Light Pollution

 

Note: all information on this page is public content and may be referenced back to the International Dark Sky Association (IDA)


For most of Earth’s history, our spectacular Universe of stars and galaxies has been visible in the darkness of the night sky. From our earliest beginnings, this cosmic array has inspired questions about our Universe and our relation to it. The history of scientific discovery, art, literature, astronomy, navigation, exploration, philosophy, and even human curiosity itself would be diminished without our view of the stars. But today, the increasing number of people living in cities and the corresponding increase in inappropriate and unshielded outdoor lighting has resulted in light pollution—a brightening night sky that has obliterated the stars for much of the world’s population. Most people must travel far from home, away from the glow of artificial lighting, to experience the awe-inspiring expanse of the Milky Way as our ancestors once knew it.

What is Light Pollution?

Light pollution is excessive and inappropriate artificial light. The four components of light pollution are often combined and overlapping:

  • Urban sky glow – the brightening of the night sky over inhabited areas.
  • Light trespass – light falling where it is not intended, wanted, or needed.
  • Glare – excessive brightness which causes visual discomfort. High levels of glare can decrease visibility.
  • Clutter – bright, confusing, and excessive groupings of light sources, commonly found in over-lit urban areas. The proliferation of clutter contributes to urban sky glow, trespass, and glare.


Why Do We Care About Light Pollution?

Increased urban sky glow is responsible for the disappearance of the Milky Way from our night skies. For professional astronomers, the increasing distance to prime observing sites, well away from sources of air pollution and urban sky glow, becomes more problematic as economic and environmental energy costs continue to rise. Amateur astronomers, meanwhile, find prime observing spots eradicated by commercial and residential development and must travel farther from home for a clear view of the skies. Increasingly, the most important equipment needed to enjoy the wonders of the night sky is an automobile with a full tank of gas and a map.

Light pollution is a problem beyond Astronomy and you may read more about its adverse affects here:

Ok, So What Can I Do About It?

There are very simple and practical things that one can do to help minimize contributions to light pollution:

  • Use light only when and where it’s needed. Turn off lights when they are not needed and create a curfew for lights-out. Minimize interim light use with timers and motion detectors.
  • Use only as much light as needed. Over lighting reduces the eye’s ability to see outside of the lit area. In addition, excess light can produce glare, which also reduces visibility. Selecting the correct lamp wattage for your needs increases safety and reduces costs.
  • Shine lights down, not up. A well-designed fixture will direct the light where it’s needed most—at the ground. Select new fixtures that are fully shielded; retrofit or replace poor quality fixtures. For more information on selecting dark-sky friendly fixtures, refer to IDA’sWeb site and the fixtures featured in the IDA Fixture Seal of Approval program.
  • Use efficient light sources for outdoor lighting around homes and businesses. Consider a compact fluorescent for good, energy efficient, economical lighting—a low wattage lamp gives plenty of light for most properties and applications, and in a fully shielded fixture, it makes an excellent choice. When higher wattage lamps are necessary, be sure that they are fully shielded and energy efficient.
  • For more tips and tricks check out IDA’s guide.
  • And most importantly SPREAD THE WORD!

How Can I Find Out More?



International Dark Skies
(IDA) website for more information. McDonald Observatory has another great page summarizing Light Pollution and how to fight it.

Watch this great video about the science of the dark and an exploration of our relationship to the stars by  filmmaker Ian Cheney.

Find out about the hidden costs of light pollution.

You may always contact us for more information.