Topline
“Rapidly growing” human-caused light pollution has made the night sky nearly 10% brighter each year, according to new research published on Thursday, obscuring astronomical observations and posing a threat to migrating birds that rely on the position of stars and the moon to travel.
Researchers found the night sky is becoming as much as 10% brighter each year.
Key Facts
Researchers at the GFZ German Research Center for Geosciences evaluated more than 51,000 observations between 2011 and 2022 and found that, each year, the brightness of the night sky increased by between 7% and 10%—the equivalent of doubling the brightness of the sky every eight years, according to the study, published Thursday in the journal Science.
Their finding was more than triple previous estimates that artificial light emissions were increasing by roughly 2% each year, based on satellite detection of the amount of human-caused light in the atmosphere, called “skyglow.”
Even though skyglow has increased “exponentially” over the past century, researchers found it has been growing even faster over the past decade, based on observations from nearly 20,000 locations around the world.
In Europe, researchers found a 6.5% increase in brightness per year, while in North America, they found an annual increase of 10.4%.
Some of the biggest contributors to skyglow are horizontal-facing lights, including from building facades and billboards, according to head researcher Christopher Kyba, while the recent switch from traditional orange-tinted sodium vapor lights to brighter LED lights has also contributed to the effect on the night sky because blue light can more easily be scattered in the atmosphere, Kyba said.
Big Number
99%. That’s the percentage of the public in the U.S. and Europe that can’t experience a natural night sky, according to a 2016 study by the International Dark Sky Association, with 80% of the world’s population living under skyglow, primarily in North America, Europe, the Middle East, India and East Asia.
Key Background
Increasing artificial light has proven to be a problem for migrating animals, as well as humans, by disrupting sleep patterns, according to National Geographic. That includes sea turtles and migrating birds that rely on the light of the moon to direct them during migratory seasons. Insects, too, are drawn to artificial light, which if too hot, can kill them instantly. For astronomers, it’s also become a key problem in gathering clear observations beyond the Earth’s atmosphere. That light pollution comes from both lights at the ground level primarily from cities and industrial areas, as well as satellites, including the SpaceX Starlink satellites that have caught astronomers off guard since they launched in 2019. Speaking to the Guardian in 2020, Alice Gorman, a Professor at Flinders University in Australia, warned the increase in satellites could bring “radical change” to the view of the night sky. Even on Nantucket, 30 miles off the coast of Cape Cod, Massachusetts, light pollution has increased by more than 20% over the past 10 years, according to an April, 2022 study by Nantucket Lights, a group of islanders that formed to preserve the island’s view of an unobscured night sky.
Further Reading
Light pollution damaging views of space for majority of large observatories, survey finds (Space)
Picture imperfect: light pollution from satellites is becoming an existential threat to astronomy (The Guardian)
Source: https://www.forbes.com/sites/brianbushard/2023/01/19/cant-see-the-stars-night-skies-are-becoming-rapidly-brighter-as-light-pollution-intensifies-study-finds/