Struve (shtrōˈvə) [key], family of astronomers. Friedrich Georg Wilhelm von Struve, 1793–1864, was born in Germany but later lived in Russia. While director (1817–39) of Dorpat Observatory he wrote Stellarum Duplicum et Multiplicum (1837), which proved that double stars are not exceptional and that star systems are governed by the laws of gravity. He made substantial contributions to the study of galactic structure and also engaged in notable geodetic operations such as the triangulation of Livonia and the measurement of an arc of the meridian. In 1839 he became director of the new Pulkovo Observatory and was one of the first three astronomers who almost simultaneously obtained an approximate stellar parallax. His son, Otto Wilhelm von Struve, 1819–1905, succeeded him as director (1862–89) of the Pulkovo Observatory. He discovered about 500 double stars and a satellite of Uranus, estimated the sun's velocity, made micrometrical measurements of Saturn's ring system, and studied nebulae and comets. Otto Struve, 1897–1963, grandson of Otto Wilhelm, was born in Russia and came to the United States in 1921 (he was naturalized in 1927). He received his Ph.D. (1923) from the Univ. of Chicago; in 1921 he joined the staff of its Yerkes Observatory. From 1932 to 1947 he was professor of astrophysics at the Univ. of Chicago and director of Yerkes Observatory and of McDonald Observatory (of the universities of Texas and Chicago). He served from 1950 to 1959 as professor of astrophysics at the Univ. of California and as director of its Leuschner Observatory; in 1960 he became director of the National Radio Astronomy Observatory at Green Bank, W.Va. He made many important studies of radial velocity, interstellar matter, and stellar evolution.