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Sir Martin Ryle

1918-1984

English Radio Astronomer

Martin Ryle did not establish radio astronomy, but he made it practical by overcoming difficulties astronomers encountered when trying to study stars by analyzing their radio emissions. Due to the long wavelengths of radio waves, it was thought that a radio telescope would have to be impossibly large and too expensive to build. It was Ryle's achievement to develop a giant "phantom" telescope, actually a series of measurements made from smaller telescopes, linked by computer. He shared the 1974 Nobel Prize in physics with Antony Hewish (1924- ).

Born on September 27, 1918, in Brighton, England, Ryle was the son of physician John A. Ryle and Miriam Scully Ryle. His was an exceedingly distinguished family: not only was his father the director of the Institute of Social Medicine at Oxford University, as well as Oxford's first professor of social medicine, his uncle Gilbert Ryle was a well-known philosopher. Ryle attended Bradfield College and Christ Church at Oxford, earning first-class honors in the latter's school of natural sciences.

Just after Ryle graduated from Christ Church in 1939, World War II broke out, and he went to work for the British government in the Telecommunications Research Establishment. (The latter was later renamed the Royal Radar Establishment.) While there, he met his fellow future Nobel laureate Antony Hewish, and worked on developing countermeasures against German radar.

In 1947 Ryle married Ella Rowena Palmer, a nurse and psychotherapist. By that time the war had ended, and Ryle had returned to Cambridge, where he had worked briefly before it began. It was there that he began his first important work in radio astronomy. The latter had been developed during the 1930s by Karl Guthe Jansky (1905-1950), an American engineer who noted that certain stars emitted very short radio waves. These, Jansky postulated, might carry useful information in the same way that light waves do, but the idea was a controversial one.

The first great contribution to the field of radio astronomy made by Ryle was the development of a map showing the radio-emitting sources in the sky. His first map, made in 1950, identified 50 of these, but a second map made five years later showed nearly 2,000.

These investigations led Ryle face-to-face with the problem that would win him the Nobel more than two decades later. Because radio waves have a much longer wavelength than light waves, a radio telescope must be much larger than a light telescope—so big, in fact, that it would be too costly to build. Ryle attacked this problem by envisioning a phantom giant telescope; then he designed a number of telescope parts that could be moved to different places along the imaginary apparatus. He took readings from various spots, and tied these together using a master computer. The latter then generated a picture of the type that might have been obtained by a single large radio telescope.

In addition to the Nobel, Ryle earned the Hughes Medal from the Royal Society in 1954, the Gold Medal of the Royal Astronomical Society in 1964, the Henry Draper Medal of the United States National Academy of Sciences in 1965, and the Royal Medal of the Royal Society in 1973. He was knighted in 1966. Ryle devoted the last decade of his life to developing wind power as a renewable source of energy. He retired in 1982, and died of lung cancer in Cambridge on October 16, 1984.

JUDSON KNIGHT

Sir Martin Ryle

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