Night Sky

Milky Way over Logan Pass

NPS/Jacob W. Frank

Dark night skies are environments undisturbed by light and air pollution. Dark night skies have natural, cultural, and scenic importance. Wildlife is impacted by light pollution because animals often depend on darkness in order to hunt, conceal their location, navigate, or reproduce. For nocturnal animals, light pollution also means habitat disruption. Additionally, many species have far more sensitive vision than humans. Plants are affected by artificial light because it disrupts their natural cycles.

Dark night skies are also culturally important because they are a resource common to all cultures on Earth. For millennia, Montana tribes have observed the sky to inform their seasonal rounds, or the way tribes used the landscape for subsistence during each season. The night sky is a treasure trove in terms of Indigenous knowledge.

Natural lightscapes, including dark night skies, are a scenic resource integral to many people's Waterton-Glacier experience. Currently, 80 percent of Americans cannot see the Milky Way from their backyard, and if current light pollution trends continue, there will be almost skies left untouched by light pollution in the contiguous United States by 2025. Many people visit national parks to experience this vanishing resource. Waterton-Glacier hopes to provide and preserve this important opportunity by meeting the requirements and objectives of Dark Sky Parks.

Glacier National Park and its sister park, Waterton Lakes National Park of Canada, have been certified as an International Dark Sky Park by the International Dark Sky Association (IDA). The certification requires a long-term commitment to preserving dark skies and requires the parks to meet specific objectives. These include preservation or restoration of outstanding night skies, protection of nocturnal habitat, public enjoyment of the night sky and its heritage, and demonstrating environmental leadership on dark sky issues by communicating the importance of dark skies to the general public and surrounding communities, and by providing an example of what is possible.

 

NPS Graphic

Half the Park Happens After Dark

The National Park Service has collaborated with several partners—the Glacier National Park Conservancy, the International Dark Sky Association, the NPS Night Sky Program, and the Big Sky Astronomy Club—to provide park-wide night time viewing events, as well as daytime viewing of the sun. Park astronomy programs provide participants with an opportunity to see the night sky in all its glory using sophisticated telescopes, in a location with a minimal number of artificial lights.

Check the Ranger-led Activity Schedule for dates and times. Nightly program take place throughout the summer at St. Mary and Apgar. Special Logan Pass Star Parties, when scheduled, will be announced too.

If staying up late isn't your thing or you want to enjoy Glacier's night sky from afar, visit the Dusty Star Observatory Sky Cam to see a live view of the sky or view a video of the night sky automatically created after sunrise each morning. You can also look at the park's collection of night sky photographs and deep sky telescope images on the park's Flickr page.

 

Light Pollution Monitoring

Left image
Lights on the right side are from businesses outside the park, 1/2 mile away. The light at the bottom is the visitor center and the light at the top of the image is a weak Aurora.
Credit: NPS

Right image
Brighter colors correspond to more light pollution. The lights in the town site are just below the horizon of the tool used to produce this map.
Credit: NPS

Light pollution's effects are evident even in Glacier's protected skies. Glacier National Park has worked to protect the night sky by minimizing light pollution sources from within the park. However, light pollution knows no bounds and can spread into the park from sources near and far. In support of our International Dark Sky Park certification, Glacier monitors the levels of light pollution in the skies above the park. Use this comparison tool to see how bright lights near the ground send sky glow upwards to cause light pollution.