Laniakea Supercluster

The Laniakea Supercluster (considered the Local Supercluster) is a supercluster stretched out across ~125 megaparsecs, including 300-500 galaxy clusters and galaxy groups with total a mass of about 10¹⁷ solar masses. It has at least 100,000 galaxies, including the Milky Way. It was defined as such in September 2014 based upon a study of the velocities of the galaxies. It combines four groups traditionally labeled superclusters:

• Virgo Supercluster, which was traditionally considered the Local Supercluster.
• Hydra-Centaurus Supercluster which includes the Great Attractor.
• Pavo-Indus Supercluster.
• Southern Supercluster.

A study has suggested Laniakea is not gravitationally bound, and if so, it is a matter of nomenclature whether it should be termed a supercluster.