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 color of the
Witch Head Nebula and of the dust surrounding
Rigel
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 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.
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