Uranus's Internal Structure
Evidence indicates that Uranus may have a silicate rock core (perhaps rich in iron and magnesium), which is 4,800 km in diameter (approximately 40% of the planet's mass). The mantle is likely ice or ice-rock mixture (water ice, methane ice, ammonia ice) that may be molten in part (perhaps evidence of convention produced in the magnetic field). Above the mantle is the lower atmosphere, which consists of molecular (gaseous) hydrogen, helium, and traces of other gasses (approximately 10% of planet's mass). Finally, the upper atmosphere is methane with cloud layers of ammonia or water ice. The magnetic field discovered and mapped by Voyager 2 implies a field generating region in Uranus' interior which extends out to 0.7 of Uranus radius from the center, and that part of Uranus' interior is a fluid and has a high internal temperature.