For the more information about natural sounds and night skies in the National Park Service, please visit http://www.nature.nps.gov/sound_night/.


Night Skies as a Natural Resource

Kemp's ridley hatchling
Kemp's ridley hatchling

Within national parks we preserve the continuation of natural processes. This includes allowing bears to roam, letting rivers run free of dams and diversions, and understanding the beneficial roles that fire can play. A dark night is one of these natural resources integral to many natural processes.

We generally think of natural lightscapes as a scenic resource, allowing humans to see spectacular starry skies. Many of the darkest night skies in the country are found within national park boundaries. Amidst the loss of night sky quality over the last five decades, those resources have become nationally significant. The nighttime scenery of a national park is valued by intrepid amateur astronomers as well as casual stargazers.

Dark night skies are also considered an air quality related value under the 1977 Clean Air Act Amendments, and air quality in turn affects the quality of the night sky. Just as air pollution decreases the visibility during the day, at night hazy air dims the stars and scatters more light from cities. This results in a hazy gray appearance to the night sky as opposed to sparkling stars on a black canvas.

Sometimes forgotten is the importance of natural darkness for wildlife. Nearly half the species on Earth are nocturnal—choosing night to be active instead of during the day. The absence of light, natural or otherwise, is a key element of this habitat. Adding artificial light to such habitat may result in substantial impact to certain species (Rich & Longcore, 2006). For example, migrating passerine birds fly at night with reference to the stars and can be disoriented by lights from cities and towers. Sea turtles' hatchlings orient toward the brightest light on the beach, but instead of being drawn to the safety of sparkling waves on the ocean, they are often drawn toward roads and parking lots where they quickly perish. And amphibians, with vision far more sensitive than that of humans, are apt to be disoriented by light. Changes to cave environments can have a similarly disruptive effect. Research into the ecological consequences of artificial night lighting is revealing numerous connections between light pollution and species disruption.

References

Rich C. and Longcore T. 2006. Ecological Consequences of Artificial Night Lighting, Island Press.

Last Updated: April 20, 2012