is a topic of interest to all amateur astronomers and astrophotographers. With growing light pollution we wonder how far do we have to travel to reach "dark" skies, and how much farther do we have to go to reach really dark skies?
How do factors such as man-made light pollution, natural air glow and light from interplanetary dust affect the darkness of the night sky? What about elevation, transparency and atmospheric particles?
What color, if any, does the dark night sky have?
The following material was posted to the newsgroup sci.astro.amateur in 1996 and 2001 by Brian Skiff, of Lowell Observatory. He has recently re-edited and updated the material and graciously granted permission to post it here.