Solar System imagery, and sorted by volume. Some omitted objects are larger than the ones included here, notably Eris, because these have not been imaged in high quality. Solar System The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, such as the five dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury. The Solar System formed
Water on terrestrial planets of the Solar System primordial ×1.6 SMOW ratio suggests that ~ of has been lost to space via solar wind stripping. The cometary and asteroidal delivery of water to accreting Earth and Mars has significant caveats, even though it is favored by D/H isotopic ratios. Key issues include: An alternative to the cometary and asteroidal delivery of HO would be the accretion via physisorption during the formation of the terrestrial planets in the solar nebula. This would be consistent with the thermodynamic estimate of around two Earth masses of water vapor within 3AU of the solar accretionary disk, which would exceed by a factor