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Fortunately, as far as environmental problems go, light pollution is an easy one to reverse. Fully shielded fixtures that direct light downward greatly reduce the amount of light pollution, as do less powerful bulbs, says Johanna Duffek, outreach education manager of the International Dark-Sky Association in Tucson, Ariz. So far, thousands of towns and cities have enacted lighting ordinances, but Duffek is emphatic that no one is asking people to go without light at night.

“We’re asking people to light better,” she says. “There’s a belief that more light means better safety and security, but it’s not the case. All that’s needed is the right amount in the right place and at the right time.”

Moore and his Night Skies Team began tracking light pollution in national parks in 1999 after noticing a decline in star visibility. Using a special digital camera, they began measuring brightness values to assess the purity of the night sky. The results weren’t encouraging: In some parks, the team documented errant light from cities more than 200 miles away. The glitz from Las Vegas was visible from nine parks, and of the more than 85 parks surveyed, only a handful still have pristine night skies.

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Owachomo Bridge at night in Natural Bridges National Monument in Utah
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Some parks have taken their commitment to the night sky a step further. In 2006, Natural Bridges National Monument in Utah was the first park in the world certified as a dark-sky enclave by the International Dark-Sky Association, followed by Cherry Springs State Park two years later. Grand Canyon National Park in Arizona, Lava Beds National Monument in Tulelake, Calif., and Great Basin National Park in Baker, Nev., have also pursued dark-sky designations.

The distinction is a draw for tourists, says Chip Harrison of Cherry Springs. “It’s not uncommon for people to drive more than 100 miles to come to one of our programs,” he says, which can range from telescopic viewing of deep-space objects to observing planets to star parties on the astrology field where people pitch tents and spend the night gazing at the sky. “It’s really cool to see how excited some people get when they see the Milky Way,” he adds. “They go, ‘Wow, I haven’t seen this since I was a kid.’ ”