In the American West, city and towns mark their boundaries with signs giving visitors what they think is the most pertinent information. Often, that’s often not the population, but their altitude and the date when they were founded. Thus, Tombstone, Arizona—home of Wyatt Earp and the shootout at the OK Corral—welcomes visitors with: “Elevation 4339. Founded 1879.”
Flagstaff, Arizona, is different. Yes, it tells everyone it lies at an elevation of 6906 feet (2105 meters) and was founded in 1882. But then it adds an additional line: “World’s First International Dark Sky City.”
That designation marks a quest Flagstaff has been on for 65 years: to remain a city where you can look up, and see the Milky Way, even as business has blossomed and the city’s population quadrupled. That’s unusual, because in most of the world, the night sky is increasingly invaded by the glare of streetlights, soccer lights, security lights, and pretty much anything that allows light to escape upward.
At a recent meeting of the American Astronomical Society (AAS) in Albuquerque, New Mexico, James Lowenthal, an astronomer at Smith College, Massachusetts, noted that until recently, astronomers thought the problem was worsening at the rate of about two percent per year. But this January, a paper appeared in Science, showing that thanks to the rapidly increased use of super-bright LED lighting, the trend had accelerated by a factor of five, equivalent to doubling the sky’s brightness every eight years. “This means that in a decade, most parts of the United States could lose thousands of stars from their sky, at a rate of about one star per day, day after day after day,” Lowenthal says.
But not for Flagstaff. In 1958, it passed the first-ever outdoor lighting ordinance. That ordinance was mainly designed to ban the use of searchlights in advertising, but since then, it has been repeatedly updated. It now limits the amount of light in commercial and residential developments; sets standards for the preferred color spectrum of the lighting (blue is bad); modifies the city’s streetlights; and ensures that when possible, lights are either fully or partially shielded, so that light can only go where it’s needed. It even has a novel concept of “light trespass,” says Daniel Folke, the city’s director of community development, in which my light has to stay on my property, and not invade yours.
And, it’s got teeth. “We are able to take someone to a hearing, basically, and cite the bejesus out of them if we need to,” says Mark Stento, former dark skies compliance officer for Flagstaff, now doing the same for the surrounding county, which has a similar lighting code. Though, he notes, that’s a last resort; he’d much rather work through building permits and public outreach than through the courts, especially for private residences. “You don’t want to be banging on people’s doors in the middle of the night, telling them to turn their lights off,” he says.
All of that might sound a bit overbearing, but the reality is that there is overwhelming buy-in from the community. Flagstaff even has a Dark Sky Brewing Company (advertising craft beers “as unique and beautiful as every star, meteor, and comet we can see from our backyard”), a coffee shop that offers Dark Sky Latte, and a road called Dark Sky Lane.
“It’s definitely not a hassle,” says Kim Conley, a two-time Olympian track and field athlete who is one of many elite athletes and other location-mobile professionals to choose the city as home. “Flagstaff is very proud to be a dark sky city.”
Much of the impetus comes from the city’s history. Flagstaff is home to Lowell Observatory, where 120 years ago, Percival Lowell sketched maps of Mars, and where, a couple of decades later, Clyde Tombaugh discovered Pluto. Since then, it has been joined by the U.S. Naval Observatory, which operates only 8 kilometers west of the city. Flagstaff is a city for which stars are in its DNA.
Today, it is no longer the only International Dark Sky City but it remains the most prominent—enough so that the AAS meeting devoted a 4½ hour “meeting-in-the meeting” to lessons that can be learned from its success.
Top of the list, says Lowenthal, is to realize that light pollution is not just a problem for cities with strong connections to observatories. “We astronomers are sort of the canary in the coal mine,” he says, but light pollution impacts many other things. “Most life on Earth has evolved to have a 24-hour cycle of light and dark,” he says. Light pollution easily disrupts that.
Folke notes that in Florida, “turtle lighting” is a big issue, meaning not that turtles need light, but that beach communities need to be dark enough to avoid disorient hatchling sea turtles, causing them to move toward the lights, rather than the safety of the sea.
Light pollution may also impact human health. Jeffrey Hall, executive director of Lowell Observatory, notes that for several years he’s been part of a study by the American Cancer Society, in which 300,000 randomly chosen people were asked to fill out periodic surveys about health and lifestyle. In 2018, he says, “there was a whole new section, asking about my daily exposure to light. Clearly this is responding to the medical community’s growing awareness of the impact of degradation of the natural light-and-dark cycle.”
Meanwhile, Folke emphasizes the need to look for win/win solutions, many of which, he suggests, can come from following five principles of outdoor lighting developed by the Illuminating Engineering Society—an organization astronomers might once have considered “our enemy.”
The principles are simple, common sense, and energy efficient. Nighttime lighting needs to have a well-understood purpose, be no brighter than needed, be aimed only where it’s needed, turned off when it isn’t needed, and to the extent possible, minimize its use of blue light. “Who could disagree with that?” Folke asks.
Also important is to persuade people that safety doesn’t require them to splash high-intensity spotlights all over the place. “I think that’s probably the biggest challenge we have,” Folke says, even though, “the police department has never come to us and said we need more lighting. The emphasis is not on more lighting; it’s lighting the right places.”
Hall, however, adds that addressing these issues requires astronomers and other scientists to emerge from their ivory towers into the world of politics. But that’s not as bad as it sounds, he says, because even in today’s politically fractured landscape, most legislators are easy to work with, once out of the partisan media spotlight. “By and large, they [are] really trying to find the answers,” he says.
Though, he admits, sometimes they may have picked up odd bits of misinformation. When working on a bill to reduce light pollution around another Arizona observatory, Kitt Peak, southwest of Tucson, he says, one legislator suggested that all that might be needed to deal with LED billboards was an 11 pm curfew, because when that legislator had toured Kitt Peak, they remembered a tour guide saying that astronomers don’t start making observations until midnight. “I very much doubt that a Kitt Peak tour guide said, that,” Hall says, “but that was what was heard.”
Bottom line: reclaiming the night sky isn’t something that’s going to occur everywhere, all at once. To the extent it happens, it will be one small community at a time, with a lot of one-on-one engagement.