Johann Franz Encke
Johann Franz Encke ( born September 23, 1791 in Hamburg, † August 26 1865 in Spandau in Berlin) was a German astronomer. He discovered, among other things named after him Encke division of Saturn's rings, led to many comets that time still difficult orbit determination (also see Encke 's Comet ) and later dealt intensively with asteroids. He also determined with high accuracy the solar parallax, and thus the astronomical unit ( Earth-Sun distance ).
Life and work
Encke, with nicknames Johann, was the youngest of eight children of a deacon of the Hamburg Jacobi Church. His father died when John was only four years old, and the family lived in the subsequent period in poverty. Thanks to the financial support of a teacher Encke was able to visit the Johanneum Gymnasium and study later.
The study of mathematics and physics began Encke 1811 - together with Friedrich Bernhard Gottfried Nicolai - Carl Friedrich Gauss at Göttingen University. He broke it, however in 1813 and joined the military because he as a patriot, he wanted to participate in the liberation of Germany from the Napoleonic troops. After the liberation of Hamburg in the same year he joined the Hanseatic Legion and served as a sergeant of artillery in Holstein and Mecklenburg. In the fall of 1814, he resumed his studies in Göttingen on again. Napoleon's return from exile on Elba and the mobilization of French troops led Encke again to go to the military. In 1815 he finished his service as a lieutenant and returned to Göttingen.
During his military Encke had met the astronomer and statesman Bernard von Lindenau, the director of the observatory Gotha. Lindenau Encke gave a job as an adjunct to the observatory, which he took up in 1816. 1820 Encke was deputy director and as Lindenau 1822 all the way back went into politics, he took over his position. During this time, Encke completed his work on the Venus transits of 1761 and 1769, from which he derived the parallax of the sun. He calculated the orbits of several comets, including the Great Comet of 1680 (now called 12P/Pons-Brooks ) and named after him short-period comet Encke. When evaluating the observational data he used the method of least squares to minimize statistical errors.
In 1823 he married Amalie Becker, the daughter of the bookseller and publisher Rudolph Zacharias Becker, the editor of the German national newspaper and publisher of the writings of the Seeberg observatory. With her he had three sons and two daughters.
Two years later, in July 1826 Encke joined the Monday Club in Berlin and was also selected to be equal to the archivist. Since 1858 he was senior of the Monday Club. This office he held until 1864 when he retired from public life.
On the recommendation of Friedrich Bessel Encke in 1825 was appointed director of the observatory of Berlin and member of the Academy of Sciences, whose secretary he became. The observatory was then housed in the tower of the extended Dorotheenstädtischer Marstalles. Since the equipment of the observatory poor and the facilities were inadequate, Encke was planning a new building. With the support of Alexander von Humboldt and the approval of the Prussian King Friedrich Wilhelm III. originated in the south of Berlin an observatory that was executed by the architect Karl Friedrich Schinkel. The new Berlin Observatory was commissioned in 1835 under Encke's Directorate in operation.
He led the writing of the star maps of the Berlin Academy and revised the Astronomical Yearbook.
In 1844 he was appointed Professor of Astronomy at the Friedrich -Wilhelms -Universität zu Berlin. Among his pupils were, inter alia, the later professors Wilhelm Foerster and Franz Brünnow.
In 1837 he discovered a 325 km wide division in Saturn's rings, now called the Encke division.
Encke turned to the problem of orbit determination of asteroids. Due to the gravitational effect of larger celestial bodies are sometimes susceptible to larger perturbations. Encke applied the calculus to the problem and introduced in 1849 described a method by which the orbital elements of a celestial body can be determined from only three observations.
1859 Encke suffered a stroke, the consequences of which he suffered for the rest of his life. In 1864 he asked to be relieved from his position and withdrew from public life. He died the following year in Spandau. His successor was Wilhelm Julius Foerster.
Honors
For his achievements Encke numerous honors and awards were bestowed. He was twice (1824 and 1830 ), the Gold Medal of the Royal Astronomical Society. 1828 awarded him the Royal Society with the Royal Medal. In 1842 he was admitted to the Prussian Order Pour le Mérite for Arts and Sciences and in 1853 in the Bavarian Maximilian Order for Science and Art. In 1858 he was elected a member of the Leopoldina.
In his memory, were next to the Encke division and Encke 's comet and the moon crater Encke, the Berlin Encke road, at their location at the Berlin Observatory had found, and named the Encke place in Hamburg.