Dedication of McDonald Observatory, 1939
Many of the world's foremost astronomers attended the dedication of McDonald Observatory on May 5, 1939. This photo includes, among others, Walter Baade, Bart Bok, Edwin Hubble, Jan Oort, Cecilia Payne-Gaposchkin, Henry Norris Russel, Martin Schwarzschild, and R.J. Trumpler. Credit: McDonald Observatory.