Georges-Achille van Biesbroeck (January 21, 1880 – February 23, 1974) was a Belgian-American astronomer. He worked at observatories in Belgium, Germany and the United States. He specialized in the observation of double stars, asteroids and comets. He is notable for his long career as an observational astronomer.

Albrecht Otto Johannes Unsöld (20 April 1905 – 23 September 1995) was a German astrophysicist known for his contributions to spectroscopic analysis of stellar atmospheres.

Anne Barbara Underhill was one of the pioneers of studies of early-type stars during the 1950s and remained a major figure in this field throughout her lifetime. To all those who knew and interacted with her, an abiding memory must be the vigorous way she pressed her views at international conferences. Although diminutive, and often standing alone in her opinions, she was fully capable of making her voice heard.

Otto Lyudvigovich Struvé (August 12, 1897-April 6, 1963), was a Russian astronomer, the last of a remarkable astronomical lineage. His great-grandfather, Wilhelm Struvé, founded the Pulkovo Observatory in 1839; his grandfather (Otto), uncle (Hermann) and father (Ludwig) were also distinguished astronomers. He began his academic career in Kharkiv, his native city.

Bengt Georg Daniel Strömgren (21 January 1908 – 4 July 1987) was a Danish astronomer and astrophysicist.

Harlow Shapley (November 2, 1885 – October 20, 1972) is notable for his groundbreaking 1918 work using Cepheid variables to estimate the size of the Milky Way Galaxy and the sun's position within it as well as in 1953 proposing the "Liquid Water Belt" theory, now known as the concept of a habitable zone.

Martin Ryle (1918-1984) was a British astrophysicist who developed the aperture synthesis technique of interferometry and constructed large radio telescopes, using them to discover and catalogue numerous radio sources. He guided the Cambridge radio astronomy group in the production of several important radio source catalogues.