Shifting Orbits Gave Solar System A Big Shakeup, Model Suggests

摘要

Isaac Newton inspired generations with his vision of the planets, their moons, and all the miscellaneous flotsam of the solar system as one huge planetary clock that has kept precise time over the eons. But planetary scientists are finding that the most massive pendulums within the planetary timepiece-the four outermost planets-haven't always been orbiting where they are today. They've moved, some a considerable distance outward.rnThe most catastrophic scenario for such planet migration, dubbed the Nice model (after the French city), has been gaining ground of late. It envisions the great reshuffling as a brief, violent affair that not only put the outer planets where they are today but also created the Kuiper belt of small icy bodies beyond Neptune, gave the planets scores of oddly orbiting moons, and bombarded the solar system with a rain of asteroids and comets so fierce that it would have cooked all but the deepest subterranean life on early Earth.