Armillary sphere made by Girolamo Della Volpaia, Florence, Italy, 1554. Inscribed ‘'Hieronymus Carmilli Vulpariae, Florentin, F.1554'.
The armillary sphere is a demonstration device to explain the movements of the Sun, Moon, stars and planets across the sky. Its interlocking rings and zodiac band can be used to teach astronomical principles in same manner as a celestial globe or act as a model of the universe. This armillary sphere encloses a manuscript terrestrial globe and is known as a Ptolemaic armillary sphere because it is based on the idea of the Earth-centred universe. Later examples placed the Sun at the centre and are known as Copernican armillary spheres.