New data show how quickly light pollution is darkening the night sky

The night sky is getting brighter faster than the researchers realized, using the night sky for the night sky. A study of more than 50,000 star observations by citizen scientists indicates that the night sky grew about 10 percent brighter, on average, every year from 2011 to 2022.

In other words, a baby born in a country where about 250 stars were seen each night, could see only 100 stars on his 18th birthday, researchers in Science 20 Jan.

The dangers of rain go beyond being unable to see as many stars. Too much light at night can harm people’s health, sending migratory birds flying into buildings, disrupting food webs by drawing pollinating insects to lights instead of plants and even disrupting fireplaces trying to roost (SN: 8/2/17; SN: 8/12/15).

“Well, this is a call to action,” said astronomer Connie Walker of the National Optical-Infrared Astronomy Research Laboratory in Tucson. “People need to consider the impact this has on our lives. But not astronomy. It affects our health. It affects other animals that cannot speak for themselves.

Walker works with the Globe for the Nocturnal campaign, which began in the mid-2000s as a projection project uniting students in Arizona and Chile and now has thousands of participants worldwide. Contributors can compare the stars with maps of what stars would be visible in different levels of light pollution and the results in the app.

“I am quite skeptical of the Night Globe” as a tool for precision research, admits physicist Christopher Kyba of the GFZ German Research Center for Geosciences in Potsdam. And the power is in sheer numbers: Kyba and colleagues analyzed 51,351 individual points collected from 2011 to 2022.

“The details are not exact, but there is a whole lot of them,” he said. “This Globe is not a nightly strategy game; it’s actually useful data. And the more people participate, the more powerful it gets.’

Those data, from the Global Sky Atlas published in 2016 by the group, concluded that the brightness of the night sky increased by an average of 9.6 percent per year from 2011 to 2022 (SN: 6/10/16).

Most of that growth required satellites that collected data on the brightness of the globe around the world. Those measurements showed just a 2 percent increase in brightness per year over just a decade.

Kyba says there are several reasons. Since the early 2010s, many outdoor lights have switched from high-pressure sodium lightbulbs to LEDs. LEDs are more energy efficient, which has environmental benefits and cost savings.

But LEDs also emit more short-lived blue light, which scatters particles in the atmosphere, than the orange light of sodium bulbs, which glows brighter in the sky. Existing satellites are not sensitive to blue waves, so they estimate light pollution coming from LEDs. And the satellites shine towards the horizon, like a light emitted by a signal or from a window, rather than straight up or down.

Astronomer and light pollution researcher John Barentine isn’t surprised that satellites have underestimated the problem. But “I’m still amazed at how much it’s underestimated,” he said. “This paper confirms that we are subject to light pollution in the world.”

The good news is that we don’t need any major technological breakthroughs to fix the problem. Scientists and planners just need to convince people to change how they use light at night – easier said than done.

“People sometimes say that light pollution is the easiest pollution to solve, because you just turn on the contract and it goes away,” Kyba says. “It’s true. But it’s a social problem that’s being ignored – this larger problem is being fueled by billions of individual decisions.”

Some simple solutions include dimming or turning off lights overnight, especially lighting or lights in empty parking lots.

Kyba shared a story about a church in Slovenia that switched from four 400-watt floodlights to one 58-watt led, lighting the back of the church’s cutout to put a light on its door. The result was a 96 percent reduction in energy use and much less wasted light, Kyba announced in the news International Journal of Sustainable Lighting 2018. The church was still lit, but the grass, trees and sky around it remained dark.

“If it is possible to replicate that story over and over again throughout our society, you could suggest that you could actually reduce the light in the sky, still be in the environment and have a better vision and consume a lot less energy,” he said. . This is the kind of dream.

Barentino, who leads a private dark-sky consulting firm, believes widespread awareness of the problem — and subsequent action — could be imminent. For comparison, he points to the oil slick fire in the Cuyahoga River, outside Cleveland, in 1969, which fueled the environmental movement of the 1960s and ’70s, and pushed the US Congress to pass the Clean Water Act.

“I think we’re on a precipice, maybe we’ll have a river-on-fire moment of light,” he said.