Shop Windows to the Universe

Arches National Park Geology Tour provides an extensive, visually rich description of the geology of Arches, by Deborah Ragland, Ph.D. See our DVD collection.
This image shows the lights of Earth as seen from a satellite orbiting our planet.
Click on image for full size
Image courtesy of NASA, DMSP, and NOAA NGDC.

Light Pollution

What is light pollution? Simply put, light pollution is the unwanted illumination of the night sky created by human activity. Light pollution is sometimes said to be an undesirable byproduct of our industrialized civilization. Light pollution is a broad term that refers to multiple problems, all of which are caused by inefficient, annoying, or arguably unnecessary use of artificial light. Specific types of light pollution include light trespass, over-illumination, and sky glow.

Where is light pollution found? The now-classic Earth at Night composite image (left) suggests that light pollution is a problem in many parts of the world, with the worst concentration of light pollution being found in urbanized areas. In the highly industrialized and populated areas such as many parts of Europe, Asia, and North America, light pollution is a real problem. For example, in the Eastern United States, there are many areas where large expanses of land are illuminated at night. As cities and suburban areas grow, the number of lights at night also increases.

Why do we care about light pollution? Light pollution is a strong indicator of wasted energy. Lights, contrast, and glare all impact the number of stars that are visible in a given location. Only the brightest stars are visible when there is a lot of nighttime lighting. Many people in the urban locations have never seen the Milky Way.

Astronomers (both professional and amateur) have been concerned about the deteriorating quality of the night sky for some time. The excess of light has resulted in obscuring the night sky making observations difficult. It is not surprising to learn that astronomers need very dark skies to conduct their observations and research.

In addition to the concerns of astronomers, we have learned that light pollution causes problems to human and environmental health. Medical research on the effects of excessive indoor light on the human body suggests a variety of adverse health effects including increased headaches, fatigue, and stress.

There is also a strong case that light pollution is harmful to the economy as well as our ecology. When you look at the Earth at Night image above, think about all that light escaping into space. All of this light is wasted, so all the energy that was produced and consumed to create the light was also wasted. Ultimately, everyone pays for this wasted energy.

With the pervasive level of light pollution, the natural patterns of light and dark have been altered, impacting animal behavior. Lights at night can impact both the biology and ecology of species in the wild. Some examples include the disorientation of sea turtle hatchlings by beachfront lighting; nesting choices and breeding success of birds; behavioral and physiological changes in salamanders; disturbances of nocturnal animals; and altered natural light regimes in terrestrial and aquatic ecosystems.

Since the 1980's, there has been a global movement to learn more about light pollution, its impacts, and ways to mitigate or reduce its effects. Light pollution impacts most of the world's citizens in one way or another. It may be that you no longer are able to go outside and enjoy an unobstructed view of the night sky.

Last modified September 11, 2007 by Randy Russell.

Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Types of Light Pollution

Light pollution is the unwanted illumination of the night sky created by human activity. Light pollution is a broad term that refers to multiple problems, all of which are caused by inefficient, annoying,...more

Magnitude - a measure of brightness

Astronomers use the term "magnitude" to describe the brightness of an object. The magnitude scale for stars was invented by the ancient Greeks, possibly by Hipparchus around 150 B.C. The Greeks grouped...more

Citizen Science

Citizen science projects involve the public in scientific research and data collection. Typically, people around the world observe phenomena from their own locale, send in data via the Internet, and then...more

Life in the Atacama Desert

Chile's Atacama Desert is one of the driest places on Earth. Few people live there, and most animals, plants, and even microbes find it difficult to scratch out a living in such an arid environment. There...more

Gamma Ray Bursts - The Most Powerful Objects in the Universe?

In the 1960's, the United States launched a series of satellites to look for very high energy photons, called Gamma Rays, that are produced whenever a nuclear bomb explodes. These satellites soon detected...more

Galaxies

The introduction of telescopes to the study of astronomy opened up the universe, but it took some time for astronomers to realize how vast the universe could be. Telescopes revealed that our night sky...more

Neutron Stars

Neutron Stars are the end point of a massive star's life. When a really massive star runs out of nuclear fuel in its core the core begins to collapse under gravity. When the core collapses the entire star...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA