At Caltech, Christy taught theoretical physics, nuclear physics and astrophysics and went on to serve as faculty chair, vice president and provost, and acting president.
While at Caltech, he investigated pulsations in the brightness of stars, which are used to measure cosmic distances. Christy was awarded the Royal Astronomical Society's Eddington Medal for his work.
He was elected to the National Academy of Sciences in 1965.
Caltech Physics, Mathematics and Astronomy Chair B. Thomas Soifer said Thursday that Christy was a major figure at the private university and a founder of a very important area of astrophysical research.
"Bob was an outstanding theoretical physicist; his contributions to scientific research, to public policy and his leadership helped in shaping what Caltech is today," said Soifer.