The Organic Act of 1916 directs the National Park Service to—"conserve the scenery and the natural and historic objects and the wildlife therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations." While scenery has been traditionally thought of as being geologic curiosities, distant vistas, and sublime landscapes, it also includes the night sky.
The night sky is a natural resource. Naturally dark skies provide refuge for wildlife, and allow natural processes and rhythms to evolve unimpeded. They yield scientific insights into our complex natural world, and allow natural physical processes to churn unabated. In such a landscape, artificial light is inappropriate and potentially harmful.
The night sky is a cultural resource. First-hand 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 discoveries, in turn, had a palpable influence on culture, religion, and art. Today, space is still the frontier of science, enticing children's interest in science and concealing some of the greatest questions humans have ever asked.
With the popularity of stargazing program, night walks, full moon hikes, and other nighttime activities in parks, natural lightscapes have become an economic resource as well. 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.
Everyone has a right to starlight—whether a turtle making its way to the sea or a curious child asking questions about the cosmos or an adult following in the footsteps of great scientists.