Asaph Hall

Asaph Hall
Professor Asaph Hall.jpg
Asaph Hall at the USNO in 1899
Born(1829-10-15)October 15, 1829
Goshen, Connecticut
DiedNovember 22, 1907(1907-11-22) (aged 78)
Annapolis, Maryland
ResidenceUnited States
Alma materNew-York Central College, McGrawville
Known forDiscovery of two Martian moons
Spouse(s)Angeline Stickney; Mary Gauthier
ChildrenAsaph Hall, Jr., Samuel Stickney Hall, Angelo Hall, and Percival Hall.
Parent(s)Asaph Hall II
Hannah Palmer

Asaph Hall III (October 15, 1829 – November 22, 1907) was an American astronomer who is most famous for having discovered the moons of Mars, Deimos and Phobos, in 1877.[1] He determined the orbits of satellites of other planets and of double stars, the rotation of Saturn, and the mass of Mars.


Hall was born in Goshen, Connecticut, the son of Asaph Hall II (1800–42), a clockmaker, and Hannah Palmer (1804–80). His paternal grandfather Asaph Hall I (June 11, 1735 – Mar. 29, 1800) was a Revolutionary War officer and Connecticut state legislator.[2][3] His father died when he was 13, leaving the family in financial difficulty, so Hall left school at 16 to become an apprentice to a carpenter. He later enrolled at the Central College in McGrawville, New York, where he studied mathematics. There he took classes from an instructor of geometry and German, Angeline Stickney. In 1856 they married.

In 1856, Hall took a job at the Harvard College Observatory in Cambridge, Massachusetts, and turned out to be an expert computer of orbits. Hall became assistant astronomer at the US Naval Observatory in Washington DC in 1862, and within a year of his arrival he was made professor.

In 1875 Hall was given responsibility for the USNO 26-inch (66-cm) telescope, the largest refracting telescope in the world at the time. It was with this telescope that he discovered Phobos and Deimos in August 1877. Hall also noticed a white spot on Saturn which he used as a marker to ascertain the planet's rotational period. In 1884, Hall showed that the position of the elliptical orbit of Saturn's moon, Hyperion, was retrograding by about 20° per year. Hall also investigated stellar parallaxes and the positions of the stars in the Pleiades star cluster.

Hall was responsible for apprenticing Henry S. Pritchett at the Naval Observatory in 1875.

Hall's former home in the Georgetown neighborhood of Washington, D.C.

On June 5, 1872 Hall submitted an article entitled "On an Experimental Determination of Pi" to the journal Messenger of Mathematics. The article appeared in the 1873 edition of the journal, volume 2, pages 113–114. In this article Hall reported the results of an experiment in random sampling that Hall had persuaded his friend, Captain O.C. Fox, to perform when Fox was recuperating from a wound received at the Second Battle of Bull Run. The experiment involved repetitively throwing at random a fine steel wire onto a plane wooden surface ruled with equidistant parallel lines. Pi was computed as 2ml/an where m is the number of trials, l is the length of the steel wire, a is the distance between parallel lines, and n was the number of intersections. This paper, an experiment on the Buffon's needle problem, is a very early documented use of random sampling (which Nicholas Metropolis would name the Monte Carlo method during the Manhattan Project of World War II) in scientific inquiry.

Hall retired from the Navy in 1891. He became a lecturer in celestial mechanics at Harvard University in 1896, and continued to teach there until 1901.

The Halls had four children. Asaph Hall, Jr. (1859–1930) became an astronomer, Samuel Stickney Hall (1864–1936) worked for Mutual Life Insurance Company, Angelo Hall (1868–1922) became a Unitarian minister and professor of mathematics at the US Naval Academy, and Percival Hall (1872–1953) became president of Gallaudet University. Angeline Hall died in 1892. Hall married Mary Gauthier after he fully retired to Goshen, Connecticut in 1901.

Hall died in November 1907 while visiting his son Angelo in Annapolis, Maryland.

Other Languages
Afrikaans: Asaph Hall
العربية: أساف هول
تۆرکجه: آساف هال
беларуская: Асаф Хол
български: Асаф Хол
català: Asaph Hall
čeština: Asaph Hall
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Deutsch: Asaph Hall
Ελληνικά: Έιζαφ Χολ
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euskara: Asaph Hall
فارسی: آساف هال
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한국어: 아사프 홀
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hrvatski: Asaph Hall
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italiano: Asaph Hall
עברית: אסף הול
ქართული: ესაფ ჰოლი
Lëtzebuergesch: Asaph Hall
lietuvių: Asafas Holas
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português: Asaph Hall
română: Asaph Hall
русский: Холл, Асаф
Scots: Asaph Hall
slovenčina: Asaph Hall
slovenščina: Asaph Hall
српски / srpski: Асаф Хол
suomi: Asaph Hall
svenska: Asaph Hall
தமிழ்: ஆசப் ஆல்
Türkçe: Asaph Hall
українська: Асаф Голл