Morgan, William Wilson

▪ 1995

      U.S. astronomer (b. Jan. 3, 1906, Bethesda, Tenn.—d. June 21, 1994, Williams Bay, Wis.), discovered the spiral shape of the Milky Way Galaxy after years of observing and analyzing the distances and arrangements of stars. Morgan's feat was complicated because our solar system lies within the Milky Way, thus making outside telescopic observation of its configuration impossible. With Philip C. Keenan he had developed the MK (for Morgan Keenan) system for using observations of stars' spectra to determine their luminosity and therefore their distance from Earth, and in 1943 he published An Atlas of Stellar Spectra, a classification guide. Using the MK system, he estimated the distances of bright stars within the Milky Way. In 1951 at an American Astronomical Society meeting, Morgan received a standing ovation when he revealed that the structure of the Milky Way Galaxy includes two spiral arms and provided evidence for a third arm. After earning a Ph.D. (1931) from the University of Chicago, Morgan spent his entire career associated with his alma mater and its Yerkes Observatory, of which he was director from 1960 to 1963. An astronomical morphologist, Morgan devoted his career to studying and classifying stars and galaxies, and he also proved the existence of super-giant galaxies. Morgan, who was a member of the National Academy of Sciences and the American Academy of Arts, was the recipient of the Bruce Gold Medal from the Astronomical Society of the Pacific and the Herschel Medal from the Royal Astronomical Society of London.

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▪ American astronomer

born Jan. 3, 1906, Bethesda, Tenn., U.S.

died June 21, 1994, Williams Bay, Wis.

      American astronomer who, in 1951, provided the first evidence that the Milky Way Galaxy has spiral arms.

      Morgan studied at the University of Chicago (Ph.D., 1931) and then became an instructor at the Yerkes Observatory of the University of Chicago. He taught at that university from 1947 until his retirement in 1974, and he was director of the Yerkes and McDonald Observatories from 1960 to 1963. During his career he received many awards and honours.

      Morgan was an astronomical morphologist who devoted his career to studying and classifying stars and galaxies. His first significant contribution was a correlation of the spectra of stars with their distances from the Earth, published as the Atlas of Stellar Spectra (1943). After discovering the spiral structure of the Milky Way Galaxy, he focused on problems of star brightness, devising a system of classifying star magnitude and colour, discovering “flash” variable stars (stars that have quickly changing luminosity), and establishing the UBV (ultraviolet-blue-visual) magnitudes system for photometry. In 1956 Morgan began to study and classify galaxies, grouping them by stellar qualities, stellar population, and form.

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