Nicholas Copernicus’ Revolutions

Abstract

Thus far to the best of my ability I have discussed the earth’s revolution around the sun [Book III], and the moon’s revolution around the earth [Book IV]. Now I tackle the motions of the five planets. The order and size of their spheres are connected with remarkable agreement and precise symmetry by the earth’s motion, as I indicated generally in Book I [ch. 9], when I showed that the centers of these spheres are not near the earth, but rather near the sun. It therefore remains for me to prove all these statements one at a time and more clearly, and to fulfill my promises as well as I can. In particular I shall utilize observations of phenomena, which I have taken not only from antiquity but also from our own times, and by which the theory of those motions is made more certain.