Chapter III: Part 3

The figures representing the constellations were originally drawn on spheres, or celestial globes, as they are now called. The ancient astronomers attributed the invention of the sphere to Atlas. It seems certain that a celestial sphere was constructed by Eudoxus in the Fourth Century B. C. Strabo speaks of one made by Krates about the year 130 B. C., and according to Ovid, Archimedes had constructed one at a considerably earlier period. None of these ancient spheres has been preserved. There is, however, in the Vatican a fragment in marble of a Græco-Egyptian planisphere, and a globe in the museum of Arolsen, but these are of much later date. Our knowledge of the original constellation figures is derived from the accounts given by Ptolemy and his successors, and from a few globes which only date back to the Arabian period of astronomy. Among the Arabian globes still existing the most famous is one made of copper, and preserved in the Borgia Museum at Velletri in Italy. It is supposed to have been made by a person called Caisar, who was executed by the Sultan of Egypt in A. D. 1225. The most ancient of all is one discovered some years ago at Florence. It is supposed to date back to A. D. 1081, and to have been made by Meucci. There is also one in the Farnese Museum at Naples, made in A. D. 1225. Of modern celestial globes the oldest is one made by Jansson Blaeu in 1603. This gives all the constellations of the Southern Hemisphere as well as the Northern.

Ptolemy’s figures of the constellations were restored by the famous painter Albert Dürer of Nuremberg in 1515. The figures on modern globes and maps have been copied from this restoration. Dürer’s maps are now very rare.

In 1603, an atlas was published by Bayer. This was the first atlas to show the southern sky, and the first to designate the brightest stars by the letters of the Greek alphabet.[5] Flamsteed published an atlas in 1729. Maps and catalogues of the lucid stars have been published in recent times by Argelander, Behrmann, Heis, Houzeau, Proctor, and others. Of these Heis’s is, perhaps, the most reliable, at least so far as accurate star magnitudes are concerned. Houzeau shows _both_ hemispheres, all the stars had been observed by himself in Jamaica and South America. Behrmann’s maps are confined to the Southern Hemisphere, between the South Pole and 20 degrees south of the Equator. The maps of the _Uranometria Argentina_, made at Cordoba in the Argentine Republic, show all the southern stars to the seventh magnitude, but many of these are beyond the reach of ordinary eyesight.

It is a well-known fact that the planets Venus and Jupiter are bright enough to form shadows of objects on a white background. It has also been found that the brightest stars, especially Sirius, are sufficiently brilliant to cast shadows. Kepler stated that a shadow was formed by even Spica, but I am not aware that this has been confirmed by modern observations.

There are some remarkable collections or clusters of stars visible to the naked eye, of these the Pleiades are probably the best known. To ordinary eyesight 6 stars are visible, but Möstlin, Kepler’s tutor, is said to have seen 14 with the naked eye, and some observers in modern times have seen 11 or 12. Other naked-eye clusters are the Hyades in Taurus, called _Palilicium_ by Halley, and the Præsepe, or Bee-Hive in Cancer. Of larger groups, the Plow or Great Bear, Cassiopeia’s Chair, and Orion are probably known to most people.

Many of the lucid stars are double, that is, consist of two components, but most of these are only visible in powerful telescopes. There are, however, a few objects visible to the naked eye as double, and these have been called “naked-eye doubles,” although not strictly double in the correct sense of the term.

Ptolemy applied the term double to the star ν Sagittarii, which consists of two stars separated by a distance of fourteen minutes of arc, or about half the apparent diameter of the moon. According to Riccioli, Van der Hove saw two naked-eye doubles, one in Capricornus, 5 to 5½ minutes distant, and the other in the Hyades, 4½ or 5 minutes apart. The one in Capricornus was probably α, and the one in the Hyades θ Tauri. The middle star in the tail of the Great Bear, or handle of the Plow, has near it a small star, Alcor, which to many eyes is distinctly visible without optical aid. The famous Belgian astronomer, Houzeau, who seems to have had excellent sight, saw the star χ Tauri double, and 51 and 56 Tauri separated, also ι Orionis, and others.

Many of the stars are variable in their light, and several hundred of these curious and interesting objects are now known to astronomers. In a few of these the light changes may be followed with the naked eye. It is an interesting question whether any of the lucid stars have disappeared or changed in brightness since the early ages of astronomical observations. Al-Sûfi failed to find seven of Ptolemy’s stars, and Ulug Bekh, comparing his observations with the catalogues of Ptolemy and Al-Sûfi, announced twelve cases of supposed disappearance. Some of these may, however, be due to errors of observation. Montanari, writing in 1672, mentions two stars as having disappeared, namely β and γ of the constellation Argo, but these stars are now visible in the positions originally assigned to them.

In a careful examination of Al-Sûfi’s description of the stars written in the Tenth Century, and a comparison with modern estimates and measures, I have found several very interesting cases of apparent change in the brightness of the lucid stars. Al-Sûfi was an excellent and careful observer, and as a rule his estimates agree well with modern observations. We can therefore place considerable reliance on his estimates of star magnitudes. _The Story of Theta Eridani_ has been well told by Dr. Anderson, and there seems to be no doubt that this southern star, which is now only of the third magnitude, was a bright star of the first magnitude in Al-Sûfi’s time! The following are other interesting cases of apparent change which I have met with in my examination of Al-Sûfi’s work. The Pole Star was rated third magnitude by both Ptolemy and Al-Sûfi, but it is now of the second magnitude, or a little less. The star γ Geminorum was rated third magnitude by Ptolemy and Al-Sûfi, or equal to δ Geminorum, but γ is now of the second magnitude, and its great superiority in brightness over δ is noticeable at a glance. Another interesting case is that of ζ and ο Persei, two stars which lie near each other, about seven degrees north of the Pleiades. Al-Sûfi distinctly describes these stars as _both_ of the 3—4 magnitude; but Argelander, Heis, and the photometric measures at Harvard agree in making ζ about one magnitude brighter than ο. The stars being close are easily compared, and their present great difference in brightness is very noticeable. This is one of the most remarkable cases I have met with in Al-Sûfi’s work, and strongly suggests variation in ο, as ζ is still about the same brightness as Al-Sûfi made it. The identity of the stars is beyond all doubt, as Al-Sûfi describes their positions very clearly, and says there is no star between them and the Pleiades, a remark which is quite correct for the naked eye. The remarkable decrease in brightness of β Leonis (Denebola) since Al-Sûfi’s time has been considered in my paper on _Some Suspected Variable Stars_. That it was a bright star of the first magnitude is fully proved by the observations of Al-Sûfi and Tycho Brahe. These were careful and accurate observers, and they could not have been mistaken about a star of the first magnitude. β Leonis is now fainter than an average star of the second magnitude, and there can be no reasonable doubt that it has faded considerably since the Tenth Century.

There are some other discrepancies between Al-Sûfi’s observations and modern estimates, but the above are perhaps the most remarkable. With reference to lucid stars not mentioned by Al-Sûfi, he has not, I think, omitted any star brighter than the fourth magnitude in that portion of the sky visible from his station. There are, however, a number of stars between the fourth and sixth magnitudes which he does not mention. Of these the brightest seem to be ε Aquilæ, ρ and μ Cygni, and ζ Coronæ Borealis.

With reference to the distribution of the lucid stars in the sky there seems to be a well-marked tendency to congregate on the Milky Way. It is a remarkable fact that of the 15 brightest stars in the heavens, no less than 11 lie on or near the Milky Way, although the space covered by the Galaxy does not exceed one-fifth or one-sixth of the whole sky. From a careful enumeration of the stars in or near the Milky Way which I made some years ago, I found that of stars brighter than the fourth magnitude there are 118 on the Milky Way out of a total of 392, or about 30 per cent. From the Southern catalogue known as the _Uranometria Argentina_, Colonel Markwick, F.R.A.S., found 121 out of 228 stars to fourth magnitude, or a percentage of 53 per cent. These results seem to show some intimate relation between the lucid stars and the Galaxy.

FOOTNOTES:

[4] Except concave spectacles used by short-sighted persons.

[5] This custom has since prevailed. The following are the letters and their names:

α Alpha η Eta ν Nu τ Tau
β Beta θ Theta ξ Xi υ Upsilon
γ Gamma ι Iota ο Omicron φ Phi
δ Delta κ Kappa π Pi χ Chi
ε Epsilon λ Lambda ρ Rho ψ Psi
ζ Zeta μ Mu σ Sigma ω Omega

THE CONSTELLATIONS.—CAMILLE FLAMMARION

The earth is forgotten, with its small and ephemeral history. The sun himself, with all his immense system, has sunk in the infinite night. On the wings of inter-sidereal comets we have taken our flight toward the stars, the suns of space. Have we exactly measured, have we worthily realized the road passed over by our thoughts? The nearest star to us reigns at a distance of 275,000 times 37 millions of leagues—that is to say, at ten trillions[6] of leagues (about twenty-five billions of miles); out to that star an immense desert surrounds us, the most profound, the darkest, and the most silent of solitudes.

The solar system seems to us very vast, the abyss which separates our world from Mars, Jupiter, Saturn, and Neptune appears to us immense; relatively to the fixed stars, however, our whole system represents but an isolated family immediately surrounding us: a sphere as vast as the whole solar system would be reduced to the size of a simple point if it were transported to the distance of the nearest star. The space which extends between the solar system and the stars, and which separates the stars from each other, appears to be entirely void of visible matter, with the exception of nebulous fragments, cometary or meteoric, which circulate here and there in the immense voids. Nine thousand two hundred and fifty systems like ours (bounded by Neptune), would be contained in the space which isolates us from the nearest star!

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.

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.

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_.

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.

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.

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).

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.

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.

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.

We have here the principal stars and constellations of the Northern Hemisphere, the North Pole being at the centre of the circle. We come now in the order of our description to the twelve constellations of the zodiacal belt, which makes the circuit of the sky, inclined at 23° to the Equator, and of which the ecliptic, the apparent path of the sun, forms the centre line.

The name of zodiac, given to the zone of stars which the sun traverses during the course of the year, comes from ζώδια, _animals_, an etymology which is due to the species of figures traced on this belt of stars. Animals, in fact, predominate in these figures. The entire circumference of the sky has been divided into twelve parts, which have been named the twelve signs of the zodiac; our ancestors called them the “houses of the sun,” or “the monthly abodes of Apollo,” because the day star visits them each month, and returns every spring to the beginning of the zodiacal city. Two memorable Latin verses of the poet Ausonius present to us these twelve signs in the order in which the sun travels through them, and this still appears the easiest method of learning them by heart.

Sunt _Aries_, _Taurus_, _Gemini_, _Cancer_, _Leo_, _Virgo_,
_Libraque_, _Scorpius_, _Arciteneus_, _Caper_, _Amphora_, _Pisces_;

or, in English, the Ram ♈︎, the Bull ♉︎, the Twins ♊︎, the Crab ♋︎, the Lion ♌︎, the Virgin ♍︎, the Balance ♎︎, the Scorpion ♏︎, the Archer ♐︎, Capricornus ♑︎, Aquarius ♒︎, and the Fishes ♓︎. The signs placed beside these names are a vestige of the primitive hieroglyphics which described them: ♈︎ represents the horns of the Ram, ♉︎ the head of the Bull; ♒︎ is a stream of water, etc.

If we now know our northern sky, if its most important stars are sufficiently noted down in our mind, with the reciprocal relations which they preserve among themselves, we have no more confusion to fear, and it will be easy to recognize the zodiacal constellations. This zone may be of use to us as a line of division between the north and the south. Here is a description of it:

The Ram, which, moving in front of the herd, and regulating, so to
say, the march, opens the series. This constellation has in itself
nothing remarkable; the brightness of its stars indicates the
base of one of the horns of the leader of the sheep; it is but of
the second magnitude. After the _Ram_ comes the Bull. Admire on a
fine winter’s night the charming Pleiades which scintillate in the
ether; not far from them shines a fine red star—this is the _eye_
of the Bull—Aldebaran, a star of the first magnitude and one of
the finest of our sky. We now arrive at the Twins, whose heads are
marked by two fine stars of the second magnitude, situated a little
above a star of the first magnitude—_Procyon_, or the Little Dog;
_Cancer_, or the Crab, a constellation very little conspicuous (its
most visible stars are but of the fourth magnitude, and occupy the
body of the animal); the _Lion_, a fine constellation, marked by a
star of the first magnitude, _Regulus_, by one of the second, β,
and by several others of the second and third magnitudes arranged
in a trapezium; the _Virgin_, indicated by a very brilliant star
of the first magnitude; _Spica_, situated in the neighborhood
of a star, also of the first magnitude, Arcturus, which is found
on the prolongation of the tail of the Great Bear; the _Balance_
(Libra), indicated by two stars of the second magnitude, which
would exactly resemble the Twins if they were nearer to each
other; the _Scorpion_, a remarkable constellation; a star of the
first magnitude, of a fine red color, marks the _Heart_ (Antares),
in the middle of two stars of the third magnitude, above which
are three bright stars arranged in a diadem; _Sagittarius_, the
Archer, of which the arrow, indicated by three stars of the
second and third magnitudes, is pointed toward the tail of the
Scorpion; _Capricornus_, a constellation not conspicuous, which
is recognized by two stars of the third magnitude very near each
other, and representing the base of the horns of the hieroglyphic
animal; _Aquarius_, indicated by three stars of the third magnitude
arranged in a triangle, of which the most northern occupies a
point on the equator; _Pisces_, the _Fishes_, composed of stars,
barely conspicuous, of the third to fourth magnitudes, situated to
the south of a large and magnificent quadrilateral—the Square of
Pegasus—of which we have already spoken.

We have now enumerated the zodiacal constellations in the order of the direct motion (from west to east) of the sun, moon, and planets which traverse them. They marked at the epoch of their formation, the monthly passage of the sun into each of them. The distribution of the stars in figurative groups was the first truly hieroglyphical writing; it was engraved on the firmament in indelible characters.

The zodiac has played a great part in the ancient history of every nation—in the formation of the calendar, in the appointment of public festivals, and in the constitution of eras. The zodiac of Denderah, discovered by the French _savants_ in Egypt at the end of the Eighteenth Century, was at first believed to have an antiquity of 15,000 years; but it is now proved that it is necessary to deduct from that number of years half the cycle of precession—that is to say, nearly 13,000 years—which brings down the date of this sculpture to 2,000 years before our epoch; and this in fact corresponds with the evidence of archæology. It is remarkable that all the ancient zodiacs and calendars which have been preserved to us begin the year with the constellation of the Bull, as we have already noticed. The zodiac of the Elephanta Pagoda (Salsette) has at the head of the procession the sign of the sacred Bull, the ox Apis, Mithra—of which the promenade of the fat ox, which is still performed in the environs of Paris, is a vestige. The ceiling of a sepulchral chamber at Thebes shows the Bull at the head of the procession. The zodiac of Esne, the astronomical picture discovered by Champollion in the Ramesseum of Thebes, carries us back to the same origin, between two and three thousand years before our era; Biot supposes the date of this to be the year 3285, the vernal equinox passing through the Hyades on the forehead of Taurus. Father Gaubil has proved that from ancient times the Chinese have referred the beginning of the apparent motion of the sun to the stars of Taurus; and we have a Chinese observation of the star η of the Pleiades as marking the vernal equinox in the year 2357 before our era. Hesiod sings of the Pleiades as ruling the labors of the year, and the name of Vergilia, which the ancient Romans gave them, associates them with the beginning of the year in spring.

Without entering into any details of the different zodiacs which have been preserved to us from the most ancient and diverse nations, a glance at those which are reproduced here will lead us to appreciate the part which they have played in ancient religions. Several zodiacal signs have become veritable gods. The zodiac represented by Fig. 11 was engraved, in the Thirteenth Century, on an Arabic magic mirror, and dedicated to the sovereign prince Aboulfald, “Victorious Sultan, Light of the World,” if we are to believe the bombastic inscription which encircles it. Fig. 12 shows an ancient Hindoo zodiac. Fig. 13 shows a Chinese zodiac stamped upon a talisman, even now in use. The twelve signs differ from ours; they are: the Mouse, the Cow, the Tiger, the Rabbit, the Dragon, the Serpent, the Horse, the Ram, the Ape, the Hen, the Dog, and the Pig. Fig. 14 represents a Chinese medal, on which we see the constellation _Teou_, the Great Bear[9] (which they call the Bushel), the Serpent, the Sword, and the Tortoise. This is a talisman intended to give courage; it appears that it is in great demand among the Chinese, and is as well circulated as the medals of the Immaculate Conception are in France.

Of all the zodiacal constellations, that of the Bull has played the principal rôle in ancient myths; and in this constellation it was the sparkling cluster of the Pleiades which appears to have regulated the year and the calendar among all the ancient nations. The Mosaic deluge itself, referred to 17 Athir (November), in commemoration of an important inundation, had its date coincident with the appearance of the Pleiades.[10]

Fig. 14.—Chinese Medal, showing the Great Bear]

But we forget the stars. If our descriptions have been carefully followed, the reader will now know the zodiacal constellations as well as those of the north. There remains but little to do to know the entire sky. But there is an indispensable addition to be made to what precedes. The circumpolar stars are perpetually visible above the London horizon; at any time of the year when we wish to observe them it is sufficient to turn to the north, and we shall always find them, either above the pole star or below it, to one side or the other, and always maintaining among themselves the relations which we have employed to find them. The stars of the zodiac do not resemble them from this point of view, for they are sometimes above the horizon, sometimes below. It is necessary, then, to know at what epoch they are visible. For this purpose it will be sufficient to remember the constellation which is found in the middle of the sky at _nine o’clock in the evening_ on the first day of each month—that, for example, which crosses at that moment a line descending from the zenith to the south. This line is the _meridian_, of which we have already spoken; all the stars cross it once a day, moving from east to west—that is to say, from left to right. In indicating each of the constellations which pass at the hour indicated, we also give the centre of the visible constellations.

On January 1 Taurus passes the meridian at 9 o’clock in the
evening; notice Aldebaran, the Pleiades. On February 1 the Twins
(Gemini) are not yet there; we see them a little to the left. March
1, Castor and Pollux have passed; Procyon to the south, the little
stars of the Crab (Cancer) to the left. April 1, the Lion, Regulus.
May 1, β of the Lion, Berenice’s Hair. June 1, Spica of the Virgin,
Arcturus. July 1, the Balance (Libra), the Scorpion. August 1,
Antares, Ophiuchus. September 1, Sagittarius, Aquila. October 1,
Capricornus, Aquarius. November 1, Pisces, Pegasus. December 1,
Aries, the Ram.

Our general review of the starry sky must now be completed by the stars of the southern heavens.

Below Taurus and Gemini, to the south of the zodiac, you notice the giant Orion, who raises his club toward the forehead of the Bull. Seven brilliant stars are here distinguished; two of them, α and β, are of the first magnitude; the five others are of the second magnitude, α and γ mark the shoulders, κ the right knee, β the left knee; δ, ε, ζ mark the belt or girdle. Below this line is a luminous train of three stars, very near each other; this is the Sword. Between the western shoulder and Taurus is seen the Shield, composed of a row of small stars. The head is marked by a little star (λ) of the fourth magnitude.

On a fine winter’s night turn toward the south, and you will immediately recognize this giant constellation. The four stars, α, γ, β, κ, occupy the angles of a great quadrilateral. The three others, δ, ε, ζ, are crowded in an oblique line in the middle of this quadrilateral; α, at the northeast angle, is named _Betelgeuse_ (not Beteigeuse, as some books print it); β, at the southeast angle, is called _Rigel_.

The line of the Belt, produced both ways, passes to the northeast near _Aldebaran_, the Eye of the Bull, which we know already, and to the southeast near _Sirius_, the finest star of the sky, which we shall soon consider.

It is during the fine nights of winter that this constellation shines in the evening above our heads. No other season is so magnificently constellated as the months of winter. While nature deprives us of certain enjoyments in one way, it offers us in exchange others no less precious. The marvels of the heavens present themselves from Taurus and Orion in the east to Virgo and Boötes on the west. Of eighteen stars of the first magnitude which are counted in the whole extent of the firmament, a dozen are visible from nine o’clock to midnight, not to mention some fine stars of the second magnitude, remarkable nebulæ, and celestial objects well worthy of the attention of mortals. It is thus that nature establishes a harmonious compensation, and while it darkens our short and frosty days of winter, it gives us long nights enriched with the most opulent creations of the sky.

The constellation of Orion is not only the richest in brilliant stars, but it conceals for the initiated treasures which no other is known to afford. We might almost call it the California of the sky.

To the southeast of Orion, on the line of the Three Kings, shines the most magnificent of all the stars, _Sirius_, or α of the constellation of the Great Dog. This star of the first magnitude marks the upper eastern angle of a great quadrilateral, of which the base near the horizon of London, is adjacent to a triangle. This constellation rises in the evening at the end of November, passes the meridian at midnight at the end of January, and sets at the end of March. It played the greatest part in Egyptian astronomy, for it regulated the ancient calendar. It was the famous Dog Star; it predicted the inundation of the Nile, the summer solstice, great heats and fevers; but the precession of the equinoxes has in 3,000 years moved back the time of its appearance by a month and a half, and now this fine star announces nothing, either to the Egyptians who are dead or to their successors.

The _Little Dog_, or Procyon, is found above the Great Dog and below the Twins (Castor and Pollux), to the east of Orion. With the exception of α Procyon, no brilliant star distinguishes it.

_Hydra_ is a long constellation, which occupies a quarter of the horizon, under Cancer, the Lion, and the Virgin. The head, formed of four stars of the fourth magnitude, is to the left of Procyon, on the prolongation of a line drawn from that star to Betelgeuse. The western side of the great trapezium of the Lion, like the line from Castor and Pollux, points to α, of the second magnitude. This is the Heart of Hydra; we remark the asterisms of the second class, Corvus the Crow, and Crater the Cup.

_Eridanus_, _Cetus_, _Piscis Australis_, and the _Centaur_ are the only important constellations which remain to be described. We find them, in the order which we have indicated, to the right of Orion. Eridanus is a river composed of a train of stars winding from the left foot of Orion and losing itself below the horizon. After following long windings, it ends with a fine star of the first magnitude, α Eridani, or Achernar. This is the river into which Phaeton fell when he unskilfully directed the Chariot of the Sun. It was placed in the sky to console Apollo for the death of his son.

To find the Whale (Cetus), we may notice below the Ram a star of the second magnitude which forms an equilateral triangle with the Ram and the Pleiades; this is α of Cetus, or the Jaw; α, μ, ξ, and γ form a parallelogram which represents the head. The base, α, γ, may be produced to a star of the third magnitude, δ, and to a star of the neck marked ο. This star is one of the most curious in the heavens. It is named the Wonderful, _Mira Ceti_. It belongs to the class of variable stars. Sometimes it equals in brightness stars of the second magnitude, sometimes it becomes completely invisible.[11] Its variations have been followed since the end of the Sixteenth Century, and it has been found that they are reproduced periodically every 331 days on the average. The study of these singular stars presents us with curious phenomena.

Lastly, the constellation of the Centaur is situated below Spica of the Virgin. The star θ, of the second magnitude, and the star ι, of the third, mark the head and the shoulder. This is the only part of this figure which rises above our horizon. The Centaur contains the _nearest star_ to us (α) of the first magnitude, the distance of which is about twenty-five billions of miles. The feet of the Centaur touch the _Southern Cross_, formed of four stars of the second magnitude, always hidden below our horizon. It reigns in silence above the icy solitudes of the Southern Pole, where ships proceed only with difficulty. Further on, at the centre of the other hemisphere, is the southern celestial pole, which is not marked by any remarkable star.

It was from this region, Dante relates, that, having visited hell, inclosed in the centre of the earth, he went to the Mountain of Purgatory, and from there to the Heights of Paradise. These beautiful dreams have disappeared in the sunshine of modern astronomy.

We will complete these descriptions by a little astronomical chronology, which is not without interest. From a careful examination of the most ancient historical sources of classical astronomy, the following is the order in which the constellations appear to have been noticed, formed, and named, beginning with the most ancient:

Most Ancient Reference