What is Shapley Supercluster?
The '''Shapley Supercluster''' or '''Shapley Concentration''' ('''SCl 124''') is the largest concentration of [[galaxies]] in our nearby [[universe]]. It is a [[Gravitation|gravitationally interacting unit]] 650 million [[light years]] away (z=0.046). This means it pulls itself together, instead of expanding with the universe. It is an overdensity in the distribution of galaxies in the [[constellation]] of [[Centaurus]]. == History == In the late 1920s, [[:en:Harlow_Shapley|Harlow Shapley]] and his colleagues at the Harvard College Observatory started a survey of galaxies in the southern sky, using photographic plates obtained at the 24-inch Bruce [[telescope]] at [[Bloemfontein]], [[South Africa]]. He found a 'cloud' in the constellation of Centaurus to be the most striking concentration of galaxies. In recent times, the Shapley Supercluster was rediscovered,<ref>[http://www.nature.com/nature/journal/v342/n6247/abs/342251a0.html The distribution of galaxies in the direction of the 'Great Attractor' Somak Raychaudhury 1989. ''Nature'' '''342''', 251-255]</ref> in a survey of galaxies at the [[University of Cambridge]] in England. In this [[paper]], the supercluster was named after Shapley, in recognition of his pioneering survey of galaxies in which this concentration of galaxies was first seen. Around the same time, others had noticed a remarkable concentration of clusters in the [[Abell catalogue]] of [[galaxy clusters]]: they had named it the ''Alpha concentration''.<ref>[http://www.nature.com/nature/journal/v338/n6216/abs/338562a0.html A marked concentration of galaxy clusters: is this the origin of large-scale motions? R. Scaramella ''et a''l 1989. ''Nature'' '''338'', 562]</ref> == References == {{Reflist}} [[Category:Galaxy clusters]]