Tuesday, November 20, 2012
Astronomer Edwin Hubble was born on November 20, 1889, in Marshfield, Missouri. Though he studied law as a Rhodes scholar, he became an astronomer working at Mount Wilson Observatory near Pasadena, where his studies of very luminous stars (Cepheid variables) proved they are located outside our own galaxy, thereby determining the existence of galaxies beyond the Milky Way – which until then had been believed to be the universe. His observations of redshifts in light emissions from galaxies indicated that they were moving away from each other – meaning that the universe is expanding. The resulting Hubble's Law (1929) confirmed earlier theories of astronomer Georges Lemaître. Pictured: Andromeda galaxy, where Hubble discovered the Cepheid variable that placed this "nebula" outside the Milky Way.