average only about one degree a month and spending two or three years in each zodiacal constellation. This is because its pathway lies millions of miles beyond that of Jupiter's, and is so large that it takes the planet 29½ years to complete its circuit around the sun.
Saturn is believed to be composed mainly of gases and vapors or to be at least in a fluid condition with no solid crust. Its density is less than that of any other planet in the solar system, being only 0.70 as compared with water as unity. This is only about one-half as great as the density of Jupiter, which is somewhat greater than that of water. The weight of the earth is five and one-half times that of water. If the earth and Saturn were two balls immersed in an ocean large enough to hold them, the earth would sink like a ball of metal while Saturn would float like a ball of wood.
A white belt may usually be seen near the equator of Saturn and curious pale gray caps cover both the poles. Between these are faint colors and other dim belts. Its colors as markings are not as pronounced as in the case of Jupiter, on which they are far more distinct as this latter planet is 400,000,000 miles closer to the earth. The mysterious gray color of the caps at the poles of Saturn remain an enigma and the spectroscope shows that Saturn contains some substance which has not yet been identified.
Saturn's equator is inclined to the plane of its orbit at an angle of 27 degrees—a direct contrast to the axis of Jupiter which is almost perpendicular. This would cause Saturn to have very marked seasonal changes and very long seasons for one of its years is equal to almost 30 of ours.
Day and night on Saturn are very short for this huge planet turns completely around in 10¼ hours. With only 5⅛ hours of daylight (and Saturn receives only 1⁄90th as much light per unit area as that received by the earth), one would hardly get up be-
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