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. Jupiter has forty-nine named moons (and may have as many as 63!). One of Jupiter's moons, Io, has active volcanoes on it. Areas on Io that are near the volcanoes are very, very hot.