Editing Coma Berenices (section)

====Coma Supercluster====
The [[Coma Supercluster]], itself part of the [[Coma Filament]], contains the [[Coma Cluster|Coma]] and [[Leo Cluster]] of galaxies. The Coma Cluster ([[Abell catalogue|Abell]] 1656) is 230 to 300 million light-years away. It is one of the largest-known clusters, with at least 10,000 galaxies (mainly [[elliptical galaxy|elliptical]], with a few [[spiral galaxies]]).<ref name="earthsky">{{cite web | url =http://earthsky.org/clusters-nebulae-galaxies/the-coma-berenices-galaxy-cluster|title=Coma Cluster of galaxies|publisher=EarthSky| author=Larry Sessions|date=April 6, 2016| access-date =6 November 2016}}</ref> Due to its distance from Earth, most of the galaxies are visible only through large telescopes. Its brightest members are [[NGC 4874]] and [[NGC 4889]], both with a magnitude of 13; most others are magnitude 15 or dimmer. NGC 4889 is a giant elliptical galaxy with one of the largest-known [[black hole]]s (21 billion [[solar mass]]es),<ref>{{cite journal|title=Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies |author=Nicholas J. McConnell |date=2011-12-08 |journal=Nature |volume=480|issue=7376 |doi=10.1038/nature10636 |pages=215–218|arxiv = 1112.1078 |bibcode = 2011Natur.480..215M |pmid=22158244 |s2cid=4408896 }}</ref> and [[NGC 4921]] is the cluster's brightest spiral galaxy.<ref>{{cite journal
 | author= S. van den Bergh
 | title=A new classification system for galaxies
 | journal=Astrophysical Journal | volume=206
 | date=1976-06-15 | pages=883–887
 | doi=10.1086/154452
| bibcode=1976ApJ...206..883V| doi-access=free}}</ref> After observing the Coma Cluster, astronomer [[Fritz Zwicky]] first postulated the existence of [[dark matter]] during the 1930s.<ref name="earthsky"/> The massive galaxy [[Dragonfly 44]] discovered in 2015 was found to consist almost entirely of dark matter.<ref name="keck">{{cite web| url =http://www.keckobservatory.org/recent/entry/scientists_discover_massive_galaxy_made_of_99.99_percent_dark_matter| title =Scientists Discover Massive Galaxy Made of 99.99 Percent Dark Matter| publisher =[[Keck Observatory]]| date =25 August 2016| access-date =11 December 2016| archive-url =https://web.archive.org/web/20180525213725/http://www.keckobservatory.org/recent/entry/scientists_discover_massive_galaxy_made_of_99.99_percent_dark_matter| archive-date =25 May 2018| url-status =dead}}</ref> Its mass is very similar to that of the [[Milky Way]],<ref name="keck"/> but it emits only 1% of the light emitted by the Milky Way.<ref>{{cite journal|last1=Crosswell|first1=Ken|title=The Milky Way's dark twin revealed|url=http://www.nature.com/news/the-milky-way-s-dark-twin-revealed-1.20333|access-date=30 July 2016|journal=Nature News|date=26 July 2016|doi=10.1038/nature.2016.20333|s2cid=124730115}}</ref> NGC 4676, sometimes called the [[Mice Galaxies]], is a pair of [[interacting galaxy|interacting galaxies]] 300 million light-years from Earth. Its progenitor galaxies were [[spiral galaxy|spiral]], and astronomers estimate that they had their closest approach about 160 million years ago. That approach triggered large regions of [[star formation]] in both galaxies, with long "tails" of dust, stars and gas. The two progenitor galaxies are predicted to interact significantly at least one more time before they merge into a larger, probably-[[elliptical galaxy|elliptical]] galaxy.<ref name="objects">{{cite book |title = 300 Astronomical Objects: A Visual Reference to the Universe |first1 = Jamie |last1 = Wilkins |first2 = Robert |last2 = Dunn |publisher = Firefly Books |year = 2006 |location = Buffalo, New York |isbn = 978-1-55407-175-3}}</ref>