« ПредыдущаяПродолжить »
It is very common to speak in superlative terms of the wonderful works of God, of the stupendous scale on which the universe is built up. It is common to hear, and speak, of the distances of the heavenly bodies from each other; to name the number of millions of miles in. tervening between the earth and the sun, the sun and the more distant planets, the earth and the fixed stars and the stellar clusters. Thousands daily speak of these things with utmost calmness, and with familiar air, as though the vastness of the numbers was no burthen to their thought; as though the infinite sweep of time and space embodied in the facts was fully comprehended.
But after all, how few have any tolerable conception of the subject. How few, even of those best instructed in the matter, have found, after most diligent and laborious effort, that the distances, and measures of time, and relative proportions involved, have taken any well defined shape in their thought. The calculations may be mathematically correct, and the results perfectly reliable ; but the numbers descriptive of time and space, are too vast for the mind to map out into distinct form, too immense for us to grasp and mould into intelligible conception.
And yet the facts are real and not pretended, demonstrative and not speculative,-at least to a very large extent. The science of astronomy, in its lower and middle walks, has all the certainty and exactness of the multiplication table, and rests its magnificent achievements on the precision and infallibility of geometry on the one hand, and on the visible realities and revelations of the telescope on the other. In its higher reaches, it has its speculations, but its principal results are as certain as the coming of the day and night; and the familiar facts of the almanac are a perpetual witness to the beautiful precision with which these results are wrought out. But I pass from this to the more immediate purpose
of this article.
The planet on which we live is 25,000 miles in circumference, and its surface is diversified and adorned with oceans, continents and islands, with mountains, valleys, forests and rivers; and over all is stretched the glorious canopy of the heavens, forever lovely with the golden light of the stars.
The distance of the earth from the sun is, in round numbers (which I shall mostly employ) 100 millions of miles ; which is of course the radius or semi-diameter of its orbit. This orbit, therefore, reaches through a circuit of 600 mil. lions of miles, along which the earth passes at the rate of 70,000 miles an hour. And we are at this moment more than 35,000 miles distant from the point in space where we were thirty minutes ago. We have actually travelled 35,000 miles, beside being carried by the diurnal motion of the earth 500 miles further east than we were half an hour ago! It is difficult to feel the reality of this, and yet it is as certain as figures.
Let this be the starting point, and from it let us mount over the next three or four rounds in the shining ladder by which we rise out of our little solar system, into the infinite abysses beyond. The planet Jupiter is 1400 times larger than our earth, and the sun 1400 thousand times larger. Saturn rejoices in seven moons, and in the additional glory of two magnificent rings belting her heavens with a splendor inconceivable to us, who are favored only with the light of one humble little moon for half the time. And this last body, with its stupendous
accompaniments of moons and rings, is rushing through space at the rate of more than 22,000 miles an hour ! Jupiter is more than 260,000 miles in circumference, and is less than ten hours in its revolution on its axis. earth moved at the same rate it would turn on its axis in less than an hour, and our days and nights would be about thirty minutes each !
Neptune, the outermost body of our solar family, is thirty times as far from the sun as we are, or 3000 millions of miles. This is the last round in the celestial ladder which our system supplies. From this we mount to the nearest fixed star, or the sun in our cluster next to us; and that is twenty millions of millions of miles distant from the earth. And this, though in round numbers, is not guessing, not speculation, but actual demonstration! And over this
space it takes the light more than three years to come to us, travelling at the rate of 200,000 miles in a second ! How overwhelming the thought! And yet this star is only the first mile-stone on the great highway that stretches along the measureless abysses of space. Standing by it for a moment, let us look back upon our system, whose circuit runs through some eighteen thousand millions of miles.
Lo, what a change! The Earth, Jupiter, and Saturn with its stupendous rings, have all become invisible in the distance, and the Sun itself has dwindled into a small point of light, faintly twinkling as a star amid the hosts of heaven. On all sides these myriad stars stretch out, and the Milky Way still lifts above us a thin fleecy cloud, so densely are its suns and systems crowded together, and so immense the distances which separate us from them. There is no end to them in that direction, it would seem -hosts beyond hosts, depths within depths, exhausting the powers of the telescope, and filling the soul with a half terror of wonder, till it is ready to cry out, “ Marvellous, O Lord God, are thy works, and in wisdom and in power hast thou made them all. The heavens declare thy glory, and the firmament showeth thy handywork. Day unto day uttereth speech, and night unto night showeth knowledge of Thee." There is nothing that can so exalt our ideas of God as such contemplations and studies as these; and a feeling of reverence and devotion, and from one side a feeling of affection and calm trust, seem to be the legitimate offspring of the revelations of Astronomy. The poet saw it rightly when he exclaimed
1 The star a in the constellation Centaur.
* The undevout astronomer is mad." What nights those must have been to Herschell when he attempted to sound our firmament. Selecting a point where the naked eye could not discern a single star, he began with a telescopic power of 2, and carried it up through 3, 4, 5 to 28. The first brought out stars invisible to the unaided eye, while beyond, a whitish cloud ap. peared. The powers of 3, 4, 5 resolved this cloud, and showed it to be stars, whose immense distances were beyond the reach of the lesser lens of the telescope ; but still beyond these, other whitish spots were discovered, which the new powers could not penetrate. Still higher glasses were employed, and these spots in their turn were found to be crowds of glorious suns; while far out beyond them still stretched the milky cloud of worlds! And so the astronomer continued his tests, changing his tele. scopes, and increasing his space-penetrating power, up to 28, and at every step there burst upon his amazed sight new suns before unseen, rising solemnly and beautifully from the abysses of the night, while forever behind these were discovered the white stream of the Milky Way floating like a line of foam along the great Deep of Spacema countless congregation of systems which invited, while their measureless distances baffled, the eager eye of the astronomer ! 2
And now let us mount upward another round in the shining ladder. This whole firmament of ours, which we have been viewing thus far, including the Milky Way, of which it is a part, is only one among the myriad hosts of heaven! With all its innumerable suns and systems, and the tremendous voids that lie between, it is still only one company in the grand army of God! a single cluster among multitudes of others of equal and greater magnitude and splendor.
Along the line of the Milky Way, which is in the direc. tion of its length, we cannot penetrate through it with any
2 Nichol's Stellar Universe ; Lardner's Lectures, ii. 377-382.
instruments yet constructed; but we can look through the sides of it. Our solar system is supposed to lie nearly in the centre of the bed of stars or suns which compose the cluster, which is long and narrow. We are, there. fore, like one standing in a long and narrow strip of woods :--he may not, looking in the direction of its length, be able to see either way to the end of it, but toward the sides, or breadthwise, he is able to see out into the open space beyond.
This is precisely what the telescope has accomplished in regard to our firmament or cluster. It has penetrated the sides and looked out into the dark night, the silent and awful profound beyond ; and there it has revealed new firmaments, clusters of vast and countless suns, exceeding in splendors, the highest reach of imagination; and separated from our galaxy by blanks of space, by distances so tremendous that all those thus far named sink out of sight in the comparison. Millions of years could scarcely bring the light across these awful abysses ! 3
I would distinguish, however, in this part of our subject, between fact and speculation, between what is actually known and what is inferred, though the inference be never so just. The clusters, lying at distances, whose vastness it is almost fearful to contemplate, this is a fact, of actual observation. That these distances are exactly what the figures in each case represent, this is, to a considerable extent, inference, though often resting on the firm ground-work of what is really known.
However, the moment we remember that space is infinite, we may cease to be moved by figures. And if we start with the known, and rise gradually, we shall feel at last that there is no reason for doubting any statement on the score of its magnitude.
Our own planet is 100 millions of miles from the sun. This is the first stage. The second leaves us on the outmost limits of our solar system, 3000 millions of miles. At the next we reach out to the nearest neighbor of our sun, twenty millions of millions of miles; and to the next nearest, sixty; and to the next, one hundred and eighty millions of millions of miles. We make these steps with
3 Nichol's Architecture of the Heavens, 4 a Centaur, 61 in the Swan, and a in the Lyre.