Galaxy distribution. Illustration of the distribution of galaxies in the Universe appearing like foam on ocean waves. Galaxies are not randomly distributed in space but are collected into clusters. These are in turn connected to form superclusters. 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.