Most galaxies have only a few nearby neighbors. However, in some places, hundreds to thousands of galaxies swarm together. This is called a cluster of galaxies. All the galaxies orbit one another, held together by the gravitational forces between them.
At the center of a cluster of galaxies is often a giant elliptical galaxy. Sometimes there’s an even larger one called a central dominant. These two types of galaxies seem to grow bigger by swallowing other galaxies. Some have two centers, or nuclei. That means they’re still digesting their latest meal! Here’s a look at some galaxy clusters.
