Campbell, William Wallace (1862-1938), an American astronomer, made important measurements of the motion of stars. He also observed the deflection of starlight by the sun's gravitational field and determined that Mars's atmosphere did not hold significant amounts of water vapor.
Campbell was born in Hancock County, Ohio. He graduated from the University of Michigan with a B.S. degree in civil engineering in 1886, but he had already begun studying astronomy. After graduation, he taught mathematics at the University of Colorado and then taught astronomy at the University of Michigan from 1888 to 1891. He learned spectroscopy while working as a volunteer with astronomer James E. Keeler at the Lick Observatory in California in 1890. In 1891, he became a permanent staff member there. He and Elizabeth Ballard Thompson married in 1892 The couple had three children.
Campbell became known for his work in spectroscopy, the analysis of spectra of light. He made important measurements of the motion of stars and studies of galactic clouds of dust and gas called nebulae. He also headed a program to measure the sun's motion relative to other stars, which led to the discovery of several spectro-scopic binaries and a detailed analysis of stellar motion. His report that the atmosphere of Mars did not hold significant amounts of water vapor was questioned but later confirmed.
Campbell led expeditions around the world to view eclipses. During a solar eclipse in 1922, he observed the deflection of starlight by the sun's gravitational field. This observation, first made by British astronomer Arthur Stanley Eddington, supported the theory of general relativity of Albert Einstein.
Campbell served as director of the Lick Observatory from 1901 to 1930, president of the University of California from 1923 to 1930, and president of the National Academy of Sciences from 1931 to 1935. He took his life in 1938 after years of failing health.