3. Ptolemaic Armillary Sphere 

3. Charles Francois Delamarche, 1790 
Ptolemaic Armillary Sphere
Smith Collection: SM-1790-18 

This French armillary sphere (#3) features two brass arms representing the Sun and the Moon in orbit around the Earth. The idea that the Sun orbits around the Earth is called geocentrism, and it was a popular concept in many ancient civilizations, including Greece. One Greek philosopher that described geocentrism was Aristotle, and his ideas were further developed by a later Alexandrian astronomer named Claudius Ptolemy (100-170 CE). Thus, we call this armillary sphere “Ptolemaic,” for even though its maker did not believe in geocentrism, he modeled it after the ideas of Ptolemy.