while director of dorpat observatory (1817–39) 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. struve added a lot 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. (one of the others being bessel)