Urbain Jean Joseph Leverrier

Urbain Jean Joseph Leverrier , 1811-77, French astronomer who made calculations that led to the discovery of the planet Neptune . In considering the perturbations of Uranus , Leverrier made calculations indicating the presence of an unknown planet in an orbit outside that of Uranus. At the time, this was considered the crowning achievement of mathematical astronomy. The same conclusion had been reached by John Couch Adams a little earlier but had not been published, so Leverrier was initially given sole credit for the discovery of Neptune, which was actually first observed, as a result of Leverrier's instructions, by Johann Galle in 1846. After much controversy both Adams and Leverrier were honored as responsible for the planet's discovery. In 1854, Leverrier became director of the Paris Observatory.

Leverrier, Urbain Jean Joseph (1811–77) French astronomer. In 1845 he predicted that a planet (which he prematurely named Vulcan) lay within the orbit of Mercury, but it was never found. More successful was Leverrier's prediction, independently of John Couch Adams, that an unknown planet (Neptune) was responsible for discrepancies between the calculated and observed orbital motion of Uranus.

Le Verrier, UrbainJeanJoseph(or Joseph Leverrier) (1811–77)Frenchcelestial mechanician. From 1838 he studied the long-term stability of the Solar System, in particular the causes of perturbations, leading to a revision of the masses of the planets, the dimensions of the Solar System, and the velocity of light. In 1845 D. J. F.Arago alerted him to irregularities in observed positions of Uranus. The next year he ascribed these to the presence of an undiscovered planet, and supplied a predicted position to J. G.Galle who located Neptune in 1846November. In 1859 Le Verrier suggested that a small planet or belt of asteroids within Mercury's orbit would account for irregularities in Mercury's observed positions (see vulcan).