![](\"http:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2018\/01\/a_gargantuan_collision\/17330055-1-eng-GB\/A_gargantuan_collision_small.jpg\")
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In 2014, astronomers using the NASA\/ESA Hubble Space Telescope found that this enormous galaxy cluster contains the mass of a staggering three million billion Suns \u2014 so it\u2019s little wonder that it has earned the nickname of ‘El Gordo’ (‘the Fat One’ in Spanish)! Known officially as ACT-CLJ0102-4915, it is the largest, hottest, and X-ray brightest galaxy cluster ever discovered in the distant Universe.
\nGalaxy clusters are the largest objects in the Universe that are bound together by gravity. They form over billions of years as smaller groups of galaxies slowly come together. In 2012, observations from ESO\u2019s Very Large Telescope, NASA\u2019s Chandra X-ray Observatory and the Atacama Cosmology Telescope showed that El Gordo is actually composed of two galaxy clusters colliding at millions of kilometres per hour.
\nThe formation of galaxy clusters depends heavily on dark matter and dark energy; studying such clusters can therefore help shed light on these elusive phenomena. In 2014, Hubble found that most of El Gordo\u2019s mass is concealed in the form of dark matter. Evidence suggests that El Gordo\u2019s \u201cnormal\u201d matter \u2014 largely composed of hot gas that is bright in the X-ray wavelength domain \u2014 is being torn from the dark matter in the collision. The hot gas is slowing down, while the dark matter is not.
This image was taken by Hubble\u2019s Advanced Camera for Surveys and Wide-Field Camera 3 as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA\/ESA\/CSA James Webb Space Telescope (JWST) to study.<\/p>\n","protected":false},"excerpt":{"rendered":"
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In 2014, astronomers using the NASA\/ESA Hubble Space Telescope found that this enormous galaxy cluster contains the mass of a staggering three million billion Suns — so it’s little wonder that it has earned the nickname of ‘El Gordo’ (‘the Fat One’ in Spanish)! Known officially as ACT-CLJ0102-4915, it is the largest, hottest, and X-ray brightest galaxy cluster ever discovered in the distant Universe.
\nGalaxy clusters are the largest objects in the Universe that are bound together by gravity. They form over billions of years as smaller groups of galaxies slowly come together. In 2012, observations from ESO’s Very Large Telescope, NASA’s Chandra X-ray Observatory and the Atacama Cosmology Telescope showed that El Gordo is actually composed of two galaxy clusters colliding at millions of kilometres per hour.
\nThe formation of galaxy clusters depends heavily on dark matter and dark energy; studying such clusters can therefore help shed light on these elusive phenomena. In 2014, Hubble found that most of El Gordo’s mass is concealed in the form of dark matter. Evidence suggests that El Gordo’s “normal” matter — largely composed of hot gas that is bright in the X-ray wavelength domain — is being torn from the dark matter in the collision. The hot gas is slowing down, while the dark matter is not.
This image was taken by Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 as part of an observing programme called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA\/ESA\/CSA James Webb Space Telescope (JWST) to study.<\/p>\n","protected":false},"author":5,"featured_media":615444,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[27],"tags":[],"class_list":["post-433586","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-multimedia"],"_links":{"self":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts\/433586","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=433586"}],"version-history":[{"count":1,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts\/433586\/revisions"}],"predecessor-version":[{"id":433588,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/posts\/433586\/revisions\/433588"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=\/wp\/v2\/media\/615444"}],"wp:attachment":[{"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=433586"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=433586"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spaceweekly.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=433586"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}