The Laniakea Supercluster (considered the Local Supercluster)
is a supercluster stretched out across ~120 megaparsecs,
including 300-500 galaxy clusters and galaxy groups
with total a mass of about 1017solar masses.
It has on the order of 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.
At least one subsequent study has suggested Laniakea is not gravitationally bound,
and if so, it is a matter of nomenclature whether it should be
termed a supercluster.