This story was updated at 2:40 EST. Astronomers on Tuesday (Dec. 20) announced the discovery of the first two Earth-size alien planets — a historic find for sure, but the newfound worlds didn't ...
NASA’s Kepler mission 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 ...