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SKETCHES OF ASTRONOMY.

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ORIGIN OF THE SOLAR SYSTEM.

Many theories have been propounded at different periods of the history of astronomy, respecting the original formation of our Solar System, as well as all other suns and systems, which it has pleased the GREAT CREATOR OF ALL THINGS to call into existence, but no one has gained so great favor or excited so violent opposition, as the theory first proposed by Sir William Herschel, and afterwards more especially applied by the celebrated La Place to the formation of the solar system.

This theory may be thus stated :- In the beginning all the datter composing the sun, planets, and satellites was diffused through space, in a state of exceedingly minute division, the ultimate particles being held asunder by the repulsion of heat. In process of time, under the action of gravitation, tha mass assumed a round or globular shape, and the particles tending to the centre of gravity, a motion of rotation on an axis would commence. The great mass, now gradually cool. ing and condensing, must increase its rotary motion, thereby increasing the centrifugal force at the equator of the revolving mass, until, finally, a ring of matter is actually detached from the equator, and is left revolving in space by the shrink. ing away from it, of the interior mass. If now we follow this isolated ring of matter, we find every reason to believe that its particles will gradually coalesce into a globular form, and in turn form satellites, as it was itself formed. It is unnecessary to pursue the reasoning further, for the same laws which produce one planet from the equator of the central revolving mass, may produce many—until finally, the process is ended by a partial solidification of the central mass, so great, that gravity aided by the attraction of cohesion, is more than suf ficient to resist the action of the centrifugal force, and no fur ther change occurs.

It has been urged in favor of this theory, that it accounts for the striking peculiarities which are found in the organization of the solar system. That the rings of Saturn are positive proofs of the truth of the theory, they having cooled and condensed without breaking. That the individuals constituting a system thus produced, must revolve and rotate as do the planets and satellites, and in orbits of the precise figure and position, as those occupied by the planets. It accounts for the rotation of the sun on its axis, and presents a solution of the strange appearance connected with the sun called the Zodiacal Light. It goes further and accounts for the formation of single, double, and multiple suns and stars-and by the remains of chaotic matter in the interstics between the stars, and which are finally drawn to some particular sun, whose influence in the end preponderates, accounts for the comets which enter our system from every region in space.

In support of this theory it has been urged that the comets, in their organization, presents us with specimens of this finely divided nebulous or chaotic matter-and that the telescope reveals cloudy patches of light of indefinite extent, scattered throughout space, which give evidence of being yet unformed and chaotic. That many stars are found in which the bright nucleus or centre is surrounded by a halo or haze of nebulous light, and that round nebulous bodies are seen with the telescope, of an extent vastly greater than would fill the entire space encircled by the enormous orbit of the planet La Verrier, or having a diameter greater than 7,000 millions of miles.

Such are a few of the arguments in support of this most extraordinary theory. We now present the objections which have been most strongly insisted on. The retrogade motions of the satellites of Herschel, and their great inclination to the plane of the ecliptic can not be accounted for by this theory. That computation shows that no atmosphere of condensed nebulous matter can extend to so great a distance from the sun, as does the matter composing the Zodiacal Light, and, finally, that the nebulous matter in the heavens will ultimately be resolved into immense congeries and clusters of stars, whose great distance has hitherto defied the power of the best instruments.

In reply to the first objection, the friends of the theory doubt the facts with reference to the satellites of Herschel. They reply that the matter composing the Zodiacal Light being in the nature of cometary matter, is thrown to a greater distance from the sun than gravity would warrant, by that power residing in the sun which is able on the approach of comets to project those enormous trains of light, which sometimes render them so wonderful. As to the last objection, it is urged that although many nebulæ will doubtless be resolved into stars, by using more powerful telescopes, yet that these same telescopes will reveal more new nebulæ which cannot be resolved, than they will resolve-and as to the existence of nebulous matter, it is perfectly demonstrated by the physical organization of comets, and the existence of nebulous stars.

Such was the state of the Astronomical argument, when Lord Rosse's Great Reflector was first applied to the exploration of the distant regions of space. In a religious point of view, this theory had excited no small amount of discussion, in consequence of its supposed Atheistical tendencies. The friends of the theory contend that it was no more Atheistical to admit the formation of the universe by law, than to acknowledge that it is now sustained by laws. Indeed since we must go to the first great cause for matter in its chaotic state, as well as for the laws which govern matter, that this theory gave to us a grander view of the omniscience and omnipotence of God than could be obtained from any other source. In fine, that it harmonized with the declaration of scripture, which tells us that “In the beginning God created the heavens and the earth, and the earth was without form and void.If the earth came into existence in its present condition, then it had form and was not void. Hence, this first grand declaration of the inspired writer must refer to the formation of the matter of which the heavens and earth were afterwards formed. Some went so far as to trace out dimly a full account of this theory in the order of creation, as laid down in Gensis.

Let us now proceed to the discoveries of Lord Rosse, and their influence on this greatly disputed theory. The space penetrating power of his six feet reflector is much greater than that of Sir William Herschel's great telescope, and it was anticipated that many nebulæ which were unresolved into clusters of stars by Hershel, would yield under the greater power and light of Lord Rosse's telescope. This has proved to be the

fact. Very many nebulæ have been removed from their old places, and must hereafter figure among the clusters, while we are informed that many yet remain, even of the old nebulæ, which defy the power of the monster telescope.

The most remarkable object which has been resolved by Lord Rosse, is the great nebula in Orion, one of the most extraordiuary objects in the heavens. Its size is enormous, and its figure very extraordinary. In certain parts adjoining the nebula the heavens are jet black, either from contrast or by the vacuity of these regions. Two immense spurs of light are seen to project from the principal mass of the nebula, and to extend to a most extraordinary distance. This will be better understood, by remembering that at the distance at which this nebula is removed from us, the entire diameter of the earth's orbit, 190 millions of miles, is an invisable point, less than one second, while this nebula extends to many thousands of times this distance, and more probably to many millions of times.

Several stars have been found, and are visible on the nebula, but have hitherto been regarded as being between the eye of the observer and this remote object. Sir William Herschel was unable to resolve this mysterious body, and yet the nebula gave indications of being of the resolvable kind by its irregular and curdled appearance under high powers. Several years since Dr. J. Lamont, of Munich, after a rigid scrutiny, of this nebula with his great Refractor, pronounced a portion of it to be composed of minute stellar points, and predicted its final perfect resolution into stars by greater power. This prediction has been fully verified, for Lord Rosse's great Reflector has solved the mystery, and filled this extraordinary object with the jewelry of stars."

But the question recurs, what have the defenders of the nebular theory lost, or its enemies gained by this interesting discovery? We are all liable to reach conclusions too hastily, and to join issue on false points. If the nebular theory depended for its existance upon the irresolvability of the nebula in Orion, then indeed has the theory been entirely exploded. But this is not the fact. No one has asserted that tho great nebula in Orion was nebulous matter, and if it were not, then none existed. Such an issue would have been a false ong, had it been made.

The theory has neithor lost nor gained by the discovorios thus far made; what time may develope it is impossible to say. In case certain data can be obtained, which appear to be accessible, then indeed may we demonstrate its truth or false. hood, by mathematical investigation. Until then, the safer plan is neither to adopt nor reject, but investigate until absolute truth shall reward our long continued labor, and reveal the mystery of the organization of that stupendous system, of which our humble planet forms an insignificant part.-Smith's Astronomy.

The sun is the center of the solar system, around which all other planets belonging to our universe revolve. The names of all the primary planets that have been discovered that constitute the solar system, are the Sun, Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Herschel, Uranus, Neptane, and twenty-three asteroids, or small planets. The approximate distance each of the large planets travel in making one revolution around the sun is about as follows: Mercury, number of miles...........

.220,000,000 Venus,

..408,000,000 Earth,

..570,000,000 Mars,

..852,000,000 Jupiter,

.2,910,000,000 Saturn,

..5,340,000,000 Herschel

...........10,800,000,000 La Verrier

.........17,100,000,000

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COMETS.

Very little is known of the physical nature of comets. They are thought by some astronomers to be about as dense as smoke. They are bodies that revolve around the sun in very elongated orbits, and some astronomers think that the greater number visit our system but once, and then fly off in nearly straight lines, and go to revolve around other suns in the far-off distant heavens. The length of the tail of a comet, as measured by astronomers, seem almost incredible. Comet of 1680, length of the tail................ ...123,000,000 miles. Do. 1744,

35,000,000
Do. 1769,

48,000,000
Do.
1811,

.130,000 000
Do. 1843,

..............130,000,000 The sun is 1,384,472 times as large as the earth; Jupiter is 1,280 times larger than the earth, and Saturn 1,000 times.

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