Dark Matter Hunters Suspect They've Found 'Galaxy X'

Dark Matter Hunters Suspect They've Found 'Galaxy X' - NBC News.com: "Years ago, astronomers mapped out curious ripples in the cold hydrogen gas that lies within the disk of our Milky Way galaxy — and suggested that the ripples were caused by the gravitational influence of an unseen dwarf galaxy dominated by dark matter. Now those astronomers say they may have found the lurker, nicknamed "Galaxy X.""