Astronomical Armillary Sphere

The armillary sphere functions as a model of objects in the sky, or the celestial sphere. It is used to calculate the Earth’s position and track the movements of celestial bodies like planets and star constellations. The spherical framework of rings are centred around either the Earth or the Sun and are known respectively as Ptolemaic and Copernican. During the 8th century, Persian and Arab astronomers improved on versions of the device that originated in ancient Greece.