Brendel, Otto Rudolf Martin

(b. Niederschönhausen, near Berlin, Germany, 12 August 1862; d. Freiburg, Germany, 6 September 1939)

astronomy.

After extensive study of astronomy and mathematics from 1883 to Berlin, Munich, London, Paris, and primarily in Stockholm, Brendel received his doctorate for “Anwendung der Gyldenschen absoluten Störungstheorie auf die Breitenstörungen” (1890); all his life Brendel considered himself a disciple of Gyldén, the Swedish expert on celestial mechanics. This aspect of celestial mechanics—the development of mathematical methods to consider the influence of perturbations upon the computation of orbits—remained his chief concern.

Whereas the problem of the computation of the orbits of the major planets had been nearly solved by the great works of Laplace, Lagrange, Olbers, and Gauss in the eighteenth and nineteenth centuries, the great number of hard–to–observe minor planets presented the oreticians with entirely new tasks. A complete consideration of the perturbations to which the minor planets are subjected by Jupiter and Saturn would require considerable time. The methods developed by Brendel are based on consideration of only the largest perturbations and their tabulation, so that the minor planets will not again be lost; this way, at least over a certain period (say about one hundred years) they can again be looked for and identified with certainty during their opposition.

After his habilitation in Greifswald in 1892, Brendel devoted himself to this work. He became extraordinary professor of theoretical astronomy at Göttingen in 1898, also undertaking the teaching of insurance mathematics and geodesy in 1902. In 1907 he went to the Academy of Commerce, Frankfurtam-Main, where he was lecturer in mathematics and insurance mathematics, and the next year he became director of the newly founded observatory of the Physikalische Verein there. With the support of various foreign academies, he established the Internationales Planeteninstitut, which was to develop his ideas. In 1914 he was appointed ordinary professor at the University of Frankfurt and director of the university’s observatory. In 1927 he retired.

Brendel’s book on the minor planets was awarded the Prix Damoiseau by the Paris Academy. He participated in the publication of Gauss’s works (Volumes VII–XII, 1898–1929).

BIBLIOGRAPHY

I. Original Works. Brendel’s writings include Theorie der kleinen Planeten, 4 vols. (Göttingen, 1897–1911); Theorie des Mondes (Göttingen, 1905); and Theorie der grossen Planeten, 2 vols. (Kiel, 1930–1933).

II. Secondary Literature. Obituaries of Brendel are Astronomische Nachrichten, 270 (1940), 248 ; Neue deutsche Biographie, II, 584; and Poggendorff, IV (1904), 180: V (1926), 164–165; VI (1936), 322.

Bernhard Sticker