Hubble was born in Marshfield, Missouri and his studies at the University of Chicago concentrated on mathematics and astronomy which led to a B.S. degree in 1910. He spent the next three years as a Rhodes Scholar at Oxford, where he studied in the field of law and received the M.A. degree.
He returned to astronomy at the Yerkes Observatory of the University of Chicago, where he earned a Ph.D. in 1917. Hubble was offered a staff position by George Ellery Hale, the founder and director of Carnegie Institution's Mount Wilson Observatory, near Pasadena, California. He remained with Carnegie until his death in 1953. Shortly before his death, Palomar's 200-inch Hale Telescope was completed. Hubble was the first to use it. He died of stroke on September 28, 1953.
His arrival at Mount Wilson coincided roughly with the completion of the 100-inch Hooker Telescope, then the world's most powerful telescope. Hubble's observations in 1923-1924 with the Hooker Telescope established beyond doubt that the fuzzy "nebulae" seen earlier with less powerful telescopes were not part of our galaxy, as had been thought, but were galaxies themselves, outside the Milky Way. He announced his discoveries on December 30, 1924. Subsequently, with Milton Humanson, Hubble discovered the velocity-distance relation, now know as the Hubble's law, which led to the concept of the expanding universe. The orbiting Hubble Space Telescope is named in his honor.