Image Description

M31, the Andromeda galaxy, is the closest galaxy of comparable comparible size to our Milky Way.  It is a member of the local group of about 50 galaxies and about the same size as our galaxy; each contains an estimated 10 billion stars.  M31 has two bright satellite galaxies designated as M32 / NGC221 and M110 / NGC205 and thousands of globular star clusters in its galactic halo. Two faint companion galaxies, NGC147 and NGC185, are nearby in the constellation Cassiopea.

M31 is a spiral class galaxy containing clouds of cold hydrogen gas and dust in its arms.  Recent studies estimate its distance to be 2.3 million light-years.

Almost all the "dots" in this image are foreground stars located in the Milky Way.  Only very large telescopes have resolved stars in M31 and only the brightest and largest ones. 

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To view an edited image of M31 as it would appear from the outer edge of our galaxy, LeftClick the appropriate screen size link below.
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