The key force in astronomy is gravitational attraction. Planets orbit stars, and stars are part of galaxies. But even galaxies come together into groups with dozens of members. One of the larger structures in the Universe are galaxy clusters; collections of thousands of galaxies. And our Milky Way is no exception. We’re a part of a much larger structure known as the Virgo Cluster.
The Virgo Cluster contains about 1300-2000 member galaxies, which are all connected together by mutual gravity. Astronomers estimate that it contains a total mass of about 1.2 quadrillion times the mass of the Sun. It covers a total volume of space with a diameter of 15 million light-years across.
Just like it’s name, the galaxies in the Virgo Cluster are mostly located in the constellation of Virgo, and one of the largest members of the cluster is the giant elliptical galaxy Messier 87. This monster is thought to have about 2.7 trillion solar masses all on its own.
The Virgo Cluster is just one member of an even larger structure: the Virgo Supercluster. This supercluster, also located in the constellation of Virgo is thought to have more than a million member galaxies, and stretches across a region of space 110 million light-years in size.
Superclusters are the largest structures in the Universe, and there are thought to be millions of them across the entire Universe. From the largest scales, these superclusters are stretched out into long filaments with large voids in between them. Seem from the longest distances, they would look like foam bubbles.
We have written many articles about galaxies for Universe Today. Here’s an article about the Virgo Cluster sucking in a distant galaxy, and here’s another article detailing a study of the Virgo Cluster.
We have also recorded an episode of Astronomy Cast about galaxies – Episode 97: Galaxies.