[[File:Leverrier grave.jpg|thumb|Urbain Le Verrier'in mezarı.]]
1859'da, Le Verrier [[Merkür]]'ün [[Güneş]] çevresindeki yavaş yörüngesel hareketinin yalnızca [[Newton hareket yasaları|Newton mekaniği]] ile açıklanamayacağını belirten ilk bilim insanı oldu. Onun önerdiği olası açıklamalar arasında, kullandığı [[permütasyon]] hesaplarıyla; Merkür'ün diğer gezegenlere göre Güneş'e daha yakın yakınyörüngelerde yörüngelerindeolduğu olduğunugerçeği saptamıştırvardı. <ref>U. Le Verrier (1859), (in French), [http://www.archive.org/stream/comptesrendusheb49acad#page/378/mode/2up "Lettre de M. Le Verrier à M. Faye sur la théorie de Mercure et sur le mouvement du périhélie de cette planète"], Comptes rendus hebdomadaires des séances de l'Académie des sciences (Paris), vol. 49 (1859), pp. 379–383. (At p. 383 in the same volume Le Verrier's report is followed by another, from Faye, enthusiastically recommending to astronomers to search for a previously undetected intra-mercurial object.)</ref> (Other explanations considered included a slight oblateness of the Sun.) The success of the search for [[Neptune]] based on its perturbations of the orbit of [[Uranus]] led astronomers to place some faith in this possible explanation, and the hypothetical planet was even named [[Vulcan (hypothetical planet)|Vulcan]]. However, no such planet was ever found,<ref>{{cite book | first=Richard | last=Baum |coauthors=Sheehan, William | title = In Search of Planet Vulcan, The Ghost in Newton's Clockwork Machine | year = 1997 | isbn=0-306-45567-6 | publisher=Plenum Press | location=New York }}</ref> and the anomalous precession was eventually explained by [[Tests of general relativity#Perihelion precession of Mercury|general relativity theory]].
