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...