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.