If you live in a large town or city, you probably see only a few dim stars when you look up at the night sky. Things like streetlamps and lights in and on buildings create an artificial glow that makes it hard to see many stars. This problem is known as light pollution. And it may be worse than we thought.
Scientists often measure light pollution using satellites. Unfortunately, satellites don’t detect all types of light, like white LED lights and light that shines horizontally. That’s why researchers in Germany decided to use data collected by citizen scientists.
For the past decade, volunteers with the project Globe at Night have been documenting which stars are visible with the naked eye where they live. The German team analyzed their observations from 2011 to 2022. Previous studies estimated that nights were growing about 2 percent brighter each year. This study found that, globally, the night sky is actually growing about 10 percent brighter annually.