A forum for scientific discussion of optical phenomena in the atmosphere and the natural environment,
sponsored by the Optical Technology Center at Montana State University in Bozeman, Montana.

This picture shows the blue sky at night, caused by Rayleigh scattering of light from a full moon on October 18, 2005. The photo was taken with a Nikon D70 digital SLR camera and a 20-mm lens with an exposure time of approximately 60 seconds at ISO 400. The view is looking north into the Gallatin mountain range (toward Bozeman, Montana) from the northwest end of Yellowstone National Park. For more information about photographing the blue sky at night, please see "The Digital Blue Sky at Night" by Joseph A. Shaw in Optics and Photonics News, Nov. 2005.

The picture is copyright Joseph A. Shaw, 2005. Please contact me if you are interested in obtaining a copy for use in any setting.