Formation and evolution of the Solar System timescale of their formation. At the current locations it would have taken millions of years for their cores to accrete. This means that Uranus and Neptune may have formed closer to the Sun—near or even between Jupiter and Saturn—and later migrated or were ejected outward (see Planetary migration below). Motion in the planetesimal era was not all inward toward the Sun; the "Stardust" sample return from Comet Wild 2 has suggested that materials from the early formation of the Solar System migrated from the warmer inner Solar System to the region of the Kuiper belt. After between three and ten
Wheelers (novel) presence of gas giants may actually be a necessary factor in the formation of habitable terrestrial planets, as their mass deflects and breaks up potentially devastating threats. Earth-bound comets from outside the solar system tend to either slingshot past Jupiter and launch into hyperbolic orbits that take them far from the terrestrial planets, or may lose momentum and drift peaceably into the Sun. Without the incredible gravitational presence of Jupiter, it's possible that our planet would experience so many impacts and close calls as to prevent advanced evolution or even the formation of life. All the same, Jupiter also pulls