<P> The planet Neptune was mathematically predicted before it was directly observed . With a prediction by Urbain Le Verrier , telescopic observations confirming the existence of a major planet were made on the night of September 23 -- 24 , 1846 , at the Berlin Observatory , by astronomer Johann Gottfried Galle ( assisted by Heinrich Louis d'Arrest ) , working from Le Verrier 's calculations . It was a sensational moment of 19th century science and dramatic confirmation of Newtonian gravitational theory . In François Arago 's apt phrase , Le Verrier had discovered a planet `` with the point of his pen '' . </P>
<P> The planet Neptune was mathematically predicted before it was directly observed . With a prediction by Urbain Le Verrier , telescopic observations confirming the existence of a major planet were made on the night of September 23 -- 24 , 1846 , at the Berlin Observatory , by astronomer Johann Gottfried Galle ( assisted by Heinrich Louis d'Arrest ) , working from Le Verrier 's calculations . It was a sensational moment of 19th century science and dramatic confirmation of Newtonian gravitational theory . In François Arago 's apt phrase , Le Verrier had discovered a planet `` with the point of his pen '' . </P>
who discovered neptune in the late 19th century
who discovered neptune in the late 19th century
Johann Gottfried Galle
Johann Gottfried Galle