Jacobus Kapteyn
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Jacobus Cornelius Kapteyn was a Dutch astronomer. He carried out extensive studies of the Milky Way. He found that the apparent movement of stars was not randomly distributed but had two preferential
Jacobus Kapteyn. Painting by Jan Veth (1921).
Jacobus Kapteyn on the occasion of his 40th anniversary as professor in Groningen. Sir David Gill in background. Painting by Jan Veth.
Willem de Sitter
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Willem de Sitter was a Dutch mathematician, physicist, and astronomer. He is known for the de Sitter universe, which is a cosmological model that was named after him.
Jacobus Kapteyn
…Watson Medal in 1913. Kapteyn later retired in 1921 at the age of seventy, but on the request of his former student and director of Leiden Observatory Willem de Sitter, Kapteyn went back to Leiden to assist in upgrading the observatory to contemporary astronomical standards. His life's work, First attempt at a theory…
De Sitter, c. 1930s
Albert Einstein, Paul Ehrenfest, Willem de Sitter, Arthur Eddington, and Hendrik Lorentz in Leiden (1923)