The Andromeda Galaxy (/ænˈdrɒmədə/) is a spiral galaxy approximately 2.5 million light-years (2.4×1019 km) from Earthin the Andromeda constellation. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula in older texts. The Andromeda Galaxy is the nearest spiral galaxy to our galaxy (Milky Way), but not the closest galaxy overall.
In the image
1. 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
2. The Andromeda Galaxy as seen by NASA’s Wide-field Infrared Survey Explorer
3. The Andromeda Galaxy pictured in ultraviolet light by GALEX
4. Stars in the Andromeda Galaxy’s disc.