Encke, Johann Franz (1791-1865), a German astronomer, was born at Hamburg. He studied under the astronomer Gauss at Gottingen, and during the War of Liberation served in the artillery from 1813 to 1815. He was then appointed assistant in the observatory at Seeburg, and here it was that he calculated the orbit of the comet now bearing his name, predicted the times of its reappearance, and discovered an acceleration in its motion. In 1825 he became director of the observatory at Berlin, a post which he retained till death. Besides many papers in astronomical transactions, he wrote in 1822 Die Entfernung der Sonne, and in 1823 Der Venus-Durchgang von 1769.