Andromeda galaxy

The Andromeda galaxy

Andromeda galaxy

At a distance of about 2.5 million light years, the Andromeda galaxy (also known as NGC 224 and M31) is the nearest galaxy to the Earth apart from smaller companion galaxies such as the Magellanic Clouds.

Like the Milky Way, Andromeda is a spiral galaxy. It can be spotted with the naked eye and so has been known to humans for a very long time.

In the 1920s astronomer Edwin Hubble confirmed that Andromeda is another galaxy and not just a gas cloud in the Milky Way as was previously thought.

Image: A mosaic view of the Andromeda galaxy created from 10 Galaxy Evolution Explorer images (credit: NASA/JPL-Caltech)

Watch and listen to clips from past programmes TV clips [6] Radio Programmes [1]

The Andromeda galaxy

Introduction

A nearby galaxy is similar to our own.

About Andromeda galaxy

The Andromeda Galaxy /ænˈdrɒmɨdə/ is a spiral galaxy approximately 2.5 million light-years (2.4×1019 km) from Earth in the Andromeda constellation. Also known as Messier 31, M31, or NGC 224, it is often referred to as the Great Andromeda Nebula in older texts. The Andromeda Galaxy is the nearest spiral galaxy to our Milky Way galaxy, but not the nearest galaxy overall. It gets its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. The Andromeda Galaxy is the largest galaxy of the Local Group, which also contains the Milky Way, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, the Andromeda Galaxy may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and could be the most massive in the grouping. The 2006 observations by the Spitzer Space Telescope revealed that M31 contains one trillion (1012) stars: at least twice the number of stars in the Milky Way galaxy, which is estimated to be 200–400 billion.

The Andromeda Galaxy is estimated to be 7.1×1011solar masses. In comparison a 2009 study estimated that the Milky Way and M31 are about equal in mass, while a 2006 study put the mass of the Milky Way at ~80% of the mass of the Andromeda Galaxy. The two galaxies are expected to collide in 3.75 billion years, eventually merging to form a giant elliptical galaxy.

At 3.4, the apparent magnitude of Andromeda Galaxy is one of the brightest of any Messier objects, making it visible to the naked eye on moonless nights even when viewed from areas with moderate 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 to the naked eye or when viewed using binoculars or a small telescope.

Read more at Wikipedia

This entry is from Wikipedia, the user-contributed encyclopedia. If you find the content in the 'About' section factually incorrect, defamatory or highly offensive you can edit this article at Wikipedia.

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.