Working at near-infrared wavelengths, the Gemini Planet Imager, now entering regular operations at the Gemini South Telescope in Cerro Pachon (Chile), is producing striking work, including images of exoplanets and circumstellar disks. Have a look at the image below, which highlights the instrument's ability to achieve high contrast at small angular separations. Such capabilities make it possible to image exoplanets around nearby stars, as seen here in the case of the star HR 8799. Image: GPI imaging of the planetary system HR 8799 in K band, showing 3 of the 4 planets. (Planet b is outside the field of view shown here, off to the left.) These data were obtained on November 17, 2013 during the first week of operation of GPI and in relatively challenging weather conditions, but with GPI's advanced adaptive optics system and coronagraph the planets can still be clearly seen and their spectra measured. Credit: Christian Marois (NRC Canada), Patrick Ingraham (Stanford University) and the...

The eight ‘habitable zone’ planets we discussed yesterday appear today in a much broader context. The Kepler mission has verified its 1000th planet, and with the detection of 554 more planet candidates, the total candidate count has now reached 4175. According to this NASA news release, six of the new planet candidates are near-Earth size and orbit in the habitable zone of stars similar to the Sun. These all require follow-up observation to confirm their status as planets, but with confirmed planets like Kepler-438b and Kepler-442b, along with these further candidates in the habitable zone, the numbers keep inching us closer to an Earth 2.0. “Kepler collected data for four years -- long enough that we can now tease out the Earth-size candidates in one Earth-year orbits,” says Fergal Mullally, a SETI Institute Kepler scientist at Ames who led the analysis of a new candidate catalog. “We’re closer than we’ve ever been to finding Earth twins around other sun-like stars. These are the...

One way to confirm the existence of a transiting planet is to run a radial velocity check to see if it shows up there as a gravitationally induced 'wobble' in the host star. But in many cases, the parent stars are too far away to allow accurate measurements of the planet's mass. What Guillermo Torres (Harvard-Smithsonian Center for Astrophysics) did in the case of eight new candidates possibly in their stars' habitable zones was to use BLENDER, a software program he and Francois Fressin developed that runs at NASA Ames on the Pleiades supercomputer. A BLENDER analysis can determine whether candidates are statistically likely to be planets. Torres and Fressin have applied it before in the case of small worlds like Kepler 20e and Kepler 20f, important finds because both were exoplanets near the size of the Earth. Using the software allowed the researchers to create a range of false-positive scenarios to see which could reproduce the observed signal. A nearby binary star system, for...

We often think about how thin Earth's atmosphere is, imagining our planet as an apple, with the atmosphere no thicker than the skin of the fruit. That vast blue sky can seem all but infinite, but the great bulk of it is within sixteen kilometers of the surface, always thinning as we climb toward space. Now a presentation by graduate student Laura Schaefer (Harvard-Smithsonian Center for Astrophysics) at the 225th meeting of the American Astronomical Society in Seattle points out that, like the atmosphere, water is also a tiny fraction of what makes up our planet. A small enough fraction, in fact, that although water does cover seventy percent of the Earth's surface, it makes up only about a tenth of one percent of the overall bulk of a world that is predominantly rock and iron. Dimitar Sasselov (CfA), co-author of the paper on this work, thinks of Earth's oceans as a film as thin as fog on a bathroom mirror. But we've seen recently that water isn't strictly a surface phenomenon. The...