Thirty minutes after sunset, a small group of writers walked out onto a dry lakebed in south-east Oregon, headlamps switched to red so their eyes could adjust. They were staying near a stretch of protected land recognized by the International Dark Sky Places network, 2.5 million acres where almost no artificial light reaches the ground. One of them, a longtime resident of Portland, had not seen a truly dark sky in decades.

Above her building at home, the glow of streetlights and parking lots always crept through the curtains, no matter how carefully she closed them. Lying on blankets in the grass, the group watched Venus rise over the hills as Vega appeared directly overhead, followed by satellites whose steady movement gave them away as artificial. As darkness deepened, constellations emerged one by one, Ursa Major, Cassiopeia, Cygnus, until the Milky Way itself became visible as a pale band stretching across the sky. Two meteors crossed overhead before anyone spoke again.

The experience is becoming rarer everywhere, not just in the American West. Researchers estimate that the night sky is growing about 10% brighter each year, largely because of artificial lighting, and roughly 80% of the world's population now lives under skies affected by light pollution, from São Paulo to Seoul. In 2022, the United Nations affirmed that a healthy environment, including clean air and water, is a human right; some scientists and dark-sky advocates argue that unpolluted darkness deserves similar protection, since it affects human sleep, migrating birds and nocturnal ecosystems alike. Communities from Flagstaff, Arizona to parts of rural Chile have already introduced lighting ordinances, requiring warmer bulbs, shielded fixtures, and stricter limits on brightness.