NASA Finds Smallest Planet Outside Our Solar System But Kepler-10b is too hot for human habitation By Kevin Spak, Newser Staff Posted Jan 11, 2011 1:42 PM CST 9 comments Comments An artist's concept drawing of Kepler-10b. (NASA) (Newser) – The Kepler space telescope has discovered a rocky planet that’s just 1.4 times the size of Earth orbiting a distant star—making it the smallest planet NASA has ever discovered outside of our solar system, and the only rocky one, NASA announced today. The bad news: The planet, dubbed Kepler-10b, appears far too hot to support any kind of life. The planet is 20 times closer to its star than Mercury is to ours. That puts its expected daytime temperature at more than 2,500 degrees Farenheit, hotter than flowing lava. But NASA was pleased anyway. “The discovery of Kepler-10b, a bona fide rocky world, is a significant milestone in the search for planets similar to our own,” says the program’s scientist. “Although this planet is not in the habitable zone, the exciting find showcases the kinds of discoveries made possible by” the Kepler mission.