The study revealed an “unnatural” reason that prevents most astronomical observatories around the world from seeing space clearly.
A new study warns that man-made light pollution on Earth is preventing a clear view of space through most of the world’s major astronomical observatories.
For the study, which was recently published in the Monthly Notices of the Royal Astronomical Society, scientists estimated light pollution levels at nearly 50 observatories around the world, from the world’s largest professional observatories to smaller amateur observatories.
Researchers from Italy, Chile and Galicia have studied and compared levels of light pollution at major astronomical observatories around the world. The study shows that light pollutes the sky above most observatories. pic.twitter.com/uxvXvHAVI8
— Royal Astronomical Society (@RoyalAstroSoc) December 20, 2022
An international team of scientists, including scientists from Chile, Italy and Spain, said the skies over two-thirds of all major observatories are subject to light pollution and called for urgent action to reduce levels of pollution caused by artificial lighting.
“The results show that most large astronomical observatories are already at high risk of artificial lighting, and the sky of some of them is very polluted,” the scientists write in the article.
The term “light pollution” refers to pollution resulting from abnormal artificial lighting at night, such as the exterior and interior lighting of buildings, shops, and street lights.
Here, the scientists applied a model of how light travels through the Earth’s atmosphere to nighttime images taken from satellites.
Signs of light pollution were assessed throughout the night sky. This included the brightness of the sky, known as the “zenithal brightness of the sky”: the point to which a line from the center of the Earth ends at the straightness of a person’s height and meets it at the end of the diagonal. to the feet.” As well as brightness at heights of 10 and 30 degrees above the horizon.
The team also measured the overall average brightness across the sky, as well as ground illumination due to artificial lighting in the night sky.
One of the main metrics used was to compare these artificial values with the natural brightness of the sky, caused by the faint emission of light from the Earth’s atmosphere, starlight, and the Milky Way.
Only seven of the 28 major astronomical observatories that have telescopes of 3 meters or more in diameter have “azimuthal brightness” with a hint of light pollution below the expected threshold of 1% of normal sky brightness.
The scientists said the remaining 21 large objects – three-quarters of all major observatories – are above that level.
Worse, only one of the 28 large sites studied by scientists had light pollution below the 1% threshold at 30 degrees above the horizon.
Despite the fact that the International Astronomical Union set a maximum allowable threshold for artificial brightness for large observatories in the 1970s at 10%, a study shows that light pollution in the atmospheres of two-thirds of Earth’s observatories has now exceeded this upper limit.
“In order to maintain our ability to conduct high-quality astronomical research, it is critical that night-time artificial light that affects observatories be dimmed as quickly as possible,” the scientists wrote.
The study’s lead author, Fabio Falci of the University of Santiago de Compostela in Spain, said the least polluted of these places is a hostel in Namibia, home to many telescopes rented out to amateur astronomers.
He added: “I was there recently and I can confirm that this is the place with the least light pollution I have ever seen. We must try to reduce light pollution elsewhere to protect the future of terrestrial astronomy.”