Johann Franz Encke (Encke Johann Franz)

(1791-1865)
Born September 23, 1791 in Hamburg. He studied at Gottingen University in K. Gauss. In 1816-1825 - Observatory astronomer at Gotha, from 1825 for nearly 40 years - the director of the Berlin Observatory.
Encke is known for his work to determine the solar parallax, which lay at the basis of observation from different points of the globe for the transit of Venus across the solar disk (the idea of this method belongs to E. Halle). Processing of two such transits - in 1761 and 1769 - allowed Encke calculate the parallax of the Sun and on its basis to clarify the distance between the Sun and the Earth. Important were studies Encke on comet now bearing his name. In 1819, he found that the comet discovered at different times of P. Mц?chain, W. Herschel and J. Pons, is a short-period comets with an orbital period of 3.3 years. Analyzed the motion of comet Encke for a long period of time, given the factor of disturbance caused by the six planets, has developed a new method for calculating the perturbations in the rectangular coordinate system (the method of Encke). He died in Spandau Enke August 26, 1865.