Knowra Yerkes Observatory Yerkes Observatory An astronomical observatory in Williams Bay, Wisconsin, opened in 1897 and operated by the University of Chicago. It is known for its 40-inch refracting telescope and research in stellar astronomy.
Yerkes Observatory 40-inch refractor : A 40-inch-aperture refracting telescope installed at Yerkes Observatory in 1897, the largest refracting telescope used for astronomical research. This telescope is Yerkes Observatory’s defining instrument and gave the institution its scientific reach.
Stellar astronomy : The study of stars, including their physical properties, formation, evolution, and distribution. Yerkes’s instruments and researchers advanced the study of stars rather than focusing only on planets.
Charles T. Yerkes : An American financier and streetcar magnate whose donations funded the University of Chicago and its observatory. His gift paid for the observatory and its telescope, which bears his name.
William Wilson Morgan : An American astronomer known for stellar classification and research on the structure of the Milky Way. Morgan led the Yerkes Observatory and helped establish its influential stellar classification tradition.
Reflecting telescope : An optical telescope that gathers and focuses light with mirrors. Reflectors avoid the size and weight constraints that limit large refracting telescope lenses.
Refracting telescope : An optical telescope that gathers and focuses light with lenses. The 40-inch instrument belongs to this telescope design, whose size is limited by lens engineering.
Stellar parallax : The apparent shift of a nearby star against distant background stars as Earth orbits the Sun. Yerkes astronomers used precise observations to improve measurements of stellar distances.
1893 World's Columbian Exposition : A world’s fair held in Chicago in 1893 to mark the 400th anniversary of Columbus’s arrival in the Americas. Hale displayed a large telescope at the exposition, helping build support for a permanent observatory.
Edwin Hubble : An American astronomer who established that galaxies exist beyond the Milky Way and discovered the expansion of the universe. Hubble studied at Yerkes before moving to Mount Wilson Observatory, where he made his major discoveries.
Hooker Telescope : A 100-inch reflecting telescope at Mount Wilson Observatory, completed in 1917. Its larger aperture demonstrated the research advantage of reflectors over Yerkes’s 40-inch refractor.
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