François Viète and his versions of the Tychonic lunar models

Abstract

In his unfinished Ad harmonicon coeleste, François Viète (1540–1603) approached the astronomical models of his predecessors in a purely mathematical way, analyzing the equations involved and suggesting new geometrical devices, usually equivalent to but simpler than the originals. After dealing with the Copernican planetary models, he developed three different lunar models. The first one describes a geometrically similar, though not identical, model to the Ptolemaic lunar model. The second is identical to that of Copernicus, but he significantly simplifies the calculation methods; and the third one is inspired by Tycho’s lunar models. In previous papers, I have analyzed the first two models. In this paper, I describe and analyze Viète’s versions of the Tychonic lunar models.