Kepler-10b exoplanet landscape and its parent star, artwork. The discovery of this rocky alien planet was announced on 10 January 2011. It was found by NASA's Kepler Mission, a space observatory launched in 2009 and scanning tens of thousands of stars in the Milky Way to discover Earth-like planets. Kepler-10b is the smallest rocky planet found so far outside the solar system. It has a diameter 1.4 times that of Earth, but orbits close to its parent star, making it more like Mercury in terms of surface temperature. The parent star, Kepler-10, is 560 light years from Earth, in the constellation of Draco.