This paper traces the evolutionary path of western astronomical thoughts from Copernicus to Kepler by utilizing the notion of theory version. Like the paradigm theory and research programme methodology, the theory of theory version is also a philosophical one, but it has a view of its own. Unlike other philosophical theories emphasizing why and how a grand scientific theory (a paradigm or a research programme) was accepted or rejected, theory version focuses on each individual scientist's own knowledge-claims and shows how these claims come to be accepted or rejected by successors. A genealogical path thus can be reconstructed by showing the acceptances and rejections of knowledge-claims. I first account for the relation between history and the philosophy of science in this paper. Next, I outline the historical background of astronomical problems before Kepler.