Ptolemy (c. 90 – c. 168 A.D.)--The Great Compiler

Courtesy of The Granger Collection, New York


Ptolemaic model

  1. Moon
  2. Mercury
  3. Venus
  4. Sun
  5. Mars
  6. Jupiter
  7. Saturn
  8. Fixed Stars

The resultant system which eventually came to be widely accepted in the west was an unwieldy one to modern eyes; each planet required an epicycle revolving on a deferent, offset by an equant which was different for each planet. But it predicted various celestial motions, including the beginnings and ends of retrograde motion, fairly well at the time it was developed.