Clusters of galaxies are groups of galaxies that are gravitationally
to one another. Clusters may come in small
groups of a dozen to two dozen members, such as the Local Group which
includes the Milky Way and the Andromeda galaxy. Larger clusters of
galaxies can contain several thousand members. On even larger
scales, galaxy superclusters may exist, containing about a hundred
clusters of galaxies.
Click any thumbnail below to view the details of
that image. Other images of the atomic hydrogen in clusters of galaxies
can be found in the . Visit non-NRAO website
for more information on clusters of galaxies.