In many inhabited places on Earth, the night sky never completely darkens.
Instead, it glows with an artificial twilight caused by anthropogenic light scattering in the atmosphere.
A recent investigation reveals that the night sky is becoming increasingly brighter because of this light pollution, with the result, among other things, that the visibility of the stars is reduced throughout the world.
That decrease in the visibility of night sky stars, according to the new study’s conclusions, is equivalent to a 9.6% annual increase in sky brightness; a faster increase than the satellites point to and which ended up taking place despite policies to prevent the increase in light pollution. To put this question in perspective, the study authors note that under a change in sky brightness of this magnitude, a child born in an area where 250 stars were visible would likely see fewer than 100 in the same location 18 years later.
Although the ubiquity and luminosity of skyglow have increased exponentially for much of the past century, its global change over time is not well understood. Satellites that can measure global skyglow are limited in resolution and sensitivity, and are often “blind” to the wavelengths of light produced by modern LED light sources, which have come to dominate in the last decade. the lighting.
To better understand how increasing light pollution is affecting our vision of the stars, Christopher Kyba’s international team from the German Research Center for Geosciences (GFZ) evaluated 51,351 volunteer observations of naked-eye stellar visibility to the period 2011-2022.
To determine the background brightness of the night sky, Kyba and his colleagues asked volunteers, from around the world, to compare star maps of the night sky at different levels of light pollution with what they could see with their own eyes through the Internet platform “Globe at Night”.
Judging by the results, the night sky has experienced an increase in brightness from artificial light of between 7 and 10% per year in recent years, which is equivalent to doubling the brightness of the night sky in less than 8 years. This increase is much higher than the estimates of the evolution of artificial light emissions (approximately 2% per year) based on radiation measurements taken by satellites.
Is the night sky getting brighter? The new study corroborates that yes, because of artificial lighting. (Photo: NASA)
The new study is titled “Citizen scientists report global rapid reductions in the visibility of stars from 2011 to 2022”. And it has been published in the academic journal Science.
Other recent studies have shown the environmental risks associated with artificial lighting, such as the detrimental effects of public lighting at night on daily habits and the life cycle of many animal species, and many other harmful effects on ecosystems. (Source: AAAS)