Geocentric Model

  • Overly complex
    • Lack of understanding led to things like an equant point
  • Predicted positions of planets for any date and time
  • All orbits were circular
  • Retrograde motion had to be explained in a unique way since Earth was not moving
    • Planets revolved in their own epicycles
    • Those epicycles revolved around Earth

Space Astronomy Ptolemy Planetary Motion