Urbain Jean Joseph Leverrier

Urbain Jean Joseph Leverrier (1811-77), French astronomer, who predicted the existence of the planet Neptune. Leverrier was born in Saint-Lô and educated at the École Polytechnique. He improved the astronomical tables on the planet Mercury, studied the perturbations, or movements, of comets, and investigated the limits within which the eccentricities and inclinations of planetary orbits vary. In 1846, after studying the planet Uranus, he concluded that another planet, hitherto not described, was responsible in some measure for the perturbations of Uranus. (The British astronomer John Couch Adams had also come to this conclusion independently at about the same time.) Later that year the German astronomer Johann Galle observed the planet one degree from where Leverrier had calculated it would be seen. The planet was named Neptune. Leverrier received many honors and in 1854 became director of the Paris Observatory.