Editing Galaxy cluster (section)

==Basic properties==
[[File:Galaxy cluster IDCS J1426.jpg|thumb|Galaxy cluster [[IDCS J1426.5+3508|IDCS J1426]] is located 10 billion light-years from Earth and has the mass of almost 500 trillion suns (multi-wavelength image: X-rays in blue, visible light in green, and infrared light in red).<ref>{{cite web|title=Galaxy cluster IDCS J1426|url=http://www.spacetelescope.org/images/opo1602a/|access-date=11 January 2016}}</ref>]]

Galaxy clusters typically have the following properties:
* They contain 100 to 1,000 galaxies, hot [[X-ray]] emitting gas and large amounts of [[dark matter]].<ref name=":0">{{Cite web | url=http://chandra.harvard.edu/xray_sources/galaxy_clusters.html | title=Groups & Clusters of Galaxies |website=Chandra X-ray Observatory}}</ref> Details are described in the "Composition" section.
* They have total masses of 10<sup>14</sup> to 10<sup>15</sup> [[Solar mass|solar masses]].
* They typically have diameters from 1 to 5 [[Megaparsec|Mpc]] (see [[1 E23 m|10<sup>23</sup> m]] for distance comparisons).
* The spread of velocities for the individual galaxies is about 800–1000&nbsp;km/s.