When I was a child, my family lived in a suburb of Washington, DC. Most of the stars were invisible against the overhead glare from streetlights. At best, there was only a faint glimpse of the vague Milky Way. The combined glow of a hundred billion stars dimmed to almost nothing by bright streetlights and storefronts.
This is light pollution, artificially generated lighting thrown into the sky, causing the sky itself to glow and the stars to disappear. Astronomers have known for years that this situation is bad for stargazing, but it actually has a negative effect on the well-being of many living beings, including plants, animals, and even humans. More than % are affected by light pollution and lose their perspective of the sky.
For most of us, the stars are essentially fading.
And it’s getting worse every year. I don’t know how bad it is, exactly. Light pollution is measured from space, but orbiting satellites don’t detect light in the same way that the human eye does, so the results may not match what you see from the ground. What is the change in sky brightness that people perceive over time when they look at the sky?
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To find out, a team of scientists led by light pollution researcher Christopher Kiva at the GFZ German Geoscience Research Center turned to a strangely obvious detection method: humans.
They used data from Globe at Night, a project run by the National Science Foundation’s National Institute of Optical and Infrared Astronomy (NOIRLab) that uses citizen science to measure light pollution. The process is pretty easy. Volunteer participants will be given a set of star maps (created by his Jan Hollan at the Institute for Global Change at the Academy of Sciences of the Czech Republic). One chart shows only the brightest stars, the next contains slightly dimmer stars, and so on to the faintest stars visible to the unaided eye under ideal conditions. Participants then observe the sky and compare the faintest stars they see to a chart to select the one that best matches what they see.
Kyba and his team looked at a staggering amount of data from over 50,000 citizen scientists around the world who sampled regional sky brightness from 2011 to 2022. Light pollution increased by 6.5% annually, and in North America he increased by 10.4%. Researchers found that worldwide light pollution he increased by 9.6%. per year over a period of time.
This may not sound like much, but it reflects an exponential growth rate similar to compound interest on debt. About 10% year-on-year growth means Sky brightness doubles about every 7 yearsA little thought should make it clear why this is a serious problem. As Kyba and his co-authors described in their paper, it was published in the journal. chemistry, If someone had 250 visible stars in the sky when they were born, by the time they turned 18 they would only see 100, a more than fourfold increase in sky brightness over the same period.
This result is all the more alarming as it could affect satellite-based measurements, which have only recorded an increase of about 2% per year. Based on their research, Kyba and his team argue that satellites greatly underestimate their impact, blinding us to a looming future in which most people lose sight of the stars. ing.
Much of this discrepancy can be attributed to changes in technology. For example, Kyba and his colleagues point out that in recent years, many older outdoor lights that emit more red light have been replaced with brighter, glowing blue LEDs. The detector becomes less sensitive. In addition, satellites almost always cast light beams horizontally, like light from poorly constructed streetlights and cities, rather than through windows and billboards, which can significantly affect observers on the ground. Perceives a light that shines straight upwards.
All this extra light at night has a huge impact on the life beneath it. Light pollution interferes with the great migration of birds, the flowering of delicate flowers, and even the glowing courtship of fireflies, just to name a few. It can also affect humans and cause insomnia among many other health problems.
In some ways this is reminiscent of the climate crisis. It is global in nature, difficult to notice on a daily basis, and difficult for individuals to grasp and mitigate on their own. But if global warming were to increase by about 10% each year, I think we would have tackled this problem head-on a long time ago.
To make matters worse, light pollution puts on a friendly face for many, meaning more light at night automatically means increased safety. But for example, the road may be illuminated to make it easier for drivers to see at night, but it can also make the situation worse. Too bright streetlights create deep shadows, making it easier to hide dangers from untrained eyes. And on average, this increased lighting just casts more unwanted light upwards.
So what can we do about the brightening sky?
A lot has already happened. Groups such as the International Dark Sky Association (IDA), rather than increasing lighting, more intelligent Lighting; smarter street lights that concentrate light downward are an example. These lights provide more efficient lighting, so you also save energy and ultimately pay for yourself. IDA provides advice on how to contact local authorities to install better fixtures and create ordinances to reduce pollution. Many cities in the United States and other countries have been designated Dark Sky Communities, demonstrating an “extraordinary dedication to the protection of the night sky” by discouraging wasteful lighting practices.
At the moment, simple recognition is one of our greatest strengths. Turning off the outdoor lights at night may not seem like a big deal, but talking to others can help. Increased awareness. Causes like this need a critical mass to become widely known so that all participants can add them to the solution.
And yet, despite recent successes in cities like Pittsburgh and Ft. Collins, Coro, such local solutions are not immediately reflected in global progress. Many areas of the developing world are dangerously poorly lit at night, using wasteful fuel that emits greenhouse gases to power scant light sources. More lighting will help lift us out of poverty, but at the cost of a significantly increased glow in the sky. Kyba et al.’s study does not cover developing countries well, so it is not clear to what extent their light pollution is increasing, but if for no other reason than to maintain more efficient lighting, these It is clear that the region will also benefit. Reduce costs in the medium to long term.
epic thread on Twitterprincipal study author Kyba details the methodology and results of the study and includes some advice on what individuals can do. He suggests placing outdoor lighting only where necessary, and preferring bulbs and LEDs that glow red over blue to reduce scattering across the sky.
We need bigger, smarter solutions. Physical and biological effects are certainly a big concern, but there’s more to it here. It is the loss of beauty and connection with nature. The night sky is simply gorgeous, with treasures scattered among the stars. Getting out under its velvet vaults and watching a meteor shower or lunar eclipse is a great way to spend time with family and friends, or just decompress. I have seen and heard countless owls, coyotes and other wildlife outside at night. Observing the sky allows me to develop a deep appreciation for the natural world around me. The awe of the night sky is so real.
This is not just a problem for inconvenient astronomers. It’s like closing the Louvre, closing concert halls, cutting vast wildflower fields. I wonder how much my own love of astronomy would have grown if I had stayed in the suburbs of DC. I struggled to see the sky through that miasma, and it was only my deep love of astronomy that kept me going. They don’t even realize they’re losing it.
We need a dark night sky, and it’s the responsibility of all of us to keep it clear every time the sun sets.
This is an opinion and analysis article and the views expressed by the author or authors are not necessarily Scientific American.
