Canadian-born US mathematician and astronomer. He compiled charts and tables of astronomical data with phenomenal accuracy. His calculations of the motions of the bodies in the Solar System were in use as daily reference all over the world for more than 50 years, and the system of astronomical constants for which he was most responsible is still the standard.
Life Newcomb was born in Wallace, Nova Scotia, and had little formal education. In his teens he ran away to the USA, and eventually enrolled at Harvard. In 1861 he joined the navy. He was appointed professor of mathematics to the US navy 1861 and later, astronomer at the US Naval Observatory, Washington, DC, where he supervised the building of the 66-cm/26-in equatorial telescope. He was secretary to the US commission for observing the transit of Venus 1871–74, and observed a transit at the Cape of Good Hope 1882. He was director of the American Nautical Almanac office 1877–97. From 1884 he was also professor of mathematics and astronomy at Johns Hopkins University, but continued to live in Washington. He retired with the rank of rear admiral.
Work Newcomb studied chiefly the problems of gravitational astronomy. At the Nautical Almanac office, he started the great work that was to occupy the rest of his life: the calculation of the motions of the bodies in the Solar System. The results were published in Astronomical Papers Prepared for the Use of the American Ephemeris and Nautical Almanac, a series he founded 1879. His other publications include Reminiscences of an Astronomer 1903, and Compendium of Spherical Astronomy 1906.
With his British counterpart Arthur Matthew Weld Downing (1850–1917), Newcomb established a universal standard system of astronomical constants. This was adopted at international conferences 1896 and 1950.