Jupiter is a large gas planet whose clouds change colors daily. This planet is made mostly of hydrogen and helium gases. Jupiter gives off two times more heat than it gets from the Sun. It shines very brightly in the night sky for nine months of the year when it is closest to Earth. Huge areas of swirling gases can be found in Jupiter's atmosphere. The largest swirling area of gas is called the Great Red Spot. Scientists believe this is a large hurricane-like storm which has lasted for hundreds of years. Large bolts of lightning have also been seen in Jupiter's atmosphere. Pictures taken by space probes have shown thin rings around Jupiter. As of January 2011, Jupiter has 50 named moons. 13 more have been discovered but not given official status or names. One of Jupiter's moons, Io, has active volcanoes on it. Areas on Io that are near the volcanoes are very, very hot.