THE EVENING SKY AT THE SUMMER SOLSTICE

At 10 o’clock p.m. on the 21st of June, the longest day of the northern hemisphere, the aspect of the sky is that shown in Chart II, accompanying this chapter. The same chart will answer for 11 p.m. on the 5th or 6th of June; 9 p.m. on the 7th of July, and 8 p.m. on the 22d or 23d of July. In fact, for any of the hours mentioned the date may be shifted several days forward or backward without seriously affecting the comparison of the chart with the sky, and the same may be said of each of the other circular charts. The stars simply rise about four minutes earlier each evening, and four minutes of time correspond to one degree of space measured on the face of the sky. So the whole sky shifts about one degree westward every twenty-four hours.

For the observation of the heavens at the epoch of the Summer Solstice, observers who are situated at least as far south as 40° north latitude have an advantage over those whose place on the earth is much farther north, because in the more northern regions sunset occurs later, and in England and Northern Europe the day, at this time, may exceed sixteen hours in length, while twilight is perceptible throughout the night. This interferes with the brilliancy of the stars.

CHART II—THE SUMMER EVENING SKY

At no other season do the heavenly bodies seem so intimately associated with the earth as in summer. All nature is now attuned, and the stars glow softly in the tepid atmosphere, stirred by faint breezes, like veritable flowers of the sky. The firmament becomes a vast garden lit with beautiful lamps, which seem to have been placed there to dimly illuminate nocturnal wanderers in the transparent gloom beneath. Their beauty is as refreshing as the cooling breath of night itself. A mystic influence steals from them over the earth.

“If a man would be alone,” says Emerson, “let him look at the stars.”

Yet he cannot be alone with them; they are too friendly; they speak too plainly a universal language, which, though he cannot translate it, he feels in every fibre. There is nothing more absolutely common to all men than the influence of the stars. No one ever gazed up at them without feeling a change come over his spirit. Truly, “they separate between him and what he touches.” They free him from the bondage of time and space. There is no trouble that they cannot assuage. And there is no time like the summer for becoming intimate with them. One who has been touched by the magic of their love could lie all the night long on a bed of pine-needles and fill his soul with their beauty. The march of red Antares and his glittering retinue across the meridian while the earth sleeps in solstitial calm—who can describe that pageant?

Antares is the summer star, and with it and the Scorpion we will begin. Not so bright as Arcturus or Vega, which are now high aloft, it has a charm peculiar to itself, arising partly from its fervid color, partly from its surroundings, and partly from its position, not too high above the southern horizon, which renders observation of the star comparatively easy. The color is so distinctive that one might think that he could recognize Antares chromatically if it were suddenly transported to some other region of the sky and placed amid a strange environment. Sometimes a flash of its fiery rays, striking sidewise into the eye as one is looking elsewhere, startles the observer like a red meteor. It is well named Antares—“Anti-Mars.” With the telescope the wonder of color is increased, for close by the great star the glass reveals a smaller one of a vivid green, an all but incredible combination of complementarily tinted suns. And these suns are undoubtedly actually linked together into a system, so that, if there are planets revolving around both or either, the inhabitants of those planets may behold the spectacle of two suns, one crimson and the other emerald! The large star is of the first magnitude, and the small one of the seventh; angular distance 3″.7.

The companion of Antares is historically associated with the most interesting of American astronomers, a man whose life was a romance, Gen. O. M. Mitchel. When his long-cherished design of setting up a great telescope in America was at last fulfilled, at Cincinnati, in 1845, one of his first achievements was the discovery, to the surprise of the astronomers of Europe, of the green star hiding in the rays of Antares. At times it has been seen emerging from behind the moon, after an occultation, ahead of its red comrade.

With a parallax of 0″.02, Newcomb estimated the luminosity of Antares at nine hundred times that of our sun, and yet the spectroscope indicates that it is a dying sun, fast approaching extinction. In its younger days it may have been an orb of prodigious splendor.

The constellation Scorpio, of which Antares is the leader, is one of the best marked in the sky. The two small stars Sigma (σ) and Tau (τ), standing like attendants on either side of Antares, lend a singular aspect to the central part of the constellation. Antares is usually represented as the heart of the imaginary scorpion. Below Tau a curving row of stars dips to the southern horizon, and then rises, farther eastward, terminating with a conspicuous pair in the uplifted sting. West of Antares a nearly vertical row represents the head. Of the stars in this row, Beta (β) is interesting as a fine and easily seen double, the distance being about 13″. A higher magnifying power shows that the larger star has another faint companion, distant only 0″.7. Nu (ν) is also telescopically interesting, for it consists of two pairs of stars. Observe in Chart VII the strange way in which the outlines of the constellation have been swung into loops in order to include certain stars in Scorpio, recalling the crooked boundary between Switzerland and Italy, by which each reserves particular peaks of the Alps for itself.

East of Scorpio, where the Milky Way, falling in flakes and sheets of silvery splendor upon the southeastern horizon, spreads abroad like an overflowing river, lies Sagittarius, the “Archer,” often represented in the old pictorial charts as a centaur. The stars Lambda (λ), Delta (δ), and Epsilon (ε) form the bent bow. But modern eyes recognize more easily a dipper, formed by the stars Zeta (ζ), Tau (τ), Sigma (σ), Phi (φ), Lambda (λ), and Mu (μ). But the star-clusters in Sagittarius are more interesting than the separate stars. A little southwest of Mu is the famous cluster 8 M., of which Barnard has made a photograph that is amazing beyond all description. Other clusters are all about in this part of the sky. A good opera-glass or field-glass is almost indispensable for one who would enjoy the glory of this wondrous region. Its riches are almost oppressive in their lavish abundance. Here one can have handfuls of stars for the picking up, like sands of gold from the bed of Pactolus. As the glittering incrustations that cover the roofs and walls of the Mammoth Cave are often compared to the starry heavens, so, reversing the image, Sagittarius is like a stupendous cavern of space all ablaze and aglitter with millions of sparkling gems.

Above Scorpio and Sagittarius are the intertwined constellations of Ophiuchus and Serpens. He who may wish to disentangle them is referred to Astronomy with the Naked Eye. But the outlines can be traced in Chart VII. The head of Serpens, like those of Hydra and Draco, is plainly marked by a striking group of stars, in this case resembling the figure called a “quincunx.” From this point just under the “Northern Crown,” the serpent’s stars wind downward in beautiful pairs and groups, crossing the meridian above Scorpio, and rising again in the eastern part of the sky, above the little constellation of Sobieski’s Shield, until they meet the borders of Aquila. Ophiuchus, with his head high up toward Hercules, where it is marked by the brightest star in that part of the sky, Alpha Ophiuchi, or Ras Alhague, the “Head of the Serpent Charmer,” stands with legs braced wide apart, grasping the serpent at the points marked by the stars Delta (δ) and Epsilon (ε), and Tau (τ) and Nu (ν). It is Esculapius with his Serpent, said the Greeks; it is St. Paul and the Viper of Melita, or Moses and the Brazen Serpent, we don’t know which, said the churchmen. I am not aware that in England they have ever been tempted to call it St. George and the Dragon. Politics and national pride have not meddled much with the stars, although there was once an attempt to fix the name of Napoleon upon Orion. Ras Alhague is described by R. H. Allen as sapphire in hue, while Alpha Serpentis is yellowish. The star Lambda (λ) in Ophiuchus, also called Marfik, the “Elbow,” is a beautiful binary, period 235 years, distance apart 1″.2. The smaller star is smalt blue, a splendid telescopic object.

But, as in the case of Sagittarius, the greater wonders here are in the form of star-clusters, and particularly nebulæ. Just above Antares, in one of the feet of Ophiuchus, is a small star, Rho (to find which the reader must consult a large star atlas, like Klein’s), around which Barnard has discovered, by photography, a truly marvellous nebula, a nebula which appears to obscure the stars like a cloud of cosmic dust. Great black lanes extend from and around it, and even the luminous parts of the nebula seem to absorb the light of the stars behind, diminishing their brightness a whole magnitude or more where they are veiled by it. This entire region of sky is most strange to the photographic eye. An outlier of the nebula just mentioned surrounds the star Nu (ν) in Scorpio, and its veiling effect upon the stars is even more evident. There is a similar appearance around the star Theta (θ) Ophiuchi, not far away. The sense of some appalling mystery in this part of the firmament is heightened by what Barnard says of a thing which has reappeared again and again on his photographs during the past fifteen years, at a point which he describes as lying very closely to R. A. xviii hours, 25 m., 31 s.; Decl. S. 26°, 9′ (near the star Lambda (λ) in Sagittarius).

“It is a small, black hole in the sky. It is round and sharply defined. Its measured diameter on the negative is 2′.6. On account of its sharpness and smallness and its isolation, this is perhaps the most remarkable of all the black holes with which I am acquainted. It lies in an ordinary part of the Milky Way, and is not due to the presence or absence of stars, but seems really to be a marking on the sky itself” (Astrophysical Journal, January, 1910).

These things really transcend explanation (see Curiosities of the Sky).

Above Ophiuchus and his Serpent, almost exactly overhead in the latitude of 40° N., we see the quadrilateral figure marked out by four of the principal stars of the constellation Hercules. The head of Draco, described in Chapter I, is beyond it toward the north-northeast. Hercules stands feet upward in the sky, his head, indicated by the star Alpha, or Ras Algethi, the “Kneeler’s Head,” being situated a few degrees west-northwest of Ras Alhague. Thus the two giants have their heads together. But while the occupation of Ophiuchus is plain, nobody, not even in ancient times, when the constellation received its name, has ever been able to say what Hercules is laboring at. When he was on the earth everybody followed his deeds and understood, if they could not emulate, them. He was as comprehensible as a modern pugilist. Now, however, that he has been translated to the stars, his labors are of a more mysterious nature, and, judging from his attitude, he finds them harder than any he undertook for the benefit of mankind here below. One is tempted to think that the powers he offended, when he boldly entered the land of shades and snatched the wife of his friend, King Admetus, from the hand of Death himself, are now taking an ample vengeance.

Ras Algethi is a very beautiful double star, one red, the other green or blue, and both, strangely enough, are variable in brightness. Their distance apart is 4″.7. Their spectrum indicates that they are advanced toward extinction many stages beyond our sun.

The star Zeta (ζ), one of those in the quadrilateral, is a closer double, distance about 1″, and is binary, the period of revolution being about thirty-five years.

And now for a great marvel. Let the eye range slowly from Eta (η) directly toward Zeta (ζ). When one-third of the distance between the two stars has been passed, a faint, glimmering speck will be perceived. Perhaps you will need an opera-glass to make sure that you see it. This is the “Great Cluster in Hercules.” You must go to the southern hemisphere to find its match anywhere in the sky. It is a ball of suns! Now you need a telescope. You must have one. You must either buy or borrow it, or you must pay a visit to an observatory, for this is a thing that no intelligent human being in these days can afford not to see. Can it be possible that any man can know that fifteen thousand suns are to be seen, burning in a compact globular cluster, and not long to regard them with his own eyes? Of what use is description in such a case? The language has not yet been invented to depict such things. Human speech comes down to us from the times when men did not need the tongue of the gods to tell what they saw. When Galileo invented the telescope, and Herschel multiplied its powers a thousandfold, they should have found a language fitted to describe their discoveries. But if you cannot get a look at the Hercules cluster through a powerful telescope, photography comes to your aid. Look at one of the wonderful Lick or Yerkes photographs of it, and pause long on what you see. Note the crowding of those suns toward the centre, note the glittering spiral lines formed by those which seem streaming and hurrying from all sides to join the marvellous congregation—and then turn again to that faint speck in the sky, which is all that the naked eye reveals of the wonder, and reflect upon the meaning of space and the universe.

We now turn farther east, still keeping the eyes directed high in the sky, and just at the edge of the Milky Way, with two minute stars making a little triangle with it, we see Vega or Alpha Lyræ, the astonishing brilliant that flashes on the strings of the heavenly Lyre. At the Vernal Equinox it was just rising far over in the northeast; now it is the unquestioned queen of that quarter of the sky. I like to think of Emerson when looking at that star. There is a sentence of his which reflects it like a mirror. When he strove to rouse the “sluggard intellect of this continent,” to “look from under its iron lids,” he could find no stronger image than that of poetry reviving here and leading in a new age, “as the star in the constellation Harp, which now flames in our zenith, astronomers announce, shall one day be the Pole-star for a thousand years.”

Of the effect of the Precession of the Equinoxes, to which Emerson refers, we have already spoken. But it is a long time in the future that Vega will begin, or rather resume, its reign as the Star of the North. And, curiously enough, when that time comes the northern hemisphere will have its Summer Solstice when the sun is just opposite to the place which it now occupies at that season, and when Antares will be no more a summer star, but will flash its ruddy light upon the snows of a winter longer and colder than the winters that we know, while Orion will blaze above the summer landscapes. This immense revolution, some have thought, may be the measure of the “Great Year” of Plato, and if the chronology adopted for dating the early remains of civilization recently uncovered in Crete is correct, we have evidence that mankind has persisted through one of these vast periods, and that nations flourished round the Mediterranean when Vega was formerly the Pole-star.

The beauty of Vega, which has been admired and commented on from the earliest times, is much enhanced when it is viewed with a telescope. Then the blueness of its light becomes evident, and one is the more astonished at the unquestionable fact that it outshines the sun a hundred times. A sapphire sun, a hundred times more brilliant than ours! The proper motion of the solar system, which carries us through space about twelve miles per second, is bearing us almost directly toward Vega, so that as future ages unroll the star should become brighter and brighter with decrease of distance, until eventually it may outshine every other orb in the firmament, and put Sirius himself to shame by its overpowering splendor.

The little star Epsilon (ε), the northernmost one of the pair near Vega, is a celebrated quadruple, easily seen as such with a telescope of moderate power.

A little less than half way from Beta (β) to Gamma (γ) the telescope discovers the wonderful “Ring Nebula,” a delicate circle of nebulous light with a star in the centre. This star is more conspicuous in photographs than in telescopic views. This object has been regarded as a visual proof of the correctness of Laplace’s theory of the origin of the solar system from nebulous rings surrounding a central sun, but the Lick photographs show that the ring in this case is of a strangely complex constitution. Beta is both a binary and a variable star.

Buried in the Milky Way, east of Lyra, lies the great “Northern Cross” in the constellation Cygnus. It is more perfect than the famous “Southern Cross,” and much larger. The star Alpha (α), at the head of the main beam of the cross, is also called Denib, the “Tail,” as it is situated in the tail of the “Swan,” Cygnus. Its parallax is undetermined, and Newcomb placed it in his “XM” class, described under Spica in Chapter I. The Milky Way is exceedingly beautiful in Cygnus. Note particularly the broad gaps and rifts in it. Around and above the head of the cross there are dark spaces, which are specially impressive when the eyes are partly averted from them. Downward from Cygnus the stream of the galaxy is seen to be partially split longitudinally. It resembles a broad river meandering, in the droughts of the “dog days,” over flats and shallows, and interrupted with long sand-bars. How can stars have been thrown together into such forms? What whirls and eddies of the ether can have made these pools of shining suns?

The star in the foot of the cross, Beta (β), or Albireo—a beautiful name without signification, since Allen shows that it originated in a blunder (see his Star Names and Their Meanings)—is one of the most attractive objects in the heavens for those who are fortunate enough to possess a telescope. The smallest glass easily shows it to be double, and the combination is unrivalled for beauty, the larger star being a pale topaz and the smaller a deep sapphire. Their magnitudes are three and seven, and their distance apart about 34″. I have separated them with a field-glass.

Cygnus contains one of the nearest stars in the sky, a twinkler not too easily seen with the naked eye—a striking proof of the fact that the mere faintness of a star is in itself no indication of excessive distance. This is known as 61 Cygni, and will be found on Chart X. It is a double, possible binary, easily separated with a small telescope, the distance being about 21″. The distance of 61 Cygni is about 40,000,000,000,000 miles. It was long known as the second nearest star in the sky, the nearest being Alpha Centauri in the southern hemisphere; but at least one nearer one has more lately been discovered, and it, too, is a very small star. The combined luminosity of the two stars in 61 Cygni is only one-tenth that of the sun. Amid so many giants it is reassuring to find a sun smaller than ours; it restores our self-esteem to find that our solar hamlet is not the very least in the empire of space.

Southeast of Cygnus, near the eastern shore of the starry river, is Aquila, the “Eagle.” Its chief star, Altair, “Eagle,” recalls Antares, not by its color, for it is not red but white, but by the singular arrangement of two small stars standing one on either side of it. Here, too, the Milky Way is very splendid, attaining astonishing brightness lower down, in Scutum Sobieskii, “Sobieski’s Shield.” The naming of this constellation was a posthumous reward to the heroic king, John Sobieski, for saving Europe by the defeat of the Turks under the walls of Vienna, after their victorious advance from Constantinople, emphasized in the public mind by the appearance of Halley’s Comet, had seemed to threaten a Moslem conquest. Twice Halley’s Comet had alarmed Europe in connection with the Turks, first in 1456, after they had taken Constantinople, and again in 1682 when they swept upon Vienna, so that it was a natural thought to associate Sobieski’s victory with some “sign in the sky,” and a more appropriate one could hardly have been found than the “shield,” bossed with star-clusters, which Hevelius selected for the purpose. The southern part of the constellation Aquila is sometimes called Antinous. For the beautiful Oriental legend of the Spinning Damsel and the Magpie Bridge connected with Aquila and Lyra, see Astronomy with the Naked Eye. Newcomb gives Altair ten times the luminosity of the sun.

The constellations Delphinus and Anser et Vulpecula will be dealt with in the next chapter. In the mean time let us turn to the western half of the sky.

Just west of the meridian, near the zenith, gleams the glorious Northern Crown, Corona Borealis. The head of Serpens is right underneath it. It is, perhaps, the most charming of all asterisms. It could hardly be called anything else than a crown or a wreath. The perfection of the figure is surprising. If its stars were larger it would be the cynosure of the sky, but small as they are they produce an effect of ensemble that could not have been exceeded if human hands had arranged them there. The superior brightness of one of them, Alpha “Gemma,” or “The Pearl,” adds greatly to the effectiveness of the combination. It is the work of a master jeweller! Yet, as I have elsewhere shown, this curious assemblage of stars is but a passing phenomenon, for they are travelling in various directions, with various speeds, and in the course of time the Northern Crown will dissolve like a figure in the clouds. In Greek mythology it was generally called the Crown of Ariadne. Just under the star Epsilon (ε) is a wonderful variable, which in 1866 suddenly blazed up to the second magnitude, and was for a time regarded as a new star. Nothing is known of its periods of change. It is not now visible to the naked eye.

West of Corona the most conspicuous object is Arcturus in Boötes. This entire constellation is now well placed for observation. But first a few words about Arcturus, a star of which one can never tire, so steeped is it in the poetry and history of the most interesting nations of the past. Like Alpha Centauri, Arcturus was used as a “temple star” in both Egypt and Greece, and it was of much importance as a prognosticator of the seasons. When a conspicuous star was seen rising just ahead of the sun, it was said to rise heliacally, and it served as a sentinel to announce the oncoming day. To the priests this was important, because it warned them of the moment when it was necessary to begin their preparations for the sunrise ceremonies in the temples. To the husbandman such a herald seemed specially connected with the particular season in which it appeared. In this way Arcturus came to give its name to the ancient Greek autumn. In Sophocles’ Œdipus the King there is a passage which affords striking evidence of the popular knowledge of Arcturus in this connection. When the herdsman from Mount Cithæron is brought to prove that he had nurtured Œdipus as a child, one of his former comrades, to recall the old man’s recollections, reminds him that they had kept their flocks together “three whole half-years from Spring to Arcturus” (meaning from Spring to Autumn, since Arcturus then rose heliacally at the beginning of September). Whatever might be the local names for Autumn, over all the Greek world it was popularly known as the “time of Arcturus.”

Although the Revised Version has struck out Arcturus and substituted “the Bear” in that famous passage in which the Almighty answers Job “out of the whirlwind,” yet for lovers of the Bible this will always be “Job’s Star,” always surrounded to the imagination with the momentous circumstances suggested by that tremendous and unanswerable demand:

“Canst thou call forth Arcturus and his sons?”

No scientific fact known about it—not its gigantic size, not its inexplicable flight through space—can be so imposing as the impressions conveyed in its choice by Jehovah to illustrate His illimitable power. One likes to think that the Hebrew poet really did mean to write “Arcturus,” for there is something sublime in the idea of representing the Great Maker of All as calling one of His stars by name.

Arcturus is sometimes referred to under the name of Arctophilax, the “Bear-driver,” a name properly belonging to the constellation Boötes. In modern astronomical history it will always be memorable for the passage over it of the celebrated Comet of 1858, Donati’s Comet. At one time the star was almost involved in the head of the great comet, and yet it shone through the obstructing vapors with virtually undiminished lustre. It was a spectacle, said Professor Nichol, the like of which no one might see again though he should spend on earth fifty lives. At the beginning the comet was a little plume of fire, “shaped like a bird of paradise,” but it soon brightened into a stupendous scimetar, brandished in the sunset, and when it swept over Arcturus the whole astronomical world was watching to see what would happen to the star.

Among the other stars of Boötes, Epsilon (ε) is specially worthy of notice, being a remarkable binary of finely contrasted colors, orange and sea-green. The distance is 2″.25, and the period of revolution long but undetermined. Struve called this star “Pulcherrima,” on account of its exceeding beauty.

Although Arcturus by its splendor belittles the rest of the constellation, yet it requires no difficult exercise of the imagination to see a giant form there, towering behind the Bear, and urging on his dogs in the chase. The dogs are represented by Canes Venatici, of the beauty of whose chief star, Cor Caroli, I have spoken in the preceding chapter. In the upper part of Canes Venatici, about 3° southwest of Benetnasch, is the celebrated “Whirlpool Nebula” of Lord Rosse, which modern photographs show in a form so suggestive of tremendous disruptive forces that cosmogonists are at a loss to explain it.

We now drop down to Libra, the “Balance,” which lies just west of Scorpio and east of Virgo. There is evidence that this constellation originally represented the outstretched claws of the Scorpion. Yet as an independent constellation it is very ancient. It has only two stars of any considerable magnitude, Alpha (α) and Beta (β). The former must have faded, for it is now the fainter. It lies almost on the ecliptic. These stars are interesting on account of their curious names, which themselves tend to prove that Libra once formed a part of Scorpio. Alpha is Zubenelgenubi, the “Southern Claw,” and Beta Zubeneschemali, the “Northern Claw.” These titles, as Allen shows, have been derived through the Arabic from the Greek names current in the time of Ptolemy. The first is yellowish-white, and the second pale green. Any good eye detects the difference of color at a glance, although the stars are about ten degrees apart. Zubenelgenubi is widely double, separable with an opera-glass.

Along the western horizon we recognize our old friends Virgo, Corvus, and Leo, while high in the northwest is Ursa Major, head downward, and directly in the north Ursa Minor, standing on the end of his tail, poised like an acrobat on Polaris. The head of Draco shows finely east of the meridian, and low down in the northeast is the “Laconian Key” of Cassiopeia. But that is for another evening.