Otto Wilhelm von Struve (May 7, 1819 (Julian calendar: April 25) – April 14, 1905) was a Russian astronomer. In Russian, his name is normally given as Otto Vasil'evich Struve (Отто Васильевич Струве). Together with his father, Friedrich Georg Wilhelm von Struve, Otto Wilhelm von Struve is considered a prominent 19th century astronomer who headed the Pulkovo Observatory between 1862 and 1889 and was a leading member of the Russian Academy of Sciences.
Struve was born in 1819 in Dorpat (Tartu), then Russian Empire, as the third son out of eighteen sons and daughters of Friedrich Georg Wilhelm von Struve and Emilie Wall (1796–1834). He graduated from a Dorpat gymnasium at the age of 15 and was one year too young by the university rules. Yet, he was admitted to the Imperial University of Dorpat as a listener and completed the program by the age of 20. While studying, he was assisting his father at the Dorpat Observatory. In 1839, he graduated from the university and moved to the newly opened Pulkovo Observatory, where he was immediately appointed as assistant of the director (his father). For his initial observations, he was given the degree of Master of Astronomy by the University of St. Petersburg in 1841. In 1842, he visited Lipetsk for observations of the solar eclipse and in 1843 defended his PhD. In 1843 Otto formally became a Russian subject.
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.