Viktor Amazasp Ambartsumian (Armenian: Վիկտոր Համբարձումյան; 18 September 1908 – 12 August 1996) was an outstanding Soviet Armenian astrophysicist and science administrator. One of the 20th century's top astronomers, he is widely regarded as the founder of theoretical astrophysics in the Soviet Union.

Educated at Leningrad State University (LSU) and the Pulkovo Observatory, Ambartsumian taught at LSU and founded the Soviet Union's first department of astrophysics there in 1934. He subsequently moved to Soviet Armenia, where he founded the Byurakan Astrophysical Observatory (BAO) in 1946. It became his institutional base for the decades to come and a major center of astronomical research. He also co-founded the Armenian Academy of Sciences and led it for almost half a century – the entire post-war period. One commentator noted that “science in Armenia was synonymous with the name Ambartsumian”. In 1965 Ambartsumian founded the journal Astrofizika and served as its editor for over 20 years.

Ambartsumian carried out basic research in astronomy and cosmogony. It covered astrophysics, theoretical physics and mathematical physics, and mostly focused on the physics of nebulae, star systems, and extragalactic astronomy. He is best known for having discovered stellar associations and predicted activity of galactic nuclei. In his later career, Ambartsumian held views in contradiction to the consequences of the general relativity, such as rejecting the existence of black holes.

Ambartsumian was one of the 20th century's leading astrophysicists and astronomers. He was the leading astronomer of the Soviet Union and is universally recognized as the founder of the Soviet school of theoretical astrophysics. Ambartsumian was also well-regarded internationally. Loren Graham called him “one of the best-known abroad of all Soviet scientists”. He was an honorary or foreign member of academies of sciences of 27 countries.

One of the “modern icons of Armenian pride”, Ambartsumian is recognized as the most prominent scientist in 20th century Armenia, and possibly the greatest since the 7th century polymath Anania Shirakatsi. He was declared a National Hero of Armenia in 1994. An asteroid discovered at the Crimean Astrophysical Observatory in 1972 by Tamara Smirnova is named 1905 Ambartsumian. In 1998 the Byurakan Observatory was officially named after Ambartsumian.

Evgeni Kirill Kharadze (Georgian: ევგენი ხარაძე; 31 October 1907 – 10 October 2001) was a famous Soviet Georgian astronomer, public figure and statesman. Member of the Academy of Sciences of the Soviet Union (1984), full member of the Georgian Academy of Sciences (1955).

He was the 17th Rector of the Tbilisi State University (1959–1966), Vice-President (1972–1980) and President (1980–1986) of the Georgian SSR Academy of Sciences. Vice-President of the International Astronomical Union (1976–1982), founding director of Abastumani Astrophysical Observatory (1932–1992).

Kharadze was born in Tbilisi, October 31, 1907 into the family of an employee of the Transcaucasus Railway. In 1930 he graduated from Tbilisi State University. Since 1949 he has been a Professor of the same University. Kharadze's monograph “Catalogue of the Color Indices of 14,000 Stars and Investigation of Light Absorption in the Galaxy on the Basis of Color Indices of Stars” was published in 1952. He was the author of a fundamental handbook “The Course of General Astrophysics” and two volumes of “Principles of Astronomy” in Georgian. The asteroid 1247 discovered by Richard Martin West was named after Evgeni Kharadze.