Johann Franz Encke

Johann Franz Encke, born in Hamburg in 1791 and dead in Spandau in 1865, was a German astronomer whose reputation rests on mathematical calculation. He studied mathematics and astronomy at Göttingen under Carl Friedrich Gauss, then worked at the Seeberg observatory near Gotha, where his investigation of the comet of 1680 won the Cotta prize. By computing the orbit of a comet discovered by Jean-Louis Pons he showed that it returned every 3.3 years and predicted its return in 1822; the object is now called Encke's Comet. From a fresh discussion of the transits of Venus in 1761 and 1769 he deduced a solar parallax of 8.57 arcseconds. He directed the Berlin observatory and held a chair of astronomy at Berlin, and he published a method of computing planetary perturbations in rectangular coordinates. The Encke Gap in Saturn's rings is named after him.