Galaxy clusters are among the largest objects in the universe!
Studying them helps us learn more about the distribution of mysterious dark matter, which makes up most of a galaxy cluster's mass.
This #HubbleFriday view shows galaxy cluster ACO S520: https://go.nasa.gov/3LCZyFZ
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Hubble Captures an Elusive Galaxy Cluster
A menagerie of interesting astronomical finds are visible in this image from the NASA/ESA Hubble Space Telescope.Andrea Gianopoulos (NASA)