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
