Astronomers find Water-world

Eso0950a In recent years, astronomers have cataloged over 400 planets orbiting other stars in our galaxy, and, as techniques are continuously refined and new missions carried out, more are being discovered regularly. Targeting a rich area of the Milky Way, scientists, for example, are pouring over the data returned by the newly launched observatory Kepler, which is seeking transiting terrestrial worlds in the habitable zone of their parent star. Follow-up missions that might directly observe these planetary finds are being considered.  

Yesterday, however, news emerged that the ground based telescopes of the MEarth Project in Arizona had located a transiting water world orbiting a star very much like ours. Though the second so-called super-Earth, this one is interesting because subsequent observations in South America have demonstrated that this planet has an atmosphere - though perhaps not for long, given the proximity to its host. Paul Gilster at Centauri Dreams provided this other bit of interesting news.

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.

The atmospheric pressures and resulting lack of light reaching the planet's surface make life improbable, or at least unlike anything we might know, but it's another step along the path toward what could be truly extraordinary find in our lifetimes.


The credit for the artist's impression of GJ 1214b goes to ESO/L. Calçada.