| Years | Events | |
| 1931-1935 | Pulkovo Observatory research associate | |
| 1931-1932 | Scientific Secretary of the Pulkovo Observatory | |
| 1931-1934 | Lecturer (Associate Professor) of Astrophysics at the Leningrad State University (courses of Astrophysics, Theoretical Astrophysics, and Theoretical Physics) | |
| 1933-1934 | Head of the Division of Astrophysics of the LSU Astronomical Observatory | |
| 1934-1946 | Head of the first in the Soviet Union Chair of astrophysics at the Leningrad State University | |
| 1937-1944 | Scientific Head of the Yerevan Astronomical Observatory | |
| 1939-1941 | Director of the Astronomical Observatory of the Leningrad State University | |
| 1941-1943 | Pro-Rector of the Leningrad State University on scientific affairs | |
| 1941-1943 | Head of the Scientific-Research branch of the University, evacuated to Elabuga (Tatar ASSR) | |
| 1943-1947 | First Vice-President of the Armenian SSR Academy of Sciences | |
| 1944-1994 | Head of the newly created Chair of Astrophysics at the Yerevan State University | |
| 1944-1946 | Director of the Yerevan Astrophysical Observatory of the Armenian SSR Academy of Sciences | |
| 1944-1946 | Chairman of the Astronomical Commission of the USSR Academy of Sciences | |
| 1944-1959 | Editor-in-Chief of the journal "Doklady Arm. SSR Acad. Sci." ("Reports of the Armenian SSR Academy of Sciences") | |
| 1946-1988 | Director of the newly founded Byurakan Astrophysical Observatory (BAO) of the Arm. SSR Acad. Sci. | |
| 1946-1985 | Editor-in-Chief of the "Communications of the Byurakan Observatory" | |
| 1947-1993 | President of the Armenian SSR Academy of Sciences | |
| 1947-1956 | Chairman of the Editorial-Publishing Council of the Armenian SSR Academy of Sciences | |
| 1947-1996 | Chairman of the Administrative Board of the "Knowledge" society of the Armenian SSR | |
| 1948-1955 | Vice-President of the International Astronomical Union (IAU) | |
| 1949-1953 | Chairman of the Armenian Republican Committee of supporters of peace | |
| 1952-1964 | Chairman of the Commission on Cosmogony of the USSR Acad. Sci. | |
| 1961-1964 | President of the International Astronomical Union (IAU) | |
| 1965-1987 | Editor-in-Chief of the newly founded journal "Astrofizika" ("Astrophysics") | |
| 1965-1974 | Chairman of the Editorial Board of the first "Armenian Soviet Encyclopedia" | |
| 1965-1987 | Chairman of the Scientific-Publishing Council of the first "Armenian Soviet Encyclopedia" | |
| 1966 | Member of the Executive Committee of the International Council of Scientific Unions (ICSU) | |
| 1968-1970 | President of the International Council of Scientific Unions (ICSU) (first term) | |
| 1970-1972 | President of the International Council of Scientific Unions (ICSU) (second term) | |
| 1970- | Chairman of the Committee of the Armenian SSR State prizes in the field of science and engineering at the Armenian SSR Council of Ministers | |
| 1974-1987 | Chairman of the United Scientific Council on Astronomy of the USSR Acad. Sci. | |
| 1977-1996 | Chairman of the Specialized Council for Theses Defense at BAO | |
| 1987 | Councilor of the Armenian Philosophical Academy | |
| 1988-1990 | Chairman of the Editorial Board of the "Armenian Brief Encyclopedia" | |
| 1988-1995 | Chairman of the Scientific-Publishing Council of the "Armenian Brief Encyclopedia" | |
| 1988-1996 | Honorary Director of the Byurakan Astrophysical Observatory (BAO) of the Armenian National Acad. Sci. | |
| 1990 | Honorary President of the Armenian Philosophical Society | |
| 1993-1996 | Honorary President of the Armenian National Academy of Sciences |