The Andromeda Galaxy. Image source: [1]
The galaxy of Andromeda is also known as MESSIER 31, since it is the Messier catalog number object 31 of fuzzy objects in the sky. It is a super giant spiral of the type Sb with a luminosity that is, apparently, something greater than the one of our galaxy. It is turned towards us so that its main plane constitutes an angle of 15 degrees with the line of sight, that is, it is almost in profile. However, a 15-degree angle is not small enough so that the dusty matter near the main plane of this galaxy can manifest itself as a dark belt. Andromeda is 2.5 million light years from us and is the closest spiral galaxy.
Messier 31 is the closest major galaxy to ours, the Milky Way. It is believed that our galaxy looks quite like Andromeda. Together, both galaxies dominate the Local Group of galaxies. The diffused light that comes to us from Andromeda has its origin in the hundreds of billions of stars that form it. The different stars that surround Messier 31.
The peculiar thing about the Andromeda Galaxy is that it approaches ours, the Milky Way, at a speed of 300 kilometers per second. It is believed that within 3,000 to 5 billion years, both could collide. The planets and stars within each galaxy would not collide, but they would alter the orbits and order within each system.
More details here: Messier 31
The Andromeda Galaxy as seen by NASA's Wide-field Infrared Survey Explorer. Image source: [2]
The Andromeda Galaxy pictured in ultraviolet light by GALEX. Image source: [3]
The Andromeda Galaxy seen in infrared by the Spitzer Space Telescope, one of NASA's four Great Space Observatories. Image source: [4]
Image of the Andromeda Galaxy taken by Spitzer in infrared, 24 micrometres (Credit:NASA/JPL–Caltech/K. Gordon, University of Arizona). Image source: [5]
Artist's concept of the Andromeda Galaxy core showing a view across a disk of young, blue stars encircling a supermassive black hole. NASA/ESA photo. Image source: [6]
