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November 2005

A Dark Nebula

Where did all of the stars go? Actually nowhere; the "C"-shaped dark patch you see in the image is a region of dense gas and dust within our Galaxy made visible only because it is blocking starlight from more distant stars. Dark nebulae are of interest to astronomers because the dense gas they contain is the raw material for the formation of stars.

If ou look closely at the image you will notice there are a number of reddish colored stars associated with the nebula. These stars are located behind he nebula. Their distinct color arises because shorter wavelength bluish light from the stars is more absorbed and scattered by the dust in thenebula, allowing only longer wavelength near infrared light ot pass through the nebula. This is essentially the same process that results in the reddish color of the setting Sun.