A Gas Giant
Saturn is a massive ball of mainly hydrogen gas. It is 9 times the width and 900 time the volume of Earth. It has a solid rocky core surrounded by liquid hydrogen and helium layers. Thick gas layers complete the planet. It rotates rapidly - a day on Saturn is only 10 hours long. Strong winds stir up massive storms in the banded atmosphere. Aurora grace its poles. A mysterious heat source wells up from its south pole.Saturn has a density of only 0.7 grams per cubic centimetre - the lowest of all the planets. It would float in water, if there was an ocean to hold it.
Saturn receives only 1 percent of the sunlight that reaches Earth. It radiates about twice as much energy as the solar radiation it receives. The excess energy is generated by the intense heat and pressure in its core.
April 2005
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