By Dawn Roberts, Senior Director of Collections
In June 1913, the Chicago Academy of Sciences presented an exhibit to its visitors unlike any other. It was a planetarium where, unlike others of the time period, visitors could walk inside to experience the night sky while the apparatus rotated around them.
The Atwood Celestial Sphere was designed by and named for Wallace W. Atwood, who served on the Academy’s Board and briefly as Acting Director of the museum. Mr. LaVerne W. Noyes, President of the Board of Trustees, had the structure crafted by his company, Aermotor Windmill Company, and donated it to the Academy.
The sphere, constructed of a thin galvanized sheet metal, was only 15 feet in diameter. Tiny perforations in the exterior of the sphere allowed light to penetrate, appearing as stars to those viewing from the inside. Atwood designed the celestial sphere to portray the stellar sky as seen from Chicago and visitors would watch as the sun, moon, and stars rotated around them in simulation of Earth’s orbit through the solar system. The sphere was utilized heavily for educational programs at the Academy. School groups, clubs, and other visitors would tour the sphere, with programs often led by Atwood himself during his time with the Academy.
The stars were positioned with such mathematical precision that in 1941, the U.S. Navy began incorporating use of the Atwood Sphere in navigational training exercises for the U.S. Naval Reserve Unit stationed on the Chicago Campus of Northwestern University. Modifications were made to the Sphere to accommodate these trainings, including the installation of a meridian (an arc that follows the circumference of the sphere and passed through the zenith) and movable arm with which to measure the zenith angle – the distance between the zenith (the point directly overhead) and any star.
In the 1960s, the Academy began extensive redesign of its exhibits and developing life zone dioramas created by William Beecher and Academy staff. The exterior of the Atwood Celestial Sphere was painted to look like the Earth and the ceiling of the Laflin Building painted to look like the night sky to blend more readily with the new exhibits.
The Atwood Celestial Sphere was transferred to the Adler Planetarium in 1995 when the Academy vacated its Laflin Building, where it currently resides.