Gas Giant - Uranus and Neptune

Uranus and Neptune

Uranus and Neptune have distinctly different interior compositions from Jupiter and Saturn. Models of their interior begin with a hydrogen-rich atmosphere that extends from the cloud-tops down to about 85% of Neptune's radius and 80% of Uranus's. Below the point is predominantly "icy", composed of water, methane and ammonia. There is also some rock and gas but various proportions of ice/rock/gas could mimic pure ice so the exact proportions are unknown.

Very hazy atmosphere layers with a small amount of methane gives them aquamarine colors such as baby blue and ultramarine colors respectively. Both have magnetic fields that are sharply inclined to their axes of rotation.

Unlike the other gas giants, Uranus has an extreme tilt that causes its seasons to be severely pronounced. The two planets have other subtle but important differences. Uranus has more hydrogen and helium than Neptune, despite being less massive overall. Neptune is therefore denser and has much more internal heat, and a more active atmosphere. The Nice model in fact suggests that Neptune formed closer to the Sun than Uranus did, and would therefore have more heavy elements.