Wondering where to go stargazing this summer? You might have to travel further than you think. According to the new world atlas of artificial sky luminance, which documents the degree to which the world is illuminated by light pollution, more than 80 percent of the world and more than 99 percent of the U.S. and European populations live under light-polluted skies. This makes it impossible for one-third of humanity—including nearly 80 percent of North Americans—to see the Milky Way, which is the galaxy that contains our solar system. Those in the northeastern U.S. are particularly out of luck, according to the atlas.
The light pollution, a great deal of which is created from un-shielded street lights, affects more than just astronomers and casual sky observers. Bright nights affect nocturnal organisms and their ecosystems—extended exposure to artificial lights has been linked to increased risk for certain types of cancer, and their installation and constant glow is considered by many to be a waste of energy and money. And although some lights are installed based on the belief that they will increase safety and reduce crime, certain research suggests the strategy could be adapted in some cases. And if nothing is done, future generations (especially those who live in big cities) may never be able to clearly observe our galaxy.
“My own ability to observe and appreciate the night sky was thwarted by living in or near non-optimal, urban, and light-polluted locations for much of my youth,” says Jonathan Kemp, a telescope specialist at Middlebury College Observatory. “It was only when I traveled to an astronomical observatory on a remote mountaintop in South America that I truly appreciated the dark, night sky for the first time in the Chilean Andes.”
And with the worldwide transition to LED technology, the visibility is only getting worse.
“Unless careful consideration is given to LED color and lighting levels, this transition could unfortunately lead to a 2-3 fold increase in skyglow on clear nights,” Fabio Falchi, lead researcher of the atlas, said in a statement.
There are a number of steps—both big and small—that can be taken to reduce light pollution. Astronomers and environmentalists can work with those responsible for implementing and regulating lighting, according to Kemp. Capping or cutting off the tops of light fixtures can help, as well as aiming the lights downwards and modifying the fixtures so they only emit light at certain wavelengths. But everyday citizens can make a difference as well.
“You can make sure that your lights are out when you’re at home,” says Bob King, long-time member of the American Association of Variable Star Observers. “And home security lighting does virtually nothing to prevent crime. If you have one of those lights, turn it off. Use a flashlight.”
On the, er, bright side, the new atlas is more user-friendly than its predecessor (which was created 15 years ago), meaning you can use it to find the best stargazing spot near you.
“It offers you a place to start if you’re looking for a dark sky,” King says. “You’d go to the atlas, you’d locate your city, and you can find out what direction to drive in where it might be darker.”