The Circle will Now be Closed, Finally (On the Inability to Adapt Circular Motion to Arbitrary Motions)

Kurzfassung

The description of the motion of the Sun, Moon, stars, planets and satellites was originally based on a model of circular uniform motion. Improved observational methods re­quired an improved model which was found by superposition of different circles, each trav­ersed by uniform motion. Copernicus seems to have been the first (or at least one of the first) to have recognized that the planets do not move in a circle. The new curve to be adapted to planetary motion was found by Kepler. Based on a general theory of adaptation of any motion as a consequence of the method of the variation of parameters, the present paper shows that the circle is the only curve which is not able to be adapted to any general motion.