Fear of the light: why we need darkness

Due to pervasive light pollution – glare from excessive, misaimed and unshielded night lighting – 80% of Europe and North America no longer experiences real darkness. For anyone living near a major metropolis, a satellite image of the Milky Way seems abstract: we understand it to be a document of something true, but our understanding is purely theoretical. In 1994, after a predawn earthquake cut power to most of Los Angeles, the Griffith Observatory received phone calls from spooked residents asking about “the strange sky”. What those callers were seeing were stars.