Jupiter rotates very fast on its axis, once every 10 hours. This has formed a patterns of stripes in its atmosphere, which runs parallel to the equator. The lighter zones are warm, rising masses of clouds, and the dark ones are cold, descending clouds. This pattern is disturbed by storms. One of these, the ‘large red spot’, is huge and can be seen from the earth. Jupiter is not only the biggest but also the heaviest planet. It has more than 60 moons. Four of them were detected by the Italian astronomer Galileo Galilei with a telescope as early as 400 years ago.