When the Northridge earthquake knocked out power in Los Angeles in 1994, numerous calls came into emergency centers and even the Griffith Observatory from people who had poured into the streets in the predawn hours. They had looked into the dark sky to see what some anxiously described as a “giant silvery cloud” over the shaken city. They were assured that it was merely the Milky Way. The vast galaxy that humans once knew so well until the glare from electric light effectively erased most traces