Night Skies: A Resource & Value

Night sky at twighlight with bristlecone pine lit and stars out. Great Basin National Park.
Night sky at twighlight with bristlecone pine lit and stars out. Great Basin National Park.  NPS

The National Park Service must leave park resources and values unimpaired unless a particular law specifically provides otherwise. This is the cornerstone of the Organic Act and establishes the primary responsibility of the Service. It ensures that park resources and values will continue to exist in a condition that will allow the American people opportunities to enjoy them. Park “resources” include many different components of a park’s environment like wildlife and water as well as scenery and natural visibility, both during the day and at night. Park “values” refer to, among other things, appropriate opportunities to experience enjoyment of the night sky and the benefits and inspiration they provide.

The 2006 NPS Management Policies 4.10 outlines the Service’s responsibility to preserve in the greatest extent possible, the natural lightscapes of parks, which are natural resources and values that exist in the absence of human-caused light. More specifically, the Service will:

  • restrict the use of artificial lighting in parks to those areas where security, basic human safety, and specific cultural resource requirements must be met;

  • use minimal-impact lighting techniques;

  • shield the use of artificial lighting where necessary to prevent the disruption of the night sky, natural cave processes, physiological processes of living organisms, and similar natural processes.

The night sky is a natural resource. A naturally dark night sky is more than a scenic canvas; it is part of a complex ecosystem that supports an environment for natural processes to occur unimpeded for national park visitors to explore and learn about celestial objects, space research, and the human connection to the sky. The night sky yields scientific insights into our complex natural world. In such a landscape, inappropriately applied or overused light is potentially harmful to animals and plants.

The night sky is a cultural resource value. Since time immemorial, indigenous people have had a connection to the night sky through origin stories and have practiced a sustainable way of living through seasonal observations and ceremonies of eclipses and equinoxes. Observations of the heavens were critical to the Age of Enlightenment, allowing Newton to write the laws of gravity, Galileo to place our sun at the center of the solar system, and Einstein to imagine the fabric of the universe. These Indigenous deep-rooted connections to the night sky and European discoveries continue to influence today’s knowledge, science, culture, religion, and art.

The night sky has an economic value. With the popularity of stargazing programs, astronomy festivals, full moon hikes, astrophotography, and other nighttime activities in parks, natural lightscapes have become an increasingly important value for our national parks and surrounding communities.  Visitor facilities in communities surrounding national parks are finding that stargazing activities draw more tourists and tend to increase the length of stay and corresponding economic benefit to those communities.

The night sky is a wilderness value. In addition to visitor enjoyment, dark night skies are essential for the preservation of wilderness character and values sought by tens of millions of park visitors each year. Remoteness from sights and sounds of human activity both inside and outside of wilderness is a good indicator for “providing outstanding opportunities for solitude or primitive… recreation,” one of five characters identified in the Wilderness Act. However, light pollution is increasing at a global average rate of 2.2% per year, leaving few dark skies in the contiguous United States. The dark night sky is intrinsically tied to a quintessential wilderness experience where a relatively light pollution free environment is maintained.

For More Information on night skies as a resource and value in the National Park System, please see the 2006 NPS Management Policies: 1.4.4 The Prohibition on Impairment of Park Resources and Values; and 1.4.6 What Constitutes Park Resources and Values.

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Illustration of Ursa Major constellation, Library of Congress
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Last updated: June 17, 2024