Light pollution is increasing rapidly and the number of stars visible to the naked eye at night could be halved in some places in less than 20 years, according to a scientific study presented Thursday in the journal Science.
The increase in this pollution from artificial light is greater than what has already been measured by satellite observations of Earth at night.
To assess the effect of artificial light on the night sky, the scientists relied on star observations made between 2011 and 2022 by around 51,000 citizen scientists, mainly in the US and Europe.
From the development of the number of reported visible stars, it can be concluded that the brightness of the sky where the participants lived increased by an average of 9.6% per year, the researchers said.
With this increase in light pollution, a place where you could see 250 stars would reduce that number to 100 in 18 years.
This study notably coincided with the replacement of many outdoor lighting systems with light-emitting diodes (LEDs), but the researchers say the impact of this transition to LEDs on skylights is not clear.
“Despite (or perhaps because of) the use of LEDs for street lighting, star visibility has been deteriorating rapidly,” the scientists said.
“Existing lighting policies do not prevent light pollution,” they say, at least on a large scale.
But light pollution goes far beyond a purely scientific aspect.
“Previously, when people went out at night, they were somehow confronted with the cosmos,” Christopher Kyba, first author of the study and physicist at the GFZ Center in Potsdam, told AFP. “You go outside, you see the stars, the Milky Way…”
“And now it’s like it’s become an unusual event,” he said. “And that certainly has consequences for us (…) to no longer live what was almost universal. »