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M31 Andromeda Galaxy
Derek Stek

Previous imageUp to Astr110 IndexNext imageAndromeda Galaxy M31

This is a photograph of the center of the Andromeda Galaxy, also known as M31. Apart from a few scattered dwarf galaxies, Andromeda is our closest neighboring galaxy, about two million light years away. Andromeda, Triangulum, our Milky Way, and approximately 30 or so dwarf galaxies all make up the Local Group--our "neighborhood" of galaxies. Interestingly, the Andromeda Galaxy and our Milky Way are predicted to collide together in about five billion years. Andromeda measures about twice the size of the Milky Way.

Notice the spiral arms Andromeda has on the outer edges of the photograph. These spiral arms are indicative that Andromeda belongs to the classification of Spiral Galaxies. More specifically, the shape, size, and "clutter" of these arms further indicate Andromeda's sub class of spiral galaxies: Sb. In this picture, the linear size of Andromeda is estimated at 22,000 light years.

Bennett, Jeffrey, Megan Donahue, Nicholas Schneider, and Mark Voit. The Cosmic Perspective. 6th ed. San Francisco: Addison-Wesley, 2010..

Frommert, Hartmut, and Christine Kronberg. "Messier 31." Students for the Exploration and Development of Space. 25 Aug. 2007. Accessed 3 Dec. 2010. <>.

Right Ascension (J2000) 00:42:70.00
Declination (J2000) +41:16:14.0
Filters used Clear
Exposure time per filter 60 seconds
Date observed

October 10, 2010

Mosaic Photograph (comprised of four separate images)



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