Light pollution blots out the Milky Way for one-third of humanity
People around the world are losing the night sky.
According to a new atlas of light pollution detailed in the journal Science Advances on Friday, more than 80% of the people on Earth live under skies polluted by artificial light.
About 99% of people in the United States and Europe live with some degree of light pollution each night, the study found.
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"There is a cultural loss" when people can't see the night sky, Fabio Falchi, co-author of the new atlas, told Mashable in an interview.
For most of human history, people have been able to look up around the world and see the clouds of the Milky Way glowing above them, but now, one-third of the world's population is unable to see our galaxy's arms stretching out in the night.
"We've got whole generations of people in the United States who have never seen the Milky Way," said Chris Elvidge, a scientist with the National Oceanic and Atmospheric Administration's National Centers for Environmental Information in a statement.
"It's a big part of our connection to the cosmos -- and it's been lost."
More than culture
The authors of the new atlas -- which is an updated and more detailed version of a light pollution atlas published in 2001 -- used satellite data and more than 30,000 observations from people on the ground to compile the report which, in digital form, looks something like a heat map showing various places where light pollution is terrible and not so bad.
The authors found that some cities are so light polluted that the people living within them never experience a true night.
"The most light-polluted country is Singapore,where the entire population lives under skies so bright that the eye cannot fully dark-adapt to night vision," the study says.
Other parts of the world fare better, however.
The Central African Republic, Chad and Madagascar have the darkest skies, with about 75% of the people in those nations living under light pollution-free skies, according to the atlas.
Light pollution is about more than just culture.
Studies have shown that harsh artificial light can have an ill effect on wildlife and even human health. For instance, some trees are unable to adjust to seasonal variations due to artificial light, according to a 2009 study published in the journal Environmental Health Perspectives. Baby sea turtles also have trouble finding the ocean under light-polluted conditions after hatching because they use the light of the moon to guide them to the sea -- a light that can become difficult to find when confused with street lamps and sky glow.
Harsh, white light can also affect a person's biological clock and natural rhythms, according to some findings. (This is part of the reason people suggest that you put your phone away before bed.)
Light pollution from space
Perhaps some of the best examples of light pollution around the world come from humans living above Earth.
For years, astronauts have been taking photos of cities from space, unwittingly documenting changes in artificial light.
Images of Milan taken in 2012, for example, show a relatively dim, yellow glow coming from the city, but a later photo in 2015 shows somewhat harsh looking white light emanating from the city. According to a report by Tech Insider, the change coincided with a transition to more energy efficient LED lighting.
Many cities have switched from softer, yellow light produced by high pressure sodium outdoor lighting to energy-efficient LEDs, which can give off a harsher light. But using different, warmer LEDs could help mitigate light pollution, according to Cheryl Ann Bishop, communications director of the International Dark-Sky Association (IDA).
"I really hope that this study puts people on notice of the breadth of light pollution across the globe," Bishop told Mashable in an interview.
A light on the horizon
But there is hope for the night sky (and those that love it) yet.
About 18 states and the District of Columbia have laws on the books to help limit light pollution, according to a report published in May by the National Conference of State Legislatures.
New LEDs on the market are also energy efficient and give off a warmer light than the harsh, blueish light favored by many municipalities today, Bishop said, so the IDA is advocating for their use.
The IDA is also working to make sure that more generations can see the clear night sky by designating various parts of the world as dark sky preserves, parks, communities, reserves and sanctuaries to aid in the conservation of the night sky. The Grand Canyon was just given provisional status as a Dark Sky Park, for example.
“Our mission to preserve and protect the canyon for future generations is important during the day -- and also at night,” Susan Schroeder, CEO of the Grand Canyon Association, said in a statement.
“We are so pleased to support this initiative."
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Miriam Kramer worked as a staff writer for Space.com for about 2.5 years before joining Mashable to cover all things outer space. She took a ride in weightlessness on a zero-gravity flight and watched rockets launch to space from places around the United States. Miriam received her Master's degree in science, health and environmental reporting from New York University in 2012, and she originally hails from Knoxville, Tennessee. Follow Miriam on Twitter at @mirikramer.
