ASTRONOMY:
Dark Dwarf Galaxy Gets Even Darker
Robert Irion
In the Draco dwarf spheroidal, a smudge of stars about 250,000 light-years away, astronomers have found the first compelling evidence that the dark matter around a dwarf galaxy sprawls deep into space, creating an extended halo similar to what is thought to shroud all bigger galaxies. Further studies of this cocoon, whose composition remains a mystery, promise to illuminate the early history of our own galaxy, which presumably acquired its heft by eating such dark-matter snacks.