Saturn

Saturn

Saturn, the most distant of the five naked-eye planets, revolves about the sun in a period of nearly 29 ½ years. Its average distance from the sun is 866 million miles, or ever nine times the corresponding distance for the Earth.

Saturn is undoubtedly the most spectacular of all the planets. Its great yellowish globe, 74, 160 miles across at the equator and second in size only to Jupiter, is girdled by a magnificent system of rings. The innermost ring, known as the Crepe ring, is dusky and so transparent that the ball of Saturn can be seen through it. The second or middle ring, is broad and bright, and is separated from the narrower outer ring by a gap known as the Cassini division. The rings were once thought to be solid, but we now know that they consist of myriads of tiny satellites. Not only do they rotate about Saturn’s ball, but when on rare occasions they pass over a bright star, the star remains visible, although greatly reduced in brightness. Yet although the three rings have a width of about 41,500 miles, their thickness may be no more than a few inches. When presented edgewise to an observer on the earth the disappear from view, even in the largest telescopes.

Saturn by Paulucci

Saturn is also unusual in the sense that it is the lightest of all the planets – so light, in fact, that it coyld float in water. Its average density is only 0.71 whereas that of Jupiter is 1.33, and that of the Earth, 5.52. In other aspects it is similar to Jupiter. The greater part of its mass is thought to be in the form of liquid and solid hydrogen, and it is completely shrouded in low-temperature clouds, rich in methane. The clouds are arranged in parallel belts, but these are less prominent and detailed than those on Jupiter. Like Jupiter, Saturn sends out sudden bursts of radio energy. It also rotates rapidly in a period of no more than 10 hours 14 minutes at the equator, and this gives it a marked polar flattening.

Ten satellites

Saturn controls a family of ten satellites, all of which lie outside the rings. By far the largest is Titan, a body about 3,000 miles across and therefore larger than our moon. Eight of the others range in diameter from about 100 to 800 miles, and are larger than their counterparts in the system of Jupiter. One of the satellites, a tiny body considerably less than 100 miles across, was discovered just outside the rings as recently in December, 1966, by the French astronomer A. Dollfus.