Used to chart movements in the heavens of other astronomical problems, the nine-ringed armillary sphere has been in use since at least AD 140 Greece.
The center sphere originally represented the earth, in keeping with Ptolemy’s idea of the planets orbiting the earth. It later came to represent the sun with the Copernican theory of planets, including earth, orbiting around a central sun.
To learn more about this fascinating and aesthetically interesting tool, visit https://sciencing.com/armillary-sphere-6112069.html
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