Part 6
If a terrible explosion occurred in this star, and if the sound could traverse the void which separates it from us, this sound would take more than three millions of years to reach us.
It is marvelous that we can perceive the stars at such a distance. What an admirable transparency in these immense spaces to permit the light to pass, without being wasted, to thousands of billions of miles! Around us, in the thick air which envelops us, the mountains are already darkened and difficult to see at seventy miles; the least fog hides from us objects on the horizon. What must be the tenuity, the rarefaction, the extreme transparency of the ethereal medium which fills the celestial spaces!
Let us suppose ourselves, then, on the sun nearest to ours. From there our dazzling furnace is already lost like a little star, hardly recognizable among the constellations: earth, planets, comets sail in the invisible. We are in a new system. If we thus approach each star we find a sun, while all the other suns of space are reduced to the rank of stars. Strange reality!—the normal state of the universe is night. What we call day only exists for us because we are near a star.
The immense distance which isolates us from all the stars reduces them to the state of motionless lights apparently fixed on the vault of the firmament. All human eyes, since humanity freed its wings from the animal chrysalis, all minds since the minds have been, have contemplated these distant stars lost in the ethereal depths; our ancestors of Central Asia, the Chaldeans of Babylon, the Egyptians of the Pyramids, the Argonauts of the Golden Fleece, the Hebrews sung by Job, the Greeks sung by Homer, the Romans sung by Virgil—all these earthly eyes, for so long dull and closed, have been fixed from age to age on these eyes of the sky, always open, animated, and living. Terrestrial generations, nations and their glories, thrones and altars have vanished: the sky of Homer is always there. Is it astonishing that the heavens were contemplated, loved, venerated, questioned, and admired even before anything was known of their true beauties and their unfathomable grandeur?
Better than the spectacle of the sea calm or agitated, grander than the spectacle of mountains adorned with forests or crowned with perpetual snow, the spectacle of the sky attracts us, envelops us, speaks to us of the infinite, gives us the dizziness of the abyss; for, more than any other, it seizes the contemplative mind and appeals to it, being the truth, the infinite, the eternal, the all. Writers who know nothing of the true poetry of modern science have supposed that the perception of the sublime is born of ignorance, and that to admire it is necessary not to know. This is assuredly a strange error, and the best proof of it is found in the captivating charm and the passionate admiration which divine science now inspires, not in some rare minds only, but in thousands of intellects, in a hundred thousand readers impassioned in the search for truth, surprised, almost ashamed at having lived in ignorance of and indifference to these splendid realities, anxious to incessantly enlarge their conception of things eternal, and feeling admiration increasing in their dazzled minds in proportion as they penetrate further into Infinitude. What was the universe of Moses, of Job, of Hesiod, or of Cicero, compared to ours! Search through all the religious mysteries, in all the surprises of art, painting, music, the theatre, or romance, search for an intellectual contemplation which produces in the mind the impression of truth, of grandeur, of the sublime, like astronomical contemplation! The smallest shooting star puts to us a question which it is difficult not to hear; it seems to say to us, What are we in the universe? The comet opens its wings to carry us into the profundities of space: the star which shines in the depths of the heavens shows us a distant sun surrounded with unknown humanities who warm themselves in his rays. Wonderful, immense, fantastic spectacles, they charm by their captivating beauty and transport into the majesty of the unfathomable the man who permits himself to soar and wing his flight to Infinitude.
Nel ciel che più della sua luce prende Fu’ io, e vidi cose che ridire Né sa, né può qual di lassù discende.
“I have ascended into the heavens, which receive most of His light, and I have seen things which he who descends from on high knows not, neither can repeat,” wrote Dante in the first canto of his poem on “Paradise.” Let us, like him, rise toward the celestial heights, no longer on the trembling wings of faith, but on the stronger wings of science. What the stars would teach us is incomparably more beautiful, more marvelous, and more splendid than anything we can dream of.
[Illustration: Chart of the Northern Constellations
Showing the principal Stars of the first five magnitudes visible to the naked eye]
Among the innumerable army of stars which sparkle in the infinite night, the gaze is especially arrested by the most brilliant lights and by certain groups which vaguely present a mysterious bond between the worlds of space. These groups have been noticed at all epochs, even among the rudest races of men, and from the earliest ages of humanity they have received names, usually derived from the organic kingdom, which give a fantastic life to the solitude and the silence of the skies. Thus were early distinguished the seven stars of the North, or the Chariot, of which Homer speaks; the _Pleiades_, or the “_Poussinière_”; the giant _Orion_; the Hyades in the head of Taurus; _Boötes_, near the Chariot or Great Bear. These five groups were already named more than 3,000 years ago, and so were the brightest stars of the sky, _Sirius_ and _Arcturus_, etc.
The epoch of the formation of the constellations is unknown, but we know that they were established successively. The centaur Chiron, Jason’s tutor, has the reputation of having first divided the sky on the sphere of the Argonauts. But this is mythology; and, besides, Job lived before the epoch at which Chiron is supposed to have flourished, and Job had already spoken of Orion, the Pleiades, and the Hyades 3,000 years ago. Homer also speaks of these constellations in describing the famous shield of Vulcan. “On its surface,” says he, “Vulcan, with a divine intelligence traces a thousand varied pictures. He represents the earth, the heavens, the sea, the indefatigable sun, the moon at its full, and all the stars which wreath the sky: the Pleiades, the Hyades, the brilliant Orion, the Bear, which they also call the Chariot, and which revolves round the pole; this is the only constellation which does not dip into the ocean waves” (_Iliad_, chapter xviii.).
Several theologians have affirmed that it was Adam himself, in the terrestrial paradise, who gave their names to the stars; the historian Josephus assures us that it was not Adam, but his son Seth, and that in any case astronomy was cultivated long before the Deluge. This nobility is sufficient for us.
Attentive observation of the sky also noticed from the beginning the beautiful stars _Vega_ of the Lyre, _Capella_ of Auriga, _Procyon_ of the Little Dog, _Antares_ of the Scorpion, _Altair_ of the Eagle, _Spica_ of the Virgin, the _Twins_, the _Chair_ of Cassiopeia, the Cross of the White _Swan_, stretched in the midst of the _Milky Way_. Although noticed at the epoch of Hesiod and Homer, these constellations and stars were probably not yet named, because doubtless men had not yet felt the necessity of registering them for any application to the calendar, to navigation, or to voyages.[7]
At the epoch when the maritime power of the Phœnicians was at its apogee, about 3,000 years ago, or twelve centuries before our era, it was the star β of the Little Bear which was the nearest bright star to the pole, and the skilful navigators of Tyre and Sidon (O purpled kings of former times! what remains of your pride?) had recognized the seven stars of the Little Bear, which they named the Tail of the Dog, _Cynosura_; they guided themselves by the pivot of the diurnal motion, and during several centuries they surpassed in precision all the mariners of the Mediterranean. The Dog has given place to a Bear, doubtless on account of the resemblance of the configuration of these seven stars to the seven of the Great Bear, but the tail remains long and curled up, in spite of the nature of the new animal.
Thus the stars of the North at first served as points of reference for the first men who dared to venture on the seas. But they served at the same time as guides on the mainland for the nomadic tribes who carried their tents from country to country. In the midst of savage nature, the first warriors themselves had nothing but the Little Bear to guide their steps.
Imperceptibly, successively, the constellations were formed. Some groups resemble the names which they still bear, and suggested their denomination to the men of ancient times, who lived in the midst of nature and sought everywhere for relations with their daily observations. The Chariot; the Chair; the Three Kings, also named the Rake; Jacob’s Staff and the Belt of Orion; the Pleiades, or the Hen and Chickens; the Arrow (Sagitta); the Crown; the Triangle; the Twins; the Dragon; the Serpent; and even the Bull, the Swan, the Giant Orion, the Dolphin, the Fishes, the Lion, Water and Aquarius (the Water-bearer), etc., have given rise to the analogy. These resemblances are sometimes vague and far-fetched, like those we find in the clouds; but it appears much more natural to admit this origin than to suppose, with the classic authors, that these names were suggested by the concordance between the seasons or the labors of the fields and the presence of the stars above the horizon. That the name of the Balance (Libra) was given to the constellation of the equinox because then the days are equal, seems to us more than questionable; that Cancer (the Crab) signifies that the sun goes back to the solstice, and that the Lion has for its object to symbolize the heat of summer, and Aquarius the rain and inundations, appears to us no less imaginary. However, they have also had other origins. Thus, the Great Dog Sirius certainly announced the rising of the Nile and the dog-days (which remain in our calendar as a fine type of anachronism). Poetry, gratitude, the deification of heroes, mythology, afterward transferred to the sky the names of personages and sovereigns—Hercules, Perseus, Andromeda, Cepheus, Cassiopeia, Pegasus; later, in the Roman epoch, they added the Hair of Berenice and Antinous; later still, in modern times, they added the Southern Cross, the Indian, the Sculptor’s Workshop (Cœlum), the Lynx, the Giraffe (Camelopardus), the Greyhounds (Canes Venatici), the Shield of Sobieski, and the little Fox (Vulpecula). They even placed in the sky a Mountain, an Oak, a Peacock, a Swordfish, a Goose, a Cat, a Crane, a Lizard, and a Fly, for which there was no necessity.
This is not the place to describe and draw in detail all these constellations, with their more or less strange figures. The important point for us here is to form a general idea.
The sky remains divided into provinces, each of which continues to bear the name of the primitive constellation. But it is important to understand that the positions of the stars themselves, as we see them, are not absolute, and that the different configurations which they may show us are only a matter of perspective. We already know that the sky is not a concave sphere on which brilliant nails could be attached; that it is not a species of vault; that an immense infinite void envelops the earth on all sides, in all directions. We know also that the stars, the suns of space, are scattered at all distances in the vast immensity. When, therefore, we remark in the sky several stars near each other, that does not imply that these stars form the same constellation, that they are on the same plane, and at an equal distance from the earth. By no means; the arrangement which they assume to our eyes is but an appearance caused by the position of the earth relatively to them. This is a mere matter of perspective. If we could leave our world, and transport ourselves to a point in space sufficiently distant, we should see a variation in the apparent arrangement of the stars so much the greater as our station of observation were more distant from where we are at present. A moment’s reflection is sufficient to convince us of this fact, and save us from insisting further on this point.
Once these illusions are appreciated at their true value, we can begin the description of the figures with which the ancient mythology has constellated the sphere. A knowledge of the constellations is necessary for the observation of the heavens and for the researches which a love of the sciences and curiosity may suggest; without it we find ourselves in an unknown country, of which the geography has not been made, and where it would be impossible to know our exact position. Let us make, then, this celestial geography; let us see how to find our way, in order to read readily in the great book of the heavens.
There is a constellation which everybody knows; for greater simplicity we will begin with it. It will serve us well as a point of departure from which to go to the others, and as a point of reference to find its companions. This constellation is the _Great Bear_, which has also been named the _Chariot of David_.
It may well boast of being celebrated. If, notwithstanding its universal notoriety, some of our readers have not yet made its acquaintance, the following is a description by which they may recognize it.
[Illustration: Fig. 2]
Turn yourself toward the north—that is to say, opposite to the point where the sun is found at noon. Whatever may be the season of the year, the day of the month, or the hour of the night, you will always see there a large constellation formed of seven fine stars, of which four are in a quadrilateral, and three at an angle with one side; all are arranged as we see in Fig. 2.
You have all seen it, have you not? It never sets. Night and day it watches above the northern horizon, _turning slowly_ in twenty-four hours round a star of which we shall speak directly. In the figure of the Great Bear, the three stars of the extremity form the tail, and the four in the quadrilateral lie in the body. In the Chariot, the four stars of the quadrilateral form the wheels, and the other three the pole, the horses, or the oxen. Above the second of these latter stars, ζ, good sight distinguishes quite a little star named Alcor, which is also called the Cavalier. It serves to test the power of the sight. Each star is designated by a letter of the Greek alphabet: α and β mark the first two stars of the quadrilateral, γ and δ the two following, ε, ζ, η, the three of the pole. Arabic names have also been given to these stars, which we will pass in silence, because they are generally obsolete, with the exception, however, of that of the second horse—Mizar. With reference to the Greek letters, many persons think that it would be preferable to suppress them and to replace them by numbers. But this would be impossible in the practice of astronomy; and, moreover, inevitable confusion would result, on account of the numbers which the stars bear in the catalogues.
The Latins gave to plowing oxen the name of _triones_; instead of speaking of a chariot and three oxen, they came to call them the seven oxen (_septemtriones_). From this is derived the word septentrion, and there are now doubtless but few persons who, in writing this word, know that they are speaking of seven oxen. It is the same, however, with many other words. Who remembers, for example, in using the word _tragedy_, that he speaks of a song of a goat: _tragôs-ode_?
Let us go back to Fig. 2. If we draw a straight line through the two stars marked α and β which form the right side of the square, and produce it beyond α to a distance equal to five times that from β to α, or to a distance equaling that from α to the end of the tail, η, we find a star a little less brilliant than at the extremity of a figure similar to the Great Bear, but smaller and pointing in the opposite direction. This is the _Little Bear_, or the _Little Chariot_, also formed of seven stars. The star to which our line leads us—that which is at the tip of the tail of the Little Bear, or at the end of the pole of the Little Chariot—is the _polar star_.
[Illustration: Fig. 3]
The polar star enjoys a certain fame, like all persons who are distinguished from the common, because, among all the bodies which scintillate in the starry night, it alone remains motionless in the heavens. At any moment of the year, by day or by night, when you observe the sky, you will always find it. All the other stars, on the contrary, turn in twenty-four hours round it, taken as the centre of this immense vortex. The pole star remains motionless at the pole of the world, from whence it serves as a fixed point to navigators on the trackless ocean, as well as to travelers in the unexplored desert.
[Illustration: Fig. 4]
In looking at the pole star, motionless in the midst of the northern region of the sky, we have the south behind us, the east to the right, the west to the left. All the stars turn round the pole star in a direction contrary to that of the hands of a watch; they should, then, be recognized according to their mutual relations rather than by reference to the cardinal points.
On the other side of the pole star, with reference to the Great Bear, is found another constellation which we can also recognize at once. If from the middle star, δ, we draw a line to the pole, and produce this line by the same distance (see Fig. 3), we arrive at _Cassiopeia_, formed of five principal stars arranged somewhat like the strokes of the letter M. The little star χ, which completes the square, gives the constellation the form of a _chair_. This group assumes all possible positions in turning round the pole; it is found sometimes above, sometimes below, sometimes to the right, and sometimes to the left; but it is always easily recognized, for, like the preceding group, it never sets, and is always opposite to the Great Bear. The pole star is the axle round which both these constellations turn.
[Illustration: Fig. 5 Fig. 6]
If, now, we draw from the stars α and δ of the Great Bear two lines through the pole, and produce them beyond Cassiopeia, we come to the Square of Pegasus (see Fig. 4), which shows a line of three stars somewhat similar to the tail of the Great Bear. These three stars belong to _Andromeda_, and lead to another constellation, _Perseus_. The last star of the Square of Pegasus is, as we see, the first (α) of Andromeda; the three others are named γ, α, and β. To the north of β of Andromeda is found, near a little star, ν, an oblong nebula, which can be distinguished with the naked eye. In Perseus, α, the brightest—on the prolongation of the three principal stars of Andromeda—appears between two others less brilliant, which form with it a concave arc very easy to distinguish. This arc serves us for a new alignment. Producing it in the direction of δ, we find a very brilliant star of the first magnitude; this is _Capella_ (the Goat). Forming a right angle with this prolongation toward the south we come to the _Pleiades_ (Fig. 5). Not far from that is a variable star, _Algol_, or the _Head of Medusa_, which varies from the second to the fourth magnitude[8] in 2 days, 20 hours, 48 minutes, 51 seconds. We may add, that in this region the star γ of Andromeda is one of the most beautiful double stars (it is even triple).
[Illustration: Fig. 7 Fig. 8]
If, now, we produce beyond the Square of Pegasus (Fig. 6) the curved line of Andromeda, we reach the Milky Way, and we meet in these parts Cygnus, like a cross; the Lyre, where Vega shines (Fig. 7); the Eagle, and Altair (not Atair, as it is sometimes written) with two companions (Fig. 8).
Such are the principal constellations visible in the circumpolar regions on one side; we shall make a fuller acquaintance with them directly. While we are tracing the lines of reference let us still have a little patience and finish our summary review of this part of the sky.
[Illustration: Fig. 9]
Look now at the side opposite to that of which we have just spoken. Let us return to the Great Bear. Producing the tail along its curve, we find at some distance from that a star of the first magnitude, _Arcturus_ (Fig. 9), or α of Boötes. A little circle of stars which we see to the left of Boötes constitutes the _Northern Crown_ (Corona Borealis). In the month of May, 1866, there was seen shining there a fine star, the brightness of which lasted only fifteen days. The constellation of Boötes is traced in the form of a pentagon. The stars which compose it are of the third magnitude, with the exception of Arcturus, which is of the first. This is one of the nearest to the earth; at least, it is one of a small number whose distance has been measured. It shines with a beautiful golden yellow color. The star ε, which we see above it, is _double_—that is to say, the telescope resolves it into two distinct stars, one yellow, the other blue.
[Illustration: Fig. 10.]
This technical description is far from the poetry of Nature; but it is especially important here to be clear and precise. Let us suppose ourselves, however, under the starry vault on a beautiful summer’s night, splendid and silent, and let us consider that each of these points which we seek to recognize is a world, or rather a system of worlds. Look at this equilateral triangle (Fig 10); it permits us to cast our eyes successively on three important suns: Vega of the Lyre, Arcturus of Boötes, and the pole star, which watches above the solitudes of our mysterious North Pole. Many martyrs of science have died looking at it! In twelve thousand years our descendants will see the Lyre at the pole, ruling the harmony of the heavens.
The stars which are near the pole, and which have for that reason received the name of circumpolar stars, are distributed in the groups which have just been indicated. I earnestly invite my readers to profit by fine evenings, and try to find for themselves these constellations in the sky.