Light Pollution

Image Credit: David Lorenz, Attribution, via Wikimedia Commons

Amateur astronomers face two overwhelming obstacles when trying to view the wonders of the night sky. The first is the weather. Well, there is little we can do about that – clouds roll in and the weather is the weather. The second, is light pollution. We are losing the night sky to artificial light at an ever-increasing rate. It not only disrupts our view, but it also has a negative impact on the natural patterns of wildlife, ecosystems, human health, and sleep. In addition, wasted light costs $2.2 billion annually.

When we look down at the Earth from space, it seems that light is everywhere. For a closer look, you can zoom in on the light pollution in any part of the world using this online light pollution map.

In 2001, amateur astronomer John Bortle develop a scale with which to classify the degree of light pollution affecting the night sky. The folks at the Skyglow project have a nice chart showing the Bortle scale. If you want to approximate the Bortle classification for your neighborhood, Steve Owens has a flow chart you can follow.

Botrle Scale. Image Credit: ESO/P. Horálek, M. Wallner, CC BY 4.0 https://creativecommons.org/licenses/by/4.0, via Wikimedia Commons

Not all light pollution is the same. There are five general categories.

  1. Over-illumination, where lights are on, but not needed.
  2. Glare, where light reflects off the ground or buildings.
  3. Light clutter, where lights are poorly placed.
  4. Sky glow, where light escapes from outdoor lighting and reflects down from the atmosphere.
  5. Light trespass, where light intrudes on another’s property.

For more on light pollution and dark skies, see our various posts and articles.

Light Pollution News and Posts

International Dark-Sky Association

The International Dark-Sky Association (IDA) provides an overview of light pollution and its impact on us and our environment.

They suggest “five principles for responsible outdoor lighting” that you should follow when installing outdoor lighting.

You can also see their “Dark Sky Friendly Home Lighting Program” for more advice and guidance. If this is too much, the IDA has a simpler set of guidelines we can all use See below.

Dark Sky Observing Sites

It is difficult to go back and remove or remedy existing light, so often the only solution is the get away from the city and find a dark sky location. The good news is, for those of us living in North Carolina, that there are some options.

FAS manages a small observation platform for its members just north of Pilot Mountain. It is a half hour to 45-minute drive from the Winston-Salem area and provides a reasonable dark sky.

FAS has also compiled a list of dark sky observation sites that club members have used in the past. If you have another site or additional information, please let us know.

Local Dark Sky Observing Sites
Dark Sky Observing Notes

Additional Resources (Light Pollution)

Additional Resources (Dark Sky Locations)

Additional Resources (Apps)

Additional Resources (Bortle Scale)

Additional Resources (Videos)