Local Group

The Local Group is the galaxy group that includes the Milky Way. The Local Group comprises more than 54 galaxies, most of them dwarf galaxies. Its gravitational center is located somewhere between the Milky Way and the Andromeda Galaxy. The Local Group covers a diameter of 10 Mly (3.1 Mpc) (about 10²³ meters) and has a binary (dumbbell) distribution. The group itself is a part of the larger Virgo Supercluster, which in turn may be a part of the Laniakea Supercluster.

The three largest members of the group (in descending order) are the Andromeda Galaxy, the Milky Way and the Triangulum Galaxy. The larger two of these spiral galaxies each have their own system of satellite galaxies.

The term "The Local Group" was introduced by Edwin Hubble in Chapter VI of his 1936 book The Realm of the Nebulae. There, he described it as "a typical small group of nebulae which is isolated in the general field" and delineated, by decreasing luminosity, its members to be M31, Milky Way, M33, Large Magellanic Cloud, Small Magellanic Cloud, M32, NGC 205, NGC 6822, NGC 185, IC 1613 and NGC 147. He also identified IC 10 as a possible Local Group member.

By 2003, the number of known Local Group members had increased from his initial 12 to 36.

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