Kepler, Keck Telescopes Discover Earth-Size Exoplanets

NASA’s Kepler mission, aided by the Keck I Telescope, has discovered the first Earth-size planets orbiting a Sun-like star outside our solar system. The planets, called Kepler-20e and Kepler-20f, are too close to their star to be in the so-called habitable zone where liquid water could exist on a planet’s surface, but they are the smallest exoplanets ever confirmed around a star like our Sun. The discovery marks the next important milestone in the ultimate search for planets like Earth. The new planets are thought to be rocky. Kepler-20e is slightly smaller than Venus, measuring 0.87 times the radius of…