Alfred Harrison Joy (September 23, 1882 inGreenville, Illinois – April 18, 1973 inPasadena, California) was anastronomer best known for his work on stellar distances, the radial motion of stars, and variable stars.
Acrater on the Moon has been named in his honor.
He was born inGreenville, Illinois, the son of F.P. Joy, a prominent clothing merchant in Greenville and one-time mayor of the town.[1] He received a BA from Greenville College in 1903 and an MA fromOberlin College the next year.[2]
After graduating, Joy went on to work at theAmerican University of Beirut in the Syrian Protestant College as a professor of astronomy and the director of the observatory. He was forced to return to the U.S. in 1915 because ofWorld War I.
In the United States, he worked at theMount Wilson Observatory from 1915 to 1952. There, he and his colleagues ascertained thespectral type,absolute magnitude, and stellar distance of over 5,000 stars. Joy also initially defined theT-Tauri type star.[3] He studied theDoppler displacement of the spectral lines of stars to determine their radial velocities deducing a star's absolute dimensions, masses, and the orbital elements of some specific stars. He won theBruce Medal in 1950.
He was president of theAstronomical Society of the Pacific in 1931 and 1939.
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