The night sky has been clearing up faster than researchers thought, thanks to the use of artificial lights at night. A study of more than 50,000 star observations by citizen scientists reveals that the night sky got about 10% brighter, on average, every year from 2011 to 2022.
In other words, a baby born in a region where about 250 stars were visible every night would only see 100 stars on his 18th birthday, researchers report in the Jan. 20 journal Science.
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The dangers of light pollution go far beyond not being able to see as many stars. Too much glare at night can harm people‘s health, send migratory birds flying into buildings, disrupt food webs by attracting pollinating insects to lights instead of plants, and can even disrupt fireflies trying to have sex (SN: 8/2 /17; SN: 8/12/15).
“In a way, this is a call to action,” says astronomer Connie Walker of the National Infrared Optical Astronomical Research Laboratory in Tucson. “People should consider that this has an impact on our lives. It’s not just astronomy. It impacts our health. It affects other animals that cannot speak for themselves.”
Walker works with the Globe at Night campaign, which began in the mid-2000s as an outreach project to connect students in Arizona and Chile and now has thousands of participants worldwide. Contributors compare the stars they can see with maps of which stars would be visible at different levels of light pollution, and feed the results into an application.
“I was quite skeptical of the Globe at Night” as a tool for precision research, admits physicist Christopher Kyba of the GFZ German Research Center for Geosciences in Potsdam. But the power is in the sheer numbers: Kyba and his colleagues analyzed 51,351 individual data points collected from 2011 to 2022.
“The individual data isn’t accurate, but there’s a lot of it,” he says. “This Globe at Night project is not just a game; it’s really useful data. And the more people participate, the more powerful it gets.”
This data, combined with a global sky luminance atlas published in 2016, allowed the team to conclude that night sky brightness increased by an average of 9.6% per year from 2011 to 2022 (SN: 6/10/16).
Most of that increase was missed by satellites collecting brightness data around the world. These measurements only saw a 2% increase in brightness per year over the last decade.
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There are several reasons for this, says Kyba. Since the early 2010s, many outdoor lights have switched from high pressure sodium bulbs to LEDs. LEDs are more energy efficient, which brings environmental benefits and cost savings.
But LEDs also emit more short-wavelength blue light, which scatters particles in the atmosphere more than the orange light from sodium lamps, creating more brightness in the sky. Existing satellites are not sensitive to blue wavelengths, so they underestimate light pollution from LEDs. And satellites can miss light that shines toward the horizon, like light emitted by a sign or a window, rather than straight up or down.
Astronomer and light pollution researcher John Barentine wasn’t surprised that satellites underestimated the problem. But “I was still surprised at how much it was underrated,” he says. “This article is confirming that we are underestimating light pollution in the world.”
The good news is that it doesn’t take huge technological advances to help solve the problem. Scientists and policymakers just need to convince people to change the way they use light at night – easier said than done.
“Sometimes people say that light pollution is the easiest pollution to solve because you just flip a switch and it disappears,” says Kyba. “That’s true. But it’s ignoring the societal problem – that this general problem of light pollution is made up of billions of individual decisions.”
Some simple solutions include dimming or turning off lights at night, especially spotlights or lights in empty parking lots.
Kyba shared a story about a church in Slovenia that switched from four 400-watt spotlights to a single 58-watt LED, shining behind a cutout of the church to focus light on its facade. The result was a 96% reduction in energy use and much less wasted light, Kyba reported in the International Journal of Sustainable Lighting in 2018. The church was still lit, but the surrounding grass, trees and sky remained dark.
“If it were possible to replicate this story over and over again across our society, it would suggest that you could actually drastically reduce the light in the sky, still have a bright environment and have better vision and consume a lot less energy,” he says. “This is kind of a dream.”
Barentine, who leads an obscure private consulting firm, believes that widespread awareness of the problem — and subsequent action — could be imminent. For comparison, he points to a highly publicized oil slick on the Cuyahoga River outside Cleveland in 1969 that fueled the environmental movement of the 1960s and 1970s and prompted the US Congress to pass the Clean Water Act.
“I think we’re on the precipice, perhaps, of having the burning river moment for light pollution,” he says.
What are the 4 most common forms of light pollution?
Components of light pollution include: This may interest you : US Environmental and Conservation Priorities – United States Department of State.
- Glare – excessive glare that causes visual discomfort.
- Skyglow – lightening of the night sky over populated areas.
- Light intrusion – light falling where it is not intended or needed.
- Clutter – Bright, fuzzy, excessive groupings of light sources.
What are the 4 effects of light pollution? Too much light pollution has consequences: it blots out starlight in the night sky, interferes with astronomical research, disrupts ecosystems, has adverse health effects, and wastes energy.
What are the 3 main types of light pollution?
There are three other types of light pollution: glare, clutter, and light invasion. Glare is excessive glare that can cause visual discomfort (for example, when driving).
What are examples of light pollution?
Common sources of light pollution include street lamps, parking lot/mall lights, outdoor lights found in most homes/businesses, neon signs and illuminated signs.
What color produces the most light pollution?
These blue wavelengths are more easily scattered by the Earth’s atmosphere than other colors, which would considerably increase the light pollution they contribute, lamp for lamp. Blue light is also more easily picked up by the human eye, meaning people would perceive even brighter skies.
Does red light cause light pollution? Quite a short time was spent waiting for the red light to turn green, but those moments had an outsized effect on exposure to pollutants: The concentration of harmful particles was 29 times higher at traffic lights than when people were driving on the road, the researchers found. .
What is the biggest source of light pollution?
The main cause of light pollution is outdoor lights that emit light upwards or sideways. Any light that escapes upwards, except where a tree or building may be blocking it, will scatter through the atmosphere and light up the night sky, thus dimming your view of it.
Which color of light produces the most light pollution?
The rich blue light from LED poles, they say, is the enemy of professional and amateur astronomers alike. Blue light is preferentially scattered by the atmosphere, resulting in potentially unacceptable levels of light pollution for astronomical observations.
What are the 4 effects of light pollution?
Too much light can damage human eyes and even disrupt the hormone melatonin, responsible for regulating daytime and nighttime vision. This can result in sleep disturbances and other health implications such as stress, exhaustion, headaches, increased anxiety and some forms of obesity.
What are the 5 effects of light pollution? More light at night reduces melatonin production, which results in sleep deprivation, fatigue, headaches, stress, anxiety and other health problems. Recent studies also show a connection between reduced melatonin levels and cancer.
What are 3 causes of light pollution?
Most light pollution comes from outdoor lighting, advertisements and street lighting. Another important source is the indoor light of large buildings such as office towers. The three main forms of light pollution are glare, sky glare, and light invasion.
What are 4 effects of pollution?
The long-term health effects of air pollution include heart disease, lung cancer and respiratory illnesses such as emphysema. Air pollution can also cause long-term damage to people’s nerves, brain, kidneys, liver and other organs. Some scientists suspect that air pollutants cause birth defects.
