Planet Guide and Information - Uranus
Uranus is another huge gas-giant planet and was discovered by William Herschel in 1781. It has a small metallic core surrounded by mostly hydrogen gas mixed with water, ammonia and methane. It is the absorbtion of red light by the methane in the planet's atmosphere which causes Uranus to look greenish; no surface detail is apparent. Uranus's axis is tilted by over 90 degrees which means that its poles point towards the sun for a considerable portion of its 84 Earth-year trip around the sun, causing each hemisphere to be warmed or cooled accordingly.