Sir Frank Watson Dyson, KBE, FRS (8 January 1868 – 25 May 1939) was an English astronomer and Astronomer Royal who is remembered today largely for introducing time signals ("pips") from Greenwich, England, and for the role he played in testing Einstein's theory of general relativity.
Dyson was born in Measham, near Ashby-de-la-Zouch, Leicestershire, the son of the Rev Watson Dyson, but soon moved to Yorkshire. There he attended Heath Grammar School, Halifax, and subsequently won scholarships to Bradford Grammar School and Trinity College, Cambridge University, where he studied mathematics and astronomy, being placed Second Wrangler in 1889.
In 1894 he was given the post of Senior Assistant at Greenwich Observatory and worked on the Astrographic Catalogue, which was published in 1905.
He was appointed Astronomer Royal for Scotland from 1905 to 1910, and Astronomer Royal (and director of the Royal Greenwich Observatory) from 1910 to 1933. In 1928, he introduced in the Observatory a new free-pendulum clock, the most accurate clock available at that time and organised the regular wireless transmission from the GPO wireless station at Rugby of Greenwich Mean Time. He also, in 1924, introduced the distribution of the "six pips" via the BBC. He was for several years President of the British Horological Institute and was awarded their Gold Medal in 1928.
Dyson was noted for his study of solar eclipses and was an authority on the spectrum of the corona and on the chromosphere. He is credited with organizing expeditions to observe the 1919 solar eclipse at Brazil and Principe, observations from which confirmed Einstein's theory of the effect of gravity on light.
Sir Frank Watson Dyson was elected an Honorary Fellow of the Royal Astronomical Society of Canada at a meeting on 1916-04-27. Dyson became familiar with many Canadian astronomers during visits to Canada, including for the opening ceremonies for the David Dunlap Observatory. On that occasion he took part in a special convocation and was made a Doctor of Laws, honoris causa together with Mrs. Dunlap and Dr. Chant.
Dyson died while travelling from Australia to England in 1939 and was buried at sea. He had married Caroline Bisset Best, the daughter of Palemon Best, with whom he had two sons and six daughters. The minor planet (1241) Dysona is dedicated to him.