1.Galaxies appear to be moving away from us at speeds proportional to their distance "Hubble's Law,". This observation supports the expansion of the universe and suggests that the universe was once compacted.
2. If the universe was initially very, very hot as the Big Bang suggests, we should be able to find some remnant of this heat in everywhere in space. In 1965, Radioastronomers Arno Penzias and Robert Wilson discovered a 2.725 degree Kelvin Cosmic Microwave Background radiation (CMB) which pervades the observable universe.
3.The abundance of the "light elements" Hydrogen and Helium found in the observable universe are thought to support the Big Bang theory.
