Artificial light is killing our view of the night sky. But we can change that.

Trevor Hughes | USA TODAY

Correction & clarification: An earlier version of this article misstated the location of Salinas Pueblo Missions National Monument. The story has been updated with the correct information.

PAGE, Ariz. – Staring up at the night sky in northern Arizona as a child, John Barentine saw something unexpected: thousands of stars.

An amateur astronomer living in a city, Barentine was used to pointing his telescope up and seeing dozens of stars. On a family trip to Flagstaff, Barentine saw something more as he marveled at the vast Milky Way blanketing the sky. Thousands of stars. Planets. Galaxies.

"I had this revelation," Barentine said. "It's there every night, but there was something in the way."

That "something" is new, at least as far as human history goes: artificial light.

Through much of human history, our ancestors looked up at a night sky filled with stars that set planting patterns and helped lead them across continents. We've since filled that night sky with artificial light, brightening our immediate surroundings and dimming the stars above. New York City residents can live their entire lives seeing fewer than a dozen of the brightest stars and planets. Most people living east of the Mississippi River will never see the Milky Way in all its sparkling glory.

That trend is about 150 years old and carries profound implications for natural cycles and our own health, experts said.

Dark skies among brightest sights at national parks Remote national parks are using their certified dark skies to attract tourists.

Thousands of people across the world are fighting to conserve the remaining dark skies. They persuade cities and towns to alter streetlights to direct the beams straight down, and they work with rural residents to reduce the number of powerful outdoor lights that can be seen for miles.

Those efforts are coordinated in large part by the International Dark Sky Association, where Barentine works. The group views access to the dark night sky as part of a shared human heritage that must be preserved for future generations. Scientists say light pollution interferes with our natural circadian rhythms, making sleep difficult even when our bedrooms are darkened. Light pollution has similar ramifications for plants and animals – all of them, essentially – that evolved under dark skies.

"How can people be concerned about something they've never had access to?" Barentine said about youngsters growing up today. "Fundamentally, it's a sense of connection with nature that's been severed."

The new world atlas of artificial night sky brightness

Photographing the stars

Photographer Tracy Lee had her own night sky epiphany on a camping trip as a kid. The California native grew up in Sacramento, where star sightings are scarce, and it wasn't until she visited Moab, Utah, with a friend two years ago that she truly began to appreciate the night sky, especially the Milky Way. Now Lee adventures around the West, shooting stunningly clear pictures of the stars.

"They get to stare at the stars and think and wonder ... and see things that, living in our bubble, people don't get to see," Lee said. "The stars have always spoken to me. I was always hyperactive, but the one thing that I would slow down for was to look at the stars."

Modern, inexpensive camera equipment has opened night sky photography to eager amateurs and professionals alike, who no longer have to develop film to check whether their settings are correct. They can take more photos in a shorter period of time, building up their skills over a weekend instead of a decade. That's led to an explosion of Instagram and Facebook accounts showcasing the work of photographers around the world.

Lee has more than 37,000 Instagram followers. Like many night sky photographers, she keeps many of her shooting locations secret, often hiking or driving long distances off road across public lands to find the best places.

"Everybody should get outside, but it's a bittersweet situation," she said. "The more people who are out there, the more chances there are that you'll run into people."

Recognizing some of the most remote parks

The National Park Service tries to strike the same balance that Lee struggles with: National parks are among the most visited public lands, but the darkest ones tend to be the least busy. Like most government programs, unpopular parks don't get a lot of funding.

One way to change that dynamic is to give a dark sky designation to some of America's most remote national parks, and the park service has more certified dark sky locations than any other organization in the world. Among those dark sky parks: Utah's Natural Bridges, Salinas Pueblo Missions in New Mexico, California's Death Valley and Colorado's Black Canyon of the Gunnison.

Worldwide, more than 100 locations are certified by the International Dark Sky Association. Not all of them are remote or even totally dark, but they offer a far darker view of the sky than what most Americans can see. Even the Grand Canyon, one of the most visited national parks, offers magnificent dark sky viewing just a few steps from the South Rim hotels.

Thanks to the explosion in the popularity of night sky viewing, national parks traditionally staffed for daytime visitors are discovering an additional set of users at night.

“There’s this saying at some of our parks: ‘Half the park is after dark,’” said Bob Meadows, a night skies specialist for the park service. “There are parks getting thousands of people in for a single evening. That didn’t really occur 15 or 20 years ago at all.”

Up to about a decade ago, few national parks even considered the night sky as a resource. That began changing once Natural Bridges National Park won recognition from the International Dark Sky Association. The park is popular with camera-toting tourists who crowd beneath the awe-inspiring stone spans on clear, moonless nights or pack into the pitch-black parking lot for a ranger-led talk about constellations and to watch the International Space Station and other satellites cruise overhead, visible to the naked eye. Meadows said national parks that won recognition from the association have seen a notable increase in tourism, especially from European and Asian visitors who are unaccustomed to truly dark skies.

“Just as someone goes to Death Valley because it’s the hottest place on Earth, they want to see the night sky in the best place,” he said.

The newest dark sky park is Arizona's Petrified Forest National Park, also in the American West, where vast tracts of public land mean little development and even fewer streetlights.

The crown jewel of dark sky parks

Visitors have to hike many miles or catch a speedboat to visit the crown jewel of dark sky parks: Rainbow Bridge National Monument in Utah.

Known to Native Americans for generations, Rainbow Bridge is the largest free-standing natural rock arch in the USA and nearly the world's largest. Tucked away in a side canyon of the Colorado River, the bridge features prominently in the generations-old creation stories of many tribes, from the Navajo to the Utes. Europeans "discovered" the eons-old span in 1909.

Federal engineers almost destroyed the bridge when they dammed and flooded Glen Canyon in nearby Page, Arizona, but they hastily shortened the dam by 13 feet to ensure the newly created Lake Powell wouldn't flood the side canyon spanned by the bridge. Rainbow Bridge is one of the least-visited national park sites and was designated in April as one of only four International Dark Sky Association Dark Sanctuaries in the world – recognizing both its dark skies and cultural significance.

“This designation is an important step to ensure we protect the entirety of the landscape at Rainbow Bridge National Monument, which is sacred to many of the Native American Tribes in the area,” William Shott, the superintendent of Rainbow Bridge National Monument and the surrounding Glen Canyon National Recreation Area, said in a statement. “We’re thrilled to be the first National Park Service unit to receive this specific designation, as this will only fuel our night sky preservation efforts.”

Few visitors remain overnight at Rainbow Bridge. The park service bans boats from tying up at the dock a mile back down the canyon, and hiking to the span requires permission from the Navajo Nation and a long slog across the desert. Barentine hasn't seen it from ground level, only on a flight in a small plane.

"It was totally amazing," he said. "It's way out there, and that's what protected it for so long."

The park service estimates artificial light from distant electric lights, when measured directly over the bridge, is less than 5 percent above the natural background level. Lee, who had a chance to shoot overnight at Rainbow Bridge several years ago, remains awed by the experience. She said everyone should have a chance to see a truly dark sky, even if all they do is sit there and marvel.

"It's so beautiful, and you realize how small and insignificant we are in the grand scheme of things," she said.

Correction & Clarification

An earlier version of this article misstated the location of Salinas Pueblo Missions National Monument. The story has been updated with the correct information.