This is true not only of the major planets Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Uranus and Neptune; it is also true of the host of more than five hundred minor planets.
The bodies of this class consist of eight major planets moving round the sun at various distances, and of an unknown number of minor planets, much smaller than the major planets, forming a separate group. Thirdly, satellites, or secondary planets revolving around the major planets, and therefore accompanying them in their revolutions around the sun.
The major planets are separated into two groups of four each, between which the minor planets, for the most part, revolve.
The outer group of major planets comprises: Jupiter, 24,24, with seven satellites; Saturn, T?, with ten satellites; Uranus, a or 1, with four satellites; Neptune, with one satellite.
But there is an obvious gap between the two groups of major planets which is filled by the group of minor planets.