LITMIR.BIZ

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      Astronomy is an ancient science; and though of late it has made a fresh start in new regions, and we are opening on the era of fresh and unlooked-for discoveries which will soon reveal our present ignorance, our advance upon primitive ideas has been so great that it is difficult for us to realize what they were without an attentive and not uninstructive study of them. No other science, not even geology, can compare with astronomy for the complete revolution which it has effected in popular notions, or for the change it has brought about in men's estimate of their place in creation. It is probable that there will always be men who believe that the whole universe was made for their benefit; but, however this may be, we have already learned from astronomy that our habitation is not that central spot men once deemed it, but only an ordinary planet circulating round an ordinary star, just as we are likely also to learn from biology, that we occupy the position, as animals, of an ordinary family in an ordinary class.

      That we may more perfectly realize this strange revolution of ideas, we must throw ourselves as far as possible into the feeling and spirit of our ancestors, when, without the knowledge we now possess, they contemplated, as they could not fail to do, the marvellous and awe-inspiring phenomena of the heavens by night. To them, for many an age, the sun and moon and stars, with all the planets, seemed absolutely to rise, to shine, and to set; the constellations to burst out by night in the east, and travel slowly and in silence to the west; the ocean waves to rise and fall and beat against the rock-bound shore as if endowed with life; and even in the infancy of the intellect they must have longed to pierce the secrets of this mysterious heavenly vault, and to know the nature of the starry firmament as it seemed to them, and the condition of the earth which appeared in the centre of these universal movements. The simplest hypothesis was for them the truth, and they believed that the sky was in reality a lofty and extended canopy bestudded with stars, and the earth a vast plain, the solid basis of the universe, on which dwelt man, sole creature that lifted his eyes and thoughts above. Two distinct regions thus appeared to compose the whole system—the upper one, or the air, in which were the moving stars, the lights of heaven, and the firmament over all; and the lower one, or earth and sea, adorned on the surface with the products of life, and below with the minerals, metals, and stones. For a long time the various theories of the universe, grotesque and changing as they might be, were but modifications of this one central idea, the earth below, the heavens above, and on this was based every religious system that was promulgated—the very phrases founded upon it remaining to this day for a testimony to the intimate relation thus manifested between the infant ideas in astronomy and theology. No wonder that early revolutions in the conceptions in one science were thought to militate against the other. It is only when the thoughts on both are enlarged that it is seen that their connection is not necessary, but accidental, or, at least, inevitable only in the infancy of both.

      It is scarcely possible to estimate fully the enormous change from these ideas representing the appearances to those which now represent the reality; or to picture to ourselves the total revolution in men's minds before they could transform the picture of a vast terrestrial surface, to which the sun and all the heavenly bodies were but accessories for various purposes, to one in which the earth is but a planet like Mars, moving in appearance among the stars, as it does, and rotating with a rapidity that brings a whole hemisphere of the heavens into view through the course of a single day and night. At first sight, what a loss of dignity! but, on closer thought, what a gain of grandeur! No longer some little neighbouring lights shine down upon us from a solid vault; but we find ourselves launched into the sea of infinity; with power to gaze into its almost immeasurable depths.

      To appreciate rightly our position, we have to plant ourselves, in imagination, in some spot removed from the surface of the earth, where we may be uninfluenced by her motion, and picture to ourselves what we should see. Were we placed in some spot far enough removed from the earth, we should find ourselves in eternal day; the sun would ever shine, for no great globe would interpose itself between it and our eyes; there would be no night there. Were we in the neighbourhood of the earth's orbit, and within it, most wonderful phenomena would present themselves. At one time the earth would appear but an ordinary planet, smaller than Venus, but, as time wore on, unmeasured by recurring days or changing seasons, it would gradually be seen to increase in size—now appearing like the moon at the full, and shining like her with a silver light. As it came nearer, and its magnitude increased, the features of the surface would be distinguished; the brighter sea and the darker shining continents, with the brilliant ice-caps at the poles; but, unlike what we see in the moon, these features would appear to move, and, one after another, every part of the earth would be visible. The actual time required for all to pass before us would be what we here call a day and night. And still, as it rotates, the earth passes nearer to us, assumes its largest apparent size, and so gradually decreasing again, becomes once more, after the interval we here call a year, an ordinary-looking star-like planet. To us, in these days, this description is easy of imagination; we find no difficulty in picturing it to ourselves; but, if we will think for a moment what such an idea would have been to the earliest observers of astronomy, we shall better appreciate the vast change that has taken place—how we are removed from them, as we may say, toto cœlo.

      But not only as to the importance of the earth in the universe, but on other matters connected with astronomy, we perceive the immensity of the change in our ideas—in that of distance, for instance. This celestial vault of the ancients was near enough for things to pass from it to us; it was in close connection with the earth, supported by it, and therefore of less diameter; but now, when our distance from the sun is expressed by numbers that we may write, indeed, but must totally fail to adequately appreciate, and the distance from the next nearest star is such, that with the velocity of light—a velocity we are accustomed to regard as instantaneous—we should only reach it after a three years' journey, we are reminded of the pathetic lines of Thomas Hood:

      "I remember, I remember, the fir trees straight and high,

       And how I thought their slender tops were close against the sky;

       It was a childish fantasy, but now 'tis little joy,

       To know I'm further off from heaven than when I was a boy."

      The astronomer's answer to the last line would be that as far as the material heaven goes, we are just as much in it as the stars or as any other member of the universe; we cannot, therefore, be far off or near to it.

      It is probable that we are even yet but little awake to true cosmical ideas in other respects;—as to velocity, for instance. We know indeed, of light and electricity and the motions of the earth, but revelations are now being made to us of motions of material substances in the sun with such velocities that in comparison with them any motions on the earth appear infinitesimally small. Our progress to our present notions, and appreciations of the truth of nature in the heavens, will thus occupy much of our thoughts; but we must also recount the history of the acquirement of those facts which have ultimately become the basis for our changes of idea.

      Our rustic forefathers, whatever their nation, were not so enamoured of the "wonders of science"—that their astronomy was greatly a collection of theories, though theories, and wild ones, they had; it was a more practical matter, and was believed too by them to be more practical than we now find reason to believe to be the case. They noticed the various seasons, and they marked the changes in the appearances of the heavens that accompanied them; they connected the two together, and conceived the latter to be the cause of the former, and so, with other apparently uncertain events. The celestial phenomena thus acquired a fictitious importance which rendered their study of primary necessity, but gave no occasion for a theory.

      That we may better appreciate the earliest observations on astronomy, it may be well to mention briefly what are the varying phenomena which may most easily be noticed. If we except the phases of the moon, which almost without observation would force their recognition on people who had no other than lunar light by night, and which must therefore, from the earliest periods of human history have divided time into lunar months; there are three different sets of phenomena which depend on the arrangement of our planetary system, and which were early observed.

      The first of these depends upon the earth's rotation

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