Andromeda (M31 or Messier 31, NGC 224) is a Spiral Galaxy about two and a half million light-years away. It used to be known as the Great Andromeda Nebula. It has about a trillion stars and is larger than the Milky Way. Andromeda and the Milky Way are the two largest galaxies of the Local Group and two of its only three spiral galaxies.
Satellite Galaxies of Andromeda are known as Andromeda I (or And I), Andromeda II, etc.
Astronomical Unit (AU)
Galaxy Main Sequence
Hierarchical Assembly of Galaxies
Large Magellanic Cloud (LMC)
Local Group (LG)
Triangulum Galaxy (M33)
Principal Galaxies Catalog (PGC)