In the Universe, galaxies exist in the vast expanse of space. But they are not alone. In fact, galaxies exist in huge groups which are closely connected 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.Galaxy Clusters are also known to contain dark matter which is invisible to telescopes since they do not emit, absorb, or reflect any electromagnetic radiation.
NASA's Astronomy Picture of the Day is a mesmerizing snapshot of the Active Galaxy NGC 1275 which spans over 100,000 light-years.Read more on tech.hindustantimes.com