Vanishing Night Skies: The Effects of Light Pollution on the National Park System

Seeing the awesome grandeur of a star-filled night sky is a wondrous experience for national park visitors–an experience seldom possible in America’s growing cities and suburbs, where most stars are not visible at night. While under ideal conditions, one might see more than 2,500 stars plus our galaxy’s Milky Way, in a typical suburb only 200 to 300 stars are visible; in large cities, perhaps only a few dozen. Estimates are that only 10 percent of the U.S. population can see an unsullied night sky.

Thus, many visitors are unexpectedly astounded and captivated when they view the night sky from within our national parks. Like clean air and water, wildlife, or the sounds of nature, a clear dark night sky is an intrinsic part of the national park experience that must be protected for present and future generations.

And just like the air and water, the skies over our national parks are increasingly threatened. Unfortunately, the stars visible from our national parks are becoming increasingly difficult to see. The biggest culprit in this quiet crisis is light pollution, which is most often caused by excessive or misdirected outdoor lighting. Light pollution from highways, homes, office buildings, and other developments can affect national parks that are more than 100 miles away. In addition, some National Park Service and private park concession facilities add unnecessary glare to the night sky.

While some remote parks are insulated from the effects of light pollution, many are not.

In addition to obscuring the stars, excessive light pollution can seriously compromise the educational story presented in many national parks. Observing the night sky has been a crucial human activity since the Pleistocene era, inspiring wonder and curiosity, shaping religious beliefs, propelling scientific inquiry, and motivating and guiding global exploration to the present day. From the builders of celestial calendars at Chaco Culture National Historical Park in New Mexico to the builders of rockets at Canaveral National Seashore in Florida, the mission of our national parks could not be complete without dark night skies to help tell these stories.

Although the public believes that the National Park System and all of its resources are protected, the truth is more complicated. Unless light pollution problems are remedied, dark night skies within parks will continue to disappear. The National Parks and Conservation Association has been concerned about this problem for some time. In the summer of 1998, NPCA asked professionals of the National Park Service for more information about light pollution problems in the national parks. NPCA distributed the survey to superintendents at 376 park units. NPCA’s analysis focused particular attention on 130 parks that allow overnight visitation, 77 percent of which responded to the survey. In all, 189 of 376 park units repsonded to the survey. Included in that total are 43 of the 54 sites designated as National Parks. We believe the responses are representative and that the survey offers the first comprehensive assessment of the status of light pollution issues across the National Park System. The results are profoundly disturbing.