Cometary globules are isolated, relatively small clouds of gas and dust
within the Milky Way. This example contains enough material to make
several sun-sized stars. The head of the nebula is itself opaque, but
glows because it is illuminated by light from very hot stars nearby.
Their energy is gradually destroying the dusty head of the globule,
sweeping away tiny particles that scatter the starlight as a faint, bluish reflection nebula. This particular globule also shows a faint red glow, probably from excited hydrogen, and seems about to devour an
edge-on spiral galaxy, which in reality is millions of light years away,
far beyond CG 4.
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