This is the Hercules galaxy cluster, located relatively close to us at just 500 million light-years away. But the way its galaxies are colliding with each other makes it look like a throwback to the chaos of the early universe.
This new image from the European Southern Observatory gives us our best look yet at this unusual cluster. Its overall shape is very different from nearby galaxy clusters, and its member galaxies are generally young and still forming stars, with none of the big, ancient elliptical galaxies that are typical in the clusters around it. You can see a few examples of the ongoing galaxy mergers in the image below.
The absence of elliptical galaxies is a major tip-off that this is still a very young cluster. That's because it doesn't matter what types of galaxies initially come together to form the cluster - say, a bunch of spiral galaxies like our own Milky Way - as the constant collisions between galaxies twist them out of their original shape and strip away the gas needed for continued star formation. The result is a mature cluster full of giant elliptical and irregular galaxies, and that's not what we see here in the Hercules cluster.
Right now, the Hercules cluster is merging together three smaller clusters and a bunch more random groups of galaxies. But even that gargantuan task still pales in comparison to the even larger process going on around it. The entire Hercules Cluster is slowly merging with other nearby galaxy clusters to form one massive supercluster, which is one of the most colossal structures in the universe.
For more, check out ESO.