What is CfA2 Great Wall?
[[File:Nearsc.gif|thumb|The Great Wall includes Coma and Hercules superclusters.]] The '''Great Wall''' is one of the largest known super-[[structure]]s in the [[Universe]].<ref>Sometimes it is called the '''CfA2 Great Wall'''.</ref> It is a huge group of [[galaxy|galaxies]] about 200 million [[light-year]]s away. The Great Wall is like a long, thin line filament: it is over 500 million light-years long, 300 million light-years wide, but only 15 million light-years thick. It was discovered in 1989 from [[redshift]] survey data.<ref>{{Cite journal | doi = 10.1126/science.246.4932.897 | volume = 246 | issue = 4932 | pages = 897–903 | last = Geller | first = Margaret J. | author2 = John P. Huchra | title = Mapping the Universe | journal = Science | date = 1989 | pmid = 17812575 | s2cid = 31328798 | url = http://www.sciencemag.org/content/246/4932/897.abstract }}</ref> We do not know how much farther the wall extends. Our view is blocked by the [[galactic plane]] of the [[Milky Way]]. The [[Interstellar medium|gas and dust]] from the Milky Way (known as the [[Zone of Avoidance]]) obscures the view of astronomers. This makes it impossible to find out if the wall ends or continues on further. 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]].<ref>{{Cite book | publisher = Freeman | isbn= 0716721570 | last = Riordan | first= Michael | author2 = David N. Schramm | title = Shadows of Creation: dark matter and the structure of the Universe | url = https://archive.org/details/shadowsofcreatio00mich | date = 1991 }}</ref> It is thought that this dark matter dictates the structure of the Universe on the grandest of scales. Dark matter gravitationally attracts [[baryon]]ic matter,<ref>Baryonic matter is matter as we know it.</ref> and it is this 'normal' matter that astronomers see forming long, thin walls of super-galactic clusters. == References == {{reflist}} == Other websites == * [http://pics.livejournal.com/vorona_1/p