What Is Light Pollution?

It's light that shines outward and upward, resulting in the unnecessary waste of electricity and glare that can dangerously impair visibility. At the same time, it washes out the natural darkness of the night sky.  Here are some all-too-familiar examples of glare, spillover (light trespass), and skyglow from poorly designed, wasteful street, business, and house lighting:

This is a light intensity map of the continental United States, excerpted from The World Atlas of Artificial Night Sky Brightness.

Click map for larger image (284 KB)

Click here to view the light intensity map for our region, centered on Caney Creek/Roane County Park/Tamke-Allan Observatory.

A different view of U.S. night light intensity, excerpted from Nighttime Lights of the World. The satellite photos from which this image was made were taken in 1994 and 1995 -- consider how many more night lights have been added to the planet in the intervening 13 years.  

Click map for larger image (199 KB)