Light pollution has robbed roughly 30 per cent of people around the world of a nightly view of the Milky Way, according to a statement from the National Science Foundation’s NOIRLab. The findings are part of NOIRLab’s Globe at Night educational program, which points to a problem that is only getting worse.

“At this rate of change, a child born in a location where 250 stars were visible would be able to see only around 100 by the time they turned 18,” said Christopher Kyba, a researcher at the German Research Centre for Geosciences and lead author of the report, in a statement.

The research analyzed more than 50,000 observations submitted to the Globe at Night project between 2011 and 2022. Entries were omitted if they were affected by cloud cover and moonlight. The team focused on data from Europe and North America.

Existing satellite observations indicate artificial lighting is growing at high rates in developing countries. But, the research found light pollution is worsening faster than what has been shown in satellite measurements of the Earth’s surface brightness at night. 

Data supplied to the authors indicates the night sky brightened by 9.6 per cent during the 10-year observational period. Satellites measuring brightness have reported a two per cent global increase, though.

NOIRLab believes satellites have failed to measure skyglow because there are no instruments monitoring the whole Earth that can detect wavelengths shorter than 500 nanometers. This corresponds to the colour cyan, or greenish blue.

Shorter wavelengths contribute disproportionately to skyglow because they scatter in the atmosphere. White LEDs, which have become increasingly common, peak between 400 and 500 nanometers. NOIRLab argues crowd-sourced observations remain invaluable for investigating the brightening night sky.

“The increase in skyglow over the past decade underscores the importance of redoubling our efforts and developing new strategies to protect dark skies,” said NOIRLab astronomer Connie Walker, who developed Globe at Night, in a statement. “The Globe at Night dataset is indispensable in our ongoing evaluation of changes in skyglow, and we encourage everyone who can to get involved to help protect the starry night sky.”