Johann Franz Encke

Johann Franz Encke , 1791-1865, German astronomer. He was assistant (1816-22) and director (1822-25) of the observatory at Seeberg (near Gotha) and director (from 1825) of the Berlin Observatory. He is known for his study of records of the orbit of the comet of 1680, for calculations—based on transits of Venus—of the earth's distance from the sun, and for his discovery of the division in Saturn 's A ring that bears his name. Encke's comet (discovered by J. L. Pons in 1818) was named for him because he calculated its orbit, finding the period of recurrence to be 3.3 years, and accurately predicted the date of its return.

Encke, JohannFranz (1791–1865)Germanmathematician and astronomer. In 1819 he calculated the orbit of a comet (subsequently named Comet Encke) that had been discovered by J. L.Pons, and found that its period was less than 4 years, still the shortest known. In 1837 he became the first to observe the gap in Saturn's A Ring, since named the Encke Division. He calculated the Sun's distance from observations of the transits of Venus in 1761 and 1769.