The Andromeda Galaxy, named after the mythological Princess Andromeda, also known as Messier 31, M31, or NGC 224, is a spiral galaxy.
Andromeda was born 10 billion years ago out of the merger of many smaller protogalaxies and then, around 8 billion years ago, it ran head-on into another galaxy to form a giant that became the M31 galaxy we see today.
At just 2.5 million light years away, this large, bright galaxy is visible with the naked eye. On a clear night, with a very dark sky, it can be seen as a diffuse blur, with the central region clearly visible through a good pair of binoculars. Larger telescopes provide even more-spectacular views of this impressive galaxy.
Andromeda is over 2.5 times longer than the entire Milky Way and appears longer than the full Moon in the night sky.
Andromeda galaxy also contains around twice the number of stars as our own galaxy, according to observations made by the Spitzer Space Telescope.
Andromeda is blue-shifted, meaning it’s moving towards us. Both the Milky Way and Andromeda are moving towards each other at a rate of 120 kilometres (75 miles) a second, putting them on course for a galactic smash- up in around 4 billion years.
The first photographs of Andromeda were taken in 1887, by Isaac Roberts.
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