Milwaukee Astronomical Society


M31 - NGC 224 - The Andromeda Galaxy


Messier 31 (M31) is a spiral galaxy in the constellation Andromeda. It is the nearest major galaxy outside our own Milky Way and the largest one in our Local Group. M31 is located about 2.5 million light years from earth and is approximately 220,000 light years in diameter. It has 14 known dwarf galaxies which are satellites. These dwarf galaxies include M32 and M110, both of which are easily seen in most images of the Andromeda Galaxy. Since it is visible to the naked eye, it is unknown who discovered it. It was described in the "Book of Fixed Stars" in 964 as a small cloud and as late as 1863 was still considered just a gaseous nebula. It wasn't until 1925 that it could be documented M31 was a separate galaxy outside our own.

Location Data
Constellation: Andromeda
Right ascension: 0h 42.8m
Declination: 41° 16′
Distance:  2,500,000 ly
Size:  220,000 ly

Observation Data
Apparent magnitude: 3.40
Apparent size: 178' arcmins

The images With Blue Borders were taken using equipment provided by the MAS Observatory
Click on the Image to View It Full Size