A supercluster is a large group of smaller

galaxy cluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. Clusters consist of galax ...

s or

galaxy group A galaxy group or group of galaxies (GrG) is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way (about 1010 times the luminosity of the Sun); collections of galaxi ...

s; they are among the largest known structures in the

universe The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...

. The

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

is part of the

Local Group The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a " dumbbell" shape; the Milky Way ...

galaxy group (which contains more than 54 galaxies), which in turn is part of the

Virgo Supercluster The Local Supercluster (LSC or LS), or Virgo Supercluster is a formerly defined supercluster containing the Virgo Cluster and Local Group, which itself contains the Milky Way and Andromeda galaxies, as well as others. At least 100 galaxy group ...

, which is part of the

Laniakea Supercluster The Laniakea Supercluster (; Hawaiian language, Hawaiian for "open skies" or "immense heaven") or the Local Supercluster (LSC or LS) is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies. It w ...

, which is part of the

Pisces–Cetus Supercluster Complex The Pisces–Cetus Supercluster Complex is a galaxy filament. It includes the Laniakea Supercluster which contains the Virgo Supercluster lobe which in turn contains the Local Group, the galaxy cluster that includes the Milky Way. This filament is ...

. The large size and low density of superclusters means that they, unlike clusters, expand with the

Hubble expansion Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther a galaxy is from the Earth, the faster ...

. The number of superclusters in the

observable universe The observable universe is a Ball (mathematics), spherical region of the universe consisting of all matter that can be observation, observed from Earth; the electromagnetic radiation from these astronomical object, objects has had time to reach t ...

is estimated to be 10 million.

Existence

The existence of superclusters indicates that the galaxies in the Universe are not uniformly distributed; most of them are drawn together in groups and clusters, with groups containing up to some dozens of galaxies and clusters up to several thousand galaxies. Those groups and clusters and additional isolated galaxies in turn form even larger structures called superclusters. An Intergalactic Heavyweight

Their existence was first postulated by George Abell in his 1958

Abell catalogue The Abell catalog of rich clusters of galaxies is an all-sky catalog of 4,073 rich galaxy clusters of nominal redshift ''z'' ≤ 0.2. This catalog supplements a revision of George O. Abell's original "Northern Survey" of 1958, whi ...

of galaxy clusters. He called them "second-order clusters", or clusters of clusters. Superclusters form massive structures of galaxies, called "filaments", "supercluster complexes", "walls" or "sheets", that may span between several hundred million light-years to 10 billion light-years, covering more than 5% of the

. These are the largest structures known to date. Observations of superclusters can give information about the initial condition of the universe, when these superclusters were created. The directions of the rotational axes of galaxies within superclusters are studied by those who believe that they may give insight and information into the early formation process of galaxies in the history of the Universe. Interspersed among superclusters are large

voids Void may refer to: Science, engineering, and technology * Void (astronomy), the spaces between galaxy filaments that contain no galaxies * Void (composites), a pore that remains unoccupied in a composite material * Void, synonym for vacuum, ...

of space where few galaxies exist. Superclusters are frequently subdivided into groups of clusters called

galaxy groups and clusters Galaxy groups and clusters are the largest known gravitationally bound objects to have arisen thus far in the process of cosmic structure formation. They form the densest part of the large-scale structure of the Universe. In models for the gra ...

. Although superclusters are supposed to be the largest structures in the universe according to the

Cosmological principle In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equa ...

, larger structures have been observed in surveys, including the

Sloan Great Wall The Sloan Great Wall (SGW) is a cosmic structure formed by a giant wall of galaxies (a galaxy filament). Its discovery was announced from Princeton University on October 20, 2003, by J. Richard Gott III, Mario Jurić, and their colleagues, ba ...

List of superclusters

Nearby superclusters

Distant superclusters

Extremely distant superclusters

Diagram

References

External links

Overview of local superclusters

{{Authority control Large-scale structure of the cosmos