Die Welt der kleinen Planeten

Summary After a historical survey on the discovery of the small planets and the international organization of the calculation of orbits the importance of the divergences from the ordinary orbits between Mars and Jupiter is discussed. On the one side those small planets which approach Mars, Jupiter, even Earth and Saturn, in strongly excentric orbits offer new methods for the mass determination of the large planets; e.g. the perigee of Eros made possible a new determination of the parallax of the sun (8,79). On the other side the group of the Trojans e.g. gives new aspects for the problem of the three bodies. In the breaches of commensurability the statistical distribution of the orbits of the small planets hints to the problem of the stability of the planetary system.