Uranus

http://en.wikipedia.org/wiki/Uranus

     Uranus is the seventh planet from the Sun. It is named after the Greek god  of the sky, Uranus, father of Kronos. It is similar in appearance and composition to Neptune and is one of the gas giants. It is the third largest planet in the solar system. Its mass is equal to 14 Earth masses. It was discovered as a planet on March 13, 1781. It is 19.6 AU away from the Sun. The atmosphere similar to those of Jupiter and Saturn, but contains more ices of water, ammonia, and methane. It has the coldest planetary atmosphere with temperatures reaching -224°C. Uranus has a ring system like the other gas giants. The axis tilts towards the sun so much that its north and south poles lie where the equator would be on other planets. This means that Uranus orbits the Sun on its side. Wind speeds here can reach speeds up to 560 m/h. It has 27 known moons.

Structure:

http://www.planetsalive.com/image/uraxsec.jpg

     The core is very small, with a mass of only 0.55 Earth masses. The radius  of the core is less than 20 percent of the planet.  Uranus's core's density is around 9 g/cm³. The pressure in the center is 8 million bars and the temperature is about 5000° K.

      The mantle is made of a hot and dense fluid made of water, ammonia and other volatiles. This mixture is referred to as icy. This fluid has a high electrical conductivity. It is called as a water–ammonia ocean. The mantle makes up the weight of the planet, with around 13.4 Earth masses.

     The upper atmosphere is insubstantial, weighing about 0.5 Earth masses. It extends for the last 20% of Uranus's radius. It is made mainly of hydrogen and helium. It contains more ices of water, ammonia and methane. It has a layered cloud structure. Water is thought to make up the lowest clouds, while methane is thought to make up the upper layers of clouds.