Monday, May 21, 2012

Galaxy Superclusters




We live in the Milky Way Galaxy, a beautiful spiral armed galaxy filled with hot gas and young stars.
Did you know that many galaxies, including the Milky Way, actually formed in clusters? Galaxy clusters are groups of 30 or more galaxies that are all gravitationally bound to each other. Galaxy clusters nearby one another can form a supercluster of galaxies, though they may not all be gravitationally bound, just spatially coincident with each other. The Milky Way is part of the Local Group, which contains roughly 40 galaxies. This group is a sub-portion of the Virgo supercluster, which contains over 2500 galaxies within 100 million light years of us! These clusters contain spiral galaxies, like the Milky Way, but also elliptical galaxies which are disk shaped collections of older stars. Some popular clusters you may have heard of are the Fornax cluster, which also lies inside the Virgo supercluster, and the Coma cluster, which is a separate cluster of over 1000 galaxies located over 300 million light years from us. The image above shows some of the superclusters of galaxies in the Universe, with the Virgo cluster at the center. Each white dot is an entire galaxy, so those white regions throughout the image are collections of hundreds of galaxies! 

Image Credit: R. Powell