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.
2009 December 29
Explanation: Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula on the lower left is associated with the bright star Rigel, to its right, in the constellation Orion. More formally known as IC 2118, the Witch Head Nebula glows primarily by light reflected from Rigel. Fine dust in the nebula reflects the light. Pictured above, the blue colour of the Witch Head Nebula and of the dust surrounding Rigel is caused not only by Rigel's blue colour 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 in Earth's atmosphere are molecules of nitrogen and oxygen. Rigel, the Witch Head Nebula, and gas and dust that surrounds them lie about 800 light-years away.
Authors & editors:
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
A service of: ASD at NASA / GSFC
& Michigan Tech. U.