Explore HubbleHubble HomeOverviewAbout HubbleThe History of HubbleHubble TimelineWhy Have a Telescope in Space?Hubble by the NumbersAt the MuseumFAQsImpact & BenefitsHubble’s Impact & BenefitsScience ImpactsCultural ImpactTechnology BenefitsImpact on Human SpaceflightAstro Community ImpactsScienceHubble ScienceScience ThemesScience HighlightsScience Behind DiscoveriesUniverse UncoveredHubble’s Partners in ScienceHubble & Citizen ScienceAI & Hubble ScienceExplore the Night SkyObservatoryHubble ObservatoryHubble DesignMission OperationsScience OperationsAstronaut Missions to HubbleHubble vs WebbTeamHubble TeamCareer AspirationsHubble AstronautsMultimediaImagesVideosOnline Activitiese-BooksSonificationsPodcasts3D Hubble ModelsLithographsFact SheetsPosters Hubble on the NASA AppGlossary NewsHubble NewsSocial MediaMedia Resources35th AnniversaryMoreOnline Activities2 min readHubble Glimpses Merging Galaxy ClustersThis NASA Hubble Space Telescope image features a swarm of galaxies in the galaxy cluster called CL0016+1609 or MACS J0018.5+1626.NASA, ESA, H. Ebeling (University of Hawaii), D. Coe (STScI, ESA, JWST); Image Processing: G. Kober (NASA/Catholic University of America)This NASA Hubble Space Telescope image features a galaxy cluster, called CL0016+1609 or MACS J0018.5+1626, that is very bright at X-ray wavelengths and is one of the most extensively studied clusters at X-ray and radio wavelengths. The X-ray observations of this cluster revealed that it is two clusters merging along our line of sight.Researchers requested time to observe CL0016+1609 with Hubble’s Advanced Camera for Surveys because that data would help them accurately measure the cluster’s dark-matter distribution, which helps them study the merger and the role of CL0016+1609 in the large-scale structure of the universe. Hubble can’t directly see dark matter, but its infrared and visible light observations can detect dark matter’s gravitational lensing effects on the normal matter Hubble observes.The data in this image also includes observations with Hubble’s Wide Field Camera 3 taken as part of an observing program that obtained the first Hubble infrared images of 46 massive galaxy clusters and looked for distant galaxies gravitationally lensed by these clusters. Called RELICS (Reionization Lensing Cluster Survey), this survey found some 300 high-redshift candidate galaxies lensed by these clusters.You can see the faint vertical arc of one of these distant galaxies in the image above. Look for it just to the left of the large elliptical galaxies in the center of the image. Another brighter, though shorter arc is visible just above and to the right of the large elliptical galaxies in the center of the image.Facebook logo@NASAHubble@NASAHubbleInstagram logo @NASAHubbleMedia Contact:Claire AndreoliNASA’s Goddard Space Flight Center, Greenbelt, MDclaire.andreoli@nasa.govShareDetailsLast UpdatedJun 18, 2026EditorAndrea GianopoulosLocationNASA Goddard Space Flight CenterRelated TermsHubble Space TelescopeAstrophysicsAstrophysics DivisionGalaxiesGalaxy clustersGoddard Space Flight CenterThe UniverseKeep ExploringDiscover More Topics From HubbleHubble Space TelescopeSince its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.Hubble’s GalaxiesHubble Science HighlightsHubble Images