Galaxy Cluster

Galaxy clusters are the largest gravitationally bound structures in the Universe, representing cosmic cities containing hundreds to thousands of galaxies held together by immense gravitational forces. These colossal assemblages typically span 10-30 million light-years across and possess masses equivalent to 100 trillion to 1,000 trillion Suns. Despite galaxies being their most visible components, they comprise only about 5% of a cluster's total mass—the remainder consists of hot intracluster gas (10-15%) radiating X-rays at temperatures of 10-100 million Kelvin, and mysterious dark matter (80-85%) detectable only through its gravitational effects.</p><p>The Coma Cluster, containing over 1,000 galaxies located 320 million light-years away, became the first system where astronomer Fritz Zwicky discovered evidence for dark matter in 1933, noting that visible matter couldn't account for the cluster's gravitational binding. The nearby Virgo Cluster, our Local Group's gravitational destination, demonstrates how clusters influence cosmic evolution by slowly consuming smaller galaxy groups. Perseus Cluster showcases another remarkable feature: its central supermassive black hole generates sound waves with the deepest note ever detected—57 octaves below middle C.</p><p>Galaxy clusters serve as cosmic laboratories for studying dark matter, galaxy evolution, and large-scale structure formation, acting as gravitational lenses that magnify distant objects and revealing the Universe's fundamental architecture.