Ryle, Martin (1918–1984)

English radio astronomer. At the Mullard Radio Astronomy Observatory, Cambridge, he developed the technique of sky-mapping using ‘aperture synthesis’, combining smaller dish aerials to give the characteristics of one large one. His work on the distribution of radio sources in the universe brought confirmation of the Big Bang theory. He was awarded with his co-worker, the English radio astronomer Antony Hewish, the Nobel Prize for Physics in 1974 for his work on the development of radio astronomy, particularly the aperture-synthesis technique, and the discovery of pulsars, rapidly rotating neutron stars that emit pulses of energy. He was knighted in 1966.

Ryle was born in Brighton, Sussex, and educated at Oxford University, graduating in 1939. During World War II he was involved in the development of radar. After the war he joined the Cavendish Laboratory in Cambridge, and in 1957 he became the first director of the Mullard Radio Astronomy Observatory, Cambridge. He became the first Cambridge professor of radio astronomy in 1959, responsible for most of the radio telescope developments at the university. Ryle became especially interested in isolated radio sources and their cosmological implications. He was elected fellow of the Royal Society in 1952, and was Astronomer Royal (an honorary position awarded to an outstanding British astronomer) 1972–82.

Larger and larger radio telescopes were built at the Cambridge sites, resulting in the Cambridge Catalogue Surveys, numbered 1C–5C, giving better and better maps of radio sources in the northern sky. The 3C survey, published in 1959, is used as reference by all radio astronomers. The 4C survey catalogued 5,000 sources.

The first ‘supersynthesis’ telescope, in which a fixed aerial maps a band of the sky using solely the rotation of the Earth, and another aerial maps successive rings out from it concentrically, was built in 1963, and the eight-dish 12.8-m/42-ft-wide Ryle Telescope, in a line 5 km/3 mi long, opened at Mullard in 1972. The programmes for which the Ryle Telescope is in use include the mapping of extragalactic sources and the study of supernovae and newly born stars. It can provide as sharp a picture as the best ground-based optical telescopes.