Water on terrestrial planets of the Solar System Water on terrestrial planets of the Solar System The origin and development of water on terrestrial planets, Venus, Earth, Mars, and the closely related Earth's Moon, varies with each planetary body, with the exact origins remaining unclear. Additionally, the terrestrial dwarf planet, Ceres is known to have water ice on its surface. A significant amount of surface hydrogen has been observed globally by the Mars Odyssey GRS. Stoichiometrically estimated water mass fractions indicate that—when free of carbon dioxide—the near surface at the poles consists almost entirely of water covered by a thin veneer of fine material. This is reinforced by
Five-planet Nice model Five-planet Nice model The five-planet Nice model is a recent variation of the Nice model that begins with five giant planets, the current four plus an additional ice giant, in a chain of mean-motion resonances. After the resonance chain is broken, the five giant planets undergo a period of planetesimal-driven migration, followed by a gravitational instability similar to that in the original Nice model. During the instability the additional giant planet is scattered inward onto a Jupiter-crossing orbit and is ejected from the Solar System following an encounter with Jupiter. An early Solar System with five giant planets was proposed