Aksel Kipper (5 November 1907 Viljandi – 25 September 1984 Tartu) Director in 1950−1964

Aksel Kipper was born to the family of an agronomist and he spent his youth at Paistu in the rural municipality of Holstre. He graduated from the Viljandi Gümnaasium (high school) in 1926 and entered the Faculty of Mathematics and Natural Science of Tartu University. In becoming a scientist Aksel Kipper was strongly influenced by his teachers Taavet Rootsmäe and Ernst Öpik. In 1930 after graduating from the university he immediately defended his Master’s thesis in which he discussed the distribution of the stellar density in the cloud of stars. His idea to find the density of the matter in the cloud of stars according to the movement of stars became the basis for the work of several later researchers.

At the beginning of the 1930s Kipper began to work as an assistant at the Tartu Observatory. In this period he mainly studied periodical variable stars summarizing his work in his Doctoral thesis “The movement of gas in the atmosphere of pulsating stars” defended in 1938. His interests were not limited only with theoretical research. From the very start he was attracted by observation, astronomical apparatus building and popularizing scientific results.

In 1941 he was promoted to the post of a professor at Tartu State University and was appointed the Deputy Vice-Rector of academic affairs. In 1944–46 Kipper worked as the Head of the Chair of Theoretical Physics and on his initiative teaching of physics at the university was reorganized and it was brought to the level of quantum theory at that time. In 1946 Kipper was elected academician of the Academy of Sciences of the Estonian SSR and the Academy’s Vice-President until 1950. Then he worked as the director of the Institute of Physics, Mathematics and Mechanics reorganizing it into the Institute of Physics and Astronomy in 1952. Being the director of the institute, Kipper started to promote a contemporary observatory in Tartu which at last was festively opened at Tõravere in 1964. Because of his failing health in 1974 Kipper retired from the post of the director of the Institute of Astrophysics and Atmospheric Physics which had been separated from the Institute of Physics and Astronomy, but he continued his scientific research until the end of his life.

Aksel Kipper won international recognition thanks to his explanation of the continuous spectrum of the planetary nebulae and the study of the magneto-hydrodynamic processes taking place in the atmospheres of the stars. He has also studied the electromagnetic qualities of the cosmological space and applied the obtained results for explaining the peculiarities of cosmological redshift. Aksel Kipper was granted the title of the Merited Scientist of the Estonian SSR in 1957, in 1955 he became a member of the International Astronomical Union and in 1967 an honorary member of the Estonian Naturalists’ Society. In the same year he was presented with the award of the Estonian SSR and in 1976 he was awarded with the Memorial Medal of K. E. von Baer.