Astronomers announced June 2 at the American Astronomical Society (AAS) meeting that they have discovered a new type of planet -- a rocky world weighing 17 times as much as Earth. Theorists believed such a world couldn't form because anything so hefty would grab hydrogen gas as it grew and become a Jupiter-like gas giant. This planet, though, is all solids and much bigger than previously discovered "super-Earths," making it a "mega-Earth."
The newfound mega-Earth, Kepler-10c, circles a Sun-like star once every 45 days. It is located about 560 light-years from Earth in the constellation Draco. The system also hosts a 3-Earth-mass "lava world," Kepler-10b, in a remarkably fast 20-hour orbit. Read more.