THE HITCHCHIKER'S GUIDE TO THE LOCAL SUPERCLUSTER

Image: Virgo Supercluster. Credit: Andrew Z. Colvin

The Virgo Supercluster is a region with a diameter of 33 megaparsecs (~1000 times larger the Milky Way's diameter) containing at least 100 galaxy groups and clusters.


The Local Group, which contains the Milky Way and Andromeda galaxies, is located on the outskirts of the Local Supercluster in a small filament extending from the Fornax Cluster to the Virgo Cluster.

The vast majority of the luminous galaxies are concentrated in a small number of clouds. This distribution indicates that most of the volume of the supergalactic plane is a great void.

The Virgo Supercluster is contained in turn in the Laniakea Supercluster, which encompasses 100,000 galaxies stretched out over 160 megaparsecs.

Image: Laniakea Supercluster. The blue dot indicates the location of the Milky Way. The rainbow colour scale indicates density (with high density regions in green and red, and low density in blue); velocity flow streams are indicated by the blue and white lines; and the orange band indicates the border of the Laniakea supercluster. Credit: Nature

Superclusters are some of the universe's largest structures, and have boundaries that are difficult to define, especially from the inside. Within a given supercluster, most galaxy motions will be directed inward, toward the center of mass.

In the case of Laniakea, this gravitational focal point is called the Great Attractor, and influences the motions of the Local Group of galaxies (where the Milky Way galaxy resides) and all others throughout our supercluster.

Image: Great Attractor. Credit: Nature

The neighbouring superclusters to Laniakea are the Shapley Supercluster, Hercules Supercluster, Coma Supercluster, Perseus-Pisces Supercluster.