History of Solar System formation and evolution hypotheses occur in the interstellar material from which stars are born) formed the Sun and protoplanets, the latter splitting to form planets. The 2 portions can not remain gravitationally bound to each other, are at a mass ratio of at least 8 to 1, and for inner planets they go into independent orbits while for outer planets one of the portions exits the Solar System. The inner protoplanets were Venus-Mercury and Earth-Mars. The moons of the greater planets were formed from "droplets" in the neck connecting the 2 portions of the dividing protoplanet and these droplets could account for some of
Lucky Starr and the Moons of Jupiter of Eternity". Consequently, there are small inconsistencies between the various novels. In the first, Ganymede is mentioned as a settled world of the Solar System, although in later novels Ganymede has no permanent settlement, and has even served as the location of a secret Sirian base. The first man on Mars is named Wingrad in "David Starr, Space Ranger", but is named Ching in "Moons of Jupiter". The name of the state that rules the Solar System also changes from novel to novel. In "Pirates of the Asteroids", it is the Terrestrial Empire; in "Oceans of Venus", it is the