Eighty percent of Americans can’t see the Milky Way from where they live, according to a new analysis of light pollution’s effect on the night sky. The global dark sky atlas, produced by an international team of researchers, suggests there’s only one spot in Washington state that’s untouched by the effect of artificial light.
“I hope that this atlas will finally open the eyes of people to light pollution,” Fabio Falchi of Italy’s Light Pollution Science and Technology Institute said in a news release. Falchi is the lead author of the analysis, published today by Science Advances.
The atlas is based on readings from the Suomi NPP satellite, which was launched in 2011 and is managed by NASA and the National Oceanic and Atmospheric Administration. Suomi’s main purpose is to provide weather data, but it’s equipped with imagers that can pick up low-light readings at night.
Falchi and his colleagues focused on levels of artificial lighting, and how much that illumination from streetlights, house lights and other sources is likely to obscure astronomical observations from locations around the globe.
They determined that one-third of humanity lives in places where the light pollution is so bad that the Milky Way, a river of stars that typically dominates unsullied skies, would be invisible. In the United States, the fade-out is worse than the global average.
“We’ve got whole generations of people in the United States who have never seen the Milky Way,” said Chris Elvidge, a scientist at NOAA’s National Centers for Environmental Information in Boulder, Colo. “It’s a big part of our connection to the cosmos – and it’s been lost.”
As expected, Washington’s hot spots center around the state’s urban areas – Seattle, Spokane, Wenatchee, Yakima, the Tri-Cities and the Portland-Vancouver area.
The darkest spots tend to be around national forests and national parks. The one spot in the state where the atlas shows totally dark skies is in the Okanogan-Wenatchee National Forest’s Paysayten Wilderness, in north central Washington. That spot takes in a few well-known skywatching sites, including Billy Goat Mountain and Hart’s Pass. (For more, check out this website, as well as the Washington Trails Association’s Dark Places Digest, the Clear Sky Chart and DarkSkies Northwest.)
The global survey found that light pollution is most extensive in countries such as Singapore, Italy and South Korea, while Canada and Australia retain the highest proportion of dark sky.
Light pollution isn’t just an aesthetic concerns. Studies have found that high levels of artificial light can confuse wildlife such as insects, birds and sea turtles, sometimes with fatal consequences. Research also has linked excessive artificial light to human maladies such as obesity, diabetes, depression and sleep disorders.
Some areas have taken measures to reduce light pollution – for example, by installing sky-friendly streetlights. A bill passed during this year’s legislative session directs the Washington State Department of Transportation to minimize light pollution on state highways.
In addition to Falchi and Elvidge, authors of “The New World Atlas of Artificial Night Sky Brightness” include Pierantonio Cinzano, Dan Duriscoe, Christopher Kyba, Kimberly Baugh, Boris Portnov, Nataliya Rybnikova and Riccardo Furgoni. The University of Colorado’s Cooperative Institute for Research in Environmental Sciences is making an interactive map with data download instructions available online.
