On a clear autumn evening in Exmoor National Park, the Milky Way remains visible to the naked eye against one of the darkest skies in Europe. As Europe's first designated international dark skies reserve, the park in south-west England recently marked its tenth dark skies festival, drawing visitors to stargaze through telescopes and examine how artificial light at night obscures the cosmos and harms nocturnal ecosystems. For astronomer Jo Richardson, observing distant planets such as Saturn—roughly 800 million miles away—serves as a tangible reminder of what urban sprawl has hidden from view.
The loss of dark skies is accelerating globally. Research indicates that the night sky grows approximately 10% brighter each year due to expanding light pollution. On the Bortle scale, a nine-level index of night sky brightness where a level nine represents the glare of central London and a level one represents remote sites like Chile's Atacama Desert, Exmoor's darkest zone rates as a level two. According to the Light Pollution Map, the United Kingdom ranks as the 14th most light-polluted country in Europe, trailing heavily built-up microstates such as Monaco and Vatican City.
Organisers note that protecting the night sky does not require switching off all illumination, but rather using lighting more selectively and responsibly. Throughout the festival, astronomers lead fireside discussions, telescope viewings, and guided walks to demonstrate how even distant towns project a visible glow across the horizon. Educational initiatives led by astronomers like Jo and Peter Richardson aim to inspire interest in space science while raising awareness about the environmental consequences of excessive artificial light.
Beyond obstructing astronomy, nocturnal light poses severe ecological risks to native species. Kate Lacey, an ecologist at the Exmoor National Park Authority, points out that darkness is vital for local wildlife, including rare Bechstein's and barbastelle bats that depend on unlit habitats for hunting, navigation, and migration. Artificial illumination also confuses migratory salmon traveling upstream to Exmoor's crucial spawning grounds, reducing their chances of survival. Festival organisers hope that experiencing genuine darkness will encourage visitors to reconsider how nighttime lighting affects both human culture and the natural world.