By Maggie Slepian
Inside the GYE Dark Skies Initiative efforts to save the night sky.
Take a flight out of Bozeman after dark, and it’s hard not to be startled by the town’s sprawling illumination. Floodlights over gravel pits give way to rows of lights along I-90 before blending into the gridded squares of subdivisions. It’s almost pretty—like an inversion of the night sky. But these swaths of light punctuating Montana’s natural darkness are a potent form of pollution, and unnatural light from even the smallest towns can travel over 120 miles from the source. This daylight-mimicking halo disorients migrating birds, and for nocturnal animals it can reduce options for hunting and foraging, and disrupt breeding rituals.
Artificial light probably isn’t the first thing that comes to mind when we think of pollution, but dark skies are integral to a healthy ecosystem, and they are disappearing at an alarming rate.
More than 80 percent of the world’s population lives under skyglow—the brightening of the night sky from artificial lights—which impacts our own circadian rhythms and physical processes. Densely populated urban areas have the most extreme skyglow, but even stargazing from Bozeman will only net about 500 visible stars. A more rural area like Gardiner, with around 800 residents, will show an estimated 5,000 stars, but a true dark sky entirely removed from anthropogenic light sources provides a dazzling three-dimensional display of 15,000 stars, planets, and the swirl of the Milky Way.
Light pollution is one of the easiest types of pollution to address (just turn off your lights!), but dark-sky conservation suffers from a lack of understanding and education. In the Greater Yellowstone Ecosystem, a group of dedicated conservationists is working to change that.
Photography guide and ecologist Angela Tempo moved to Gardiner eight years ago for a Yellowstone National Park photography fellowship. As soon as she arrived, the expanse of stars reminded her of her childhood in Colombia and Italy, sitting under the night sky and listening to birds migrating in the dark.
Soon after, Tempo started looking for ways to protect this precious natural resource, and today, she is at the helm of the GYE Dark Skies Initiative. This community-led group is focused on reducing light pollution in the region, and their ultimate goal is to become a designated Dark Sky Community through DarkSky International.
“Eight years ago, I could take a picture from outside town and not see the mountains,” Tempo said, snapping a long-exposure shot under the February sky. She holds up the image, and sure enough, the flanks of distant peaks are illuminated from Gardiner’s glow.
“We take dark skies for granted, but 20 percent of our dark skies are being removed each year. In 10 years, we won’t have those dark skies in Paradise Valley.”
While Tempo initially aimed for a DarkSky designation for Park County, the idea has snowballed into something much larger. The goal is now to protect the night skies over Yellowstone National Park, Grand Teton National Park, Teton County, Park County, and the surrounding national forests. If it reaches its objective, the 20-million-acre Greater Yellowstone Ecosystem Dark Sky Reserve will be the largest protected Dark Sky Territory in the world.
If it reaches its objective, the 20-million-acre Greater Yellowstone Ecosystem Dark Sky Reserve will be the largest protected Dark Sky Territory in the world.
What it Takes to Obtain DarkSky International Certification
DarkSky International has been certifying communities and territories through the International Dark Sky Places program since 2001. Applications (and the eventual certification) include dedicated practices to reduce light pollution and educate community members about responsible lighting. Currently, the IDSP has certified more than 61,000 miles of protected night skies in 22 countries, many of which have become natural tourist attractions purely for their night skies.
Earning an IDSP designation is a lengthy process. The application includes an exhaustive inventory of lights, including lumens, fixtures, warm versus cool, and protective shields. After the inventory, the group evaluates what needs to be fixed for output and glare reduction, then submits their application. From there, the community has a certain amount of time to make necessary improvements, though there is no finish line. The goal is to continue reducing light pollution and educating community members about night sky conservation.
The GYE Dark Skies Initiative has completed much of the background work for Gardiner and Yellowstone’s application: Yellowstone’s light inventory has been completed and Gardiner’s is well on its way. The group is also working to build a coalition of business owners and residents to help develop upcoming ordinances to limit light output and shield overhead lights.
It’s a massive endeavor, but Teton County’s eight-year effort greased the tracks for the Gardiner group. Jackson finalized their updated lighting standards in 2022 and became an official Dark Sky Community in 2025. Today, the lights in Teton County are DarkSky compliant, including restrictions on upward-facing light, glare reduction, and limited blue-light output.
“Now that we’ve finished up Teton County and the town of Jackson, I have my sights set on getting all of the GYE certified,” said Samuel Singer, founder of Wyoming Stargazing and a strong supporter of Tempo’s efforts in Gardiner.
While protecting the night skies is as important as protecting the land beneath them, Singer acknowledges there’s still a disconnect. Most people don’t think of dark night skies as a natural resource or consider the damage caused by light pollution.
While protecting the night skies is as important as protecting the land beneath them, Singer acknowledges there’s still a disconnect. Most people don’t think of dark night skies as a natural resource or consider the damage caused by light pollution. But as vacation rentals and developments push further into Paradise Valley, each new building comes with its own light sources. One by one, the visible stars fade, and the urgency to protect this resource becomes clearer.
People gravitate toward this area for its proximity to Yellowstone and the surrounding landscapes, and like Jackson, Gardiner’s community members are on board. Tempo’s group even landed a dark-sky conservation strategy as part of the town’s most recent development plan, cementing community support.
It’s also important for Tempo that business owners and residents know their existing lights can be grandfathered into the ordinance, and that the financial burden won’t fall on them. Securing grants and outside funding will be key to offsetting the cost of shielding lights and updating light sources to meet DarkSky compliance requirements. The group hopes that once people learn about the effect of light pollution on the natural ecosystem, they’ll feel more motivated to help make the changes.
So what happens after the application has been approved? Much of the heavy lifting occurs during the application process, so the majority of changes after successful DarkSky designation focus on lighting restrictions and DarkSky-compliant practices, including light type, overhead shielding, color, and fixtures.
Flagstaff, Arizona, is the world’s first International Dark Sky City and has maintained strict lighting codes since 1999. The city remains safely lit, but uses amber lighting for roadways and parking lots, fully shields exterior lights, and limits the lighting on nonresidential properties. Eventually, Gardiner’s policies will look similar. Each protected area is different, and goals will vary, but all follow the same general parameters of reducing volume, color, and visibility of lights.
What Other Towns and Individuals Can Do
Unlike more insidious forms of ecosystem damage, reducing light pollution can be as simple as turning off lights. Even in large, brightly lit towns, very rarely is it too late to make a change. The challenge is convincing people to care about the night sky as much as they care about the mountains and rivers.
Even if your town or region isn’t a designated Dark Sky Community, every light makes a difference. Talk to neighbors about the importance of dark skies, start a grassroots stargazing program, or reach out to conservation nonprofits for help spreading the word. You can take it a step further by surveying the lights in your neighborhood and comparing them to DarkSky-compliant light sources.
Replacing old bulbs with warm-tone LEDs is a good first step toward reducing high-intensity blue light. Installing glare-reduction fixtures helps nocturnal animals’ eyes adjust back to the dark, and turning off all unnecessary outdoor lights after dark makes an immediate impact. Shielding is one of the most important elements of dark-sky conservation, effectively preventing light from shining directly into the night sky. This helps preserve the navigational abilities and vision of flying nocturnal animals and insects.
For those interested in pursuing DarkSky International certification, reviewing current International Dark Sky Places to see how they got started is a good first step. Read through those current lighting policies and development plans, and see the impact the updated regulations have made on the ecosystem.
Dark-sky conservation pulls double duty, bringing in revenue as a tourist attraction while letting people know there’s something worth protecting in the skies themselves. Once people view the night sky as a feature akin to a mountain or waterfall, appreciation can turn to action, one light at a time.
Dark Sky Sites in the GYE
Montana
- Medicine Rocks State Park: An International Dark Sky Sanctuary (highest designation) known for “Dinosaurs and Dark Skies” programs.
- Glacier National Park: Certified International Dark Sky Park, hosting Logan Pass Star Parties.
- Makoshika State Park: Located in Glendive, the rugged badlands provide a dramatic backdrop for stargazing.
- Bighorn Canyon National Recreation Area: Straddles the MT/WY border with exceptional night views.
- Other Sites: Hell Creek Recreation Area (Fort Peck Lake), First Peoples Buffalo Jump State Park, Bannack State Park, and Ackley Lake State Park.
Idaho
- Central Idaho Dark Sky Reserve: The first and only Gold-tier reserve in the United States, covering 1,400 square miles. Cities within the Reserve include Ketchum, Sun Valley, Stanley, and Hailey.
- Craters of the Moon National Monument: Certified International Dark Sky Park.
Wyoming
- Yellowstone National Park: Actively working toward achieving International Dark Sky Association certification.
- Sinks Canyon State Park: First International Dark Sky Park in Wyoming.
- Teton County: Became the world’s first county to be certified as an International Dark Sky Community in 2025.
Maggie Slepian is an award-winning Bozeman-based writer with a focus on the outdoors, environment, and travel. Her work has appeared in The New York Times, Longreads, Outside Magazine, Lonely Planet, and more.
