Ices in the giant planets

Interior models show that Jupiter and Saturn consist mostly of free hydrogen and helium, while Uranus and Neptune consist mostly of material with a zero-pressure density near 1 g cm(-3) The dominant material in Uranus and Neptune is almost certainly ice, while models imply that Jupiter and Saturn each contain roughly one Uranus or Neptune mass of non-hydrogen-helium material which is probably ice. Although the ice component of the giant planets is largely inaccessible to direct observation, a considerable body of indirect evidence suggests that these four planets contain the largest reservoirs of ice in the planetary system.