At first glance, this image is dominated by the vibrant glow of the swirling spiral to the lower left of the frame. However, this galaxy is far from the most interesting spectacle here — behind it sits a galaxy cluster.
Galaxies are not randomly distributed in space; they swarm together, gathered up by the unyielding hand of gravity, to form groups and clusters. The Milky Way is a member of the Local Group, which is part of the Virgo Cluster, which in turn is part of the 100,000-galaxy-strong Laniakea Supercluster. The galaxy cluster seen in this image is known as SDSS J0333+0651. Clusters such as this can help astronomers understand the distant universe. This was imaged as part of a study of star formation in far-flung galaxies.