A mathematician, Moser is best known for proving a general theory on celestial mechanics regarding the stability of the solar system, providing a basis for significant advances in basic space science. He won the Wolf Prize in Mathematics for his work in 1964.
Born a German in what is now the Russian city of Kaliningrad, Moser was president of the International Mathematical Union from 1983 to 1986. He worked as a research associate at New York University, a visiting professor at the Massachusetts Institute of Technology, a professor and director at the Courant Institute of Mathematical Sciences in New York, and a researcher at Switzerland’s Federal Institute of Technology. He died December 17 in Zurich, Switzerland, from cancer. He was 71.