Light pollution is cutting off the view of the night sky for many.

Light pollution is cutting off the view of the night sky for many.

Light pollution is cutting off the view of the night sky for many.

If you have a passing interest in astronomy, chances are you’ve considered the problem of light pollution. As there are more and more sources of bright light at night on Earth, it becomes more and more difficult to see the stars in the sky. But recent analyzes have pointed out that the problem could be worse than anticipated, as what is visible to the human eye is even smaller than satellite measurements indicated.

According to the National Science Foundation’s NOIRLab, about 30% of the global population and 80% of the US population can no longer see our galaxy, the Milky Way. And new research shows that the problem is getting worse.

Infographic on light pollution from Globe at Night.
A startling analysis by Globe at Night – a citizen science program run by NSF’s NOIRLab – concludes that stars are disappearing from human sight at an astonishing rate. This graph illustrates how the greater the amount of light pollution, and therefore the brightness of the sky, the fewer stars are visible. The numeric scale is similar to that used by Globe at Night participants. NOIRLab/NSF/AURA, P. Marenfeld

The research, published in the journal Science, was led by citizen science group Globe at Night. He found that night sky brightness has increased by a global average of 9.6% per year over the last decade, which is much worse than the 2% increase found in satellite measurements. The Globe at Night figure comes from data collected by volunteer participants who share information about which stars and constellations are visible to them, excluding conditions such as cloud cover. Lead author of the Science paper, Christopher Kyba, says this shows how satellite measurements of light pollution are not enough to capture the scale of the problem.

Current satellites cannot see the shorter wavelengths of light that energy-efficient white LEDs typically use. “As human eyes are more sensitive to these shorter wavelengths at night, LED lights have a strong effect on our perception of the brightness of the sky,” explained Kyba. “This may be one of the reasons behind the discrepancy between satellite measurements and sky conditions reported by Globe at Night participants.”

This means that the view of the night sky, which is important to everything from professional astronomy to amateur stargazing and star-related cultural and religious practices, is under threat for many.

“At this rate of change, a child born in a place where 250 stars were visible would only be able to see about 100 by the time they turned 18,” Kyba said.

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