Analemma

The sun’s position not only varies higher and lower (north and south) in the sky, as expected with the change of seasons, but also slightly left and right (east and west). Designed and engineered by physics professors Alan Thorndike and James Evans, the analemma in Harned Hall is a clock and calendar that uses the reflection of the sun’s rays to determine date and time.

How does it work?
Installed on the right wall of the main lobby, reaching from the entry floor to the third-floor ceiling, a steel cable runs in a lop-sided figure eight to plot the path of the sun during the year. In the dome directly above the main entry of Harned Hall, a mirror reflects the sun’s rays at high noon (when the sun is highest in the sky) onto the wall with the analemma installation. Depending on where the sun’s reflected rays land on the cable figure eight, the analemma will indicate the date. Similarly, as the rays fall on arcs and notches marked on the wall behind the cable, approximate time may be determined.