Wilson, Milton Humason (who started as a mule driver during the construction of the observatory, then janitor, then night assistant), estimated the expansion rate of the universe to be 500 kilometers per second per megaparsec. Several scientists had also posed this theory based on Einstein’s General Relativity, but Hubble's data, published in 1929, helped convince the scientific community. Based on this observation, Hubble concluded that the universe expands uniformly. What Hubble found was that the farther apart galaxies are from each other, the faster they move away from each other. He created a system for classifying galaxies into ellipticals, spirals and barred spirals - a system called the Hubble tuning fork diagram, used today in an evolved form.īut the most astonishing discovery Hubble made resulted from his study of the spectra of 46 galaxies, and in particular of the Doppler velocities of those galaxies relative to our own Milky Way galaxy. By the end of that decade he had discovered enough galaxies to compare to each other. This was a shift in thought as profound as understanding the world was round and that it revolved around the sun. By the end of the 1920s, most astronomers were convinced that our Milky Way galaxy was but one of millions in the universe. In the following years he made similar discoveries with other nebulae. From this Hubble deduced that the Andromeda Nebula was not a nearby star cluster but rather an entire other galaxy, now called the Andromeda galaxy. One star he saw was a Cepheid variable, a type of star with a known, varying brightness that can be used to measure distances. He found that it contained stars just like the ones in our galaxy, only dimmer. In 1923 Hubble trained the Hooker telescope on a hazy patch of sky called the Andromeda Nebula. Our galaxy, it was thought, was synonymous with the universe. Most astronomers of Hubble's day thought that all of the universe - the planets, the stars seen with the naked eye and with powerful telescopes, and fuzzy objects called nebulae - was contained within the Milky Way galaxy. Hubble, it seemed, had the universe placed in his lap. Hubble was offered a staff position at the Mount Wilson Observatory, which housed the newly commissioned 100-inch Hooker telescope, then the largest telescope in the world. It was 1919, just a few years after Albert Einstein published his theory of general relativity, and bold, new ideas about the universe were fermenting. Hubble, a tall and athletic man who excelled at sports and even coached high school basketball for a short while, started his professional science career during one of the most exciting eras of astronomy. His discovery in the 1920s that countless galaxies exist beyond our own Milky Way galaxy revolutionized our understanding of the universe and our place within it. For instructions, click hereĮdwin Hubble, for whom the Hubble Space Telescope is named, was one of the leading astronomers of the twentieth century. The site requires that JavaScripts be enabled in your browser. All rights reserved.This website is kept for archival purposes only and is no longer updated. Copyright © 2023, Columbia University Press. The Columbia Electronic Encyclopedia, 6th ed. 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). With Milton Humason, Hubble classified the different types of galaxies including irregular galaxies, three types of spirals and barred spirals, and elliptical galaxies. 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. 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. Because of an incorrect understanding of the Cepheids, this distance was vastly increased years later. 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. Wilson Observatory, Pasadena, Calif., of which he became director. He did research (1914–17) at Yerkes Observatory, and joined (1919) the staff of Mt. Hubble, Edwin Powell, 1889–1953, American astronomer, b.
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