OF all the floating islands which compose the celestial archipelago to which the earth belongs, the planet consecrated from remotest ages to Jupiter the Mighty, king of the gods and men, is the vastest, the most important, and the most majestic. This colossal world of Jupiter has a diameter of about 89,000 miles, and which surpasses that of our earth by more than eleven times. The circumference of Jupiter's world at the equator is about 275,000,000 miles. The volume of this giant exceeds that of the earth by twelve hundred and thirty-four times. This immense globe, seen at the distance at which we are situated from the moon, would appear to us with a diameter about forty times larger than that of our satellite, and the surface of its disk would embrace on the celestial vault an extent sixteen hundred times greater than that of the full moon I This giant of the world travels through space, accom- p anied by a retinue of four satellites, at a mean distance of 496,000,uOO miles from the sun, and which is more than five times greater than that of the earth from the same. Its orbit is more than a thousand million miles in extent, and through this it passes in 4,332 days, or 11 years 10 months and 17 days. Such is the year of this immense globel In order to complete its entire orbit during this period, it speeds around the sun with a velocity of about 700,000 miles a day, or a little more than 8 miles a second. This is a little less than half the velocity of the earth in its orbit. But it revolves on its axis with very great swiftness, for its day and night combined only last nine hours and fifty-five minutes; in other words, the inhabitants of Jupiter enjoy only five hours of real day, twilight inc l uded. “If,” says Kant, “an inhabitant of Jupiter should die in childhood, having lived but one year on that planet, he would be as old as a child who should die on our globe at the age of eleven years and three hundred and fourteen days. The terrestrial child would have lived about one hundred and three thousand nine hundred and sixty-eight of Jupiter's days, and the child on Jupiter, four thousand three hundred and twenty-nine of the earth's days." THE GIANT OF THE WORLDS. The extreme velocity of Jupiter's rotatory motion has caused a considerable flattening at the poles, the length of one of this planet's meridians being to that of its equator as one hundred and sixty-seven is to one hundred and seventy-seven, or, in other words, seventeen times shorter. This flattening, which had been already noticed by Cassini, had a very great influence on the ideas of Newton touching the figure of the terrestrial globe. It does not follow, because Ju piter is a globe 1,234 times larger than the earth, that its mass ia in the same proportion; and the fact is that the density of this planet is about four times less than that of our own. It has hence been concluded that Jupiter is composed of light substances like those that we find here on the surface of our soil. The sun, which is five times more distant from this world than it is from our own, exhibits a very tame appearance to the inhabitants of Jupiter as compared with its aspect to us. They see it rise at their horizon like a fifth moon, possessing a very singular motion, and giving their planet a brighter light and an intenser heat than the others do. This light and heat is twenty-seven times less than that received by the earth from its luminary. Thia datum furnished Christiern Wolff, a German philosopher of the last century, a pretended method of determining within about an inch the stature of the men who inhabit Jupiter. This is too curious, and especially too sin gular, to be passed by in silence. We will allow the philosopher to speak for himself: Says he: “We are taught in optica that the p upil of the eye is dilated by a feeble light and contracted by an in - tense one. The light of the sun being much less intense for the inhabitants of Jupiter than for us, owing to their far greater distance from thia star, it follows that these men have pupils that are larger and much more dilated than ours. Now, we observe that the pupil is in constant proportion to the globe of the eye , and the eye to the rest of the body; so that the more an animal,s pupil is developed, the larger the eye, and the larger also the body." From this principle (the soundness of which we shall exam me) Wolff deduces the following conclusions: "In order to determine the size of the inhabitants of Jupiter, we must consi der that the distance from Jupiter to the sun is to the distance from the earth to the sun as twenty-six is to five, and, consequently, that the sun's light with respect to Jupiter is to this light with respect to the earth in the double ratio of five to twenty-six. On another hand, experience teaches us that the dilatation of the p upil iS always more than proportional to the increase of the * Transited from the Journal Ck^mUsa^s Utiles for the Soien- TIPlO AliIlIRlCAlf. light's intensity; otherwise a body placed at a great distance would appear as clearly defined as another placed nearer. The diameter of the pupil of Jupiter's inhabitants, then, is to the diameter of our own in a greater proportion than five to twenty-six. Let us suppose it ten to twenty-six. or five to thirteen. The usual height of the earth's inhabitants being about five feet four inches, we con clude that the ordinary height of Jupiter's inhabitants must be fourteen and two-thirds feet. Now this was about the size of Og, King of Bashan, whose bed, according to Moses, was nine cubits long by four wide." We do not know in what treatise on optics Wolff has seen the fact stated that the pupil of the eye is always proportional to its globe, and the latter to the rest of the body, but the simplest observations give the lie to this datum, upon which rests the whole superstructure of the fourteen and two-thirds foot men reputed to live on Jupi-ter. Thus, no one has seen a whale without being struck with the dis proportion existing between the small size of its eye and the gigantic size of its body. The elephant, so \'onderful on account of its enormous stature, in the same way attracts our notice because of the smallness of its eye, while the same organ of the fly is remarkable for its extremely large size. Has not the tiger, which is inferior to the hog as regards the size of its body, a much more largely developed eye than the latter? Let any one examine the pupil of man and that of the owl, and he will see that in this respect the king of nature is much less favored than the lugubrious bird of darkness. Finally, there are certain insects known whose eyes are infini tely larger than those of the mole, etc. These few remarks will suffice to show that the theory of Wolff is of no account. Huygens is not so dogmatic, and, for that very reason, is much more reasonable in his conjectures as to the stature of Jupiter's inhabitants: “If the proportions of organized bodies,” says he, “are in ratio to the size of these globes, there would be in ' Jupiter and Sa.turn animals ten or fifteen times higher than elephants and longer than whales. Beings endowed with reason would be there of a stature more than gigantic. All this might indeed be possible, but we have no means of proving it. Nature is in no way bound to follow measurements and proportions, which, in our estimation, might seem just and reasonable. Thus, the size of the planetary globes has not been regulated according to their distance from the sun, for Mars is evidently smaller than Venus, although much more distant from the solar orb.” Certain conditions might even lead us to think that Jupiter's inhabitants are not larger, but smaller, than we; for we are taught by what we know of the force of gravity at the surface of that planet that a man of our stature transported to Jupiter would weigh there two and a half times more than he did here, and would be greatly oppressed by his own weight. Life would be an insupportable burden to him. If we wish to find out what difference of stature would correspond (all things being equal) to our muscular activity, we will remark that the weight of bodies increases as the cube of the height, or, in other words, a body twice the height of another one weighs eight times as much. But the muscular strength of living beings does not increase in the same proportion, for it varies as the square of the section of the muscles; or, to state it in another way, of two animals similarly constituted, but one twice as large as the other, the larger of the two will be four times the stronger; but, as it would weigh eight times more, it would consequently be half less active. In a like manner, a being three times as large as another of the same conformation would possess only a third of its activity. Now, since a terrestri'al man transported to Jupiter would be two and a half times heavier than he would here, it plainly follows that a Jovian proportioned like a terrestrial would only possess an equal amount of activity with ourselves, provided he weighed two and a half times less than we. In admitting, then, Fix feet as the maximum stature of terrestrial men, we see that the best- developed men of Jupiter—its grenadiers and its giants— would be only two and a half feet tall; and that General Tom Thumb would there cut an entii ely different figure from that that he does here, since he would be able to “pose,” on the contrary, like a drum-major at the head of a liliputian regiment. The absurdity of these different conclusions is enough to convince us that our premises are erroneous, and that we must take care not to measure the inhabitants of other worlds according to the more or less incomplete conceptions that the forms of terrestrial life may suggest to us. It is, on the contrary, very natural for us to assume that nature has peopled other worlds with creatures as different one from another as the insect is from tho quadruped, and still more so, since here essential differences of composition are concerned. Let us not assume for all that, with certain authors, that the inhabitants of Jupiter are gelatinous creatures, floating like medusm in the lower strata of its thick atmosphere; for all the forms that it would be possible for us to imagine would be at once grotesque and insignificant. But one of the best of reasons that we have for not trying to guess how the inhabitants of this vast w orld are made is that it is very probable that they do not as yet exist, and that this celestial globe is not yet actually inhabited by human beings. Its meteorological condition, as we observe it from here, shows us that this planet's atmosphere undergoes greater variations than those which would be produced by the action of the sun alone. This world, in fact, receives twenty-seven times less heat from the sun than we do, and yet it appears to be at least as warm as the earth, and as varied in its meteorology; and its surface does not even seem to have reached that state of fixidity and stability that the earth has at the present day. Since the invention of telescopes has permitted us to distinguish the shape of Jupiter clearly, we see upon its disk grayish markings in the form of nearly parallel bands. Their number, their positions, and their dimensions do not always remain the same; sometimes as many as eight have been observed, while at other times a single one was perm a- nent. The latter, the largest of all, and nearly always visible, is situated in the northern hemisphere and very near the center of the planet. Another dark belt, situated in the southern hemisphere, and likewise near the center, is likewise nearly permanent. The principal ' belts are almost always parallel to Jupiter's equator. The nearly constant parallelism of the belts with respect to the equator and the latitudes of the planet is explained by the rotatory motion, and the angular velocity of this motion, which is considerable. By virtue of this very motion, it will be seen that if there are fluid, liquid, or gaseous matters on the surface of Jupiter, the velocity with which they are carried onward will tend to arrange them in long belts such as we observe; and, as the absolute velocity is greatest at the equator, these masses must accumulate in the largest proportion at that region. The brilliant belts and the polar regions of Jupiter, whoselight exceeds that of the pale or yellowish belts, are the zones in which this planet's atmosphere is most charged with clouds. The pale bands correspond with the regions in which the atmosphere, in a perfectly clear state, allows the solar rays to reach the surface of the planet, where reflection is not so strong as it is upon the clouds. The explanation of the luminous and dark belts is quite satisfactory, if we regard the brilliant zones as masses of clouds, and the others as transparent parts of the atmosphere. But is it the solid part of Jupiter that we perceive through the latter, and, if so, what are the darker and more or less permanent spots which have served to measure its rotation? The first series of observations was begun by Cassini in the month of July, 1665. The spot observed by this astronomer was black and appeared to be adherent to the southern belt; and it gave him 9 hours and 56 minutes as the time of the planet's rotation. Later on, in 1672, analogous observations of a spot which the same astronomer believed to be identical with the one that he had observed in Italy, gave him 9 hours 55 minutes and 51 seconds as the period of rotation. On resuming this interesting research II 1677 he reached the conclusion that the time of rotation was 9 hours 55 minutes and 50 seconds. But this splendid harmony disappeared in 1690; for, having at that time observed a spot which seemed to be adherent to the southern belt near the center, he found the time to be 9 hours and 51 minutes. This result, so different from the first ones, was confirmed in 1691 by the observation of two brilliant spots situated on the dark belt nearest the center and toward the north, and also by a dark spot situated between the two central bands. In 1692 the spots gave only 9 hours and 50 minutes as the time of rotation. The important differences of these various results had already led to the supposition that the spots are clouds floating II an extremely troubled atmosphere, and that the nearer their position to the center of the planet the more rapid their motion. In 1778 Sir William Herschel devoted himself to an attentive observation of the motion of a dark spot that he had remarked upon an equatorial zone, and drew the conclusion therefrom that the period of rotation varied between 9 hours 54 minutes and 53 seconds, and 9 hours 55 minutes and 40 seconds. In 1779, a clear spot, also equatorial, gave the same observer at one time 9 hours 51 minutes and 45 seconds, and at another 9 hours 50 minutes and 48 seconds. Herschel explained the great differences of all these observations by the peculiar movements of the spots. He also believed that there existed winds analogous to our trade-winds in the equinoctial regions of the planet. Afterward came the observations of Beer and Madler in 1834. _ These astronomers found themselves in the same position as those who had made observations before them; the spots which they followed up were not fixed regions, but, according to all appearances, products of the atmosphere, analogous to clouds. Their proportional size, their intensity, and their stability essentially distinguished tbem, it is true, from terrestrial clouds; but the year of Jupiter, which is longer than ours, the small variations in the seasons, and the denser atmosphere of that planet, explain these differences perfectly, and the more since its enormous gravity must prove an important obstacle to any atmospheric movement. Nevertheless, although the spots are not fixed, they may serve to indicate approximately the planet's rotatory motion. On combining all the aspects that had been observed, these two astronomers found that the mean value of rotations that had been thus determined was 9 hours 55 minutes and 26^ seconds. Since the year 1873 especially, I have diligently observed I the same planet at its four successive periods of opposition, i and every year have made thirty drawings of it. From this 1 I have been led to the conclusion that it is impossible to ex- | plain the movements of the spots if we suppose a uniform rotation. From the irregularities of the belts I have calcu- i lated the rotation to be 9 hours 54 minutes and 30 seconds I at the equator, and 9 hours 55 minutes and 45 seconds to- I ward 35° of latitude; and, moreover, I have discovered a peculiar motion of several white spots, independent of the rotatory motion, sometimes more rapid and sometimes less, and which shows that these are upper clouds that are sometimes driven by a west wind and at others by an east one. The probable time of the globe's rotation, then, is, in round numbers, 9 hours and 55 minutes. From these comparisons it may be concluded with certainty that the time of rotation of Jupiter's atmosphere is not the same in all latitudes, and that it is more rapid at the equator than on each side of it. This also happens with regard to the sun, whose period of rotation is 24 days 22 hours and 11 minutes at the equator; 25 days 17 hours and 8 minutes at 20' of north latitude, and 27 days 10 hours and 41 minutes at 60° of the same latitude. This immense planet, then, has a rotatory motion which is twice as swift as that of the earth; and the duration of its day and night, instead of being 24 hours, is not even 10. The time between the rising and setting of the sun is only 4 hours and 57 minutes, and at all times the night is still shorter owing to twilights. Since, on another hand, Jupiter,s year i s equal to nearly twelva of ours, the shortness of the. days gives the inhabitants of that planet 10,455 days II their annual calendar! The velocity of this motion is such that a point situated at the equator moves at the rate of about 8 miles per second, twenty-six times swifter than a like point at the terrestrial equator. It is this velocity of rotation that has led to the flattening of the planet's poles, and it is this evidently, too, that produces the belts of Jupiter. This planet is the one of our whole system which enjoys the most regular and uniform seasons, for it revolves on an axis almost perpendicular to its orbit. The result is that the sun deviates very little : from the planet's equator, and thus nature is maintained in a state of perpetual spring. The temperate zone occupies ! almost the total surface of the two hemispheres, so that a : perpetual equinox reigns therein; that the duration of day and night is the same in all respects for each latitude, and i that the temperature of each climate is invariable. In spite of this, the aspect of the planet varies extraordi- i narily from one year to another. Sometimes the belts are broad and separated, and sometimes, on the contrary, they : ar') narrow and close together. Occasionally their edges ; are ragged like these of broken-up clouds, then again they ; assume the form of a pefectly straight line. Luminous white ; spots have been seen fioatmg above the atmospheric belts, i and sometimes, too, round luminous points analogous to satellites; and dark stripes have also been observed crossing the belts obliquely and lasting for a long time. Finally, : the variableness of this world is such that it offers to the : observer and thinker one of the most novel and interesting i problems of planetary astronomy. These atmospheric disturbances may nevertheless take i : | place in the immense aerial envelope of Jupiter without the surface of the planet being, for all that, itself in a corresponding state of instability. This surface we rarely or never see through the clear spaces, which, to us, appear dark. It is probable that this globe, although created before the earth, has preserved its pristine heat much longer by reason of its volume and mass. Is this characteristic heat sufficiently intense to prevent all manifestations of life? And is this globe still at the present time, not in the state of a luminous sun, but in the condition of a dark and burning one, entirely liquid, or scarcely covered with a first hardened crust, as the earth was before life began to appear on its surface? Or, indeed, is this colossal planet in that condition of temperature through which our own world passed during the primary period of its geological epochs, when life began to show itself under strange forms, as animal and beings of astonishing vitality, amid the convulsions and tempests of the.new-born world? The last is the most rational conclusion that we can draw from the most recent and exact observations to which we are indebted for what we know of the present state of this vast world. Whether Jupiter be inhabited now, whether it was yesterday, or whether it will be to-morrow, is of little consequence to the grand, eternal philosophy of nature. Life is the object of its formation, as it was that of the earth's formation. Therein is everything; the moment, the hour, is of no account. Doubtless this planet may now be inhabited by beings different from us; living, perhaps, in an aerial condition in the upper regions of its atmosphere, above the fogs and vapors of the lower strata; feeding on the aerial fluid itself; resting on the wind like the eagle in the tempest; and ever dwelling in the upper heights of the Jovian heaven. That would not be a disagreeable abode, although an antiterres trial one; indeed, it would be like the abode of old Jupiter Olympius and his court. But if we do not wish, in our conception of life, to stray too far from the borders of the terrestrial cradle, there is nothing to prevent us from waiting until the planet has become cool, like our own, and enjoys a purified atmosphere, which will permit of its being compared with the earth. And what world would be better prepared to be the abode of a superior life? It is the preponderant globe of the whole solar family, the vastest in surface, the most important as regards mass, the most favored through the position of its axis, the most uniform in its course, rich in the possession of four satellites, and throned like a chief amid the planetary orbits. What marvelous conditions are prepared in this abode for the development of life, intelligence, and happiness! Ah, how much superior will such a humanity be to ours! Happy shores of Jupiter! You will not know those distresses and sorrows at which the unhappy countries of our earth are still shuddering! You will not be moistened with the blood of martyrs, which has been so many times shed here in the name of so many contradictory gods! You will not bear tumultuous armies of brothers, who periodically slaughter each other at the order of a few infamous pot en- tatesl You will not be defiled by the crimes that hunger, ambition, or pride is committing every day here below ! But you will prepare in the heavens the United States of an immense republic, blessed of the Creator, floating calmly in the luminous ether, bathed in the tepid temperature of an eternal spring, without winter and without summer, and slowly growing, in the breast of peace and harmony, toward a state of perfection which our imperfect and miserable littie planet will never approach! I It is impossible for us to imagine that the existence of the i stars can have any other object than that of receiving or of 'giving life. Life! Such is the grand obj'ect which we see shining in the destinies of the creation. The absence of life is to us a synonym for death and nothingness. Our logic refuses to believe that the millions of suns which are burning in infinite space are of no use, and that they neither illumine, warm, nor govern anything. And, if they are useful for something, for us this “ something “ is life, under whatever form it De, from the simplest blade of grass up to the highest, most intelligent, most powerful mind. This declaration, which is forced upon us by our own logic, is also the declaration of entire nature, whose unlimited fecundity has sown life around us on every spot capable of receiving it; whose singular foresight gives things and beings even a double and multiple purpose for existence; who produces several effects through the same cause; and who goes so far as to accumulate life at the expense of living beings themselves. If the gigantic world of Jupiter is now undergoing those conditions of temperature that marked the primitive epochs of the earth, we cannot consider it as being at present the | seat of intellectual life. It is the land of the Ichthyosaurus, ! but not that of man; not the calm and tranquil world which , is necessary for the manifestations of a delicate, nervous j system and of contemplative thought. It is only later an, in future ages, that Jupiter will be inhabited by an intellectual race; and who knows whether, perhaps, it may not be by | ourselves! Its situation, then, will be incomparably superior | to that of the earth: an immense empire, a perpetual spring, : long years, and a mild, unvarying temperature will form an ! abode of peace and happiness truly worthy of our ambition and our hopes. i This maj'estic world travels in space, accompanied by four ' enormous satellites. In what condition are these four worlds? Are they not themselves, and have they not been for a long time, the seat of organic life, and even of an intellectual one? Does not Jupiter's globe furnish them with a modicum ' of heat, and is it not to them a scarcely extinct sun? The ' superior volume and mass of this planet, as it moves on, sur- I rounded by these satellites, is a reproduction of the image | of the sun itself, in the midst of his four nearest planets— I Mercury, Venus, Mars, and the earth; for the distances and relative volumes of Jupiter's four satellites form a system which is singularly analogous to that of the four first planets of the great solar system. Each one of the four worlds of the Jovian system has its special years, its days, and doubtless, also, its seasons; and the inhabitants of each of them have the same reasons for believing themselves at the center of the entire universe, as the inhabitants of our little earth, who, during so many ages, have dreamed the same dream. To them Jupiter's globe has the aspect of a gigantic moon, which is capable of effectually compensating for the small quantity of light that they receive from the sun. Regarded from the first of the satellites,'tliis immense globe appears 1,400 times greater in surface than our full moon. What a Colossus! Even from the outermost satellite the apparent surface of Jupiter still exceeds by 75 times that which the moon exhibits to us. What magnificent sights are to be contemplated from these observatories! Colossal Jupiter is the most marvelous ob ject of their heavens; to them he is the sovereign of the urn- verse—the true Jupite——and they admire him no less than we admire the sun. For, to them, the sun is only a small, brilliant disk, while, viewed from the first satellite, the immense globe of Jupiter exceeds it by 35,000 times. Let us add the magic colorations which decorate this disk with glowing tints, from orange and red to violet and purple; let us add, also, the rapid changes in appearance produced by its rotatory motion, and we shall have an approximate idea of the magnificence of the pictures of nature as seen from these four worlds as they are carried along by the giant star into the far-off depths of immensity! And now a last question, and one of personal interest: What effect does the earth produce as seen from up yonder? Assuredly a very ordinary effect as regards our vanity. It is very probable that the inhabitants of Jupiter and the planets beyond consider the region of the solar system in which we live as empty. If Jupiter and the earth were to exchange situations the inhabitants of the former would see our globe as a pale star of the sixth magnitude, and scarcely perceptible to the naked eye—j'ust as Uranus appears to us. But, in the position that we occupy with respect to Jupiter, the earth, at the moment of its conjunction, is, like Venus, subjected to phases which render thewhole or the greater part of its disk invisible. Almost always lost amid the solar rays, it would appear like a black point, when an observer on Jupiter chanced to see it pass across the disk of the sun, and not, as Fontenelle supposed, with the aspect of a star visible at night. This little black point has not as much importance, in the eyes of the inhabitants of Jupiter, as that which Mr. Bismarck attaches to the momentary possession of one of his minute provinces, and, were it known on this far distant world that certain philosophers of the little black point had assumed that the whole universe was created and put in the world on purpose for them, there is reason to believe that the whole population of the four worlds of Jupiter would be seized with a fit of laughter worthy of being sung by a Homer, and that the uproar produced would be so great that it might well be heard from here.
This article was originally published with the title "The Giant of the Worlds"