MNN - Mother Nature Network

Uranus is the seventh planet from the sun in our solar system. This giant ball of gas and liquid is about four times as large as the Earth. The planet is covered by methane clouds. Further below, it is believed Uranus is covered in ammonia and water oceans surrounding a rocky core believed to be the size of Earth. In 1986, Voyager 2 passed by the planet, illuminating the blue-green gas giant as never before.