English astronomer and theoretical physicist who focused on stellar evolution and composition, as well as the nature of the Solar System.
Lyttleton was born near Birmingham and studied at Cambridge and at Princeton in the USA. He returned to Cambridge in 1937, and together with Fred Hoyle he established a research school there in theoretical astronomy. He held a number of scientific posts, including a position at the Jet Propulsion Laboratory in California 1960.
In 1939 Lyttleton and Hoyle demonstrated the presence of interstellar hydrogen on a large scale, at a time when most astronomers believed space to be devoid of interstellar gas. In the early 1940s they applied the new advances in nuclear physics to the problem of energy generation in stars.
Lyttleton published 1953 a monograph on the stability of rotating liquid masses, and later postulated that the Earth's liquid core was produced by a phase change resulting from the combined effects of intense pressure and temperature. He also stressed the hydrodynamic significance of the liquid core in the processes of precession and nutation.
In 1959 with cosmologist Hermann Bondi he proposed the electrostatic theory of the expanding universe.