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Page:Popular Science Monthly Volume 4.djvu/53

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the ring-system. The same double journey amounts in distance to but about two-thirds the breadth of the ring-system.

As to the scale on which Saturn's system of satellites is constructed, we shall merely remark that the span of the outermost satellite's orbit exceeds nearly twofold the complete span of the Jovian system of satellites, and exceeds the span of our moon's orbit nearly tenfold.

And now let us consider what is the probable nature of the vast orb which travels girt round always by its mighty ring-system—at so enormous a distance from the sun that his disk has but the ninetieth part of the size of the solar disk we see. Have we in Saturn, as has been so long the ordinary teaching of astronomy, a world like our own, though larger—the abode of millions on millions of living creatures—or must we adopt a totally different view of the planet, regarding it as differing as much from our earth as our earth differs from the moon, or as Saturn and Jupiter differ from the sun?

We must confess that, if we set on one side altogether the ideas received from books on astronomy, endeavoring to view these questions independently of all preconceived opinions, it appears antecedently improbable that Saturn or Jupiter can resemble the earth either in attributes or purpose. We conceive that, if a being capable of traversing at will the interstellar spaces were to approach the neighborhood of our solar system, and to form his opinion respecting it from what he had observed in other parts of the sidereal universe, he would regard Jupiter and Saturn, the brother giants of our system, as resembling rather those companion orbs which are seen in the case of certain unequal double stars, than small dependent worlds like our earth and Venus. There are, perhaps, no instances known to our telescopists in which the disparity of light, as distinguished from real magnitude, is quite so great as that which exists in the case of the sun and the two chief planets of the solar system.[1] But we see in the heaven of the fixed stars all orders of disproportion between double stars, from the closest approach to equality down to such extreme inequality, that, while the larger star of the pair is one of the leading brilliants of the heavens, the smaller can only just be discerned with the largest telescopes yet made, used on the darkest and clearest nights. We have no

  1. Even this is not certain. Jupiter, seen in full illumination from a stand-point so distant that both Jupiter and the sun might be regarded as equally distant from it, would appear to shine with rather more than the 3,000th part of the sun's light. This would correspond to the difference of apparent brightness between two stars of equal real magnitude and splendor, whereof one was about 54 times as far away as the other. There can be no doubt that the larger reflectors of the Herschels, Rosse, and Lassell, and the great refractors of Greenwich, Pulkowa, and Cambridge (United States), would bring the farther of two such stars into view if the nearer were of the first or second magnitude; and it is not at all unlikely that some of the exceedingly minute companions to bright stars, disclosed by these instruments, may be planets shining with reflected, not with inherent lustre.