Lyman Spitzer, Jr. studied at Yale and Cambridge Universities and earned his Ph.D. under Henry Norris Russell at Princeton University. Following research at Harvard, teaching at Yale, and war work in New York, Spitzer succeeded Russell as professor and observatory director at Princeton in 1947. He promptly hired Martin Schwarzschild, with whom he built a major research department. Spitzer worked in many areas of theoretical astrophysics, including spectral line formation, the dynamical evolution of star clusters, and star formation. His most important work was on the physics of the interstellar medium. He showed that there must be at least two phases - high temperature clouds around hot stars and cooler intercloud regions, and led in studies of interstellar dust grains and magnetic fields. Spitzer was the first to propose a large telescope in space (in 1946) - he was analyzing data from the Hubble Space Telescope the day he died. He led the development and operation of the ultraviolet astronomy satellite Copernicus. An early leader in attempts to harness controlled thermonuclear fusion on earth, he was the founder and first director of the Princeton
Plasma Physics Laboratory (originally called Project Matterhorn). Lyman Spitzer, Jr., died in 1997. One of NASA's four Great Observatories is named the Spitzer Space Telescope in his memory.