29 October 2004

The sum of all twilights

Forrest M. Mims III

This photograph shows the moon at the peak of totality during the total lunar eclipse of 27 October 2004. During a lunar eclipse, the moon is in the earth's shadow. The faint, copper-colored hue of the moon during totality is caused by sunlight filtering through the atmosphere that forms a thin film around the earth. Thus, the color of the moon during a lunar eclipse is related to the color of the twilight glow around the earth's terminator during the eclipse. High levels of atmospheric aerosols, especially following major volcano eruptions, enhance the reddish glow. This cropped photograph was made with a Nikon 4300 4-megapixel camera equipped with a telephoto lens.