Читать книгу Outlines of the Earth's History: A Popular Study in Physiography - Nathaniel Southgate Shaler - Страница 8

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Although little is known of the motions which occur among the celestial bodies beyond the sphere of our solar family, that which has been ascertained is of great importance, and serves to make it likely that all the suns in space are upon swift journeys which in their speed equal, if they do not exceed, the rate of motion among the planetary spheres, which may, in general, be reckoned at about twenty miles a second. Our whole solar system is journeying away from certain stars, and in the direction of others which are situated in the opposite part of the heavens. The proof of this fact is found in the observations which show that on one side of us the stars are apparently coming closer together, while on the other side they are going farther apart. The phenomenon, in a word, is one of perspective, and may be made real to the understanding by noting what takes place when we travel down a street along which there are lights. We readily note that these lights appear to close in behind us, and widen their intervals in the direction in which we journey. By such evidence astronomers have become convinced that our sphere, along with the sun which controls it, is each second a score of miles away from the point where it was before.

There is yet other and most curious evidence which serves to show that certain of the stars are journeying toward our part of the heavens at great speed, while others are moving away from us by their own proper motion. These indications are derived from the study of the lines in the light which the spectrum reveals to us when critically examined. The position of these cross lines is, as we know, affected by the motion of the body whence the light comes, and by close analysis of the facts it has been pretty well determined that the distortion in their positions is due to very swift motions of the several stars. It is not yet certain whether these movements of our sun and of other solar bodies are in straight lines or in great circles.

It should be noted that, although the evidence from the spectroscope serves to show that the matter in the stars is akin to that of our own earth, there is reason to believe that those great spheres differ much from each other in magnitude.

We have now set forth some of the important facts exhibited by the stellar universe. The body of details concerning that realm is vast, and the conclusions drawn from it important; only a part, however, of the matter with which it deals is of a nature to be apprehended by the student who does not approach it in a somewhat professional way. We shall therefore now turn to a description of the portion of the starry world which is found in the limits of our solar system. There the influences of the several spheres upon our planet are matters of vital importance; they in a way affect, if they do not control, all the operations which go on upon the surface of the earth.