The Kepler mission team announced today its first confirmed discovery of a small rocky planet orbiting another star. The planet, Kepler 10-b, has a mass 4.6 times that of Earth, but is only 1.4 times Earth’s diameter, the (again) smallest planet yet found orbiting another sunlike star (not counting the three similar smaller planets found way back in 1991 orbiting a pulsar or dead star). It’s average density is 8.8 grams per cubic centimetre, similar to that of an iron dumbbell. But, it orbits very close to its star, about 20 times closer than Mercury orbits our own sun, and so the surface temperature would be blistering hot and unsuitable for life as we know it. The star is about 560 light years away.
However, it is expected to be the first of many such smaller worlds that Kepler will find, with some in the “habitable zone” of their stars, where temperatures could allow liquid water to exist.
A reminder, too, that the next formal data release from Kepler is scheduled for February 1, 2011, detailing the latest information on an additional 750+ exoplanetary candidates… the current total exoplanet count also now stands at 518!