Light Pollution Threatens Global Observatories, Jeopardising Deep-Sky Astronomy

This is the alarm being sounded by astronomers around the world: artificial light pollution is wiping this darkness from the cosmos (it's night, not day) in the name of human exploration. You can find night lighting in a lot of shapes and forms — from buzzing billboards and the twinkling city glow of skylines to some, even very distant observatories. Over the 10 years up until 2023, this increase in light pollution is expected to reach a rate as high as 10 percent, threatening with disappearance of those galaxies and stars faint enough to be detected only by the most sensitive telescopes.

Artificial Light Creeps Into the World's Darkest Skies, Threatening Astronomy and the Right to Starlight

According to a report originally published by The Conversation and shared via Space.com, even facilities on distant mountaintops are no longer safe from the glow of urban expansion. In order to notice galaxies that go 100 times fainter than the atmospheric shine, telescopes such as the Vera Rubin Observatory in Chile rely on almost complete natural darkness. Even in the best conditions, light from roads, buildings, and industrial sites can negatively impact viewing or prolong exposure times.

The issue has been exacerbated as LED lighting becomes more pervasive. Although the efficiency improvements of LEDs are immense, whereas early sodium vapour lamps emitted only a small amount of blue-green light, they produce sharp spikes in the sky brightness spectrum centred around precisely those wavelengths on which astronomers used to rely. Research has also shown that, rather than dimming any street lights, most of America grew fat on energy savings and completely started lighting up whole swathes of their cities with all these lights.

Iconic observatories, like those on California's Mt. Wilson and Arizona's Kitt Peak, have had their now-light-polluted skies darken by the new housing developments sprouting around them. The European Southern Observatory in Chile is affected by skyglow from manufacturing facilities located far away, and light compliant with the law, but still polluting the area.

Beyond science, the impact is cultural and environmental. About 80 percent of the world's population can no longer see the Milky Way. The International Astronomical Union has called for protecting the “universal right to starlight,” stressing that the night sky's beauty should remain accessible to all.