Galaxy supercluster distribution. Computer artwork of the Universe on the largest scale, showing superclusters (red) and voids (blue). Galaxies are not randomly distributed in space but are collected into clusters. These are in turn connected to form superclusters, vast assemblages of thousands of galaxies or more. This leaves voids, which can be hundreds of millions of light years across, that are empty of stars. The distribution of galaxies is a result of the Big Bang, the creation of the Universe. Cosmologists are unsure of the exact mechanism but some believe that galaxies may have formed in ripples of higher density in the early Universe.