Supercluster

Superclusters are large groups of smaller galaxy clusters or galaxy groups and are among the largest known structures of the cosmos. The Milky Way is in the Local Group Galaxy Cluster (that contains more than 54 galaxies), which in turn is in the Laniakea Supercluster. This supercluster spans over 500 million light years, while the Local Group spans over 10 million light years. The number of superclusters in the observable universe is estimated to 10 million.

Galaxies are grouped into clusters instead of being dispersed randomly. Clusters of galaxies are grouped together to form superclusters. Typically, superclusters contain dozens of individual clusters throughout an area of space about 150 million lightyears across. Unlike clusters, superclusters are not bound together by gravity. They are all shifting away from each other due to the Hubble flow.

Our galaxy falls within the Local Group, which is a poor and irregular cluster of galaxies. Poor clusters may contain only a few dozen galaxies as compared to rich clusters that can contain hundreds or even thousands. The Local Group is near the Local Supercluster (also known as the Virgo Supercluster) which has a diameter of 100 million lightyears. The Local Supercluster contains a total of about 10¹⁵ times the mass of the Sun.