Vladimir Riives (28 October 1916 Tartu – 23 May 1978 Tartu) Director in 1948−1950

Riives was born to the family of a railway employee. He received his primary and secondary education studying in 1924-1935 at the Hugo Treffner Gümnaasium. In 1935 he entered the Faculty of Mathematics and Natural Sciences of Tartu University and soon became interested in astronomy. He attended the lectures delivered by Professor T. Rootsmäe and actively participated in the seminar of astrophysics supervised by Dr. E. Öpik. His first seven scientific papers were completed during his student days. He dealt with the dust matter between the stars and the impact of the interplanetary dust matter on the climate of the Earth. Together with E. Öpik and J. Gabovitsh he completed a paper about the movement of the stars. In 1938 he received a job at the Tartu Observatory, in 1938-39 he was a member of the support personnel, in 1939-40 a junior assistant. In 1940 Riives graduated from the university with honours.

In the student years Riives became interested in comets which later developed into his life-long research. In April 1939 the news about the discovery of a bright comet reached Tartu and Riives decided to photograph it. Later it came out that the telescope was a little out of focus and that is why the images of celestial bodies came out somewhat blurred. At first it seemed to be unfortunate but later Riives showed that namely the non-focused photos of comets allow to measure their brightness more exactly. The research results he summarized in his thesis “Photometry of comets” for which Tartu University conferred the Master’s degree on him in 1942.

In the post-war years Riives began to photograph small planets or asteroids. He measured their brightness and calculated the phase coefficient on the basis of which it was possible to study the roughness of the surface of asteroids. In 1950 Riives defended his Candidate thesis “Emission of gases from the nucleus of comets” and summarized the results of his earlier work in the physics-mathematics Doctoral thesis “Photometric research of comets” (1968).

In the years 1940-41 Riives was the senior laboratory assistant at the newly established Chair of Astronomy and in 1941 an assistant. In 1947 he became the senior researcher at the Institute of Physics, Mathematics and Mechanics of the Academy of Sciences of the Estonian SSR, in 1948-50 he was the head of the Tartu Observatory.

In 1952 the Institute of Physics, Mathematics and Mechanics was reorganized into the Institute of Physics and Astronomy. In 1956 the sector of astronomy was established and V. Riives was its head until 1960. In 1960-65 he was the Head of the Chair of Astronomy and Geophysics of Tartu State University until the chair merged with the Chair of Theoretical Mechanics. In 1967, when mathematicians and physicists formed separate faculties, all the astronomers belonged to the Chair of Theoretical Physics. During the last three years Riives worked at the Chair of General Physics. In 1970 he was elected Acting Professor, in 1972 Professor.

In 1952 Riives was elected a member of the Commission of Comets and Meteors of the Astronomical Council (Astrosovet) at the Academy of Sciences of the USSR and a member of the 15th Commission “Physics of comets, small planets and meteorites” of the International Astronomical Union. He belonged to several learned councils and organizations.