EMILIO SEGRE VISUAL ARCHIVES / AMERICAN INSTITUTE OF PHYSICS / SCIENCE PHOTO LIBRARY EMILIO SEGRE VISUAL ARCHIVES / AMERICAN INSTITUTE OF PHYSICS / SCIENCE PHOTO LIBRARY
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Ejnar Hertzsprung (1873-1967), Danish chemist and astronomer. Between 1911 and 1913 he developed the Hertzsprung-Russell diagram with Henry Norris Russell, which showed a correlation between spectral types and absolute magnitudes of stars. In 1913 Hertzsprung determined the distances to several Galactic Cepheid stars by statistical parallax - the measurement of an object's change in position against a background of stars, due to a change in observer position. From 1919 to 1946 he worked at Leiden Observatory, in the Netherlands, becoming director in 1937.
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