Galaxies. Illustration of an assortment of galaxies in a cluster. There are spiral galaxies (example at centre), barred spirals (red example in the bottom left corner), elliptical galaxies (white blob at lower left) and an irregular galaxy (blue, at centre right). Galaxies are large collections of stars that condensed out of clouds of hydrogen and helium gas shortly after the origin of the Universe, the Big Bang". The galaxies themselves are collected into clusters which are in turn collected into larger "superclusters"."