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The Witch Head
nebula (or IC2118)
is a reflection nebula in constellation Orion. The nebula
reflects the light from the blue giant star Rigel (upper
right corner). The blue colour is caused not only by Rigel's
blue colour but also because the dust grains reflect blue
light more efficiently than red. It is the same physical
process that causes Earth's daytime sky to appear blue (but
then due to reflection of Nitrogen and Oxygen).
The nebula is almost 1000
light years away from Earth. Also worth mentioning is that
Rigel is the seventh brightest star in the night sky.
This image was chosen
Astroimaging Challenge Yahoo Group
Winner January 2009 and was featured in
Astronomy Magazine Picture of the Day
March 2009.
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