Great Wall (astronomy)
Encyclopedia
The Great Wall sometimes specifically referred to as the CfA2 Great Wall, is one of the largest known super-structures in the Universe
(the largest two being the Sloan Great Wall
and the Pisces-Cetus Supercluster Complex
). It is a filament
of galaxies
approximately 200 million light-year
s away and has dimensions which measure over 500 million light-years long, 300 million light-years wide and 15 million light-years thick. It was discovered in 1989 by Margaret Geller
and John Huchra
based on redshift survey
data from the CfA Redshift Survey
.
It is not known how much farther the wall extends due to the plane of the Milky Way
galaxy
in which Earth
is located. The gas and dust
from the Milky Way (known as the Zone of Avoidance
) obscure the view of astronomers and have so far made it impossible to determine if the wall ends or continues on further than they can currently observe.
In the standard model of the evolution of the universe, such structures as the Great Wall form along and follow web-like strings
of dark matter
. It is thought that this dark matter dictates the structure of the Universe on the grandest of scales. Dark matter gravitationally attracts baryonic matter, and it is this "normal" matter that astronomers see forming long, thin walls of super-galactic clusters.
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
(the largest two being the Sloan Great Wall
Sloan Great Wall
The Sloan Great Wall is a cosmic structure formed by a giant wall of galaxies , and to the present day it is the largest known structure in the universe. Its discovery was announced on October 20, 2003 by J. Richard Gott III of Princeton University and Mario Jurić and their colleagues, based on...
and the Pisces-Cetus Supercluster Complex
Pisces-Cetus Supercluster Complex
The Pisces-Cetus Supercluster Complex is a complex of galaxy superclusters or galaxy filament that includes the Virgo Supercluster .-Discovery:...
). It is a filament
Galaxy filament
In physical cosmology, galaxy filaments, also called supercluster complexes or great walls, are, so far, the largest known cosmic structures in the universe. They are massive, thread-like structures with a typical length of 50 to 80 megaparsecs h-1 that form the boundaries between large voids in...
of galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
approximately 200 million light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away and has dimensions which measure over 500 million light-years long, 300 million light-years wide and 15 million light-years thick. It was discovered in 1989 by Margaret Geller
Margaret Geller
Margaret Joan Geller is an American astronomer and professor. She is a Senior Astronomer at the Smithsonian Astrophysical Observatory, and has written numerous articles and produced several award-winning scientific short films....
and John Huchra
John Huchra
John Peter Huchra [pronounced HUCK-rah] was an American astronomer and professor. He was the Vice Provost for Research Policy at Harvard University and a Professor of Astronomy at the Harvard-Smithsonian Center for Astrophysics. He was also a former chair of the United States National Committee...
based on redshift survey
Redshift survey
In astronomy, a redshift survey, or galaxy survey, is a survey of a section of the sky to measure the redshift of astronomical objects. Using Hubble's law, the redshift can be used to calculate the distance of an object from Earth. By combining redshift with angular position data, a redshift...
data from the CfA Redshift Survey
CfA Redshift Survey
The Center for Astrophysics Redshift Survey was the first attempt to map the large-scale structure of the universe. It began in 1977 with the initial data collection completed in 1982...
.
It is not known how much farther the wall extends due to the plane of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
in which Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
is located. The gas and dust
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
from the Milky Way (known as the Zone of Avoidance
Zone of Avoidance
The Zone of Avoidance is the area of the night sky that is obscured by our own galaxy, the Milky Way.-Term:The ZOA was originally called the "Zone of Few Nebulae" in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in Sir John Herschel's General...
) obscure the view of astronomers and have so far made it impossible to determine if the wall ends or continues on further than they can currently observe.
In the standard model of the evolution of the universe, such structures as the Great Wall form along and follow web-like strings
Galaxy filament
In physical cosmology, galaxy filaments, also called supercluster complexes or great walls, are, so far, the largest known cosmic structures in the universe. They are massive, thread-like structures with a typical length of 50 to 80 megaparsecs h-1 that form the boundaries between large voids in...
of dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
. It is thought that this dark matter dictates the structure of the Universe on the grandest of scales. Dark matter gravitationally attracts baryonic matter, and it is this "normal" matter that astronomers see forming long, thin walls of super-galactic clusters.
See also
- WMAP Cold Spot
- Large-scale structure of the cosmos
- Cosmic stringCosmic stringCosmic strings are hypothetical 1-dimensional topological defects which may have formed during a symmetry breaking phase transition in the early universe when the topology of the vacuum manifold associated to this symmetry breaking is not simply connected. It is expected that at least one string...
s