How galaxies are grouped - superclusters

Stars are surrounded by planets and they make up star systems, such as our own Solar System. Billions of stars make up galaxies, and galaxies are distributed similarly. Instead of arbitrarily floating through space, they are grouped together. A large group of galaxies in a region of space make up galaxy clusters or groups and are some of the most massive structures in the cosmos. Smaller galaxy clusters make up larger ones. For example, the Milky Way, along with satellite galaxies such as the Small and Large Magellanic clouds, make up the Local Group of galaxies, which, along with other smaller groups, make up the Laniakea Supercluster.

Artist's rendition of superclusters close to earth, relatively speaking

The Laniakea Supercluster is about 500 million light years across. For comparison, the Milky Way is about 100,000 light years in diameter, making the cluster 5000 times larger than our own galaxy.

An interesting anomaly in the Laniakea Supercluster

A gravitational anomaly, known as the Great Attractor, exists between galaxies at the centre of our own supercluster. Astronomers and scientists don't yet know what exactly it is, but the existence of the anomaly reveals the presence of a mass thousands of times more massive than the Milky Way galaxy.

The Great Attractor shown at the bottom right by the 2 blue arrows

The Great Attractor affects the position of the galaxies around it. Specifically, it causes the galaxies to move away relative to us and each other, a process known as redshift. However,  inconsistencies in their motion indicate the presence of an anomaly.

It is located approximately 150 - 250 million light years away from the Milky Way. The Milky Way and the Great Attractor are also moving towards something: The Shapley Attractor, located in the Shapley Supercluster, about 650 million ly away.