NASA
NASA Astronomy Picture of the Day 26 May 2023: Virgo cluster of galaxies
Galaxies which exist in the vastness of space, consist of various celestial objects such as stars, clouds of dust, and gas, all of which are bound together by gravity. Most galaxies exist in groups or clusters with dozens or hundreds of members, and these cluster galaxies are all in constant motion, pulled and twisted by their neighbour's gravity. Galaxy clusters are the largest objects in the Universe bound by gravity and astronomers can use them to measure important cosmological properties, according to NASA.