Without light, we cannot see. That’s why “dark galaxies” have eluded astronomers for so long. Two years ago, these star-starved entities were virtually unknown. But scientists now have better ways of seeing, even in dim conditions. New telescopes that can detect the faint light from these mysterious galaxies have enabled scientists to chalk up a considerable list: Dark galaxies seem to be much more common than anyone had thought. One rivals the Milky Way in size but holds only a hundredth as many stars.
Cataloging these dark galaxies, as Christopher Crockett reports (SN: 12/10/16, p. 18), is just the beginning. Scientists still don’t know how such galaxies might have formed or how their small populations of stars