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.

February 9, 1998

The Witch Head Nebula
Credit and Copyright: G. Greaney

Explanation: Have you ever seen the woman in the moon? One might think so upon at first glance at the Witch Head Nebula. This reflection nebula, however, has more to do with the bright star Rigel in Orion than with Earth's Moon. More formally known as IC 2118, the Witch Head Nebula glows primarily by light reflected from Rigel. Rigel is located about one photo-width off the image to the right. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers here are molecules of nitrogen and oxygen. The nebula lies about 1000 light-years away.

Tomorrow's picture: All of Mars


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
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&: Michigan Tech. U.