The division of the Martian eccentricity from Hipparchos to Kepler: A history of the approximations to Kepler motion

James Evans, University of Puget Sound


Any planetary theory with pretensions of quantitative validity must grapple with the inequality of movement due to Kepler motion. This was so in antiquity no less than today. The technical details of six historically important planetary models are discussed. The relationships of the models to one another and to the real motions of the planets are examined with simple geometrical techniques. The discussion centers on the history of the attempts to provide a model for the motion of Mars.