Hubble, Edwin Powell, 1889–1953, American astronomer, b. Marshfield, Mo. He did research (1914–17) at Yerkes Observatory, and joined (1919) the staff of Mt. Wilson Observatory, Pasadena, Calif., of which he became director. Building on V. M. Slipher's discovery that galaxies had strong shifts to the red end of their spectra, Hubble used the stars known as Cepheid variables in nearby galaxies to demonstrate that they lie far beyond the Milky Way. Because of an incorrect understanding of the Cepheids, this distance was vastly increased years later. He also suggested that the clusters of galaxies are distributed almost uniformly in all directions, although more recent studies show that clusters are combined into huge superclusters of galaxies: at this new level, however, the distribution appears to be even. He was the first to offer observational evidence to support the theory of the expanding universe, presenting his findings in what is now known as Hubble's law. With Milton Humason, Hubble classified the different types of galaxies including irregular galaxies, three types of spirals and barred spirals, and elliptical galaxies. Included in his writings are A General Study of Diffuse Galactic Nebulas (1926), Extra-Galactic nebulas (1927), Spiral Nebula as a Stellar System (1929), The Realm of the Nebulas (1936), and The Observational Approach to Cosmology (1937).
See biography by G. E. Christianson (1995).