Astronomia nova is a book, published in 1609, which contains the results of the astronomer Johannes Kepler. The author used precise celestial measurements of Mars carried out by Tycho Brahe and calculated various models for approximation of the orbit of Mars. This article concentrates on two unsatisfactory hypothetical models for the orbit, which preceded the correct elliptical model. The first was the vicarious hypothesis, which predicted precise longitudes well within observational accuracy, but with inaccurate distances to the Sun. Secondly, Kepler proposed the oval hypothesis, which led to errors at the octants., Vladimír Štefl., and Obsahuje bibliografické odkazy