The Perseus Cluster of Galaxies.

Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy, together making up the Perseus Cluster , one of the closest clusters of galaxies . The cluster is seen through the foreground of faint stars in our own Milky Way Galaxy . It takes light roughly 300 million years to get here from this region of the Universe, so we see this cluster as it existed before the age of the dinosaurs . Also known as Abell 426, the center of the Perseus Cluster is a prodigious source of X-ray radiation , and so helps astronomers explore how clusters formed and how gas and dark matter interact. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster of galaxies, which spans over 15 degrees and contains over 1000 galaxies.