In 1960, 1963, and 1978, W. H. McCrea proposed the protoplanet hypothesis, in which the Sun and planets individually coalesced from matter within the same cloud, with the smaller planets later captured by the Sun's larger gravity. It includes fission in a protoplanetary nebula and excludes a solar nebula. Agglomerations of floccules, which are presumed to compose the supersonic turbulence assumed to occur in the interstellar material from which stars are born, formed the Sun and protoplanets, the latter splitting to form planets. The two portions could not remain gravitationally bound to each other at a mass ratio of at least 8 to 1, and for inner planets, went into independent orbits, while for outer planets, one portion exited 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 two portions of the dividing protoplanet. These droplets could account for some asteroids. Terrestrial planets would have no major moons, which does not account for the Moon. The hypothesis also predicts certain observations, such as the similar angular velocity of Mars and Earth with similar rotation periods and axial tilts. In this scheme, there are six principal planets: two terrestrial, Venus and Earth; two major, Jupiter and Saturn; and two outer, Uranus and Neptune, along with three lesser planets: Mercury, Mars, and Pluto.