Moreover, the Mauna Kea summit lies within a conservation district, and therefore according to Hawaiian law certain (arguably unsatisfied) criteria must be met before construction there. Finally and most importantly, many believe that Mauna Kea is a sacred and special place that must be protected, and those beliefs have not been sufficiently respected by the authorities. (For more information, see here and here.)

The official position can be found on the TMT website and at Mauna Kea and TMT. Furthermore, Claire Max, Interim Director of UC Observatories, recently made an official statement promoting the latter as a source for information “with links to balanced news stories about the project and the protests” and that “TMT…[has] profound regard for Hawaii’s culture, environment and people.”

The TMT does have support among some native Hawaiians, and TMT authorities have set up a $1 million annual scholarship fund, named The Hawaii Island New Knowledge (THINK) Fund, which will be administered by the Hawaii Community Foundation. They have initiated a Workforce Pipeline Program in Hawaii as well. Like the Hawaiian organizations, they insist that they have the law on their side, but unlike them, they refer to the TMT as a done deal and fait accompli rather than as the subject of an ongoing dispute. According to the University of Hawaii position, “more than 20 public hearings have been held during the process and the project has been approved by then Governor Neil Abercrombie, the UH Board of Regents and the Board of Land and Natural Resources…The project has also cleared legal challenges and was upheld in the Third Circuit Court.”

From what I have seen, this dispute has generated heated debates in the astronomical community in various social media. For example, in the “Diversity in Physics and Astronomy” Facebook group (with 1700 members), astronomers made more posts and comments about the TMT and protests than about any other issue over the past few months. Astronomers expressed a wide range of views on Twitter as well, some of which were highlighted recently by Emily Lakdawalla’s Storify timeline, “Astronomy Progress is Not Universal.”

Like many astronomers and astrophysicists, I’m torn. While the TMT would be a boon for science and scientists, especially those who study galaxies, supernovae, stars, and planets, that is not the only criterion by which such a project should be evaluated. The state of Hawaii and the United States in general have a long history of colonialism and disrespect for indigenous peoples and cultures, and unfortunately the TMT risks falling onto the wrong side of that history. For now, I think that the moratorium on construction should continue and substantial negotiations should take place, and if that delays the schedule, so be it. If more native Hawaiians and organizations do not decide to support the TMT, the astronomical community should consider a different site or even terminate the telescope altogether. I realize that the cost of either action would be great, considering the huge international investment that has already taken place, but the price of desecrating native Hawaiians’ sacred and protected land is much higher.

I see strong opinions on each side, and many have distributed petitions and sought to gain more public and media support. How will astronomers and Hawaiians proceed? I hope that they will use this time to discuss the situation with respect and as equals, and they may determine whether a resolution that satisfies many eventually can be achieved.

Challenges of the James Webb Space Telescope, NASA’s Successor to Hubble

Everyone grows up eventually. It’s hard to believe, but the Hubble Space Telescope (HST), which many astronomers and astronomy fans consider to be one of the most important telescopes of our generation, turns 25 this month. Hubble, built and funded by NASA and the European Space Agency, was launched on 24th April 1990, only a half year after the fall of the Berlin Wall. Its instruments produced numerous iconic images, including the spectacular ones below.

Everyone is celebrating this anniversary! Check out hubble25th.org for more images, news, and information. The 2010 documentary, “Saving Hubble,” is now viewable for free. Plus, in a public lecture on 1st April as part of National Academies’ Space Science Week, Jason Kalirai (Space Telescope Science Institute) highlighted Hubble’s many scientific contributions.

Crab Nebula (Credit: Hubble Space Telescope)

Crab Nebula (Credit: Hubble Space Telescope)

Galaxy M83 (HST)

Galaxy M83 (HST)

Ultra Deep Field (HST)

Ultra Deep Field (HST)

Now astronomers and the astronomy-loving public are anticipating and preparing for Hubble’s successor, the James Webb Space Telescope (JWST, named after a former NASA administrator). Over its ambitious 5 to 10-year mission (a Star Trek-style time-scale!), its powerful cameras and spectrometers will focus on near- to mid-infrared wavelengths and will examine planetary systems in our galaxy as well as distant galaxies forming in the early universe, only a few hundred million years after the Big Bang. As you can see, it’s built with a folding segmented mirror and a deployable sunshield. It’s not servicable like Hubble was, as JWST will orbit one million miles from Earth.

Artist's impression of NASA's James Webb Space Telescope.

Artist’s impression of NASA’s James Webb Space Telescope.

As I’ve written in previous posts, JWST’s gigantic budget has been contentious in the astronomical community. While astronomers believe that JWST will likely have a big scientific impact, especially on the fields of planetary physics and galaxy formation, others are unhappy that its cost inevitably results in smaller programs being cut. NASA officials prioritize the missions and programs the agency invests in, and it is simply not feasible to fund every exciting project astronomers propose. (JWST’s budget constituted nearly half of NASA’s astrophysics budget for FY 2015.) Based on my conversations with astronomers, the community remains divided about JWST, though many astronomers are excited about the telescope and note its importance for public outreach.

Credit: NASA Astrophysics Division Director Paul Hertz

Credit: NASA Astrophysics Division Director Paul Hertz

Large projects rarely stay on schedule and on budget in astrophysics, but JWST was perhaps an extreme case. A decade ago, JWST faced considerable criticism, such as in this Nature article by Lee Billings, because of its many delays and cost overruns. But after much pressure and threats from Congress to cancel the program, NASA officials rebaselined JWST’s budget and conducted a management overhaul in 2011. Since then, scientists have kept JWST within its new $8.8-billion budget and the telescope is on schedule for launch in 2018.

Last Tuesday, the House Science Committee held a hearing reviewing JWST’s progress, called “Searching for the Origins of the Universe: An Update on the Progress of the James Webb Space Telescope (JWST).” According to the American Institute of Physics, the committee’s Chair and Ranking Member, Rep. Steven Palazzo (R-MS) and Rep. Donna Edwards (D-MD), “expressed, as did other subcommittee members, great interest in and support for the telescope.” According to Cristina Chaplain of the Government Accountability Office, JWST has ten months of unused budget reserves, which will be more than enough as it moves into the integration and testing phase.

A few challenges remain. For example, technicians have had difficulty with a “cryocooler” component, which needs to operate at much colder temperatures than other such units in order to keep the Mid-Infrared Instrument sufficiently cool, but it is still scheduled to be delivered this summer. In any case, both John Grunsfeld, associate administrator of NASA’s Science Mission Directorate, and John Mather, JWST’s Senior Project Scientist, expressed confidence to the Committee that this observatory will launch in 2018. “Expect amazing discoveries,” Mather said.

For more coverage, take a look at these articles in Scientific American, Space News, and Space.com. [Full disclosure: I am a member of the American Institute of Physics, and former colleagues at the University of Arizona helped design JWST’s NIRCam instrument.]

Nine New Dwarfs Discovered in Our Local Group of Galaxies

Just as astronomers are examining dwarf planets, they’re investigating dwarf galaxies too. Two weeks ago, an international collaboration of scientists with the Dark Energy Survey (DES) peered around the southern hemisphere and announced in a paper in the Astrophysical Journal that they found candidates for nine new “satellite” galaxies around our Milky Way. For those of you keeping count—and many people are—if confirmed, this means that we now have 35 satellites in our Local Group of galaxies, which could even tell us something about the dark matter out there.

An illustration of the previously discovered dwarf satellite galaxies (in blue) and the newly discovered candidates (in red) as they sit outside the Milky Way. (Image: Yao-Yuan Mao, Ralf Kaehler, Risa Wechsler.)

An illustration of the previously discovered dwarf satellite galaxies (in blue) and the newly discovered candidates (in red) as they sit outside the Milky Way. (Image: Yao-Yuan Mao, Ralf Kaehler, Risa Wechsler.)

The smallest known galaxies (as might be inferred from their name), dwarf galaxies are extremely faint and difficult to detect, sometimes only containing a few hundred stars and appearing to blend in with the stars in the disk of the Milky Way. They can also be difficult to distinguish from globular clusters, which are just clumps of stars that evolved with a galaxy and orbit around its core.

Astrophysicists refer to galaxies that travel around a larger galaxy as “satellite” galaxies. In many cases, these galaxies were previously floating through space, minding their own business, until the gravitational force of the massive galaxy pulled them in. Some astronomers think that that is what happened to the Small Magellanic Cloud and Large Magellanic Cloud, the brightest satellites of the Milky Way. (The Persian astronomer Abd-al-Rahman Al-Sufi discovered the LMC in 964 A.D., and it does sort of look like a “cloud.”) To give these satellites some perspective, they’re mostly between 100,000-200,000 light-years away, while the Milky Way’s radius is about 50,000 light-years, which is already much longer than the road to the chemist’s.

Keith Bechtol (University of Chicago) and Sergey Koposov (University of Cambridge) led parallel studies with the DES, which uses an optical/infrared instrument on a telescope at the Cerro Tololo Inter-American Observatory in the Chilean mountains. “The discovery of so many satellites in such a small area of the sky was completely unexpected,” says Koposov. These findings only include the first-year data of the DES though, and the research team stands poised to discover as many as two dozen more satellite galaxies as they continue their survey.

Six of the nine newly discovered dwarf satellite galaxies. (V. Belokurov, S. Koposov. Photo: Y. Beletsky.)

Six of the nine newly discovered dwarf satellite galaxies. (V. Belokurov, S. Koposov. Photo: Y. Beletsky.)

In 2005-2006, Koposov and his colleagues (Vasily Belokurov, Beth Willman, and others) found about half of the previously detected satellite galaxies of the Milky Way with the Sloan Digital Sky Survey (SDSS), the DES’s predecessor in the northern hemisphere. The SDSS and DES are powerful enough to detect and resolve faint dwarf galaxies that hadn’t been observed before, transforming this field and stimulating interest in the Milky Way’s neighborhood.

Dwarf galaxies could reveal new information about dark matter, since their mass in stars is outweighed by thousands of times by the mass of dark matter particles surrounding them. Astrophysicists developing numerical simulations of growing clumps of dark matter, thought to host galaxies within them, have been concerned that more satellite clumps form in the simulations than satellite galaxies have been observed in the Milky Way–a discrepancy referred to as the “missing satellites” problem. It’s not clear yet whether the newly discovered satellite galaxy candidates could solve or complicate this problem. Moreover, astrophysicists continue to worry about other problems, including disagreements between observed galaxies and simulations involving the masses and angular momenta of dark matter clumps. In any case, scientists working with the DES continue to push the debate further, and their ongoing survey will be of great interest to the astronomical community.

A simulated dark matter "halo" with satellites, possibly similar to the Milky Way. (Credit: Volker Springel, Aquarius Simulation.)

A simulated dark matter “halo” with satellites, possibly similar to the Milky Way. (Credit: Volker Springel, Aquarius Simulation.)

For more coverage, check out this article by Monica Young in Sky & Telescope and articles in Wired and Washington Post. If you’re interested, you can also see my own earlier research on satellite galaxies in dark matter models and on the Magellanic Clouds.

NASA Missions Exploring Dwarf Planets Ceres and Pluto

Now I’m not a planetary astronomer, but like you, I’m excited by any kind of space exploration, and this year the NASA missions, Dawn and New Horizons, will give us the closest and most detailed views of dwarf planets yet.

What is a “dwarf planet,” you ask? Excellent question. Until about ten years ago, astronomers usually referred to small planet-like objects that were not satellites (moons) as “planetoids.” In some ways, they resembled the eight more massive planets in our solar system as well as Pluto, which had a borderline status. Astronomers discovered Charon, Eris (previously called 2003 UB313), and Ceres, and they expected to discover many more, likely rapidly expanding the ranks of our esteemed class of planets. Either they all had to be included, or a clear classification system would have to be determined and Pluto would be reclassified.

Courtesy: IAU

Courtesy: IAU

At the International Astronomical Union (IAU) meeting in Prague in 2006, astronomers opted for the latter in Resolution 5. They demoted poor Pluto, but I think they did the right thing. (I was working in Heidelberg, Germany at the time, and if I’d known how historic this IAU meeting would be, maybe I would’ve tried to attend!) The IAU’s defines a dwarf planet as “a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.” The criterion (c) is the important one here, because it means that the object has not become gravitationally dominant in its orbital zone, which is the case for Pluto and the other planetoids beyond Neptune and for Ceres, the only dwarf planet in the asteroid belt between Mars and Jupiter. These are contentious issues, and the debate even made it into the New Yorker. But let’s be clear: these things are small, and they’re all less massive than Earth’s moon.

We don’t know as much about dwarf planets as we do about the planets in our system, so let’s go exploring! What do these new space missions have in store for us?

Ceres

In 2007, NASA launched the Dawn spacecraft to study Ceres up close. A couple days ago, two centuries after Sicilian astronomer Father Giuseppe Piazzi discovered Ceres, Dawn became the first spacecraft to orbit a dwarf planet. As the deputy Principal Investigator Carol Raymond put it on Friday, this is an “historic day for planetary exploration.” Jim Green, NASA’s Planetary Science Division Director, says that with Dawn, we are “learning about building blocks of terrestrial planets in our solar system.”

Dawn has obtained excellent detailed images already, as you can see in the (sped up) animation below.

Credit:  NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Credit:
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The pair of bright spots in a crater stand out, and astronomers are trying to figure out what they are. They might be an indication of geological activity on it’s changing surface. Ceres has a rocky core and an ice layer, and it’s also possible that these are reflective patches of ice that have been exposed by space rocks falling in and striking the surface. For more information, check out this blog post by Emily Lakdawalla and these articles in the LA Times and Wired.

As Dawn uses its propulsion systems to reshape its orbit and get closer views, astronomers expect to learn more about those spots, look for plumes, and examine the surface for strange craters or other distinguishing features. The spacecraft will later turn on its spectrometers and determine which minerals are present and how abundant they are.

Pluto

NASA launched New Horizons in 2006, and it had much farther to travel to reach Pluto. In January, NASA announced that New Horizons is making its approach to the erstwhile planet, though it’s still about 200 million kilometers away. Mark your calendars: it will fly by Pluto (as it will be traveling too fast to orbit) on 14th July, and at a distance of only 13,000 km, New Horizons’ instruments will obtain the best images yet of it. For more information, check out this article by Jason Major in Universe Today and Phil Plait in Slate.

Distant image of Pluto by New Horizons. Credit: NASA/Johns Hopkins APL/Southwest Research Institute.

Distant image of Pluto by New Horizons. Credit: NASA/Johns Hopkins APL/Southwest Research Institute.

A couple ago, leaders in planetary astronomy highlighted the importance of Dawn and New Horizons in their Decadal Survey. I think both space missions will turn out to be worthwhile, and let’s stay tuned to see what they discover over the next few months.