Encke, Johann Franz

Encke, Johann Franz (yō`hän fränts ĕng`kə), 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.