Astronomers discover that deep under its cloud layers, Uranus has a higher-density, and slushy interior contains thick layers of water clouds. The rings of Uranus are dark, narrow, and widely spaced. -- While Saturn's rings are bright, wide, and narrowed spaced, Uranus' rings are dark, narrow, and widely spaced. It is indicate that the moons of Jupiter actually have more water than the terrestrial planets. Venus and Mercury have no water at all, and the lower temperatures of the outer solar system, combined with Jupiter's internal heat source, suggest that there could be more water on Europa than it on Earth. Mercury is close to the Sun in the sky, which means that the Sun is usually visible when Mercury is. Although theoretical models indicate that Uranus has a rocky core similar to those of Jupiter and Saturn, the pressure outside of its core is too low to force hydrogen into the metallic state, so hydrogen stays in its molecular form all the way down into the planet's core.
