This is a list of the largest cosmic structures so far discovered. The unit of measurement used is the
light-year
A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...
(distance traveled by light in one
Julian year; approximately 9.46 trillion
kilometres
The kilometre ( SI symbol: km; or ), spelt kilometer in American and Philippine English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for ). It is the preferred measur ...
).
This list includes
supercluster
A supercluster is a large group of smaller galaxy clusters or galaxy groups; they are among the largest known structures in the universe. The Milky Way is part of the Local Group galaxy group (which contains more than 54 galaxies), which in tu ...
s,
galaxy filaments
In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters. These massive, thread-like formations can commonly reach 50 to 80 megaparsecs ()—with the largest found to date b ...
and
large quasar groups (LQGs). The structures are listed based on their longest dimension.
This list refers only to coupling of matter with defined limits, and not the coupling of matter in general (such as, for example, the
cosmic microwave background
The cosmic microwave background (CMB, CMBR), or relic radiation, is microwave radiation that fills all space in the observable universe. With a standard optical telescope, the background space between stars and galaxies is almost completely dar ...
, which fills the entire universe). All structures in this list are defined as to whether their presiding limits have been identified.
There are some reasons to be cautious about this list:
*The
Zone of Avoidance
The Zone of Avoidance (ZOA, ZoA), or Zone of Galactic Obscuration (ZGO), is the area of the sky that is obscured by the Milky Way.
The Zone of Avoidance was originally called the Zone of Few Nebulae in an 1878 paper by English astronomer Richard ...
, or the part of the sky occupied by 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 ...
, blocks out light from several structures, making their limits imprecisely identified.
*Some structures are too distant to be seen even with the most powerful telescopes.
*Some structures have no defined limits, or endpoints. All structures are believed to be part of the
cosmic web
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 ...
, which is a conclusive idea. Most structures are overlapped by nearby galaxies, creating a problem of how to carefully define the structure's limit.
*Interpreting the observational data requires assumptions about
gravitational lensing
A gravitational lens is matter, such as a galaxy cluster, cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's Ge ...
,
redshift
In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...
, etc.
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List of largest structures
List of largest voids
Void
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, a s ...
s are immense spaces between galaxy filaments and other large-scale structures. Technically they are not structures. They are vast spaces which contain very few or no galaxies. They are theorized to be caused by
quantum fluctuations
In quantum physics, a quantum fluctuation (also known as a vacuum state fluctuation or vacuum fluctuation) is the temporary random change in the amount of energy in a point in space,
as prescribed by Werner Heisenberg's uncertainty principle. ...
during the early formation of the universe.
A list of the largest voids so far discovered is below. Each is ranked according to its longest dimension.
See also
References
{{Portal bar, Astronomy, Stars, Outer space
*
Structures, largest
Largest structures
cosmic structures