Groups of Galaxies
Groups of galaxies are the smallest aggregates of galaxies. They typically contain no more than 50 galaxies in a diameter of 1 to 2 megaparsecs (Mpc)(see 1022 m for distance comparisons). Their mass is approximately 1013 solar masses. The spread of velocities for the individual galaxies is about 150 km/s. However, this definition should be used as a guide only, as larger and more massive galaxy systems are sometimes classified as galaxy groups.
Our own Galaxy, the Milky Way, is contained in the Local Group of more than 40 galaxies.
Read more about this topic: Galaxy Groups And Clusters
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