Laniakea

Laniakea is a vast, supercluster of galaxies that forms the largest known structure in the observable universe. Discovered in 2014 through a study led by astronomers at the University of Hawaii and the European Southern Observatory, Laniakea is named after the Hawaiian word for "expanding sky," reflecting its expansive and dynamic nature. This cosmic structure spans approximately 500 million light-years across and contains roughly 100,000 to 200,000 billion stars, making it far larger than the Milky Way galaxy, which is just one of its constituent members.

Laniakea is defined by its gravitational interactions and the flow of galaxies within it. Unlike smaller clusters, it is not bound by a single gravitational pull but instead is shaped by the large-scale flow of matter in the universe. The supercluster is centered around the Great Attractor, a region of unusually high density that exerts a gravitational influence on galaxies within it. The Milky Way and its local group of galaxies, including Andromeda, are part of this vast system.

Researchers identified Laniakea by mapping the motions of galaxies using data from the Sloan Digital Sky Survey and other astronomical observations. The study revealed that galaxies within the supercluster are moving away from each other at varying speeds, creating a cosmic web pattern. This movement helps define the boundaries of Laniakea, distinguishing it from other nearby structures like the Virgo Supercluster, which is part of a smaller, more localized grouping.

Understanding Laniakea provides insights into the large-scale structure of the universe and the role of dark matter in shaping cosmic evolution. Its discovery highlights the complexity of the universe’s organization on the largest scales, offering a new framework for studying galaxy distribution and the dynamics of cosmic expansion.