Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 February 4
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Shadow Set
Credit: J. Bonnell, D. Macomb, R. Canterna, WIRO

Explanation: A nearly full Moon and planet Earth's shadow set together in this scene captured on January 13th from snowy Mt. Jelm, home of the Wyoming Infrared Observatory. For early morning risers (and late to bed astronomers), shadow set in the western sky is a daily apparition whose subtle beauty is often overlooked in favor of the more colorful eastern horizon. Extending through the dense atmosphere, Earth's setting shadow is seen in this picture as a dark blue band along the distant horizon, bounded above by a pinkish glow or antitwilight arch. Known as the Belt of Venus, the arch's lovely color is due to backscattering of reddened light from the rising Sun. The setting Moon's light is also reddened by the long sight-line through the atmosphere.

Tomorrow's picture: pillar of light

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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& Michigan Tech. U.