Evershed, John

John Evershed, (born Feb. 26, 1864, Gomshall, Surrey, Eng.—died Nov. 17, 1956, Ewhurst, Surrey), English astronomer who, in 1909, discovered the horizontal motion of gases outward from the centres of sunspots, a phenomenon sometimes called the Evershed effect.

In 1906 Evershed became assistant director of the Kodaikānal and Madras observatories in India, later becoming director. On an expedition to Kashmir in 1915, he made the first measurements supporting Albert Einstein’s prediction that the wavelength of light emitted by a massive body (in this case the Sun) should be increased by an amount proportional to the intensity of the local gravitational field. Evershed retired in 1923, returning to England; in 1925 he built his own solar observatory at Ewhurst. He went on six expeditions to observe total solar eclipses from Norway (1896), India (1898), Algeria (1900), Spain (1905), Australia (1922), and Yorkshire (1927).