Leverrier, Urbain Jean Joseph

Leverrier, Urbain Jean Joseph (1811-1877), a French astronomer. Leverrier and John Couch Adams independently deduced the existence of the planet Neptune by mathematical calculations. In 1846 Johann Galle first sighted Neptune, almost exactly where Leverrier had forecast. Leverrier discovered that Mercury's orbit slowly moves in a way that cannot be accounted for by Newton's theory of gravitation. Leverrier believed an unknown planet near the sun might account for the motion, but no such planet was found. The motion was not explained until the early 20th centuryby Einstein's theory of relativity.

Leverrier studied at the Ecole Polytechnique and joined its faculty in 1837. He became director of the Paris Observatory in 1854.