Jeffreys, Sir Harold

Jeffreys, Sir Harold

(born April 22, 1891, Fatfield, Durham, Eng.—died March 18, 1989, Cambridge, Cambridgeshire) British astronomer and geophysicist. In astronomy, he established that the four large outer planets (Jupiter, Saturn, Uranus, and Neptune) are very cold, devised models of their planetary structure, and studied the origin of the solar system and the theory of latitude. In geophysics, he investigated the thermal history of the Earth, was coauthor (1940) of the standard tables of travel times for earthquake waves, and was the first to hypothesize that the Earth's core is liquid. He explained the origin of monsoons and sea breezes and showed how cyclones are vital to the general circulation of the atmosphere. Jeffreys also worked on probability theory and on methods of general mathematical physics.