The massive Perseus Cluster stretches out over 15 million light-years

At first glance, this looks like just another star field. But almost every source of light in this image is actually one of the 190 galaxies making up the massive Perseus Cluster, one of the nearest such clusters to Earth.

While even the size of the solar system, let alone the Milky Way, is far beyond human comprehension, it's when you get into galactic clusters that we're really talking about unimaginably cosmic scales. And, as NASA explains, even this behemoth is just part of a still larger structure:

Each of these fuzzy blobs is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. The cluster is seen through a foreground of faint stars in our own Milky Way Galaxy. Near the cluster center, roughly 250 million light-years away, is the cluster's dominant galaxy NGC 1275, seen above as a large galaxy on the image left. A prodigious source of x-rays and radio emission, NGC 1275 accretes matter as gas and galaxies fall into it. The Perseus Cluster of Galaxies, also cataloged as Abell 426, is part of the Pisces-Perseus supercluster spanning over 15 degrees and containing over 1,000 galaxies.

Via NASA. Image by Bob Franke.