Alfred Harrison Joy
Encyclopedia
Alfred Harrison Joy was an astronomer
best known for his work on stellar distances, the radial motion of stars, and variable stars.
, the son of F.P. Joy, a prominent clothing merchant in Greenville and one-time mayor of the town. He was educated in Greenville College and gradusted MA in 1904 from Oberlin College
.
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 of World War I
.
In the United States, he worked at the Mount Wilson Observatory
from 1915 to 1952. There, he and his colleagues ascertained the spectral type, absolute magnitude
, and stellar distance of over 5,000 stars. Joy also discovered the T-Tauri
type star. He studied the Doppler 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 the Bruce Medal
in 1950.
He was president of the Astronomical Society of the Pacific
in 1931 and 1939.
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
best known for his work on stellar distances, the radial motion of stars, and variable stars.
Early years
He was born in Greenville, IllinoisGreenville, Illinois
Greenville is a city in Bond County, Illinois, United States, east of St. Louis. The estimated population as of July 2009 is 7,284. The population was 6,955 at the 2000 census. It is the county seat of Bond County....
, the son of F.P. Joy, a prominent clothing merchant in Greenville and one-time mayor of the town. He was educated in Greenville College and gradusted MA in 1904 from Oberlin College
Oberlin College
Oberlin College is a private liberal arts college in Oberlin, Ohio, noteworthy for having been the first American institution of higher learning to regularly admit female and black students. Connected to the college is the Oberlin Conservatory of Music, the oldest continuously operating...
.
Career
After graduating, Joy went on to work at the American University of BeirutAmerican University of Beirut
The American University of Beirut is a private, independent university in Beirut, Lebanon. It was founded as the Syrian Protestant College by American missionaries in 1866...
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 of World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
.
In the United States, he worked at the Mount Wilson Observatory
Mount Wilson Observatory
The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...
from 1915 to 1952. There, he and his colleagues ascertained the spectral type, absolute magnitude
Absolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
, and stellar distance of over 5,000 stars. Joy also discovered the T-Tauri
T Tauri star
T Tauri stars are a class of variable stars named after their prototype – T Tauri. They are found near molecular clouds and identified by their optical variability and strong chromospheric lines.-Characteristics:...
type star. He studied the Doppler displacement
Doppler effect
The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...
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 the Bruce Medal
Bruce Medal
The Catherine Wolfe Bruce Gold Medal is awarded every year by the Astronomical Society of the Pacific for outstanding lifetime contributions to astronomy. It is named after Catherine Wolfe Bruce, an American patroness of astronomy, and was first awarded in 1898...
in 1950.
He was president of the Astronomical Society of the Pacific
Astronomical Society of the Pacific
The Astronomical Society of the Pacific is a scientific and educational organization, founded in San Francisco on February 7, 1889. Its name derives from its origins on the Pacific Coast, but today it has members all over the country and the world...
in 1931 and 1939.