Page:Popular Science Monthly Volume 4.djvu/50

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40
THE POPULAR SCIENCE MONTHLY.

contemplate drawings which show how the planet looks under telescopic scrutiny. This will at once appear when we consider that Saturn never lies at a less distance than 732,000,000 miles from the earth. With the most powerful telescope we see him no better (taking atmospheric effects into account) than we should if this distance were reduced to about a million miles. It is manifest that at this enormous distance all save the general features of his globe and of his rings must be indistinguishable. Where we seem to see a smooth, solid globe striped with belts, there may be an orb no part of which is solid,

Fig. 1.
PSM V04 D050 Saturn size compared with earth.jpg
Telescopic Aspect of Saturn, and Size compared with the Earth.

girt round by masses of matter lying many miles above its seeming surface. Where we seem to see solid, flat rings, neatly divided one from the other either by dark spaces or by difference of tint, there may be no continuous rings at all; the apparent spaces may be no real gaps; the difference of tint may imply no difference of material. On these and other points, the known facts afford important evidence, and, by reasoning upon them, we are carried far beyond the results directly conveyed to us by telescopic researches.

Saturn is distinguished, in the first place, by the enormous range of his orbit, not merely in distance from the sun, but in the distances which separate it from the orbits of his neighbor planets. His mean distance from the sun is about 872,000,000 miles, his actual range of distance lying between 921,000,000 and 823,000,000. These figures are imposing, but they are, in fact, meaningless save by comparison with