Most galaxies occur in clusters containing a few to a few thousand galaxies in a volume of 1-10 Mpc across The Milky Way Galaxy is a member of the Local Group, which probably contain more than 3 dozens galaxies scattered irregularly in a volume of 1 Mpc across. Clusters of galaxies seem to be associated with one another in groupings called superclusters; the Local Group is part of the Local Supercluster. Superclusters are linked in filament-like network with great voids between them. One study has found the Great Wall, a sheet containing thousands of galaxies extending over 150 million pc.