Models+of+Planetary+Motion

=Models of Planetary Motion=

In history, there have been two models of the motion of the Earth and the planetary bodies around it.

The first model is the geocentric model. Geocentric, meaning Earth-centered, was the model proposed by Aristotle, a Greek philosopher.

This model, illustrated below, had the Earth at the center of it, with the Sun, Moon, and other planets in orbits around it.



Aristotle explained that the Earth was at the center of all of the other bodies with the stars in a fixed position at the outside in a layer that he called the "celestial sphere."