The sphere is made up of wooden rings and has a pin on its axis to which a terrestrial globe (now missing) was once attached at the sphere’s centre. The Sun and Moon, attached by brass rods to one of the rings, rotate around it.
The sphere is composed of horizontal rings that represent the equator, the tropics of Cancer and Capricorn, and the Arctic and Antarctic circles, plus two vertical rings that cross the ecliptic band on the dates of solstices and equinoxes. The months, constellations of the zodiac, and winds are indicated on the horizontal circle supported by the pedestal.
The sphere is a teaching model that indicates how the relative positions of the Sun and the Earth determine day and night lengths throughout the year, the seasons, the appearance of the zodiac constellations during the months of the year, and so on.
Built by Louis Charles Desnos, Paris.
Restored in 2017 by Paolo Brenni and Anna Giatti in the Fondazione Scienza e Tecnica laboratory in Florence.
Device on display.