Astronomers have used NASA's Chandra X-ray Observatory to discover the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way. At a distance of 160 million light years, it is also the nearest known pair of supermassive black holes. The black holes are located near the center of the spiral galaxy NGC 3393. Separated by only 490 light years, the black holes are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago. "If this galaxy wasn't so close we'd have no chance of separating the two...
