Laniakea Supercluster

Laniakea is a vast region of galaxy groups and clusters whose galaxies share inward gravitational flows toward common mass concentrations. It contains the Milky Way and is defined by those flows rather than a sharply bounded edge.

Peculiar velocity: A celestial object's motion relative to the uniform expansion of the universe. Subtracting cosmic expansion from galaxy motions reveals the flows used to delineate Laniakea.
Galaxy group: A gravitationally associated collection of galaxies smaller than a galaxy cluster. Galaxy groups are among the structures whose motions contribute to Laniakea's mapped flows.
R. Brent Tully: An American astronomer known for research on galaxy distances and large-scale cosmic structure. Tully led the team that identified and named Laniakea in 2014.
Virgo Supercluster: The traditional designation for the large-scale structure centered on the Virgo Cluster and containing the Local Group. Laniakea replaced this familiar regional label with a boundary based on galaxy flows.
Cosmic flow: The collective motions of galaxies driven by cosmic expansion and unevenly distributed matter. Laniakea is identified through the converging galaxy flows within this broader pattern.
Galaxy cluster: A gravitationally bound system containing hundreds to thousands of galaxies, hot gas, and dark matter. Clusters mark major concentrations of matter within the supercluster.
Hélène Courtois: A French astrophysicist whose research includes mapping galaxy motions and cosmic structure. Courtois co-led the work that mapped Laniakea's flow-defined extent.
Sloan Great Wall: A vast arrangement of galaxy clusters identified in the Sloan Digital Sky Survey. Unlike Laniakea's flow-defined region, it is described as a mapped concentration of clusters.
Gravitational attraction: The mutual force by which matter with mass draws other matter toward it. Uneven mass concentrations steer galaxies into the flow patterns that define the supercluster.
Local Group: The galaxy group containing the Milky Way, Andromeda Galaxy, and dozens of smaller galaxies. It locates the Milky Way within Laniakea's larger structure.

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