Asaph Hall III was born on October 15, 1829 in Goshen, Connecticut, United States. He was the son of Asaph Hall II, a clockmaker, and Hannah Palmer. His paternal grandfather Asaph Hall I was a Revolutionary War officer and Connecticut state legislator.
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.
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. This paper, an experiment on the Buffon's needle problem, is a very early documented use of random sampling in scientific inquiry.
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.
During Mars' closest approached in 1877, Hall was encouraged by his wife to search for the Martian moons. Asaph Hall discovered Deimos on 12 August 1877 and Phobos on 18 August 1877, at the US Naval Observatory. At the time, he was deliberately searching for Martian moons. Hall had previously seen what appeared to be a Martian moon on 10 August, but due to bad weather, he could not definitively identify them until later.
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.
Hall won the Lalande Prize of the French Academy of Sciences in 1878, the Gold Medal of the Royal Astronomical Society in 1879, the Arago Medal in 1893, and was made a Chevalier in the Ordre national de la Légion d'honneur (French Legion of Honor) in 1896. Hall crater on the Moon as well as Hall crater on the Martian moon Phobos are named in his honor.
(Appendix II. Reports on Observations of Encke's Comet dur...)
The Halls had four children. Asaph Hall, Jr. 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 became president of Gallaudet University. Angeline Hall died in 1892. Hall married Mary Gauthier after he fully retired to Goshen, Connecticut in 1901.
(1800-1842)
(1804-1880)
(June 11, 1735 - March 29, 1800)
