Alarming report says Earth’s surface is getting brighter, leaving people in big cities with very little to see in the skies at night
POTSDAM, Germany — Stars in the night sky are vanishing due to light pollution, according to stargazers around the world. These citizen scientists say Earth’s surface is rapidly getting brighter, eroding star visibility. For those living in major cities like New York, it can be nearly impossible to see the countless stars which cover the sky each night.
The findings are based on observations from citizen astronomers worldwide over the past 12 years. They reveal a worrisome trend – most people on earth can no longer see the shimmering Milky Way without a telescope. In big cities, people are lucky to even glimpse the Big Dipper now.
Study authors from the GFZ German Research Centre for Geosciences say the change in visibility is equivalent to around a 10-percent annual increase in luminosity — faster than satellites have previously indicated. The growth of light pollution is occurring despite policies which cut down on streetlamps, billboards, neon signs, and car headlights usage.
To put this problem in perspective, lead author Dr. Christopher Kyba says estimates that a child born in an area where 250 stars were visible would likely see fewer than 100 in the same location 18 years later.
“In many inhabited places on Earth, the night sky never fully grows dark. It instead glows with an artificial twilight caused by the scatter of anthropogenic light in the atmosphere,” researchers write in a media release.
Known as skyglow, the phenomenon is responsible for the visible brightening of the night sky and the erosion of our ability to see stars. Its ubiquity and luminance has increased exponentially over much of the last century.
Light pollution can also be a health problem
Satellites that can measure global skyglow are limited in resolution and sensitivity. They are often blind to the wavelengths produced by modern LED lights that have come to dominate technology over the past decade. So, the international team evaluated 51,351 citizen scientist observations of naked-eye stellar visibility from 2011 through 2022.
They asked participants worldwide to compare star maps at different levels of light pollution to what they could see with their own eyes through the online platform Globe at Night. The study in the journal Science found the night sky has increased in brightness from artificial light by roughly seven to 10 percent per year.
“The contributions of individual people work together as if they were a global sensor network, making new science possible,” says Kyba in a statement.
Estimates show that the Milky Way galaxy is no longer fully visible to one-third of humanity — including 60 percent of Europeans and 80 percent of Americans. Scientists have found excessive artificial lighting at night can have a number of adverse consequences. It disrupts our sleep, messes with wildlife, and is a big waste of energy.
“Skyglow affects both diurnal and nocturnal animals and also destroys an important part of our cultural heritage,” says Constance Walker, co-author of the study and head of the Globe at Night project.
“Perhaps the most important message that the scientific community should glean from the Kyba et al. study is that light pollution is increasing, notwithstanding the countermeasures purportedly put into operation to limit it,” says Fabio Falchi and Salvador Bará in a related release. “Awareness must greatly increase for artificial light at night to be perceived not as an always-positive thing, but as the pollutant it really is.”