The white wisp shown on Saturn 's cloud tops is actually a major storm system only discovered in December of 1994. Saturn 's clouds are composed of primarily hydrogen and helium , but the storm's white clouds are actually ammonia ice crystals that have frozen upon upheaval to the top of the atmosphere. The storm may look small but has an extent similar to the diameter of the Earth . This picture is a color composite of several taken by the Hubble Space Telescope . Saturn is the second largest planet in the Solar System and has the most elaborate ring system.
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