Rogue planets: hunting the galaxy's most mysterious worlds

Most known planets orbit a star. These planets, including Earth, benefit from the star's warmth and light. And it is the light emitted from these stars which makes it possible for us to see them. But there are also "invisible" planets, hidden from our gaze, which float, abandoned, through the cosmos. These dark, lonely worlds have no star to orbit, no light in which to bask, no warmth to be radiated by. They are the "rogue" planets--and astronomers have just found a new one, roughly the same siz...