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The '''Andromeda''' Galaxy is a [[spiral galaxy]] approximately 2,500,000 [[light-years]] (1.58×1011 AU) away[4] in the constellation Andromeda. It is also known as [http://en.wikipedia.org/wiki/Messier_object Messier] 31, M31, or NGC 224, and is often referred to as the Great Andromeda [[Nebula]] in older [[texts]]. Andromeda is the nearest spiral galaxy to our own, the [[Milky Way]]. As it is visible as a faint smudge on a moonless night, it is one of the farthest objects visible to the naked eye, and can be seen even from urban areas with binoculars. It is named after the princess [http://en.wikipedia.org/wiki/Andromeda_(mythology) Andromeda] (Greek: Ανδρομέδη – Andromédē) in [[Greek]] [[mythology]].  

The '''Andromeda''' Galaxy is a [[spiral galaxy]] approximately 2,500,000 [[light-years]] (1.58×1011 AU) away[4] in the constellation Andromeda. It is also known as [https://en.wikipedia.org/wiki/Messier_object Messier] 31, M31, or NGC 224, and is often referred to as the Great Andromeda [[Nebula]] in older [[texts]]. Andromeda is the nearest spiral galaxy to our own, the [[Milky Way]]. As it is visible as a faint smudge on a moonless night, it is one of the farthest objects visible to the naked eye, and can be seen even from urban areas with binoculars. It is named after the princess [https://en.wikipedia.org/wiki/Andromeda_(mythology) Andromeda] (Greek: Ανδρομέδη – Andromédē) in [[Greek]] [[mythology]].  

Andromeda is the largest galaxy of the [http://en.wikipedia.org/wiki/Local_Group Local Group], which consists of the Andromeda Galaxy, the [[Milky Way]] Galaxy, the [http://en.wikipedia.org/wiki/Triangulum_Galaxy Triangulum Galaxy], and about 30 other smaller galaxies. Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more [[dark matter]] and may be the most massive in the grouping. The 2006 observations by the [http://en.wikipedia.org/wiki/Spitzer_Space_Telescope Spitzer Space Telescope] revealed that M31 contains one trillion [[stars]], several times more than the number of stars in our own galaxy, which is estimated to be c. 200-400 billion. While the 2006 estimates put the [[mass]] of the Milky Way to be ~80% of the mass of Andromeda, which is estimated to be 7.1 × 1011 [http://en.wikipedia.org/wiki/Solar_mass solar masses], a 2009 study concluded that Andromeda and the Milky Way are about equal in mass.

Andromeda is the largest galaxy of the [https://en.wikipedia.org/wiki/Local_Group Local Group], which consists of the Andromeda Galaxy, the [[Milky Way]] Galaxy, the [https://en.wikipedia.org/wiki/Triangulum_Galaxy Triangulum Galaxy], and about 30 other smaller galaxies. Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more [[dark matter]] and may be the most massive in the grouping. The 2006 observations by the [https://en.wikipedia.org/wiki/Spitzer_Space_Telescope Spitzer Space Telescope] revealed that M31 contains one trillion [[stars]], several times more than the number of stars in our own galaxy, which is estimated to be c. 200-400 billion. While the 2006 estimates put the [[mass]] of the Milky Way to be ~80% of the mass of Andromeda, which is estimated to be 7.1 × 1011 [https://en.wikipedia.org/wiki/Solar_mass solar masses], a 2009 study concluded that Andromeda and the Milky Way are about equal in mass.

At an [http://en.wikipedia.org/wiki/Apparent_magnitude apparent magnitude] of 3.4, the Andromeda Galaxy is notable for being one of the brightest [http://en.wikipedia.org/wiki/Messier_object Messier objects], making it easily visible to the naked eye even when viewed from areas with moderate [http://en.wikipedia.org/wiki/Light_pollution light pollution]. Although it appears more than six times as wide as the full [[moon]] when photographed through a larger telescope, only the brighter central region is visible with the naked eye.[http://en.wikipedia.org/wiki/Andromeda_Galaxy]

At an [https://en.wikipedia.org/wiki/Apparent_magnitude apparent magnitude] of 3.4, the Andromeda Galaxy is notable for being one of the brightest [https://en.wikipedia.org/wiki/Messier_object Messier objects], making it easily visible to the naked eye even when viewed from areas with moderate [https://en.wikipedia.org/wiki/Light_pollution light pollution]. Although it appears more than six times as wide as the full [[moon]] when photographed through a larger telescope, only the brighter central region is visible with the naked eye.[https://en.wikipedia.org/wiki/Andromeda_Galaxy]

[[Category: Astronomy]]

[[Category: Astronomy]]