A Day for Earth, but a Whole Week for Dark Skies

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Wednesday is Earth Day, but all week — Monday, April 20 through Saturday, April 26 — is National Dark Sky Week in America, when people are asked to dim the lights to see more stars.

If enough people participate, backyard and professional astronomers might be treated with a week of darker, starrier skies. The bigger idea is to raise awareness about sensible lighting practices, so skies might get a little bit darker all the time. And not just for astronomy buffs. Besides aesthetics, evidence is mounting that light pollution could have far-reaching effects for the environment and even public health.

Jennifer Barlow, founder of the event, said the only way National Dark Sky Week can succeed is if more people participate every year. “No reduction in light pollution can be made unless a significant number of people turn off their lights,” she said.

Besides turning out the lights, the participating groups are encouraging people to attend star parties, visit local observatories, or “dust off the old telescope from the attic,” Barlow said.

Year-round, the International Dark Sky Association encourages people to shield lights, or use fixtures that focus light downward instead of up into the sky. Reducing extraneous light, especially at ball fields, is a major step in the right direction. And certain types of lighting — like low-pressure sodium — are better than others.

Flagstaff, Arizona became the world’s first International Dark-Sky City in 2001, owing to the presence of several important observatories — it’s the home of Lowell Observatory and the U.S. Naval Observatory — along with the dedicated efforts of a handful of astronomers. The city government and the vast majority of businesses have readily complied with responsible lighting codes to protect views of the night sky for residents and astronomers alike. 

The skies are noticeably dark over Flagstaff; the stars are rich at night. The Grand Canyon is even more impressive, especially on the north side. The views after dark are as stunning and magical as those during  the day.

But even those skies aren’t as good as they could be, because light pollution from cities up to 200 miles away — including Las Vegas and Phoenix — is gradually creeping in. Chad Moore, a dark skies advocate who works for the National Park Service in Denver, has spent nearly a decade documenting the skies over 55 of the nation’s parks, which are usually the best places to see stars.

Parts of rare parks — Capitol Reef, Great Basin and Big Bend among them — boast truly dark skies, he said.

Moore pointed out there are reasons besides beauty to rein in light pollution: “In the last 10 years there has been a revolution in our understanding of animal habitat and what animals require,” he said. “There are links between artificial light and cancer in humans. There’s a lot we didn’t know about.”

Second photo caption: 360-degree panoramic picture of the Milky Way as seen from Death Valley. Credit: Dan Duriscoe, National Park Service.

For more information:

National Dark Sky Week 
International Dark-Sky Association
IYA Dark Skies Awareness
Starlight Initiative
World Night in Defense of Starlight
American Astronomical Society
Astronomical League
NASA IYA site