A team of astronomers have discovered what seem to be clouds of hydrogen gas which were left over when the Andromeda galaxy formed. The clouds were discovered using the Robert C. Byrd Green Bank Telescope (GBT), which is the world's largest fully steerable radio telescope. Galaxies like Andromeda, and our own Milky Way, were thought to have formed by the continuous merging of smaller galaxies as well as the accretion of clouds of hydrogen. Astronomers had been unable to find these clouds until now.