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
Moons of Neptune is the most lopsided of the satellite systems of the giant planets in the Solar System. One moon, Triton, makes up nearly all of the mass of the system, with all other moons together comprising only one third of one percent. This is similar to the moon system of Saturn, where Titan makes up more than 95% of the total mass, but is different from the more balanced systems of Jupiter and Uranus. The reason for the lopsidedness of the present Neptunian system is that Triton was captured well after the formation of Neptune's original satellite system, much of which