Armillary Sphere

• The Armillary Sphere is a model of the sky centred on the Earth used to display the positions of the Planets and Stars.
• It consists of a series of circles within circles marked off in degrees, which represent Celestial Longitude and Latitude, and shows the Ecliptic.

History

• Hipparchus (c. 190-120 BCE) wrote that Eratosthenes (c. 276-194 BC) was the inventor of the Armillary Sphere.
• The Armillary Sphere had replaced the Dioptra by the second century CE.