A tiny brown dwarf glows next to its stellar companion, Gliese 229, in this false-color image from Hubble Space Telescope. The brown dwarf, known as Gliese 229B, is a "failed star" -- an object that is more massive than a planet, but not massive enough to ignite nuclear fusion and shine as a true star. Gliese 229 is one of our closest stellar neighbors, at a distance of about 20 light-years. [NASA/JHU/Caltech]