Otto Wilhelm Von Struve - Scientific Work

Scientific Work

During 1843 and 1844, Struve participated in longitude measurements between Altona, Greenwich and Pulkovo, which were based on large displacement of chronometers over the Earth surface. This newly developed method was adopted in Russia, and from 1844, the longitude was measured starting not from the Tartu Observatory but from the Pulkovo Observatory. Much of the 1844 Struve dedicated to studying the Sun. He deduced its apex coordinates and linear velocity as 7.3 km/s. Although it was significantly smaller than the correct value of 19.5 km/s measured in 1901, Struve's result was correct in that the velocity of the Sun was smaller than that of stars.

Struve continued his father's work in several directions. In particular, they compiled famous Pulkovo catalogues of stellar coordinates, including several thousands double stars observed with a 15-inch refractor. Between 1816 and 1852, the observatory completed the famous survey triangulation measurements of the angular arc (named Struve Geodetic Arc). The measurements extended through over 2,820 km, from Hammerfest in Norway to the Staraya Nekrasovka village by the Black Sea, and aimed to establish the exact size and shape of the Earth. In 1851, while observing a solar eclipse, he came to a conclusion that solar corona and protuberances are physically connected with the Sun and are not an optical effect, as most of astronomers believed. Later in 1860 he suggested a close connection between solar protuberances and flares. Struve also observed satellites of Uranus (Ariel and Umbriel, in 1851) and of Neptune. He also measured the rings of Saturn and discovered (in parallel with other researchers) the dark inner ring of Saturn. In 1861, in his report to the Academy of Sciences, he had supported and developed the ideas of William Herschel that stars are formed from the diffuse matter. In 1872, Struve organized assistance with equipment to the newly opened observatory in Tashkent – a southern location offering clear skies for observations. In 1874, he prepared several expeditions to monitor the transit of Venus across the solar disk in eastern Asia, Caucasus, Persia and Egypt. In 1887, he sent several groups within Russia to observe the solar eclipse. In some of those expeditions, he took part personally. In 1885, a 30-inch refracting telescope was installed at Pulkovo, at the time the largest in the world (see great refractor).