In 1965, Spitzer and Donald Morton became the first to climb Mount Thor 1,675 m (5,495 ft), located in Auyuittuq National Park, on Baffin Island, Nunavut, Canada.[2]: 347 As a member of the American Alpine Club, Spitzer established the "Lyman Spitzer Cutting Edge Climbing Award" (Now called the "Cutting Edge Grant") which gives $12,000 to several mountain climbing expeditions annually.[10]
Spitzer's brief time as a faculty member at Yale was interrupted by his wartime work on the development of sonar. In 1947, at the age of 33, he succeeded Russell as director of Princeton University Observatory, an institution that, virtually jointly with his contemporary and friend Martin Schwarzschild, he continued to head until 1979.
Spitzer's research centered on the interstellar medium, to which he brought a deep understanding of plasma physics. In the 1930s and 1940s, he was among the first to recognize star formation as an ongoing contemporary process. His monographs, "Diffuse Matter in Space" (1968) and "Physical Processes in the Interstellar Medium" (1978) consolidated decades of work, and themselves became the standard texts for some decades more.
Spitzer was the founding director of Project Matterhorn, Princeton University's pioneering program in controlled thermonuclear research, renamed in 1961 as Princeton Plasma Physics Laboratory. He was an early proponent of space optical astronomy in general, and in particular of the project that became Hubble Space Telescope.
Spitzer died suddenly on March 31, 1997, after completing a regular day of work at Princeton University.[2] He was buried at Princeton Cemetery and was survived by wife Doreen Canaday Spitzer (1914-2010), four children, and ten grandchildren. Among Spitzer's four children is neurobiologist Nicholas C. Spitzer, who is currently the professor and vice chair in neurobiology at UC San Diego.