On a clear night in 1994, an earthquake rumbled beneath Los Angeles and caused a city-wide power outage just before dawn. Startled awake, some residents who had stumbled outside called various emergency centers and a local observatory to report a mysterious cloud overhead.That weird object turned out to be the band of the Milky Way, our home galaxy, which had long been obscured from view by the city’s lights.Arguably, the light bulb is the most transformative invention humans have introduced to this planet. By flicking a switch or pushing a button, we can push back the veil that would naturally shroud our lives each night. Now, we work long after the sun sinks below the horizon. We play games outside until the hours stretch into double digits. We more safely roam city streets after dark.But if light bulbs have a dark side, it’s that they have stolen the night. The excess light we dump into our environments is endangering ecosystems by harming animals whose life cycles depend on dark. W...
