Kepler's battle with the Mars orbit A modern approach to the steps taken by Kepler

Abstract

In this paper, I will give an account of Kepler's battle with the Mars orbit as described in the Astronomia Nova of 1609. This account is given in a modern approach where Kepler's train of thought is followed. This paper is mainly concerned with the different circular orbit constructions developed and employed by Kepler. Finally, I will show how this paved the road to oval orbits and the ellipse in particular. The modern literature on this subject is hardly accessible for today's students, for which a complete and modern discussion of the Astronomia Nova is the correct solution. This complete view will lead to the conclusion that Kepler's achievements were not as straight-forward as simply connecting the dots, contrary to a common misconception about Kepler's work.