this page honors Nicholas Copernicus (1473-1543)
In Book V of Revolutions, Copernicus turned his attention to the motions of Saturn, Jupiter, Mars, Venus, and Mercury. From the Introduction:
"Now I tackle the motions of the five planets. The order and size of their spheres [orbits] are connected with remarkable agreement and precise symmetry by the earth's motion, as I indicated generally in Book I, when I showed that the centers of these spheres are not near the earth, but rather near the sun."
Copernicus prepared two sets of tables containing details of the orbits of each of the five planets, and these calculations were based upon contemporary observations as well as ancient ones. In addition, he used geometric proofs to derive the various orbits and to show that the orbits are not uniform. From Chapter 4:
"Hence it will also be demonstrated that by this composite motion the [orbit of each individual] planet does not describe a perfect circle."