Stars are disappearing before our eyes faster than previously thought, with nearly a third of the world’s population now unable to see anything at all, new research suggests.
While the naked eye should be able to spot thousands of stars on a clear, dark night, our view of our galaxy — the Milky Way — and dozens of intricate constellations is rapidly disappearing.
An estimated 30% of people worldwide are deprived of night vision due to light pollution.
That staggering number comes from an analysis by a citizen science initiative called Globe at Night, which published its findings in the journal Science.
The study, by NOIRLab, a US-based nighttime astronomy research center, estimates that a child born today in a place where he can see 250 stars will see only 100 by the time he turns 18.
Astronomer Connie Walker said the findings underscore the importance of “redoubled efforts” to protect the night sky from the phenomenon known as “sky glow”.
What is Skylight?
Skyglow is the illumination of the night sky beyond that caused by natural sources such as the stars or the moon.
It’s long been known to be a problem, but Globe at Night observations show it’s increasing much faster than satellite measurements of Earth’s brightness at night.
The research is based on crowdsourced reports from around the world, with people submitting their findings online.
They would then look at a number of star maps and note which one most closely matched what they saw in the sky, providing an estimate of what’s known as the “limiting magnitude to the naked eye.”
This is a measure of how bright an object must be to be seen, and estimates the brightness of the skyglow.
Globe at Night’s findings are based on more than 50,000 observations submitted between 2011 and 2022 across Europe and North America.
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Why should we worry?
Light pollution doesn’t just spoil the view of the sky, it also affects our health – and that of wildlife.
That’s because it disrupts the natural cyclic transition from sunlight to starlight that we and other living things have evolved with – and sky glow is anything but natural.
Throughout history, humans have often had awe-inspiring visions of the starry night sky, but the path we’re on now means more and more people are losing their way.
The disappearance of visible stars reported by Globe at Night points to a 9.6% annual increase in sky brightness over the past decade, much higher than the 2% measured by satellites.
“This shows that existing satellites are not sufficient to study changes in the Earth’s night,” said the study’s lead author Christopher Kaiba of the German Research Center for Geosciences.
While the new findings focus on the Western world, the paper notes that skies may brighten faster in developing countries where the penetration of artificial lighting is growing at a higher rate.
“The increase in sky glow over the past decade highlights the importance of redoubled efforts and new strategies to protect dark skies,” said Connie Walker.
“The Globe at Night dataset is integral to our ongoing assessment of changes in the sky’s glow, and we encourage everyone who can get involved to help preserve the starry night sky.”