Receding galaxies

The radial velocity of galaxies was measured, showing that most are receding from us, some at high speeds. Hubble observed that Galaxies receded from us at a rate proportional to their distance from us (Hubble's law). This observation confirmed the theory that the Universe is expanding.
 Milton La Salle Humason United States 1929 Receding galaxies

The radial velocity of galaxies was measured, showing that most are receding from us, some at high speeds. Hubble observed that Galaxies receded from us at a rate proportional to their distance from us (Hubble's law). This observation confirmed the theory that the Universe is expanding.