Two for the price of one: The unique binary system of Pluto and Charon

NASA's New Horizons is described as a mission to Pluto, but one of the reasons the dwarf planet is so fascinating to scientists is that it's part of the only known binary system in our solar system. In a binary system, both members of the pair orbit around a common center of gravity. Earth is about 81...

via L.A. Times - Science http://ift.tt/1Mtvp4G