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Posted on: September 22, 2020

Dark Sky: What Is Light Pollution?

Light Pollution Before and After

Light pollution is the inappropriate or excessive use of artificial light. As a designated International Dark Sky Community, the Village of Hawthorn Woods is committed to preserving and protecting our night sky from the negative effects of artificial light at night.

Excess lighting affects nocturnal wildlife patterns and human sleep patterns. It also dramatically increases our carbon footprint and inhibits our ability to experience the wonder of a natural night sky. It is estimated that 80% of Americans can no longer see the Milky Way.

The four forms of light pollution illumination are:

  • Glare – excessive brightness that causes visual discomfort.
  • Skyglow – brightening of the night over inhabited areas.
  • Light trespass – light falling where it is not intended or needed, for example, when spill light from a streetlight enters a window and illuminates an indoor area.
  • Clutter – bright, confusing and excessive groupings of light sources.

Sources of light pollution include residential outdoor lighting, streetlights, floodlights, and commercial lighting.

However, light pollution is reversible and the residents of Hawthorn Woods can make a difference by following these simple steps:

  • Only use lighting when and where it is needed.
  • If safety is a concern, install motion detector lights and timers.
  • Fully shield all outdoor lighting – light should shine down, not up, to save money and energy. Fully shielded fixtures can provide the same level of illumination as unshielded fixtures.
  • Turn off indoor lights when not in use to save energy and money.

For more information about light pollution from the International Dark-Sky Association, please click here.

Photo: Before and during the 2003 Northeast blackout, a massive power outage that affected 55 million people. Photo by Todd Carlson.

International Dark-Sky Association Light Pollution
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