The French mathematical astronomer Urbain Jean Joseph Leverrier (1811-1877) made theoretical investigations which led to the discovery of the planet Neptune.

Born at Saint-Lô in Normandy on March 11, 1811, U. J. J. Leverrier entered the highly competitive École Polytechnique to prepare for a career as a professional scientist. His early interest was in chemistry; but when the teaching post in astronomy fell vacant at the Polytechnique in 1837, Leverrier took it and thereby entered the discipline in which he was to spend the rest of his life.

The aspect of astronomy with which Leverrier was primarily concerned was celestial mechanics, the mathematical analysis of the planetary motions. According to the principles of celestial mechanics, each planet was supposed to move around the sun in an essentially elliptical orbit with minor deviations due to attractions by the rest of the planets. The computations involved were very complicated, but the...