The night sky is increasingly polluted with artificial light from Earth. This affects our ability to see the stars. It also affects animal populations.
In many places on Earth, the night sky is never completely dark.
The team used observations from a citizen science project called “Earth at Night”. The project urges people to report how bright the night sky is at their private residences. They just need to look at the constellation Orion. This is a prominent constellation located on the equator and can be seen all over the world.
The team evaluated 51,351 citizen observations from 2011 to 2022 around the world. This project provides a lot of data. However, the assessment is not continuous in one place as people move to another place. On the other hand, the distribution of these citizen scientists is not globally spread.
The team used satellite measurements of the brightness of the night sky. They found that in the last 9 years, things had changed for the worst.
With the increasing speed of the night sky, it also means that someone is born to be able to see 250 stars. When they turn 18, they will only be able to see 100 stars. “It’s really a big change,” noted Dr. Kyba.
Dr. Christopher Kyba, from the German Center for Geosciences Research, told the site IFLScience : “Now, there’s a really significant decrease in the number of stars people see compared to 2014. We can interpret that data on the basis of the world getting brighter.”
However, Kyba further explained, the situation in the night sky is not uniform on Earth. There is no global “coverage”. Even the increase in brightness seems to be more pronounced in the US and less so in Europe.
Due to artificial light, the brightness of the sky in the sampled locations has increased by about 7-10% per year since 2014.
“Artificial light at night is not seen as an always positive thing, but actually a pollutant,” said Kyba.
This study was published in the journal Science.