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Page:Popular Science Monthly Volume 90.djvu/280

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The Most Wonderful of Worlds

Myriads of small particles revolve in rings around

' Saturn, a giant planet which has ten moons and

which is so light that it would float in water

��IN the entire visible universe, there is no body so mysterious, so beautiful as Saturn and his marvelous system of rings and planets. But the splendor of Saturn was revealed only to modern times. He became magnificent only after the telescope was invented; for to the naked eye, he appears only as a first magnitude star, revealing nothing of his strange appendages.

It was not only the lack of instruments that withheld the beauty of Saturn from the ancients, but his remoteness as well. The a:verage distance of Saturn from the Sun is about 886,000,000 miles. That enormous orbit around the Sun is traveled in the space of twenty-nine and a half years. In other words, a year on Saturn is the equivalent of twenty-nine and a halt of our years. But his day is only ten hours fourteen minutes long. It must not be sup- posed from this that Saturn is slow. In a single second he covers nearly six miles — a speed far greater than that of a rifle bullet.

Saturn Would Float on Water

Although Saturn is enormously larger than the Earth, he is not nearly so dense. If it were possible to drop Saturn into an inconceivably vast ocean, he would float like so much pine wood. And yet, so enormous is the bulk of Saturn (his diameter at the equator is, 75,000 miles) that he weighs more than ninety-five times as much as the Earth.

A dense, cloak of clouds envelopes Saturn constantly. What is behind that cloak? No one knows. After an exhaustive study the late Professor Percival Lowell concluded that Saturn's interior was layered like an onion. These various layer« rotate at diff^erent speeds.

The first man who ever made a study of Saturn through a telescope, first because he invented the telescope, was Galileo. He could hardly believe his eyes when he saw the planet through his feeble instru- ment. He beheld the ring on edge. As the years went by, what seemed at first two thin arms extending out from each side of the planet, opened. Once in every

��fifteen years the ring is so tilted that it appears like a mere line. So Galileo had to wait seven and a half years before the ring changed in appearance. He did not know that he was looking at a true ring — so startlingly novel was the sight. He was simply puzzled.

It remained for Huyghens to announce that "the planet is surrounded by a slender flat ring everywhere distinct from its surface." And he was the first astronomer to predict the dates for the vanishing and reappearing of the ring.

The Marvelous Rings are Thousands of Miles Broad

The single ring which the older observers studied has been resolved by modern high- power instruments into three rings — an outer bright ring, an inner bright ring and a dark ring. The dark ring is called the crape ring, because it suggests a veil in texture.

The dimensions of the various rings are given on our drawing by Mr. Scriven Bolton (reproduced from the Illustrated London News and added to by the Popular Science Monthly) and are those estab- lished by Professor Barnard of Yerkes Observatory. It is altogether probable that if we had more powerful instruments than those at present at our disposal, we would be able to resolve these three rings into still others.

Sir Robert Ball has thus vividly pictured the appearance of ringed Saturn:

"Imagine that you stood on the planet Saturn, near his equator; over your head stretches the ring, which sinks down to the horizon in the east and in the west. The half ring above your horizon would then resemble a mighty arch, with a span of a hundred thousand miles. Every particle of this arch is drawn toward Saturn by gravitation, and if the arch continues to exist, it must do so in obedience to the ordinary mechanical laws which regulate the railway arches with which we are familiar.

"The continuance of these arches depends upon the resistance of the stones forming them to a crushing force. Each stone of an arch is subjected to a vast pressure, but stone is a material capable of resisting such pressure, and the arch remains. The wider the span of the arch, the greater is the pressure to which each stone is exposed. At length

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