With much of the US east coast to the north of me digging out from the recent storm, I can only think how fortunate I am not to be trying to travel right now. The snow-clogged airports and snarled streets that are all over the news do have their effect on my thinking, though, which may be why I was reminded this morning of a much colder place, a certain Saturnian moon whose most recent image now offers yet more proof of the active hydrology going on there. Titan got a bit lost in the shuffle here late last week but I don't want to ignore this compelling new image. What we're looking at is the flash of sunlight reflecting off one of Titan's lakes. It's not a huge surprise, given that we've identified lake-shaped basins that ought to have been ideal for liquid methane. But now that the Sun is directly illuminating the northern lakes as spring breaks out on that part of Titan, we can take advantage of conditions there to see things like this, taken with Cassini's visual and infrared...

What a welcome event the release of James Cameron's new film Avatar must be for scientists working on the question of exomoons -- satellites orbiting extrasolar planets. Imagine being a Lisa Kaltenegger (CfA) or David Kipping (University College London), hard at work exploring exomoon detection and possible habitability when a blockbuster film is released that posits a habitable moon around a gas giant. The film's exomoon, called Pandora, fits a scenario that exomoon hunters tell us could exist, orbiting a giant planet in the habitable zone of its star, and it draws public attention as never before to exoplanet and exomoon detections. Interesting exomoon scenarios beyond gas giants are also possible, as this image shows. We're learning that we can detect exomoons using tools like transit time duration measurements, and there are other methods, too, like microlensing and distortions of the Rossiter-McLaughlin effect. A paper from Kipping that we examined here recently makes the case...

Picking up on yesterday's theme of planetary detections from ground-based observatories, we now get word of the detection of a transiting 'super-Earth' -- one that may well have an atmosphere we can study -- with the kind of equipment many amateurs already use to observe the sky. The new world is GJ 1214b, about 6.5 times as massive as the Earth, orbiting a small M-dwarf about a fifth the size of the Sun some forty light years from Earth. But there's more, a good deal more. At a distance of 1.3 million miles, the planet orbits its star every 38 hours, with an estimated temperature a little over 200 degrees Celsius. Because GJ 1214b transits the star, astronomers are able to measure its radius, which turns out to be 2.7 times that of Earth. The density derived from this suggests a composition of about three-fourths water and other ices and one-fourth rock. Some of the planet's water should be in the form of exotic materials like Ice VII, a crystalline form of water that is found at...

What jumps out at the reader when examining yesterday's exoplanet news is not so much that we've found as many as six low-mass planets, but that the two stars involved are both near twins of the Sun. Steven Vogt (UC-Santa Cruz) and Paul Butler (Carnegie Institution of Washington) led this work, and Vogt is quick to point out that two of the planets are 'super-Earths,' the first we've ever found around stars so similar to our own. Vogt notes this has implications for the broader hunt for planets that could sustain life: "These detections indicate that low-mass planets are quite common around nearby stars. The discovery of potentially habitable nearby worlds may be just a few years away." A Bonanza Around 61 Virginis And Sun-like they are, these stars. 61 Virginis, 28 light years from Earth, has long fascinated astrobiologists because it is more similar to the Sun than any of our nearest neighbors in terms of age, mass and other properties. Moreover, a separate team working with the...

We don't exactly know what to call GJ 758 B, which may be a brown dwarf or simply a large planet of between ten and forty Jupiter masses. But the detection is being hailed as the first direct observation of a 'planet-like object' orbiting a star similar to our own Sun. We have the new High Contrast Coronagraphic Imager with Adaptive Optics (HiCIAO), recently attached to the Subaru Telescope and working in the near infrared, to thank for the detection. Image: The August 2009 discovery image of GJ758 B and C, taken with Subaru HiCIAO in the near infrared wavelength. Without angular differential imaging, the star's speckle halo (burst-like feature in the center) would overwhelm the signals from the planet candidates. Credit: Subaru Telescope/NAOJ. Masking the star's intense light and using a technique known as angular differential imaging, HiCIAO seems to promise great things in the way of future direct detections of exoplanets, where the object is directly seen rather than having its...

You won't want to miss an interview with Debra Fischer now available on the MarketSaw site. The latter is a blog focused on 3D motion pictures, and thus the interest in Fischer's work on Alpha Centauri draws from a cinematic base. Specifically, James Cameron's new movie Avatar depicts a gas giant with a habitable moon around it, and the MarketSaw editors are interested in whether such a planet could exist around one of the Centauri stars. The interview that follows, discussing Fischer's ongoing hunt for Centauri planets, is prime reading. I'll quote from it, but you'll want to read the whole thing (thanks to Vincenzo Liguori for the tip). As to the gas giant question, we can answer that one quickly. Neither Centauri A nor Centauri B is orbited by a gas giant. We know this because enough data have accumulated on the question to rule such planets out. Stable orbits, says Fischer, don't reach out much further than 2 AU around either star, and the lack of gas giants leaves smaller worlds...

To the two ongoing hunts for planets around the Alpha Centauri stars we can now add a third. John Hearnshaw (University of Canterbury, Christchurch) reports in a recent post on Cosmic Diary that the university's Mt. John Observatory has begun a program to search for Earth-mass planets around Centauri A and B. Although the observatory is heavily invested in microlensing technologies (working with the Microlensing Observations in Astrophysics collaboration), the new efforts will put radial velocity methods to work using the Hercules spectrograph. The program is a joint effort with Stuart Barnes at the Anglo-Australian Observatory and Mike Endl at the University of Texas (Austin). And as Hearnshaw notes, the problem is a formidable one, given that an Earth-mass planet in the habitable zone around Centauri A creates a 'wobble' of only 10 cm/s (slightly larger for the less massive Centauri B). Yet the observatory is banking on Hearnshaw's statement that 30,000 spectra of Centauri A or B...

The goal of detecting a terrestrial class exoplanet has burned bright in the imagination ever since the discovery of the first planets orbiting main sequence stars. In a recent SEED Magazine story, Lee Billings (one of the most graceful science writers now working) harkens back to then NASA administrator Daniel Goldin's 1996 speech at the American Astronomical Society meeting in San Antonio, Texas. Goldin talked about seeing Earth-like exoplanets up close, speculating that in 25 years we might be able to obtain images with a resolution to see clouds, continents and oceans. I'm going to use a different Goldin quote than Lee did, from a later speech, but the idea is clear enough in either iteration. Here Goldin is speaking about the classrooms of the mid-21st Century and what they might look like: When you look on the walls, you see a dozen maps detailing the features of Earth-like planets orbiting neighboring stars. Schoolchildren can study the geography, oceans, and continents of...

When the stars are properly aligned, expect remarkable things. How useful, for example, to find that a planet we would like to know much more about -- HAT-P-7b, about 1000 light years from Earth -- is not only providing intriguing transit information right now, but is also in Kepler's field of view. We'd like to know whether there are massive outer planets in this system, or possibly a binary companion. These are questions that the Kepler observatory may be able to answer. Any transiting exoplanet is obviously of high interest, but HAT-P-7b stands out a bit more following the publication of two recent papers in separate journals. Both used the Subaru Telescope to examine the planet's unusual orbit, which appears to be retrograde or polar. This is useful stuff, because it's telling us something about how planetary systems form, offering useful evidence about planetary migration models. What we would expect is that planets that form in protoplanetary disks around young stars would have...

Friday is a travel day for me, so be aware that comment moderation will be slow and sporadic. I just have time to get in word about the upcoming launch of the WISE mission, slated for December 7. NASA is planning a media briefing next Tuesday (November 17) to discuss the mission, which is designed to scan the entire sky at infrared wavelengths, spotting perhaps hundreds of thousands of asteroids and studying a wide range of stars and galaxies. The technology is fascinating in and of itself. WISE will image the entire sky in the infrared, using detectors kept below 15 Kelvins (which is only 15 degrees C above absolute zero) by a solid hydrogen cryostat. The telescope will be oriented to look out at right angles to the Sun, always pointing away from the Earth, so that its observations sweep out a circle in the sky. After six months, the instrument will have observed the entire sky, producing nearly 1.5 million images and creating, ultimately, an atlas of the entire celestial sphere....

The exoplanet watch among our readers is clearly in full operation, to judge from the number of backchannel messages I received about the latest work from HARPS (High Accuracy Radial Velocity Planet Searcher). The remarkable ESO spectrograph attached to the La Silla 3.6-meter telescope now offers evidence that Sun-like stars that host planets will show a sparser lithium signature than stars without planets. Says Garik Israelian, lead author of the paper now appearing in Nature: "For almost ten years we have tried to find out what distinguishes stars with planetary systems from their barren cousins. We have now found that the amount of lithium in Sun-like stars depends on whether or not they have planets." All of this helps us understand our own star, whose low levels of lithium (140 times less than it should have had when formed) have long been apparent. The HARPS work draws on an analysis of some 500 stars, including seventy known to host planets. Ace planet hunter Michel Mayor...

It was a busy weekend for backchannel emails. I got off a Twitter post (OK, a 'tweet') on the centauri_dreams channel on Friday about the disturbing news from Kepler. The reaction was swift. The problem is caused by noisy amplifiers in the electronics of the space-borne telescope, which means the powers that be have to fiddle with the way data from Kepler is processed. This article in Nature News (thanks to all who forwarded links) spells it all out, saying that the planet hunt could be delayed. The article has circulated widely but apparently has problems of its own. William Borucki, Kepler principal investigator, posted this on Ian O'Neill's SpaceDisco site: "There is a mistake in the Nature article. The Kepler Mission is actually doing very well and is producing planet discoveries that will be announced early next year. Data from 3 of the 84 channels that have more noise than the others will be corrected or the data flagged to avoid being mixed in with the low noise data prior to...

While we've looked several times in these pages at David Kipping's work on exomoons, the investigation of moons much closer to home reminds us that finding a habitable satellite of another planet may not be out of our reach. After all, we're gaining insights into possible habitats for at least microbial life on (or in) places like Europa and Enceladus, and speculations about similar biospheres within some Kuiper Belt objects also keep them in contention. So what about a habitable moon around a distant gas giant? Kipping (University College London) has now gone to work on the question in relation to the Kepler space telescope. His findings are striking: A Saturn-sized planet in the habitable zone of an M-dwarf star would allow the detection of an exomoon down to 0.2 Earth masses. Image: A habitable exomoon would offer an exotic vista, a view that may be more common in the galaxy than we have previously imagined. Credit: Dan Durda. Now that sounds unusual, given that Kepler can't find...

We're making progress at detecting the signatures of organic chemicals on other planets. Mark Swain (JPL) and team have already made a name for themselves in this arena by their detection of carbon dioxide in the atmosphere of the 'hot Jupiter' HD 189733b, which followed earlier Hubble and Spitzer observations that revealed water vapor and methane there. Now they've used the same observatories to study another hot gas giant, HD 209458b, which orbits a star 150 light years away in Pegasus. The result: A detection of basic materials necessary for life. Swain spells out what the team found and its significance: "[HD 209458b is] the second planet outside our solar system in which water, methane and carbon dioxide have been found, which are potentially important for biological processes in habitable planets. Detecting organic compounds in two exoplanets now raises the possibility that it will become commonplace to find planets with molecules that may be tied to life." No one is suggesting...

After we've found an Earth-like planet with a potential for life, what further things can we do to investigate it? A team led by Jean Schneider (Paris Observatory) asks this question in a new paper, speculating that there are things a technological society does that leave a sure trace. Given the right instruments (no small requirement), we might look, for example, for Carbon Fluoro Compounds (CFCs). Well known for their damaging effects on our ozone layer, CFCs absorb infrared light at characteristic wavelengths, making their signature a revealing one. Spotting an Extraterrestrial 'Techno-Signature' Schneider calls markers like this 'techno-signatures' (as opposed to the more familiar 'bio-signatures'). They're spectral features that can't be explained by complex organic chemistry. Find CFCs in the atmosphere of a distant world and you've got a snapshot of technological chemical synthesis at work. We might speculate as to whether the average civilization produces CFCs in abundance,...

More than 75 exoplanets in thirty different planetary systems is an impressive score, and that's what HARPS has compiled since its installation in 2003. The High Accuracy Radial Velocity Planet Searcher is the spectrograph for the European Southern Observatory's 3.6-meter telescope at La Silla (Chile). Built by a consortium led by Michel Mayor (Geneva Observatory), HARPS does its work by measuring the minute changes in a star's radial velocity that flag the presence of an unseen companion. Most of the roughly four hundred exoplanets discovered to date have been found through radial velocity methods. The figure of 400 includes the latest results from HARPS, which is back in the news with the announcement of 32 new exoplanets, found as part of a five year program using observing time given to the HARPS consortium in return for building the instrument. One of the new worlds is Gliese 667 Cb [see andy's note below], a six Earth-mass planet in a triple star system. The planets announced...

I'm a great believer in getting the most out of older systems. The computer I do most of my work on is now eight years old. I have access to newer equipment, but I built this box with an eye toward longevity and I'm still happy with it. With the pace of technological change, it's definitely gotten creaky despite additional memory, a new video card and various other upgrades. That means that Windows gets slower and slower on it, but then, I rarely use Windows, being an open source guy to the bone. Linux has always been my choice. Now the nice thing about Linux is that, no matter which version I run (and I've run quite a few by now), I can get snappy performance out of this old box. The astronomical analogy isn't too far to seek -- these days we're talking about building larger and larger Earth-based telescopes, and in fact have just inaugurated the Gran Telescopio Canarias on a 7,874-foot mountaintop in the Canary Islands, an instrument that has the largest segmented mirror -- 10.4...

Protoplanetary disks may not raise the same level of excitement that the discovery of new planets does, but to me, the idea of watching a planetary system form is awe-inspiring. I can't help but wonder whether, going back about five billion years or so, astronomers around some distant star weren't watching the early signs of planetary formation around our own star. Disks in their various stages give us a sense of the continuity of solar system development. Continuity, that is, in the sense that stars seem to form planets as a matter of course. But we're seeing yet more evidence this week that protoplanetary disks can vary markedly from star to star. Now comes news of the dust cloud around 51 Ophiuchi, which turns out to be not one but two distinct disks, an inner one with grains 10 micrometers and larger in diameter (based on infrared observations), and an outer one made up of primarily 0.1 micrometer grains. Image: This graphic compares the inner and outer disk of the 51 Ophiuchi...

?I love to run into genuine enthusiasm when someone is doing cutting-edge science, and Didier Queloz (Observatoire de Geneve) has not let me down. Here the astronomer is discussing CoRoT-7b, which new studies have determined is a rocky world: "This is science at its thrilling and amazing best. We did everything we could to learn what the object discovered by the CoRoT satellite looks like and we found a unique system." Amazing indeed. We knew from CoRoT's transit measurements that the radius of this planet was about twice that of Earth. Queloz and team went to work with the HARPS spectroscope (High Accuracy Radial velocity Planet Searcher) at ESO's La Silla site in Chile, gathering fully seventy hours of observations on the system. What emerged was the best mass measurement for an exoplanet yet. Combining that revealed mass -- five times that of the Earth -- with CoRoT's radius readings, we can deduce that CoRoT-7b is about as dense as Earth, and thus almost certainly a rocky world....

The exoplanet hunt has entered a significant new phase, one focused on transiting planets and the useful things we can learn about their physical properties and atmospheres through such events. Driven by CoRoT and Kepler, we're now in position to use those transits to spot smaller worlds than ever, down to terrestrial size, and naturally the focus is on Earth analogs located in the habitable zones of their stars. So think of it this way: We've gone from a broad-brush approach based largely on radial velocity methods to a more selective hunt, one that will take us to the realm of planets that can have liquid water on their surfaces and aren't so different from our own. Not that the continuing work on characterizing planetary systems is of any less importance, but we've found plenty of gas giants, and now we're trying to learn something about how common these smaller worlds may be. Putting an exclamation point on this focus is a conference called Pathways Towards Habitable Planets, to...