When is exoplanet news “juicy”? Yesterday at a Kepler press conference held at NASA Ames, Roger Hunter, Kepler project manager, introduced the proceedings as juicy. And as three scientists presented the findings, it turned out to be a good adjective. The researchers believe they have discovered the first water worlds (besides Earth) in our galaxy.

Two systems are providing new evidence of rocky Earth-like planets in the habitable zone—the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water. Kepler 62 has five planets total, but two of those, 62e and 62f, orbit inside the habitable zone. Kepler 69 has two planets but only one in the habitable zone, 69c.

For exoplanets and their stars, size matters when it comes to habitability. At 1,200 light years away, the star Kepler 62 is two-thirds the size of our Sun. That brings the habitable zone in a bit closer to the star. The two planets of interest, 62e and 62f, are 1.6 and 1.4 times the diameter of Earth, respectively. This also puts them in the “just-right” size for habitability.

At the press conference, William Borucki, Kepler science principal investigator at NASA Ames, said that 62e and 62f “are the best candidates to be habitable, not just within the habitable zone.”

Computer models suggest that the largest rocky planets will have a diameter no greater than 1.5 times that of Earth’s, explained Lisa Kaltenegger of the Max Planck Institute for Astronomy and Harvard-Smithsonian Center for Astrophysics. And a planet’s mass, between 1.2-2.5 times Earth’s mass, can be an indicator for liquid water. While Kepler 62e and 62f are too small to measure their mass, Kaltenegger and her team’s modeling makes these planets very wet, indeed.

Kepler 69c, on the other hand, is 2,700 light years away and 1.5 times Earth’s diameter. It orbits near the inner, hotter edge of its star’s habitable zone. Thomas Barclay, Kepler scientist from the Bay Area Environmental Research Institute, likens it to a super Venus, rather than a super Earth. “We don’t have anything like it in our solar system,” he said.

“The Kepler spacecraft has certainly turned out to be a rock star of science,” said John Grunsfeld, at NASA Headquarters in Washington. “The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity.”

The findings are published this week in Science (Kepler 62) and the Astrophysical Journal (Kepler 69).

For an interactive on Kepler’s planetary discoveries and their orbits, click here.

Image: NASA Ames/JPL-Caltech

After avoiding exoplanets in my first post from this meeting, I’ll take a stab at the topic today, but I hope to put some of the announcements in context. And luckily, one of the presentations here provides a perfect launching-off point for thinking about the current state of affairs.

Like many professional organizations, the AAS hands out awards: one example, the Newton Lacy Pierce Prize, honors outstanding achievement in observational astronomy, and award winners deliver a lecture to conference attendees about their work. This year, John A. Johnson of Caltech received the honor, and he presented a lively talk, “Hot on the Trail of Warm Planets around Cool Stars.” (If you attended the Academy’s Benjamin Dean Lecture Series last spring, you might have caught Johnson’s presentation in the Morrison Planetarium.)

In the maelstrom of exoplanet announcements (I’ll mention a few below), the big picture sometimes gets lost. But Johnson avoided getting mired in minutiae by framing his talk with the overarching process of making sense of new discoveries… The first question to ask: do the objects in question actually exist? If so, as we discover more of them, what can we learn from the statistical ensemble, or how do we think of them as a collection of objects? And finally, what are their detailed properties?

For exoplanets, the first question was answered more than twenty years ago with the discovery of a planetary system around a pulsar (not someplace you’d want to call home), followed a few years later by the announcement of a planet orbiting a main-sequence (more ordinary) star. Thus, we confirmed that exoplanets exist.

Over the intervening years, the astronomical community—Johnson included—has moved onto the second and third challenges. The statistical challenges are especially evident at this meeting.

The all-important Kepler Mission has revolutionized the exoplanet-finding business, and indeed, the Kepler team announced 461 new planetary candidates this week, bringing the total to 2,740 (these have yet to be confirmed as planets, although the success rate seems to be greater than 90%). But the mission’s primary goals all center on cataloging extrasolar planetary systems in a fundamentally statistical fashion: look at one part of the sky in great detail and then extrapolate (mathematically, responsibly) those results to the galaxy as a whole.

Astronomers thus use the Kepler data to estimate how many stars have planets with specific characteristics. Johnson’s team, for example, announced this week that our galaxy is home to “at least 100 billion planets,” roughly equivalent to the number of stars in the galaxy. Using similar techniques, astronomer Courtney Dressing announced that, “with 95% confidence, there is a transiting Earth-sized planet in the habitable zone of small star within [roughly 100 light years].” Many other groups are trying to make similar statistical predictions.

And the third stage? Investigating the detailed properties of these objects? Johnson mentioned a few of his favorites: a planet that orbits its parent star in the opposite direction that the star itself rotates, a tiny planetary system that resembles Jupiter and its moons, and of course, the system that led to his aforementioned recent announcement. And many reports from this week’s meeting also fall into this category…

Paul Kalas and James Graham, both at U.C. Berkeley announced that the hotly-debated Fomalhaut planet (pictured above) appears to follow a highly elliptical orbit around its parent star, getting as “close” 4.6 billion miles (that’s about 40 times farther than Earth ever gets from the Sun) and as far as 27 billion miles away!

Another team of astronomers has detected evidence for an asteroid belt around the star Vega. This makes Vega much like Fomalhaut, and a nifty image compares the two systems.

Much talk centers on finding planets around stars like the Sun—mostly in hopes of finding Earth-like planets where life could exist. But we know of planets around other, weirder stars (cf. my mention of pulsar planets above), and these can shed light on how our own solar system has evolved. In particular, we’re seeing evidence that many white dwarfs have been “polluted” by debris from planets that orbited them previously: our own Sun will end its life as a white dwarf, and the net result of this discovery is that Earth-like planets could be quite common.

And finally, a combined effort by two space-based observatories has given us a glimpse at the weather on a brown dwarf, and similar techniques could eventually tease out weather on exoplanets as well.

Stay tuned for more astronomy the rest of the week…

Image: NASA, ESA, and P. Kalas (University of California, Berkeley and SETI Institute)

I’m not going to get into exoplanet announcements such as this one or this one from yesterday morning’s meeting (as one attendee tweeted in summary, “There’s more exoplanets than you can shake an exostick at.”). We have ten press conferences scheduled, and three of them revolve around (pun intended) exoplanet discoveries. So I’ll plan for an exoplanet wrap-up toward the end of the conference.

Instead, I’d like to talk about the work of a few of those spiffy space-based telescopes—yes, the ever-popular Hubble Space Telescope, but also Chandra X-Ray Observatory and a new mission known as NuSTAR.

A grand effort known as the Hubble Ultra Deep Field (HUDF) has imaged the same, small, seemingly-dull part of the sky repeatedly at numerous, finely-tuned wavelengths of light, revealing distant galaxies that reside farther than just about anything we can see. Looking out into space means looking back into time, so the HUDF reveals an important epoch in the history of the Universe.

It turns out the Universe in its youth went through an unusual phase when most of the hydrogen in deep space was in the form of molecules, with no net electrical charge… By the time the Universe reached the age of about 800 million years, however, most of the hydrogen had become ionized, which is to say broken down into electrons and protons (both of which have electrical charge). But it takes energy to ionize hydrogen, so where did that energy come from?

This is the kind of puzzle that keeps astronomers busy (and employed) for decades. Since 2004, astronomers have refined and extended the HUDF observations to eke out more information about this epoch, and the most recent observations have allowed scientists to reach some well-founded, long-sought conclusions.

We know that young galaxies would emit radiation that could ionize the Universe, but can they produce enough radiation to light up the “Cosmic Dawn,” as it’s sometimes called? Astronomers love to come up with more exotic theories, such as the annihilation of dark matter, to explain things like this, but are such puzzling processes required?

Turns out they aren’t. Galaxies can do the job on their own. That’s not the sexiest answer, but it should ultimately feel quite satisfying: the Universe behaves in a way that we understand and can predict. But it took a remarkable amount of sleuthing to come up with this relatively mundane response.

First off, we tally up the galaxies we see, and we estimate how much radiation they would emit. And the first surprise? Small, faint (the researchers like to call ’em “feeble”) galaxies make a significant contribution to the total energy output, and the large, luminous can’t do the job on their own.

Turns out that the currently-observed population of galaxies does not produce enough radiation to ionize all that intergalactic hydrogen. Bummer. But we know that we’re not seeing all the galaxies! We can detect only the brightest ones at these great distances, and the HUDF team’s work suggests that an earlier generation of galaxies existed before the ones we’re seeing. So how can we estimate the energy contribution from what we’re not seeing directly?

The team of astronomers undertook the challenge of tallying the luminous galaxies versus the number of feeble galaxies, and projecting those estimates back in time. Based on HUDF and other observations from, for example, the Wilkinson Microwave Anisotropy Probe (WMAP), we can determine when stars and galaxies started lighting up the Universe, so when the team added up all the light from all the galaxies they estimated to have existed over that time… Bingo! Just enough light energy to ionize the Universe’s hydrogen.

All this work actually pushed Hubble to its limits. And it promises many more discoveries from the James Webb Space Telescope, due to launch in 2018, which will peer back farther in time to see earlier generations of galaxies.

Hubble isn’t alone out there, and x-ray astronomy in particular benefits from having telescopes in space. Stephen S. Murray from Johns Hopkins gave a review of “50 Years of X-Ray Astronomy,” describing remarkable successes in the field. From 1962 to 1999, x-ray astronomy has experienced an increase in sensitivity of 10 billion! (And Murray noted that it took astronomers 400 years to achieve that kind of gain in optical sensitivity…) That kind of revolutionary change has led to spectacular discoveries related to some of the most exotic objects in astronomy—including black holes, pulsars, and supernovae.

An impressive video from Chandra shows a curlicue jet streaming from the pulsar at the center of the Vela Supernova Remnant. This complex structure provides a nifty puzzle for astronomers to describe its origin.

And the recently-launched Nuclear Spectroscopic Telescope Array (NuSTAR), one of the least expensive missions ever launched by NASA, has released its first images. The pair of telescopes spotted two bright, energetic sources of x-rays in the galaxy IC 342—capturing black holes in the process of “feeding” (as NuSTAR team leader Fiona Harrison puts it).

Stay tuned for more spacy stuff the rest of the week…

NuSTAR image courtesy of CalTech

The third Thursday of every month, give or take, Morrison Planetarium hosts “Universe Update” at the 6:30 planetarium shows during NightLife. We select our favorite astronomy stories from the past month, and give a brief run-down of current discoveries while taking audiences on a guided tour of the Universe.

We always start at Earth and work our way out to cosmological distances, and we’ll list the news stories in the same order—from closest to farthest from home.

Let’s start at Mars. Curiosity, the latest addition to our growing team of Martian rovers, landed on the Red Planet just a few months ago.  Previous landers sent back pictures and performed basic measurements, but Curiosity brought an entire geology and chemistry lab on a 225-million-kilometer expedition to Gale Crater, where the rover is using its instruments to search for evidence of Mars’s past.

In its “rocknest,” Curiosity found wind-swept dunes containing material similar to volcanic soil in Hawaii.  After vaporizing samples with its onboard laser, Curiosity’s CheMin instrument then used X-ray diffraction to search for clues to understanding the history of Mars’s atmosphere.  Evidence suggests that Mars once had a much thicker atmosphere, which disappeared a long time ago, leaving the thin layer we observe today.  As previous landers found layers of frozen water beneath Mars’s surface, Curiosity is taking the next step, equipped to hunt for methane, an organic molecule that’s a good indicator of life.  So far, Gale Crater seems devoid of this malodorous precursor, but Curiosity has two years and many kilometers of Martian soil to cover.

Our next stop is the giant asteroid Vesta: over 500 kilometers in diameter (the distance from San Francisco to Los Angeles), it’s the second-largest asteroid in our solar system.  The Dawn mission photographed it for over a year, looking at Vesta as a good example of what Earth may have looked like when it was just a wee baby protoplanet.  The big differences between light and dark in these photos puzzled scientists, since asteroid terrain isn’t usually so varied.  Space weathering should homogenize the surface, leaving a matte gray all over the surface.  But scientists now think that the dark material comes not from Vesta but from 300 smaller asteroid impacts over the last 3.5 billion years, each of which brought material such as the metallic dust, carbon, and hydrated minerals (minerals containing water) Dawn detected.  This mélange can account for the difference in light and dark areas, wrapping Vesta in powdered asteroid debris, one-to-two meters thick.

With a constant influx of data, astronomers are discovering new exoplanets faster than ever.  Re-examining old data can produce useful results, too, and astronomers have just announced that a planet somewhere between Earth- and Neptune-sized is orbiting HD 40307.  Despite only being three quarters as massive as our Sun, this star hosts six planets in total.  Most importantly, the new planet is orbiting right in that habitable sweet spot: not too cold and not too hot, this is a strong contender to have liquid water, that necessary ingredient for life on Earth (and very possibly elsewhere).

Our view of the stars from Earth is strictly two-dimensional, and even with visualizations like the planetarium’s Digital Universe, we still rely on our Earth-bound view to determine distances to objects in space.  A new image (see above) from a 340-megapixel camera on a telescope in Hawaii has found a heretofore unidentified cluster of stars in the familiar Orion constellation.  The most studied part of our night sky, the Orion Nebula turns out to have many layers, and the stars we see in the middle are in fact older stars closer to us than we previously suspected.

Two twelve-billion-year-old supernovae live far, far from our starting point on Earth: because looking out into space also means looking back in time, the Universe has changed a lot since these stars exploded, so it’s hard to give you a distance in kilometers or even lightyears, but one of them holds the record as the most distant supernova yet observed.  Needless to say, these are very, very old explosions that came from even older, supermassive stars, the likes of which don’t exist in the nearby, more recent Universe.

As the Universe continues to accelerate outward, the light we can see here on Earth fades into the cosmos.  In a few billion years, information from these distant galaxies simply won’t make it to Earth anymore, and we’ll be living in a rather empty neighborhood.  The parallels with the economic downturn are a little alarming, and a press release from a group of European cosmologists hammers it home.  It turns out that stars in the Universe are only forming at 1/30 the rate they once were: a cosmic market crash that looks to continue till the end of time.  The Universe seemed to peak about 11 billion years ago… Let’s hope the same isn’t true for the American GDP!

Dan Brady is a planetarium presenter at the California Academy of Sciences. He earned his BS in Physics from UCLA and has taught science since 2008.

Image: CFHT/Coelum (J.-C. Cuillandre & G. Anselmi)

Two researchers hypothesize that an asteroid belt, just the right size and distance from its star, might be necessary for a star system to support a life-bearing planet.

This might sound surprising, since asteroids can occasionally impact Earth and trigger mass extinctions. Ouch! But an emerging view proposes that asteroid collisions with planets may provide a boost to the birth and evolution of complex life.

For one thing, asteroids delivered water and organic compounds to the early Earth. Consistent with the theory of punctuated equilibrium, occasional asteroid impacts might also accelerate the rate of biological evolution by disrupting a planet’s environment to the point that species must evolve new adaptation strategies.

Rebecca Martin, of the University of Colorado, and Mario Livio, of the Space Telescope Science Institute, looked at our solar system and used theoretical models and actual observations of other star systems and exoplanets to study the theory that life needs an asteroid belt.

They suggest that the location of an asteroid belt relative to a Jupiter-like planet is particularly favorable to life. The asteroid belt in our solar system, located between Mars and Jupiter, is a region of millions of space rocks sitting near the “snow line,” beyond which volatile materials such as water ice are far enough from the Sun’s heat to remain intact.

Our solar system’s formation was just right for life, Livio says. “To have such ideal conditions you need a giant planet like Jupiter that is just outside the asteroid belt [and] that migrated a little bit, but not through the belt,” he explains. “If a large planet like Jupiter migrates through the belt, it would scatter the material. If, on the other hand, a large planet did not migrate at all, that, too, is not good because the asteroid belt would be too massive. There would be so much bombardment from asteroids that life may never evolve.”

Using our solar system as a model, Martin and Livio proposed that asteroid belts in other solar systems would always be located approximately at the snow line. They created models of protoplanetary disks, the dense gas and dust around a newly formed star; then they looked at observations from NASA’s Spitzer Space Telescope of 90 such regions that have warm dust, which could indicate the presence of an asteroid belt-like structure. The warm dust fell right near the snow line.

But for life to exist, the system also needs a large gas giant, like Jupiter, to “manage” the size of the asteroid belt. So Martin and Livio looked at data for 520 giant planets found outside our solar system. Only 19 of them reside outside the snow line, suggesting that most of the giant planets that formed outside the snow line have migrated too far inward to preserve the right-sized asteroid belt needed to foster life on an Earth-like planet near the belt. The team calculated that less than four percent of the observed systems may actually harbor such a compact asteroid belt.

“Our study shows that only a tiny fraction of planetary systems observed to date seem to have giant planets in the right location to produce an asteroid belt of the appropriate size, offering the potential for life on a nearby rocky planet,” says Martin. “Our study suggests that our solar system may be rather special.”

Their findings are published in the Monthly Notices of the Royal Astronomical Society: Letters.

Image: NASA, ESA, and A. Feild (STScI)

Phil Plait seemed to appreciate the news just as much. His Discover headline read in all-caps, “ALPHA CENTAURI HAS A PLANET!”

Let’s analyze all of this excitement…

Yesterday, astronomers announced they discovered an Earth-sized planet orbiting Alpha Centauri. The finding is also published in Nature today.

Alpha Centauri lies only 4.3 light-years away—closer than any other star system. And it’s not one star but three—two binary stars similar to the Sun orbiting close to each other, called Alpha Centauri A and B, plus a more distant and faint red companion known as Proxima Centauri. Since the nineteenth century, astronomers have speculated about planets orbiting these bodies, the closest possible abodes for life beyond the Solar System, but searches of increasing precision had revealed nothing. Until now.

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” says Xavier Dumusque, lead author of the paper. “It’s an extraordinary discovery and it has pushed our technique to the limit!”

A period of 3.2 days means that this new planet orbits extremely close to its parent star, “roasting at perhaps 2,200 degrees Fahrenheit with a surface likely composed of molten lava,” writes Adam Mann in Wired. Not exactly a hospitable neighbor! (Sorry, Mr. Rogers.)

This news comes right on the heels of another exoplanet discovery. On Monday, our friends at Zooniverse announced the first ever confirmed exoplanet discovered by the citizen scientists at Planet Hunters—a gas giant dubbed “PH1” with a radius about 6.2 times that of Earth, making it a bit bigger than Neptune. PH1 resides in a four-star system—twin suns that in turn are orbited by a second distant pair of stars.

These discoveries provide further evidence that, with the number of eyeballs looking for exoplanets (professional astronomers and citizen scientists alike), an Earth-like exoplanet can’t be far off. Again from the Bad Astronomer:

…we’re zeroing in on Terra Nova, folks, and statistically speaking there should be millions of them in the galaxy. It’s only a matter of time before we find the first one.

Image: ESO/L. Calçada

It was a weekend full of aliens and black hole theories at the Hyatt Regency in Santa Clara, California. Scientists, professors, artists, authors, and science enthusiasts gathered for SETIcon II, a conference organized by the SETI Institute to learn about and celebrate recent developments in the search for extraterrestrial intelligence.

The conference consisted of a series of panels discussing everything from potential asteroid resources to Hollywood Sci-Fi movies.

Each discussion had a diverse set of panelists that complimented each other—each speaker with a different background, adding different perspectives to each panel. For example, in a panel titled “Black Holes in Space—Hearts of Darkness”, Robert J. Sawyer, Andre Bormanis, Alex Filippenko, and Leonard Mlodinow discussed theories about black holes while also calling upon movies and books to identify and clarify any misconceptions.

Alex Filippenko, Seth Shostak, Richard Rhodes, and Marc Okrand even discussed religion (with much sensitivity… especially because SETI has been accused of being a religion) during the “Did the Big Bang Require a Divine Spark?” panel.

The panelists Cynthia B. Phillips, Mark R. Showalter, and Charles Lindsay informed the audience about planetary art in “The Magnificence and Majesty of the Outer Solar System” while a slideshow of the artfully embellished planets played in the background.

In addition to the regular excitement about science, the conference was heavily fueled by Kepler’s recent success. The Kepler telescope is currently looking for planets in the habitable zone, because these planets are likely to be more earth-like and therefore more likely to be suitable for life.

The telescope has already found over 2,000 transiting planets, an abundance that led NASA to approve the extension of the Kepler mission until 2016. The panelists could not hide their enthusiasm: such success in the search for extraterrestrial intelligence is worthy of celebration.

The conference also included an evening honoring Jill Tarter, director of the search for intelligent life and inspiration for Jodie Foster’s role in the movie, “Contact”.

Whether a Battlestar Galactica enthusiast or a NASA researcher, it was truly a conference for everyone.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and volunteers for the Morrison Planetarium.

Perhaps our solar system is rarer than we thought.

As astronomers search for exoplanets, the bigger, more massive planets prove easier to spot.  One of the easiest type of planets to find are hot Jupiters, planets similar in size to Jupiter that maintain a very close and fast orbit around their parent stars—even closer than Mercury orbits around our Sun! (For comparison, Jupiter orbits the Sun more than 20 times farther away than Mercury.) These big, hot planets have enough mass to exert a noticeable gravitational pull on their hosts.

There is more to these planets than meets the eye… Or perhaps less than meets the eye, according to a recent study published in the Proceedings of the National Academy of Sciences.

Typically, a hot Jupiter doesn’t have any companion planets—you might think of it as an only child compared to our family of eight planets orbiting the Sun. Astronomers theorize that many of these massive planets migrated from a large orbit to a smaller one. Their gravitational influence simply ejected other planets that got in their way. Even if a system started out with multiple planets, it might end up with only one.

Astronomers at the Fermilab Center for particle Astrophysics used data from NASA’s Kepler mission to look for transiting planets (we can see this in our own solar system on June 5th when Venus transits the Sun). The researchers analyzed 63 hot Jupiters, 31 warm Jupiters (which reside in slightly larger orbits around their parent stars), and 222 hot Neptunes (close to their parent stars, but not as hefty as hot Jupiters). The research team found no additional planets in any of the hot Jupiter systems, but on average, they found evidence for three possible companion planets around warm Jupiters, and two around hot Neptunes.

These results could imply that our home is unusual than other planetary systems. “The implications of these findings are that systems with Earth-like planets formed differently than systems with hot Jupiters,” says co-author Alan Boss. “Since we believe that hot Jupiters formed farther out, and then migrated inward toward their stars, the inward migration disrupted the formation of Earth-like planets. If our sun had a hot Jupiter, we would not be here.”

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and volunteers for the Morrison Planetarium.

Image: NASA, ESA, and G. Bacon

An international research team, which includes astronomers from UC Santa Cruz, has discovered a new exoplanet in a system about 22 light years from Earth (pretty close, in the scheme of things). The planet, called GJ 667Cc, has an orbital period of 28.15 days and a minimum mass of 4.5 times that of Earth—and it sits smack dab in the parent star’s habitable zone.

Its host star is a member of a triple-star system and has a different makeup than our sun, with a much lower abundance of elements heavier than helium (such as iron, carbon, and silicon). This discovery indicates that potentially habitable planets can occur in a greater variety of environments than previously believed.

The new planet receives 90 percent of the light that Earth receives. However, because most of its incoming light is in infrared wavelengths, the researchers speculate that the planet absorbs a higher percentage of this incoming energy. When both these effects are taken into account, the planet is expected to absorb about the same amount of energy from its star that the Earth absorbs from the sun.

The researchers used public data from the European Southern Observatory and analyzed it with a novel data-analysis method. They also incorporated new measurements from the W. M. Keck Observatory’s High Resolution Echelle Spectrograph and the new Carnegie Planet Finder Spectrograph at the Magellan II Telescope. Their planet-finding technique involved measuring the small wobbles in the star’s motion caused by the gravitational tug of a planet.

The team found that the system might also contain a giant planet and an additional super-Earth with an orbital period of 75 days. However, further observations are needed to confirm these two possibilities.

“This was expected to be a rather unlikely star to host planets. Yet there they are, around a very nearby, metal-poor example of the most common type of star in our galaxy,” says Steven Vogt, a professor of astronomy and astrophysics at UCSC. “The detection of this planet, this nearby and this soon, implies that our galaxy must be teeming with billions of potentially habitable rocky planets.”

“This planet is the new best candidate to support liquid water and, perhaps, life as we know it,” according to team lead Guillem Anglada-Escudé of the Carnegie Institution for Science.

The finding is published in Astrophysical Journal Letters.

Image: Guillem Anglada-Escudé, Carnegie Institution

The third Thursday of every month, the Morrison Planetarium hosts “Universe Update” at the 6:30 planetarium show during NightLife. I select my favorite astronomy stories from the past month, and I give a brief run-down of current discoveries while taking audiences on a guided tour of the Universe. As you may or may not know, the planetarium sports a three-dimensional atlas of the Universe, so we can take you places virtually while talking about the latest astronomy news.

I always start at Earth and work my way out to cosmological distances, so I’ll list the news stories in the same order—from closest to farthest from home.

Fourth graders from the Emily Dickinson Elementary School in Bozeman, Montana, proved themselves more creative than NASA engineers! Crazy rocket scientists named their two lunar-orbiting spacecraft “GRAIL-A” and “GRAIL-B” (where, of course, “GRAIL” is an acronym, which stands for “Gravity Recovery and Interior Laboratory”). The elementary school students selected the names “Ebb” and “Flow,” which NASA selected as the winning contribution in a nationwide contest. The GRAIL mission measures the ebb and flow of gravity, in a sense, as the two spacecraft orbit the Moon and measure variations in its gravitational pull. From the GRAIL website:

As they fly over areas of greater and lesser gravity, caused both by visible features such as mountains and craters and by masses hidden beneath the lunar surface, they will move slightly toward and away from each other. An instrument aboard each spacecraft will measure the changes in their relative velocity very precisely, and scientists will translate this information into a high-resolution map of the Moon’s gravitational field.

A little farther from home, new reports from a comet impact on the Sun that took place last July. We like to describe comets as “dirty snowballs,” and as you might imagine, a comet getting too close to the Sun stands a snow ball’s chance in… Well, a million-degree plasma irradiated by incident solar flux. The comet evaporated over a period of about 20 minutes, and as described in a paper that appears in today’s Science magazine, it probably measured between 150 and 300 feet across and had a mass equivalent to an aircraft carrier. According to Karel Schrijver, a solar scientist at Lockheed Martin in Palo Alto, the comet moved speedily to its demise: “It was moving along at almost 400 miles per second through the intense heat of the Sun—and was literally being evaporated away.”

A fair bit farther from the scorching heat of the Sun, the Dawn spacecraft is sending back gorgeous images of the asteroid Vesta, including this gorgeous snapshot of a crater on the asteroid’s surface. Dawn has entered a low-altitude orbit that gives it a close look at the potato-shaped planetoid. Learning more about such objects should help us better understand the formation of the solar system, and after its stay at Vesta, Dawn will move on to Ceres, the dwarf planet (like Pluto) that resides between the orbits of Mars and Jupiter.

Beyond our own solar system, of course, we are rapidly discovering planets in orbit around other stars: these extrasolar planets (or exoplanets) now number in excess of 700, and astronomers find more all the time.

As I described in one of my updates from the American Astronomical Society meeting last week, astronomers have announced the discovery of the most compact extrasolar planetary system yet detected. Looking at the KOI 961 system side-by-side with Jupiter and its major satellites strikes me as a particularly illuminating comparison: only 70% larger than Jupiter, the host star (the smallest known to have planets) has at least three planets (the smallest yet found) in orbit around it, the smallest of which is about the size of Mars. John Johnson, an astronomer at Caltech, announced the superlative system last week, and on April 2nd, he will give a talk in the Morrison Planetarium as part of our Benjamin Dean Lecture Series, “The Quest for Habitable Planets Orbiting Red Dwarfs.”

And astronomers have help in their search. Just this week, we had a glimpse into the democratization of astronomy… Viewers of a British television program(me) may have discovered a new exoplanet! Evidence from the Kepler mission suggests the existence of a Neptune-sized planet around the star SPH10066540, orbiting every 90 days at a distance equivalent to Mercury from our Sun. The discovery awaits confirmation, but you don’t have to watch telly in the U.K. to join in the search for such objects. You can go to the PlanetHunters website and start sifting through Kepler data in hopes of finding a planet of your own…

In another of my posts last week, I mentioned the spectacular new Spitzer image of Cygnus X, a massive star-forming region in the constellation (you guessed it) Cygnus. Ten times the size of the Orion Molecular Cloud Complex, Cygnus X appears to host some 26,000 possible young stellar objects, according to an announcement last week.

Moving farther from home, I talked a bit about the new dark matter map that I previously described in a post from Austin. It turns out that analyzing the light from 10 million galaxies call tell you a lot about where dark matter resides, and since dark matter drives the formation of much of the structure in the Universe, that knowledge helps us understand more about the evolution of the cosmos…

The dark matter maps tell one part of the story, but we also rely on studies of the cosmic microwave background to tease out how the Universe has evolved over time. Since 2003, the gold standard of such measurements have come from the Wilkinson Microwave Anisotropy Probe (WMAP). But ESA’s Planck mission recently completed its survey of the cosmic microwave background: the sensor used to make the observations ran out of its coolant a little less than a week ago. It had collected more than two years’ worth of data, however, and the first new high-resolution maps will be released early next year. (Hey! It takes a while to process all that data.)

That’s all for now. Check back for next month’s update! Or come to NightLife on Thursday, 15 February, and check out “Universe Update” live in the Morrison Planetarium.

Ryan Wyatt is the director of the Morrison Planetarium and Science Visualization at the California Academy of Sciences.

Image: SOHO (ESA & NASA)