Newcomb, Simon (nōˈkəm, nyōˈ–) [key], 1835–1909, American astronomer, b. Nova Scotia, grad. Lawrence Scientific School, Harvard, 1858. Living in the United States from 1853, he was appointed (1857) a computer on the *American Nautical Almanac* and later (1877–97) was its director. He was professor of mathematics in the U.S. navy from 1861 until his retirement in 1897, professor of mathematics and astronomy at Johns Hopkins from 1884 to 1894, and for several years editor of the *American Journal of Mathematics.* Newcomb participated in several eclipse expeditions and in 1882 went to the Cape of Good Hope to observe the transit of Venus. The record of many of his researches was published in the *Astronomical Papers of the American Ephemeris,* a series that he established in 1879. His investigations and computations of the orbits of six planets resulted in his tables of the planetary system, which were almost universally adopted by the observatories of the world. Newcomb urged the use of a common system of constants and fundamental stars by astronomers of all nations. A subject to which he devoted many years of study was the theory of the moon's motion. From the formulas he established it was possible to construct accurate lunar tables. His writings include a valuable early paper, *On the Secular Variations and Mutual Relations of the Orbits of the Asteroids* (1860) and *On the Motion of Hyperion* (1891).

See his *Reminiscences of an Astronomer* (1903); study by L. M. Dunphy (1956).

*The Columbia Electronic Encyclopedia,* 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.