“In fancy’s eye encount’ring armies glare,And sanguine ensigns wave unfurled in air!Hence the deep vulgar deem impending fate,A monarch ruined, or unpeopled state.Thus comets, dreadful visitants! arise,Tothemwild omens, science to thewise,These mark the comet to the sun incline,While deep red flames around its centre shine!While its fierce rear a winding trail displays,And lights all ether with a sweeping blaze!Or when, compell’d, it flies the torrid zone,And shoots by worlds unnumbered and unknown;By worlds, whose people, all aghast with fear,May view that minister of vengeance near.”
“In fancy’s eye encount’ring armies glare,
And sanguine ensigns wave unfurled in air!
Hence the deep vulgar deem impending fate,
A monarch ruined, or unpeopled state.
Thus comets, dreadful visitants! arise,
Tothemwild omens, science to thewise,
These mark the comet to the sun incline,
While deep red flames around its centre shine!
While its fierce rear a winding trail displays,
And lights all ether with a sweeping blaze!
Or when, compell’d, it flies the torrid zone,
And shoots by worlds unnumbered and unknown;
By worlds, whose people, all aghast with fear,
May view that minister of vengeance near.”
Notwithstanding the present improved state of astronomical science, it is evident that the philosophy of comets is very imperfect. Kepler, though in other respects a very great genius, and to whose useful labors astronomy is deeply indebted, indulged in the most extravagant conjectures; he imagined that the planets were large animals, swimming round the sun: and that the comets were animals still more huge and monstrous, which had been generated in the celestial spaces. Jean Bodin, a learned Frenchman of the 16th century, entertained an opinion, if possible, still more absurd and ridiculous. He maintained that the comets are spirits, which having lived on the earth innumerable ages, and being at last arrived on the confines of death, celebrated their last triumph, or are recalled to the firmament like shining stars! Mr. Whiston was of opinion, that comets are so many hells, appointed in their orbits alternately to carry the damned into the confines of the sun, there to be scorched by its violent heat, and then to return with them beyond the orb of Saturn, there to starve them in those cold and dismal regions. Thus
“Born in an age more curious than devout;More fond to fix the place of heaven or hell,Than studious this to shun, or that secure.”131
“Born in an age more curious than devout;
More fond to fix the place of heaven or hell,
Than studious this to shun, or that secure.”131
James Bernoulli, in his Systema Cometarum, says, that comets are no other than the satellites of some very distant planet, which is itself invisible to us on account of its vast distance, as are also the satellites, unless when they are in that part of their orbits which is nearest the earth. Comets, according to Des Cartes, were formerly fixed stars: but which becoming gradually covered with maculæ, and at length wholly deprived of their light, cannot keep their places, but are carried off by the vortices of the circumjacent stars; and in proportion to their magnitude and solidity, moved in such a manner as to be brought nearer the orb of Saturn; and thus, coming within reach of the sun’s light, are rendered visible.
Aristotle, Seneca, Plutarch, and others, testify, that the Pythagoreans, and the whole Italian sect, maintained, that a comet was a kind of planet or wandering star, which appeared again after a long interval of time. Hippocrates Chius was of the same opinion as Aristotle informs us. Democritus held also the same opinion, as Seneca tells us in his “Natural Questions;” book vii, chap. 3, “For,” says he, “Democritus, the most curious and subtle of all the ancients, suspected that there were many more stars which moved, meaning by this expression the comets; but he neither established their number, or their names, the courses of the five planets not having as yet been discovered.” Again, Seneca assures us, that Apollonius Myndius, one of the most skilful philosophers in the search of natural causes, asserted, that the Chaldeans reckoned comets among the other wandering stars, and that they knew their courses. Apollonius himself maintained, that a comet was a star of its own kind, as the sun and moon are, but that its course was not yet known; that by its motions it mounts very high in the heavens, and only appears when it descends into the lower part of its orbit. And Seneca himself embraces this opinion in the following truly philosophical words: “I cannot believe,” says he, “that a comet is a fire suddenly kindled, but that it ought to be ranked among the eternal works of nature. A comet has its proper place, and is not easily moved from thence; it goes its course, and is not extinguished, but runs off from us. But you will say, if it were a wandering star it would keep in the zodiac. But who can set one boundary to all the stars? Who can restrain the works of the Divinity to a narrow compass? For each ofthose bodies, which you imagine to be the only ones that have motion, have very different circles; why, therefore, may there not be some that have peculiar ways of their own, wherein they recede far from the rest? But that their courses may be known, it is necessary to have a collection of all the ancient observations about comets; for their appearances are so rare, that their orbits are not yet determined; nor can we as yet find whether they have their periods, or whether they return again in a certain order.”—“The time will come,” continues he, “wherein these things which are now hid from us will be discovered; which observation, and the diligence of after ages, will find out. For it is not one age that is sufficient for so great matters: the time will be when posterity will wonder that we were ignorant of things so plain; one will arise who will demonstrate in what regions of space the comets wander, why they recede so far from the other planets; how great and what sort of bodies they are.”132The period, predicted by Seneca, in the first century of the Christian era, is not yet arrived. “After all that has been done and written on the subject of comets,” says a late writer, “we must confess, that our knowledge of these wandering bodies is still very imperfect.” “It appears to me,” says La Lande, “that almost every thing depends on comets. The only thing that I recommend to my correspondents, is to look after and attend to comets: the knowledge of comets is alone wanting to complete the science of astronomy.”
Several ages elapsed before this prediction of Seneca seemed likely to be fulfilled. Tycho Brahé was the first who attempted to restore the comets to their proper rank in creation. Having diligently observed the comet of 1577, and finding that it had no sensible diurnal parallax, he very properly determined its true place to be among the other revolving bodies in the planetary regions, as appears by his book De Cometa, 1577. And Sir Isaac Newton, from his amazing discoveries, gives the following theory of comets: “They are,” says he, “compact, solid, fixed, and durable bodies; in fact, a kind of planets, which move in very oblique and eccentric orbits, every way with the greatest freedom; persevering in their motions even against the course and direction of the planets: and their tail is a very thin and slender vapor, emitted by the head or nucleus of the comet, ignited or heated by the sun.”
Various conjectures have been formed concerning the nature of the tails of comets. Dr. Hamilton, of Dublin, in the second of his Philosophical Essays, urges several objections against the Newtonian hypothesis: he remarks, that, since the tail of a comet, though exceedingly rare, meets with no resistance in its rapid motion round the sun (except so slight a one as can only cause a very small condensation on that side of it which moves foremost, and thereby may make it a little brighter than the other side), it cannotpossibly move in a medium denser and heavier than itself, and therefore cannot be raised up from the sun by the superior gravity of such a medium. And since the stars seen through all parts of a comet’s tail appear in their proper places, and with their usual colors, he infers that the rays of light suffer no refraction in passing through the tail; therefore, since bodies reflect and refract light by one and the same power, he concludes that the matter of a comet’s tail has not the power of refracting or reflecting light, and is, of consequence, a lucid or self shining substance. Also from what astronomers say of the splendor of comets’ tails, it is manifest they do not shine with such a dull light as would be reflected to us by the clouds or vapors at so great a distance, but with a brisker though a glimmering light, such as would arise from a very thin, volatile, burning matter. Dr. Halley, speaking of the great streams of light in the remarkable aurora borealis seen in 1716, says, “they so much resembled the long tails of comets, that at first sight they might be taken for such:” and afterwards, “this light seems to have a great affinity to that which the effluvia of electric bodies emit in the dark.”Dr. Hamilton improves upon these hints: and since, as he shows, the tails of comets, the aurora borealis, and the electric fluid, agree remarkably, not only in their appearance, but also in such properties as we can observe of each of them, he concludes that they are substances of the same nature. And, because the electric matter, from its vast subtility and velocity, seems capable of making great excursions from the planetary system, he imagines that the several comets, in their long excursions from the sun in all directions, may overtake this matter; and by attracting it to themselves may come back replete with it, and being again heated by the sun, may disperse it among the planets, and so keep up a circulation of this matter, which there is reason to think is necessary in our system.133
Comets, descending from the remote parts of the system with great rapidity become visible to us in the lower parts of their orbits; and after a short stay, go off again to vast distances, and disappear. They move about the sun in very eccentric ellipses; and the velocity with which they seem to move is variable in every part of their path round the sun; when near to which they appear to move with great swiftness, and, when very remote, their motion is slow. They are opake bodies, but of a much greater density than the earth; for some of them are heated in every period to such a degree, as would vitrify or dissipate any substance known to us. Sir Isaac Newton computed the heat of the comet, which appeared in the year 1680, when nearest the sun, to be 2,000 times hotter than red hot iron, and that, being thus heated, it must retain its heat till it comes round again, although its period should be more than 20,000 years; and it is computed to be only 575.
The number of the comets is much greater than that of the planets belonging to our system. From the beginning of the Christian era, till now, there have appeared about five hundred. Before that time, we have accounts of about one hundred others. But, when it is considered that there may have been many that have not been seen, from being too near the sun, from appearing in moon-light, from being in the other hemisphere, or from being too small, or from not being recorded, the number is probably much greater. Miss Herschell, by means of the telescope, has, within the last twenty years, discovered several comets. The orbits of about one hundred comets have been calculated with sufficient accuracy for ascertaining their identity on any future appearance.Many of these orbits are inclined to the plane of the ecliptic in large angles, and many of them approach much nearer the sun than the earth does. Their motions are also different from those of the planets, some of them being direct and others retrograde, nearly half the number moving each way. The different motions of the comets, and the various inclinations of their orbits to the plane of the ecliptic, must not be regarded as the work of chance, but as calculated to answer beneficial purposes, or avoid baneful consequences; for if these orbits had been nearly coincident with that of the earth, both bodies might have arrived at the common point of intersection of their orbits at the same time; in which case a derangement of both motions must, at least, have been the necessary result.134But, according to all the observations that have been made respecting their present distribution and direction, there is not the least reason to apprehend any such consequence.
The following table contains a list of the last twenty-three of the principal comets that have been observed, with the time of passing their perihelia, and their nearest approach to the sun.
But of all the comets, the periods of three only are known with any degree of certainty, being found to return at intervals of 75, 129, and 575 years; and of these, that which appeared in 1680 is the most remarkable. This comet, at its greatest distance, is about 11,200 millions of miles from the sun, while its least distance from the centre of the sun is about 490,000 miles; being less than one third part of the sun’s semi-diameter from his surface. In that part of its orbit which is nearest the sun, it flies with the amazing velocity of 880,000 miles in an hour; and the sun, as seen from it, appears 100 degrees in breadth, consequently 40,000 times as large as he appears to us. The astonishing distance that this comet runs out into empty space, naturally suggests to our imagination the vast distance between our sun and the nearest of the fixed stars, of whose attractions all the comets must keep clear, to return periodically and go round the sun. How wonderful that, though this body travelled almost two thousand times faster than a cannon ball, yet it drew after it a tail of fire, or of phosphoric gas, eight millions of miles in length! How amazing to consider, that this stupendous body, traversing the immensity of the creation with such rapidity, and at the same time wheeling about in that line which its great Creator prescribed to it, should move with such inconceivable velocity, and at the same time with such exact regularity! How spacious must the universe be, that,gives such bodies as these full play, without suffering the least disorder or confusion by it! With what a glorious exhibition must those beings be entertained, who can look into this great theatre of nature, and see myriads of these tremendous objects wandering through those immeasurable depths of æther, and running their appointed courses! Our eyes may hereafter be strong enough to command this magnificent prospect, and our understandings able to find out the several uses of these immense parts of the universe. In the mean time, they are most suitable objects for our imagination to contemplate,that we may form more extensive notions of infinite wisdom and power, and learn to think humbly of ourselves, and of all the little works of human invention.135
TheFixed Starsare objects of peculiar interest, and are so denominated, because they are observed always to preserve the same distance from each other; and are distinguished from the planets by their twinkling, which seems to depend on the atmosphere; for we are assured, that where the air is exceedingly pure and dry, the stars appear with a light altogether free from scintillation. All the heavenly bodies, the sun, moon, and stars, appear to move round the earth, in circles parallel to the equinoctial, once in the compass of twenty-four hours; though theseapparentmotions are almost entirety to be accounted for by therealmotions of the earth: but by far the greater number of them never change their relative situations, each (so long as an observer continues in the same place) rising and setting at the same interval of time, and at the same points of the horizon;—these are called thefixed stars.
The fixed stars, as appears from several considerations, are placed at immense distances from us. Mr. Exley, in a friendly communication, says, “It should be noticed, that the distances of the fixed stars have never yet been discovered; not indeed so much for want of a method, as for want of a base line sufficiently large for this admeasurement. The diameter of the earth’s orbit is about one hundred and ninety millions of miles; and the fixed stars, viewed from the opposite ends of this extensive base line or diameter, have no sensible parallax, but all appear in the very same situations, and of the same magnitudes; and as this is the greatest line to the extremities of which we can have access, it is very probable we shall ever remain in ignorance of the true distances of the fixed stars. One thing, however, is fully ascertained by the observations which have been made to find the parallax of the stars, which is, that they are so immensely distant from our planetary regions, that the whole solar system, consisting of the sun and planets, with their satellites, and the comets, would, if viewed from the nearest fixed star, appear as crowded into one single point of space, which is also known from other observations. How astonishingly extensive is the view of the universe which such observations furnish!”
Our earth is at so great a distance from the sun, that if seen from thence, it would appear no bigger than a point, although its diameter is 7,954 miles. Yet that distance is so small, compared with the earth’s remote situation from the fixed stars, that if the orbit in which the earth moves round the sun were the circumference of a globe, that globe, seen from the nearest star, would likewise appear no bigger than a point, although, it is at least 190,000,000 miles in diameter. For the earth in going round thesun is 190,000,000 miles nearer to some of the stars at one time of the year than at another, and yet their apparent magnitudes, situations, and distances from one another still remain the same; and being viewed through a telescope which magnifies above 200 times, they still appear as mere points: which proves them to be at least 400,000 times further from us than we are from the sun.
It is not to be imagined, that all the stars are placed in one concave surface, so as to be equally distant from us; but that they are scattered at immense distances from one another through unlimited space. So that there may be as great a distance between any two neighboring stars, as between our sun and those which are nearest to him. Therefore an observer, who is nearest any fixed star, will look on it alone as a real sun; and consider the rest as so many shining points, placed apparently at equal distances from him in the firmament. The star nearest to us, or the largest in appearance, is Sirius, or the Dog Star, and astronomers have calculated from indubitable principles, that its distance from us is considerably more than two millions of millions of miles! The apparent magnitude of Sirius has been computed at 27,000 times less than the sun, and, therefore, supposing their magnitudes equal, is 27,000 times more distant. If so, as our earth is ninety-five millions of miles from the sun, that multiplied by twenty-seven thousand, will give two millions of millions, and an addition of 565 thousand millions, for the distance of this star from the sun.136Our earth, in moving round the sun, is 195,000,000 miles nearer to this star in one part of its orbit, than in the opposite one; and yet the magnitude of the star appears not to be in the least altered or affected by it. A cannon-ball flying from thence at the rate of 400 miles in an hour, would not reach us in 732,000 years! The distance of the starγDraconis appears, by Dr. Bradley’s observations, to be at least 400,000 times that of the sun, and the distance of the nearest fixed star not less than 80,000 diameters of the earth’s annual orbit; that is, the distance of the earth from the former is = to 400,000 × 95,000,000 = 38,000,000,000,000, and the latter not less than 7,600,000,000,000. As these distances are much too great to be comprehended by the human imagination, we shall, perhaps, obtain a better idea of them by comparing them with the velocity of some moving body, by which they may, in some way, be estimated. The swiftest motion we know of is that of light, which passes from the sun to the earth in about eight minutes, or, at the rate of 200,000 miles nearly in a second of time: and yet even light would be more than six years in traversing the first space, and a year and a quarter nearly, in passing from the nearest fixed star to the earth. Again, a cannon ball, moving with itsinitial or greatest velocity of about ten miles in a minute, would be more than seven millions of years in passing from the starγDraconis to the earth. The celebrated M. Huygens carried his thoughts so far upon this subject, as to believe that there might be stars at such inconceivable distances from our earth, that their light, though it is known to travel at the rate of 12,000,000 miles in a minute, has not yet reached us, since the creation of the world!
“How distant some of the nocturnal suns!So distant, says the sage, ‘twere not absurdTo doubt, if beams, set out at nature’s birth,Are yet arrived at this so foreign world;Though nothing half so rapid as their flight.”
“How distant some of the nocturnal suns!
So distant, says the sage, ‘twere not absurd
To doubt, if beams, set out at nature’s birth,
Are yet arrived at this so foreign world;
Though nothing half so rapid as their flight.”
And Mr. Addison observes, that this thought of Mr. Huygens is far from being extravagant, when we consider that the universe is the work of infinite power, prompted by infinite goodness, having an infinite space wherein to exert itself, so that our imaginations can set no bounds to it.
The magnitudes of the stars appear to be very different from one another; which difference may probably arise, partly from a diversity in their real magnitude, but chiefly, no doubt, from their different distances. Hence it is, that the fixed stars have been divided, for the sake of distinction, into six orders or classes. Those which appear largest, are considered as stars of the first magnitude; the next to them in lustre, stars of the second magnitude; and so on, through the different gradations, to the smallest that are visible to the naked eye, which are said to be of the sixth magnitude. This distribution having been made long before the invention of telescopes, the stars which cannot be seen without the assistance of these instruments, are distinguished by the name of telescopic stars. Bayer, besides accurately distinguishing the relative size and situation of each star, marked the stars in each constellation with the letters of the Greek and Roman alphabets, setting the first Greek letter to the first or principal star in each constellation, to the second in order; then, when the Greek alphabet was gone over, he passed toa,b,c, of the Roman, and so on. This useful method of noting and describing the stars has been adopted by all astronomers since the time of Bayer; and they have further enlarged it, by adding the ordinal numbers 1, 2, 3, &c., when any constellation contains more stars than can be marked by the two alphabets.
As it would be impossible to furnish names for all the fixed stars, and retain those names in the memory; it became necessary not only to ascertain their exact relative situations, but to invent some method by which the principal part of the stars which can be seen may be known, without having recourse to a separate name for each. Ancient astronomers formed a commodious plan of arranging the fixed stars in constellations under names and figures of variouspersonages, celebrated in antiquity, and even of birds, beasts, fishes, &c. This division of the heavens into constellations is obviously very ancient; for some of them are mentioned by Hesiod and Homer, both of whom probably flourished nearly 1000 years before the Christian era. Arcturus, Orion, and the Pleiades, are twice mentioned in the book of Job: and in the prophecy of Amos, composed about 400 years before Christ, theseven starsandOrionare mentioned. As the knowledge of the stars became more extensive, the number of the constellations was increased; and at the same time more stars were introduced into each constellation. Such of the stars as were not comprehended under any constellations, were by the ancient astronomers, called unformed stars. The modern astronomers have reduced not these unformed stars only, but many other stars, into new figures; and it is probable that other constellations will still continue to be invented.137
With respect to the number of fixed stars, there have been several accounts, given by different persons, at various times. The celebrated Hipparchus, of Rhodes, 120 years before Christ, formed a catalogue of 1,022 stars; to which Ptolemy added four more. Ulug Beigh, the grandson of Tamerlane, formed a catalogue of 1,017 stars. Tycho Brahé’s catalogue only extended to 777; but he took care to ascertain all their places. Kepler’s catalogue amounted to 1,163, which Ricciolus enlarged to 1,468. Bayerus extended his catalogue further than any of his predecessors, having described the places of 1,725. Hevelius increased the catalogue to 1,888. Flamsteed enlarged these catalogues to the number of about 3,000. But by means of the telescope, which affords us a glimpse of infinite space, and presents to our view myriads of worlds, and systems of worlds, by which it is filled, the number of the stars is astonishingly increased. Galileo found eighty stars in the space of the belt of Orion’s sword, and F. de Rheita observed more than 2,000 in the whole constellation of Orion, of which not more than seventy or eighty can ever be seen without glasses. Dr. Hook reckoned seventy-eight stars in the single constellation of the Pleiades; and F. de Rheita, with a better telescope, discovered 188: whereas we cannot reckon above seven or eight seen by the naked eye. At the present period, the positions of 60,000 fixed stars have been exactly recorded, and they are generally arranged according to the size they appear; 20 of the largest are called stars of the firstmagnitude; 65 are of the second magnitude; 205 of the third; 485 of the fourth; 648 of the fifth; and about 1,500 of the sixth magnitude; the remainder, being invisible to the naked eye, are called telescopic stars.
Where the stars are in great abundance, Dr. Herschell supposes they form primaries and secondaries, that is, suns revolving about suns, as planets revolve about the sun in our system. He considers that this must be the case in what is called themilky way, the stars being there in prodigious quantity. Of this he gives the following proof: on August 22, 1792, he found that in forty-one minutes of time, not less than 258,000 stars had passed through the field of view in his telescope! Dr. Chalmers observes, If we ask the number of suns and of systems—the unassisted eye of man can take in a thousand, and the best telescope which the genius of man has constructed can take in eighty millions. Thus, by the help of telescopes, we discover a vast multitude of stars which are invisible to the naked eye; and the better the glasses are, still the more become visible; so that we can set no limits either to their number, or to their distances.
“Myriads beyond with blended rays inflameThemilky way, whose stream of vivid light,Poured from innumerable fountains round,Flows trembling, wave on wave, from sun to sun,And whitens the long path to heaven’s extreme:Distinguished tract!“
“Myriads beyond with blended rays inflame
Themilky way, whose stream of vivid light,
Poured from innumerable fountains round,
Flows trembling, wave on wave, from sun to sun,
And whitens the long path to heaven’s extreme:
Distinguished tract!“
From an attentive examination of the stars with good telescopes, many that appear only single to the naked eye, are found to consist of two, three, or more stars. The late Dr. Maskelyne observed theαHerculis to be a double star, and other astronomers have discovered many more to be double. Dr. Herschell has found 700; of these about forty had been observed before. The following will serve as a specimen, and afford the observer a few objects for his attention.αHerculis is a beautiful double star: the two bodies are apparently unequal: the largest is red, and the smallest of a blueish color inclining to green.γAndromedæ, double, very unequal: the larger of a reddish white color; the smaller a fine bright sky blue, inclining to green.βLyræ, quadruple, unequal white, but three out of the four inclined to red.εBootis, double, very unequal, larger, of a reddish color; the smaller is blue, or of a faint lilac color.αLyræ, double, very unequal; the larger is a fine brilliant white, the smaller dusky.
New stars sometimes appear, while others disappear. Several stars mentioned by ancient astronomers are not now to be found: several are now visible to the naked eye, which are not mentioned in ancient catalogues; and some stars have suddenly appeared, and again after a considerable interval vanished. Fortunio Liceti, a celebrated physician, who died in 1656, in Padua, published a treatise, entitled, “De novis Astris et Cometis.” In it he gives usan ample account of the several new stars spoken of by the ancients, among which he mentions that remarkable one which appeared A.D. 389, near the Eagle. It was as bright as the planet Venus, for the space of three weeks, but afterwards entirely disappeared. In the ninth century, the Arabian astronomers, Massahala, Haly, and Albumazar, observed a new star in the 15th degree of Scorpio, whose light equalled that of the moon in her first octant: it was visible for four months. Cyprianus Leovitius relates, that in the reign of the emperor Otho, A.D. 946, a new star was seen between the constellations of Cepheus and Cassiopeia; and also that another was seen A.D. 1264, very near the same part of the heavens, which had no proper motion. One of the most celebrated of the new stars is that discovered by Cornelius Jansen, November 8, 1572, in the chair of Cassiopeia: it exceeded Sirius in brilliancy, and Jupiter in apparent magnitude; it gradually decayed; and, after sixteen months, disappeared. On the 13th of August, 1596, David Fabricius observed a new star in the neck of the Whale, and it disappeared after October in the same year, but was supposed to be again discovered in the year 1637. In the year 1600, William Jansen discovered a changeable star in the neck of the Swan. It was seen by Kepler, who wrote a treatise upon it, and determined its place to be 16° 18ʹ ♒, and 55° 30ʹ or 32ʹ north latitude. Ricciolus saw it in 1616, 1621, and 1624. Cassini saw it again in 1655; it increased till 1660; then decreased, and at the end of 1661 it disappeared. In November, 1665, it appeared again, and disappeared in 1681. In 1715 it appeared, as it does at present, and is of the sixth magnitude. In 1686, Kircher observedχin the Swan, to be a changeable star in the neck of that constellation; and, from twenty years’ observations, the period of the return of the same phases was found to be 405 days. In 1604, Kepler discovered a new star near the heel of Serpentarius, so very brilliant that it exceeded every fixed star, and even Jupiter, in apparent magnitude. For more recent discoveries, see Dr. Herschell’s paper, “On the proper Motion of the Sun and the Solar System, with an account of the several changes that have happened among the fixed stars since the time of Mr. Flamsteed,” vol. lxxiii, of the Philosophical Transactions, or the fifteenth of the Abridgment.
All the stars seem to have a common and general motion about the pole of the ecliptic, at the rate of a degree in seventy-two years; this is occasioned by the precession of the equinoctial points. In consequence of this apparent motion, the constellations change their positions in regard to the equinoctial points. Hence it is, that the constellation Aries now is in the sign Taurus, and Taurus occupies the sign Gemini. It has been the common opinion that the fixed stars have no real motion, but the accurate observations of modern astronomers show, that some of them have amotion peculiar to themselves, by which they slowly change their places. Thus Arcturus is found to approach the ecliptic about four minutes in 100 years; and its distance from a small star near it has been sensibly changed during the last century. Sirius seems to recede from the ecliptic about two minutes per century. Similar motions have been observed in Aldebaran, Rigel, the eastern shoulder of Orion, the Goat, the Eagle, &c. Other stars have been observed to have a motion in different directions. Perhaps all the stars have similar motions, which are performed by certain fixed laws in spaces, which, though very large in reality, yet, because of their immense distance, subtend at the earth angles so very small, as in some cases to be quite imperceptible, while in other cases they may be observed, as in the stars above-mentioned; and on this rational supposition the appearance and disappearance, and variations in magnitude, of some stars may be accounted for.
The fixed stars do not appear to be all regularly disseminated through the heavens, but the greater part of them are collected into clusters; and it requires a large magnifying power, with a great quantity of light, to distinguish separately the stars which compose these clusters. With a small magnifying power, and small quantity of light, they only appear as minute whitish spots, much like small light clouds, and thence they are called nebulæ. The number of nebulæ was formerly imagined to be about 103; but Dr. Herschell, early in the year 1784, had discovered 469 more, and since then has given a catalogue of 2,000 nebulæ which he has discovered. The most careful and accurate observations give great reason to conclude, that they all consist of large masses or clusters of stars at prodigious distances from our system. Dr. Herschell is of opinion the starry heaven is replete with these nebulæ, and that each of them is a distinct and separate system independent of the rest. The milky way he supposes to be that particular nebulæ in which our sun is placed; and, in order to account for the appearance it exhibits, he supposes its figure to be much more extended towards the apparent zone of illumination, than in any other direction; which is a supposition that he thinks allowable, from the observations he has made on the figures of other nebulæ.
That there are other worlds, beside our earth, inhabited by rational beings, endued with bodily constitutions adapted to the nature and economy of the respective planets for which they are destined, is a conjecture that approaches the nearest to certainty. There is scarcely any doubt now remaining amongst philosophers, that our moon is a habitable globe. The most accurate observations that have been made with the most powerful telescopes, have confirmed the opinion. The surface of the moon seems to be diversified by high mountains, large valleys, and small and larger collections of water; consequently she resembles our earth; and there can beno doubt that our earth serves as a moon to the moon, whose inhabitants, comparing it with the sun, may well say,
——“gives us his blaze againVoid of its flame, and sheds a softer day;“
——“gives us his blaze again
Void of its flame, and sheds a softer day;“
which similarity existing between them, is a presumptive proof that the moon, like our earth, is a commodious habitation for creatures endowed with capacity for knowing and adoring their beneficent Creator. By a very correct analogy we are led to infer, says a learned author, that all theplanetsand theirsatellitesor attendant moons, areinhabited; for matter seems only to exist for the sake of intelligent beings. And Dr. Herschell’s discoveries have, by the general consent of philosophers, added, besides the Georgian planet, anew habitable worldto our system, which is theSun.
To an attentive mind it will appear highly probable, that the planets of our system, and their moons, are much of the same nature with our earth, and destined for the like purposes; for they are solid opaque globes, capable of supporting animals and vegetables. Some of them are bigger, some less, and others about the size of our earth. They move round the sun, as the earth does, in a shorter or longer time, according to their respective distances from him: and have, where it would not be inconvenient, regular returns of summer and winter, spring and autumn. They have warmer and colder climates, as the various productions of our earth require: and, in such as afford a possibility of discovering it, we observe a regular motion round their axis like that of our earth, causing an alternate return of day and night; which is necessary for labor, rest, and vegetation, and that all their surfaces may be exposed to the rays of the sun.
Can a person who attends to the vast magnitude of the three planets, Jupiter, Saturn, and Herschell or the Georgium Sidus, and compares the systems of moons together which belong to them, bring himself to think, that an infinitely wise Creator should dispose of all his animals and vegetables here, leaving the other planets destitute of living and rational creatures? To suppose that he had any view to our benefit in creating these moons, and giving them their motions round their respective primaries; to imagine, that he intended these vast bodies for any advantage to us, when he well knew, that they could not be seen but by a few astronomers looking through telescopes; and that he gave to the planets regular returns of day and night, and different seasons to all where they would be convenient, but of no manner of service to us, except only what immediately concerns our own planet, the earth; to imagine, I say, that, he did all this on our account, would, I presume, be charging him with having done much in vain: and be as absurd, as to fancy that he has created a little sun, and a planetary system within the shell of our earth, and intended them for our use.
“As well might the minutest emmet say,That Caucasus was raised to pave his wayThe snail, that Lebanon’s extended woodWas destin’d only for his walk and food.The vilest cockle, gaping on the coast,That rounds the ample seas, as well may boast,The craggy rock projects above the sky,That he in safety at its foot may lie;And the whole ocean’s confluent waters swell,Only to quench his thirst, and move and blanch his shell.”
“As well might the minutest emmet say,
That Caucasus was raised to pave his way
The snail, that Lebanon’s extended wood
Was destin’d only for his walk and food.
The vilest cockle, gaping on the coast,
That rounds the ample seas, as well may boast,
The craggy rock projects above the sky,
That he in safety at its foot may lie;
And the whole ocean’s confluent waters swell,
Only to quench his thirst, and move and blanch his shell.”
These considerations amount to little less than a positive proof, that all the planets are inhabited: for if they are not, why all this care in furnishing them with so many moons, to supply those with light which are at the greater distances from the sun? Do we not see, that the further a planet is from the sun, the greater apparatus it has for that purpose? Such of the planets as are most remote from the sun, and therefore enjoy least of his light, have that deficiency made up by several moons, which constantly accompany, and revolve about them, as our moon revolves round our earth. So that if the more distant planets have the sun’s light in less proportion by day than we, they have an addition made to it morning and evening by one or more of their moons, and a greater proportion of light during the night. We know that the earth goes round the sun, and turns round upon its own axis, to produce the vicissitudes of summer and winter by the former, and of day and night by the latter motion, for the benefit of its inhabitants: may we not then fairly conclude, by parity of reason, that the end or design of all the other planets is the same? And is not this agreeable to the beautiful harmony which exists throughout the works of nature? Surely it is! and it raises in us the most magnificent ideas of the supreme Being, who is every where, and at all times present; displaying his power, wisdom, and goodness, among all his creatures; and distributing happiness to innumerable beings of various ranks!
When we consider the infinite power and goodness of God; the latter inclining, the former enabling him to make creatures suited to all states and circumstances; that matter exists only for the sake of intelligent beings; and that wherever we see it, we always find it pregnant with life, or necessarily subservient thereto; the numberless species, the astonishing diversity of animals in earth, air, water, and even on other animals; every blade of grass, every tender leaf, every natural fluid, swarming with life; and every one of these enjoying such gratifications as the nature and state of each requires: when we reflect also, that some centuries ago, till experience undeceived us, a great part of the earth was judged uninhabitable; the Torrid Zone, by reason of excessive heat, and the two Frigid Zones because of their intolerable cold; it seems highly probable, that these numerous and large masses of the planets are not destitute of beings capable of contemplating with wonder, and acknowledging with gratitude, the wisdom, symmetry, and beautyof the creation. It is an undoubted truth, that wherever God exerts his power, there also he manifests his wisdom and goodness.
From what we know of our own system, it may be reasonably concluded, that all the rest are with equal wisdom contrived, situated, and provided with accommodations for rational inhabitants. Taking a survey of the system to which we belong; the only one accessible to us; from thence we are the better enabled to judge of the nature and end of the other systems of the universe. For although there is almost an infinite variety in the parts of the creation which we have opportunities of examining, yet there is a general analogy running through and connecting all the parts into one scheme, one design, one whole!
The stars, being at such immense distances from the sun, cannot possibly receive from him so strong a light as they seem to have; nor any brightness sufficient to make them visible to us. For the sun’s rays must be scattered and dissipated before they reach such remote objects, that they can never be transmitted back to our eyes, so as to render these objects visible by reflection.