Photoelectric Relay

Image of Photoelectric Relay.
Capturing a moment in time

The Chicago Century of Progress Exposition of 1933-34 celebrated the alliance between science and industry, conveying a message of hope for a better future in times of depression. The most dramatic and anticipated moment of the opening ceremony in the evening of May 27, 1933, was when the illumination of the fair was turned on, unfolding as a spectacle of light and color.

The circuit was activated with light from the star Arcturus, which was collected with the large refracting telescope of the Yerkes Observatory, converted into an electric signal by means of a photoelectric cell, and then transmitted to the Century of Progress grounds in Northerly Island through the telephone wires. At the time, the distance to Arcturus was reckoned at 40 light years; light captured in 1933 would thus have left Arcturus during the Columbian Exposition of 1893, establishing a cosmic connection between the two great world fairs in Chicago history. The image shows a photoelectric relay used in the Arcturus stunt, as well as two photoelectric cells displayed at the Adler Planetarium during Century of Progress. Inaugurated in 1930, Adler was the first planetarium in America, and one of the major attractions in Century of Progress.

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