Unsociable galaxies are unusual. Astronomers think that galaxies grow from scraggly clusters of stars to elegant spirals like the Milky Way by merging and pooling their resources. Loner galaxies like NGC 4178, which has spent most of the lifetime of the universe avoiding the company of other galaxies, are useful tools for disentangling how this happens. They are rare snapshots of a simpler time. “They are more representative of the initial stuff, from when structure started to form in the universe,” says Nathan Secrest, a graduate student at George Mason University.

One of the puzzles they can help solve is the origin of supermassive black holes. Most large galaxies seem to have a giant black hole, millions or billions of times larger than the sun, at their centers. How these black holes got so big is still a mystery: did they grow gradually from mergers of smaller black holes, coalescing when their host galaxies merged? Or did they form when gas clouds collapsed in the early universe?