Together with Samuel A. Goudsmit, Dutch-American physicist George E. Uhlenbeck (1900-1988) proposed the concept of electron spin at the University of Leiden in 1925. Spin is a fundamental property of neutrons, protons and other elementary particles. The name was suggested by W. A. Fröger.
Discovered on 24-9-1960 in Palomar by van Houten, C. J., van Houten-Groeneveld, I., Gehrels, T.