Mojave National Preserve - Lightscape / Night Sky

The movements of celestial bodies has allowed mankind to keep sophisticated calendars for thousands of years. In addition to being a source of practical knowledge, the night sky has captivated our imaginations and inspired poets, playrights, and artists throughout the ages and has influenced the development of cultures the world over. On a dark, cloudless, moonless night there are over 2500 stars visible to the unaided eye from the surface of our planet. Yet astronomers estimate today that about two thirds of the world population and 99 percent of the population in the European Union and United States live in areas where the night sky is light polluted. Additionally, about one fifth of the world population, more than one half of the population of the European Union, and more than two thirds of the population of the United States cannot see the Milky Way with the naked eye. In many cities, all but the very brightest stars and constellations, such as Orion and the Big Dipper, are blotted from view by the pervasive skyglow. There is so much light in city centers that the sky may be 25 to 50 times brighter than the natural sky, and even a typical suburban sky today is about 5 to 10 times brighter than the natural sky. In recent decades light pollution has spread from a problem only in cities to a major astronomical disruption almost everywhere.

The term light pollution, coined only about 30 years ago, refers to artificial skylight (as from city lights) that interferes with astronomical observations. However, light pollution is not something which should only be a concern of astronomers and sky watchers. Glare, light that shines directly into your eyes, is one of the most destructive problems, potentially distracting or blinding pedestrians and motorists, and contributing considerably to skyglow over great horizontal distances. Tremendous above-the-horizon waste is also tolerated because it goes unseen. It is estimated that about 30 percent of all light generated in the United States is wasted light, directed upwards or horizontally. All that wasted light equates to wasted energy, about $1 billion to $2 billion annually in the United States.

Light pollution also has a negative impact on wildlife. Many bird species migrate at night, navigating by the stars, and will fly off course when influenced by bright artificial light. An extreme example of this occurred in 1954, when 50,000 birds died following an Air Force beacon straight into the ground. More recently, 10,000 birds died in 1981 when they flew into smokestacks illuminated by floodlights at an Ontario hydroelectric station. Other animals are also influenced by artificial light. Instead of heading toward the ocean, sea turtle hatchlings often crawl inland toward artificial lights and their deaths. Additionally, some scientists believe the energy and time wasted flittering around outside lights may be behind the decline in population of many moth species in the northeastern United States.

Mojave National Preserve, relatively far from urban centers, is located in one of the best areas in the United States for night sky viewing. Humidity and air pollution, which act to refract and reflect light, are low and result in clear skies. The number of cloudless nights is also higher than most places in the United States. Dark night sky is a natural resource on par with clean air and water and it is the goal of the preserve to perpetuate and improve dark night sky conditions for the enjoyment of visitors for generations to come. A study is currently underway to monitor the dark sky conditions at several parks in the western United States, including Joshua Tree National Park and Death Valley National Park, and the preserve may soon be included in the second or third round of this groundbreaking project.