Sir Martin Ryle, 66, an astrophysicist who was cowinner of the 1974 Nobel Prize for Physics and who was a leading British opponent of nuclear power, died Oct. 14 at his home in Cambridge, England. The cause of death was not reported.

He and Antony Hewish, the first two radio astronomers to win a Nobel Prize, were hailed for their research in radioastrophysics, in which they both made important discoveries. The award cited Sir Martin for his work in developing advanced techniques for using telescopes in observing detail in celestial bodies.

At the time of the award, Sir Martin was a professor of radio astronomy and director of the huge Mullard Radio Astronomy Observatory, both at Cambridge University. Research he conducted there was precise in that, in terms of visible light, it was equal to an earthbound observer being able to read a postage stamp on the moon.

Educated at Bradfield College and Christ Church, Oxford, he took first class honors in the university's school of natural sciences. During World War II, he worked at the Telecommunications Research Establishment, where he helped pioneer military uses of radar. After the war, he joined Cambridge University's legendary Cavandish Laboratory. He joined the university faculty in 1948.

His research at Cavendish included development of the interferometric telescope, an instrument that could reach some 6 billion miles into space. This telescope tripled the range of the Mt. Palomar Observatory's reflecting telescope and led to the first measurement of "radio" stars.

Work he did with aperture synthesis telescopes in the 1960s led to the detection of pulsars, sources of powerful radio signals from deep space. This research led Sir Martin to the conclusion that the universe was cooling and that the proponents of the "Big Bang" school of physics were correct. Those theorists believe that the universe resulted from the explosion of a single, very dense, star.

In 1962, Sir Martin led the assault on a United States plan to explode a trio of "rainbow" nuclear bombs 500 miles over the Pacific Ocean. In a White Paper prepared for Britain's Minister of Science Viscount Hailsham, he pointed out that these detonations could cause destruction of the Van Allen radiation belts around the earth.

This was an early step in his journey to becoming a vocal opponent of nuclear weapons and power.

In addition to the Nobel Prize, Sir Martin's awards included a knighthood, the Hughes Medal of the Royal Society, the Gold Medal of the Royal Astronomical Society and the Henry Draper Medal of the National Academy of Sciences. From 1972 to 1982, when he retired from active research, he was Britain's Astronomer Royal.