A total solar eclipse occurs when the moon, moving between the sun and the earth, completely blocks the light of the sun. An optimal view of this type of event can be found within the path of totality – the area where the umbral, or darkest portion, of the moon’s shadow falls upon the earth's surface. The path of totality is typically thousands of miles long but often less than one hundred miles wide.
When a total solar eclipse was anticipated in the mid to late nineteenth century, astronomers began travelling to areas within the path of totality to take pictures and record their observations. Staff members of the University of Chicago’s Yerkes Observatory were among those early adapters of astronomical photographic technology. From the year 1900 onward, these scientists left their observatory in Williams Bay, Wisconsin, and journeyed to distant regions in order to document the moments in the brief life of an eclipse.
Solar eclipse images, including close-ups of prominences, coronas, and Baily's Beads, taken by Yerkes staff are available in the University of Chicago Photographic Archive as are snapshots of life on eclipse expeditions.
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Prominences around the sun taken with the 61.5-foot coelostat telescope at Green River, Wyoming. Photograph taken on the Yerkes Observatory expedition to Wyoming to record the total solar eclipse of 8 June 1918.
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"Heliosaurus" prominence on the sun's western limb (edge). Photograph taken on the Yerkes Observatory expedition to Wyoming and Colorado to record the total solar eclipse of 8 June 1918.
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Baily's Beads are beads of sunlight seen round the sun during a total solar eclipse. These are named for their discoverer, the English astronomer Francis Baily. Photographed by George Van Biesbroeck at Khartoum, Egypt during the eclipse of 25 February 1952.
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Corona of the sun. Photograph taken on the Yerkes Observatory expedition to Wadesboro, North Carolina to record the total solar eclipse of 28 May 1900.
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Edward Emerson Barnard at the Yerkes Observatory eclipse camp in Wadesboro, North Carolina. Photograph taken on the observatory expedition to record the total solar eclipse of 28 May 1900.
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Yerkes Observatory group and associates at Camp Wrigley. Photograph taken on the Yerkes Observatory expedition to Santa Catalina Island, California to record the total solar eclipse of 10 September 1923.
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Harriet W. Bigelow and Charles Ridell and Dr. George S. Isham's hawk-eye lens on a universal movie camera with Isham's telescope. Photograph taken on the Yerkes Observatory expedition to Santa Catalina Island, California to record the total solar eclipse of 10 September 1923.
For information and maps about modern and historical eclipses, visit the Eclipse Website of the National Aeronautics and Space Administration (NASA)