Chris Impey and Connie Walker in The Conversation:
For most of human history, the stars blazed in an otherwise dark night sky. But starting around the Industrial Revolution, as artificial light increasingly lit cities and towns at night, the stars began to disappear.
We are two astronomers who depend on dark night skies to do our research. For decades, astronomers have been building telescopes in the darkest places on Earth to avoid light pollution.
Today, most people live in cities or suburbs that needlessly shine light into the sky at night, dramatically reducing the visibility of stars. Satellite data suggests that light pollution over North America and Europe has remained constant or has slightly decreased over the last decade, while increasing in other parts of the world, such as Africa, Asia and South America. However, satellites miss the blue light of LEDs, which are commonly used for outdoor lighting – resulting in an underestimate of light pollution.
An international citizen science project called Globe at Night aims to measure how everyday people’s view of the sky is changing.