Circles and PiEpicycles

To fix this, astronomers added Epicycles to their model of the solar system: planets move on a large circle around Earth, while simultaneously rotating on a smaller circle. While very complicated, this was the most widely accepted model of our universe for more than 1000 years:

This planet makes ${n} rotations around the small circle (the epicycle) during one rotation around the large circle (the deferent).

A 16-century drawing of epicycles in the Geocentric model. The Greek word “planetes” means “wanderers”.