At 16, he enrolled in the University of Denver to study chemistry. His interest in astronomy was aroused through a boyhood friend (Edgar Kettering), through observing the solar eclipse of June 8, 1918, and through observing the eruption of Nova Aquilae 1918 (V603 Aquilae). He graduated from the University of Denver in 1920 with a degree in chemistry and a master's degree in chemistry and mathematics in 1921. He also found summer positions in 1922, 1923, and 1924 as research assistant to Harlow Shapley at the Harvard College Observatory. At Princeton University he acquired a second master's degree in astronomy in 1923, and in 1924 a Ph.D. in astrophysics for which his advisor was Henry Norris Russell, who inspired his interest in theoretical astronomy. After teaching two years at the University of Iowa and Ohio State University, in 1926 he was appointed assistant Professor at Lick Observatory in San Jose CA, where he worked for several years. In 1932 he moved to Harvard. During World War II Menzel was asked to join the Navy as Lieutenant commander, to head a division of intelligence, where he used his many-sided talents, including deciphering enemy codes. Even until 1955, he worked with the Navy improving radio-wave propagation by tracking the Sun's emissions and studying the effect of the aurora on radio propagation for the Department of Defense (Menzel & Boyd, p. 60). Returning to Harvard after the war, he was appointed acting director of the Harvard Observatory in 1952, and was the full director from 1954 to 1966. The term "Menzel Gap" was used to refer to the absence of astronomical photographic plates during a brief period in the 1950s when plate-making operations were temporarily halted by Menzel as a cost-cutting measure. He retired from Harvard in 1971. From 1964 to his death, Menzel was a U.S. State Department consultant for Latin American affairs.