Western cities try to cut light pollution

Hitting the dimmer switch on city light helps animals and skygazers, too.

 

The next best chance for Westerners to see shooting stars is coming soon, between April 16 and 25, when the Lyrids meteor shower, one of the oldest known, will streak across the sky after midnight. In May the Eta Aquariids arrive, followed by the Delta Aquariids in July, and then the most spectacular of the year — the Perseids, fast, bright meteors, up to 200 an hour during Aug. 12 to 13, and the Geminids, kid-friendly because they show up soon after dark, from Dec. 7 to 17. But none of these, of course, will be visible without sufficiently dark skies.

For most of us, that will mean traveling far outside city limits to a place away from streetlights and other artificial illumination. But in some less-populated places, like High Country News’s western Colorado hometown of Paonia, the Milky Way’s glow can be seen on any clear night. That’s because Paonia is a tiny town in the high desert, with just 1,500 residents surrounded by public lands, orchards and farms.

Map of North America’s artificial sky brightness.

Natural darkness is important for a lot more than just stargazing, though. It’s also vital to scientific astronomy studies, migrating birds and night-flying insects. And exposure to blue-rich light at night, from computer screens and outdoor LED lights, disrupts people’s sleep cycles and may even contribute to cancer. At its January meeting, the American Astronomical Society passed a resolution “affirming that access to a dark night sky is a universal human right, making quality outdoor lighting a worldwide imperative.”

Some bigger Western cities have put a lot of effort into curbing and redesigning their light usage so that they can have dark skies, too. Flagstaff, Arizona, passed the nation’s first dark-sky ordinance in 1958, to preserve starry conditions necessary for research at the Lowell Observatory.

That nearly six-decade-old effort seems to have paid off. Today, nighttime images captured by the National Park Service show that Flagstaff emits far less artificial light than other cities of its size. The 65,000-resident city uses sodium street lights. In contrast to LED lights, which save energy but produce bright blue and white light that washes out stars and planets, sodium lights emit a warm red-yellow light that doesn’t contribute much to overall sky glow. Flagstaff also banned commercial searchlights and shielded outdoor lights around schools and shopping centers. In 2001, it became the world’s first international dark-sky city, as designated by the nonprofit International Dark-Sky Association.

Nighttime observations taken in July and August 2016 show light pollution from Flagstaff, top, and Cheyenne, Wyoming, bottom.
National Park Service

Other Western cities, following Flagstaff’s lead, are making an effort to turn down the wattage and return to darker skies. Last year, Phoenix voted to replace the 90,000 lights on its streets and parks with LEDs that have a more yellow hue than the standard blue-white LEDs. Los Angeles also adopted a plan to phase in warmer-colored LED lights, as did Montreal, Canada. “No one is saying that cities shouldn't be well lit,” astronomy author Bob Berman recently told NBC. “Everything has its time and place, and the same is true of light and darkness. And there is a place for darkness, and, I think that is slowly being realized.”

That’s true for national parks as well. Because dark skies and all that they entail are such an integral part of an outdoors experience, and because parks offer some of the darkest skies still to be found, the National Park Service is studying how different types of lighting affect the natural world. Its Natural Sounds and Night Skies division has tracked light pollution in parks for years; development and oil and gas production are driving the largest increases in nighttime glow. Some public lands are trying to cut down on the artificial light – near northwestern Colorado’s Dinosaur National Monument, energy companies will have to shield bright lights on rigs.  (Congress, however, is moving to weaken the National Park Service’s ability to oversee oil and gas drilling within park boundaries.)

To monitor light pollution, the agency has developed a special panoramic camera that produces a 360-degree view of the sky and horizon. It measures the light emitted by cities near national parks such as Flagstaff and Las Vegas; staffers presented the data gathered at the American Astronomical Society’s meeting in January. The information will help the agency work with city managers to reduce light pollution. Cities up to 250 miles away contribute to lighter skies in the parks. The neon glow of Las Vegas can be seen from eight national parks, including Death Valley.

Flagstaff’s dark-sky efforts, along with those of nearby Oak Creek and Sedona, earned all three towns certification from the IDA as Dark Skies Communities during the past few years. And they contributed to Grand Canyon National Park getting provisional Dark Sky Park designation last summer (to gain full status, it will have to retrofit two-thirds of its roughly 5,000 outdoor light fixtures, which it plans to do by 2019). Three national monuments near Flagstaff, Sunset Crater Volcano, Walnut Canyon and Wupatki, were also designated as International Dark Sky Parks in 2016. The designation recognizes “an exceptional or distinguished quality of starry nights and a nocturnal environment that is specifically protected for its scientific, natural, educational, cultural heritage and/or public enjoyment.” About 30 U.S. parks have been so designated, most of them in the Southwest.

The constellation Orion rises over Arizona's Sunset Crater Volcano National Monument.
NPS/Elliot Schultz

Nevada’s Great Basin National Park gained Dark Sky Park status in spring 2016, and is one of the least-lit places remaining on the continent. That made it the perfect place for the first-ever research-level observatory built in a national park. The Great Basin Observatory, constructed in cooperation with four universities, opened last August. Its 28-inch telescope will be used by researchers all over the country as well as students at universities and high schools, who will aim it remotely through the internet.

Here are a few handy tools for those inspired by the night sky:

The New World Atlas of Artificial Night Sky Brightness, published by Science Advances, draws on NPS research and on-the-ground measurements of night sky brightness. Clear Dark Sky provides forecasts for specific observation sites. Astronomy Calendar of Celestial Events tracks comets, moon phases, meteor showers, eclipses and more. The Dark Sky Weather app lets you know if it’s going to rain or snow in your location in the next hour.

Other useful astronomy apps are listed here.

 Jodi Peterson is High Country News’ senior editor.