Читать книгу Outlines of Creation - Elisha Noyce - Страница 7

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The thousands of stars which spangle the heavens are all part of one "system;" but it has been found by the aid of the telescope that this system is but one out of many. Our system of stars occupies a space somewhat in the form of a thick lens or much-flattened sphere, but others are of very different forms, and some have but little regularity of form at all; our sun is one of the stars of this system. It is not known whether there are planets revolving round the other stars, the distance being far too great for any telescope to render them visible. Our sun occupies a somewhat central position in the system. The stars are classed into sizes, as first magnitude, second magnitude, &c., on to the thirteenth or fourteenth magnitude, but all beyond the fifth magnitude (by far the greater number) are only visible by the aid of the telescope. There are about 5000 stars visible to the naked eye. But fourteen stars of the first magnitude are in our hemisphere of the heavens, and about fifty of the second, but the number of stars of each magnitude increases prodigiously in the higher numbers, so that those stars capable only of being seen by the aid of powerful telescopes, amount to many millions; these are chiefly situated in a great belt which encircles the heavens, called the "Milky Way," which is caused by the line of vision passing through the breadth of our starry system, and consequently meeting with a greater number of stars than in other directions, where it only crosses its thickness.

The other systems of stars, called "nebulæ," from their resemblance to little clouds, were supposed to consist of luminous matter of but little density, and which might at some future period be condensed into stars; but the improved power and construction of telescopes have enabled astronomers to resolve many of these nebulæ into clusters of stars, and there is but little doubt that all could be thus resolved, were the telescope of sufficient power; and thus it appears that in the infinity of space collections of systems are placed, each one too distant from the others to be calculated or written in numbers, but each consisting of thousands of suns many hundred times greater than this earth, and many millions of miles from each other. What an idea of space does this afford, and how soon do all our narrow notions of possibility and impossibility vanish before such facts accomplished by the hands of God!

FIG. 24.

FIG. 25.

Amongst the stars composing our system there are certain conspicuous groups or constellations, which were named by the earliest astronomers, and compose a list of the most ridiculous imaginary figures, as useless to the casual observer of the stars as to the astronomer, and have not the most distant resemblance to the figures after which they are named, as for instance the "Great Bear" (Ursa Major) fig. 24. The grouping of stars into constellations serves, however, to find any one required (provided the groups on the chart can be identified with those in the heavens), as for instance the three conspicuous stars forming "Orion's belt" (fig. 25), from which a line produced eastward will point to Sirius, the brightest star in the heavens, and another line produced westward will serve to point out "Aldebaran," also a star of the first magnitude, &c.; also a line drawn from a to b in the Great Bear will nearly point to the pole-star—the star situated nearly (although not exactly) at the pole, or that part of the heavens which would be indicated by a line drawn through the earth at its axis of rotation. Amongst the stars scattered over the vault of heaven there are many which to the naked eye appear single, but which when seen through the telescope prove to be two stars closely approaching each other. These "double stars" are of two kinds, "optical" and "physical;" optical double stars are those which appear to be near each other merely from the accident of one being placed behind the other, nearly in a straight line, although in reality at an immense distance and in no way connected. Physical double stars (usually called "binary systems") consist of two suns comparatively near each other and revolving about their common centre of gravity. Sir William Herschell first discovered their physical connection, and thereby proved that the great law of gravitation was not confined to our system, but was the ruling power which controlled and regulated other systems. Astronomers have calculated the orbits of only fourteen such "binary systems" at present with any degree of certainty; about a thousand double stars are known, but only about one hundred "binary systems." In some "binary systems" the two suns are of different colours; white and purple, red and green, or yellow and blue. If any planets revolve about such suns, when situated between the two, what strange phenomena must occur! Imagine a day during which a red sun had tinted everything crimson, being succeeded at sunset (not, as with us, by darkness) by the rising of a green sun, changing the colour of every object from red to green, and how curious and beautiful must be the shades of light and colour during the transition from one day to the other. Can anything be conceived more gorgeous?—no shadow, but every object tinted with a combination of colours of the most brilliant hues! Triple, quadruple, and multiple stars are known in abundance, but all probably optically so, and not in any way connected with each other by attraction. Others of the stars are called "variable," they are those whose light gradually diminishes and after a time regains its former brightness; some of them not only vary in brilliancy but in colour; the cause of these phenomena is totally unknown, and fortunate will he be who discovers it; it will be a great stride in the science of astronomy, for at present everything proposed has been quite inadequate to account for such phenomena. About 60 of these variable stars are at present known, but others are constantly being added to the list. Hind has discovered twenty-one, Pogson seven, and other astronomers have taken their share in discerning them.

But, of all the heavenly bodies, none have excited so much wonder, and in former times so much fear, as the Comets. The orbits of these are for the most part in very eccentric ellipses, some of them comprised within the limits of our solar system, while those of others extend millions of miles beyond it, so that they only reappear to us after hundreds of years. The matter of which these bodies is composed is certainly not solid, as the smallest telescopic stars may be seen through the very middle of it, although many thousand miles in thickness. When comets approach the sun, their substance appears to become more condensed, and therefore to possess a greater power of reflecting light. The cause of the "tails" which appear appended to comets when they approach the sun is not known, but this tail extends always in a direction from the sun, and passes over many degrees of the heavens' space. As comets obey strictly the law of gravitation, they must possess some amount of weight or mass, however small it may be, and that it is inconceivably small is proved by the fact of comets having passed close to Jupiter, right amongst his four moons, without in any way affecting or disturbing their well-known motions; the comets have, however, been terribly tossed about on such occasions, one having been totally lost to us by such an occurrence.

Thus it is seen how the same laws of gravity exist throughout all the infinity of space. The comets traverse our system of suns, and passing onwards with incredible rapidity, for years upon years, through that great space beyond it, at last visit some other system—perhaps to be as much an object of regard and wonderment there as they were here. The same ray of light which emanated from one of the distant stars of some one of the clusters situated far out in space, and which has travelled for thousands of years at the rate of 200,000 miles for every second of time, serves us here on this globe to distinguish it—it enters the tube of our telescope and affects our optic nerve; and the Creator who caused it there to be given off, has here made our senses capable of perceiving it. Is not this a clear demonstration of the fact, that one hand has designed the whole; and one Creator provided for all?