Encke, Johann Franz 1791-1865
German astronomer

Born in Hamburg, he was educated at the University of G�ttingen where he studied mathematics under Carl Friedrich Gauss. In 1816 he became assistant to Bernhard von Lindenau at the Seeberg Observatory, near Gotha, then succeeded him as director in 1822. Later he moved to Berlin (1825), where he superintended the building of a new observatory which had been promoted by Baron Alexander von Humboldt, and became Professor of Astronomy at the university there. His principal work was concerned with facilitating computations of the movements of comets and asteroids, and included a method of calculating the gravitational influences of the planets on the motion of comets. On investigating the orbit of a comet discovered by Jean-Louis Pons in Marseilles (1818), he demonstrated that the same comet had been observed on previous returns and deduced that it moved around the Sun in an elliptic orbit with a period of only 3.25 years. Encke's comet, as it is called, has the shortest known period of any comet. Encke was twice awarded the Gold Medal of the Royal Astronomical Society (1823, 1830).