FIXED STARS—MAGNITUDE OF THE STARS—CONSTELLATIONS—DESCRIPTIONS OF THE ZODIACAL CONSTELLATIONS—NORTHERN AND SOUTHERN STAR GROUPS—DISTANCE OF STARS.

We have been considering the planets so far as they are known to astronomers, but no doubt we shall find out others some day beyond Neptune in space, for it must be assumed that there are other planets wandering about in the infinite firmament. At present, however, we cannot spare time for such speculation; we have got to peep at the stars and their groupings.

“What little bits of things the stars are,” a child said once in our hearing; and there were others present who were inclined to believe that the tiny light spots we could see looked small—not because they were distant, but because they were of no great magnitude; and when those children were told that the tiny stars were “suns” like our sun, giving heat and light millions and millions of miles away,—and, so far as we can tell, some are much bigger and hotter than our own sun,—they were very much surprised indeed, and one little girl aptly quoted Dr. Watts:—

Now let us endeavour to learn something about these apparently tiny specks, and why they “twinkle.”

At a very early period in the history of astronomy the observers of the heavens grouped stars together in fancied resemblances to men or animals; and these “constellations,” as they are termed, are combinations of fixed stars—that is, of stars which do not wander about as the planets do. But these so-called fixed stars have motions; they are only relatively fixed with reference to their positions to each other as they appear to revolve daily round the earth. But stars have a movement of their own, which is termed their “proper motion.”

It is to Halley that the discovery of these real star motions is due. He saw three very bright stars (Sirius, Aldebaran, and Arcturus) were not in the places they had been assigned. The sun also has been found to possess a “proper motion,” and, with the planets, is travelling as determined by Sir J. Herschel, to a particular place in the constellation called Hercules. There are now star catalogues and star maps, for the heavens have been as closely surveyed as the earth, and by accurate observations it has now become possible to find the position of every star usually visible. Some of the stars are used as “clock” stars, by which sidereal time can be calculated accurately, and the clocks thereby corrected. The stars, though termed “fixed,” are in perpetual movement—Arcturus at the rate of fifty miles a second, and others less. Only the rates of a few are known.

The number of the stars is beyond our calculation, and even the number of stars only visible in the telescope amount to millions, and these are called telescopic stars. The visible stars amount to about six thousand, and of course these are the brightest up to the sixth magnitude. There are more visible in the southern than in the northern hemisphere. The magnitudes of the stars range in classes according to the brightness of the stars observed, for this is really the test from the first magnitude to the sixth; after that the telescopic stars are seen up to the fifteenth or sixteenth. We can only see about three thousand stars at any one time from any place, although, as remarked above, many millions may be observed with a good telescope, and as many more, probably twenty millions, are invisible.

We will now proceed to detail the constellations, which are familiar by name to everybody. We have already given the names of the zodiacal groups, which consist of many stars, each designated by a letter of the Greek alphabet so far as possible, then the Roman letters and numerals are employed. Thus a (Alpha) is the most brilliant star; (Beta) the next bright ? (Gamma) the next, and so on; so the relative brilliancy of the stars in the constellation is indicated, but not the very biggest star of the first magnitude is intended by a, for the star d in one constellation may equal a in another. John Bayer originated this method in 1603.

The arrangement of the constellations is plunged in the obscurity of ages, but B.C. 370 there were forty-five thus grouped. There are northern and southern constellations which are visible above our old friends Aries, Taurus, Cancer, etc. We will, as in duty bound, consider our old acquaintances first, and then give a list of the northern and southern groups of stars; but we shall find that the forms are in the greater part due to the imagination of the ancients, and do not bear out our ideas of the animals they are supposed to represent, while at the same time they cross and recross with other constellations in the skies in a very puzzling way.

The first constellation is Aries, the Ram, which is celebrated in mythology as the proud possessor of the Golden Fleece, which we may remember was seized and carried away by Jason and the Argonauts. The Hellespont is so called from Helle, who fell from the Ram’s back when being carried upon it over the Black Sea. The Ram is here represented with the equinoctial ring.

We perceive in Aries two very bright stars near the head. These are (a) Arietis and (?) Sheretan. The signs and constellations do not now correspond as they used to do, because of the change in the position of the stars, which gives rise to the Precession of the Equinoxes (vide ante., p. 497), so that the stars which two thousand years ago were in conjunction with the sun, are much more to the eastward. In olden time (when astronomy was young), the sun entered Aries on the 21st March, and now a change has taken place. But in about another twenty thousand years, they will all come right again. This will be perceived by reference to the celestial globe. The Ram has sixty-six stars in his constitution.

Taurus, the Bull, is the next constellation. He received his name from the celebrated animal into which Jupiter transformed himself when he wished to carry away Europa. The star Aldebaran (a) is the end of a kind of V in the Bull’s face. The Pleiades are on the shoulder to the right. This cluster of twinkling stars is well known, and will guide the observer towards the imaginary Bull, which we must nowadays describe as rather a fanciful delineation. Europe is called after Europa, because Jupiter, as a Bull, carried her to this continent. There are 141 stars in Taurus, according to the number found in the list of Aratus, and probably more.

Gemini, the Twins, which are supposed to be Castor and Pollux, though it is believed that two goats were the original sign—which statement, taken in connection with the ram and the bull, that were also turned out in the spring-time, may have something to recommend it. But now Castor and Pollux are generally recognized as the constellation. During the expedition for the Golden Fleece, the electric appearance, now known as St. Elmo’s Fire, became visible upon them, and their effigies were placed in the forepart of ships as a good omen. This led to the adoption of the “figure-head.” They were made into stars when Pollux was immortalized by Jupiter, for he divided the boon with his brother. The planet Uranus was discovered near this constellation, which contains eighty-five stars.

Cancer, the Crab, is the next in order, and the only derivation we can find for this is that Juno sent a crab to attack Hercules when he was busily engaged with the many-headed Hydra. The crab was directed to pinch the hero’s foot, but it appears rather a lame device for the Queen to adopt. The crab, however, was killed by Hercules, and placed amongst the stars by Juno as a reward; so he gained immortality cheaply. He, Cancer, contains more than eighty stars, but none of them of any particular note. Some writers explain the sign as reminding the ancients of “the retrograde movement of the sun to the north”; but as a crab does not move “backwards,” we will still adhere to mythology as equally satisfactory at any rate. Cancer, however, was termed the “northern gate of the sun.”

The next is Leo, the Lion, which came round in summer and at the period of much heat, so this fierce animal may have been chosen to represent that season. But mythology will have us credit the NemÆan Lion sent against Hercules by Juno as the origin of this constellation. The lion was, like the crab, placed amongst the stars when he was killed. He is a very brilliant constellation, and a very bright star called Regulus is to be seen in his chest—“Cor Leonis.” Another very fine star of the second magnitude is observable in the tail. The Lion consists of ninety-five stars, the principal ones being of the first and second magnitudes.

Virgo is supposed to be outlined by a very rich cluster of stars, and one of the first magnitude. The Virgin is by some supposed to be AstrÆa, the goddess, but is more likely referable to a girl gleaning, or holding an ear of corn in semblance of the harvest. This constellation contains more than one hundred stars. One of them in the wheat-ear is a particularly brilliant one, and noted for its “solitary splendour,” as no star of large magnitude is near it. The Arabs used to call it the Solitary Simak; Spica Virginis is the modern name.

Libra, which follows, may either indicate the balance, or scales of justice, of AstrÆa, or the equal day and night at the autumnal equinox. Virgil mentions AstrÆa’s balance, and thus we have a classical authority for the very mythological view of the two foregoing constellations. Libra is not very distinct; it contains fifty-one stars, four of which are very bright.

Scorpio, the Scorpion, according to classical writers, encountered Orion, who is also met with in the stellar universe. The scorpion stung Orion because he declared there was no living creature he could not overcome by force. On the other hand, this sign may have some reference to the unhealthy time of year, and the prevalence of disease about the time that Scorpio appeared. A beautiful star of reddish hue and of the first magnitude is prominent amongst the brilliant assembly of the Scorpion’s forty-four stars.

Sagittarius, the Archer, is, as one can see, a Centaur, and said to be Chiron, who was wounded by Hercules, and cured by being taken up to Heaven by Jupiter. This Chiron is represented as a great patron of the arts, and thus the fable may be said to exemplify the proverb, “Art is long, time is fleeting”; for readers of mythology will find much more in the legends than is apparent on the surface. But we can now only regard the Centaur from an astronomical, and not a philosophical standpoint. Sagittarius has no very brilliant stars. He is close to the Milky Way, and contains sixty-nine stars, five forming a sort of V in the bow, sometimes compared to a ladle or “dipper.”

Capricornus, the Goat, is supposed to be Pan—“the great god Pan,” who turned himself into a goat. The sun was in Capricornus at mid-winter, so the “southern gate of the sun” was a title bestowed upon him. But now the constellation is later. It does not include any very striking stars, of which there are fifty-one in the “Goat.”

Aquarius, or the Waterbearer, may have referred to wet weather, or as others declare, to Ganymede, the Cupbearer. There are four stars in the waterpot like a Y; and more than one hundred stars of small brilliancy are included in this constellation. But here again fancy must come to our assistance, for without a diagram the ordinary observer could not distinguish the Waterbearer.

Pisces, the Fishes, are not plainly defined. It is supposed that Venus and Cupid turned themselves into fish when the Titans assailed Heaven. This Constellation occupies a triangle in the sky.

The foregoing are the zodiacal constellations, and may be more easily remembered by repeating an old rhyme, which runs as follows:—

The arrangement of the various Constellations at which we have so rapidly glanced, as well as of those that follow, has been the work of many different periods. Aratus and Ptolemy are the oldest enumerators, but modern research has added immensely to the store of knowledge. Many of the most prominent stars were named by Grecian and Arabian observers, and many of the names are still retained—such as Arcturus, Rigel, Capella, and others.

The Northern Constellations.

There are, altogether, thirty-five of these, as per list on next page. It is of course impossible to describe them all, but we will make a few remarks respecting those which will be distinguished most readily, and the manner of finding out particular stars. There are star maps published, and with a little attention and reading, a great many very pleasant evening excursions may be made across the sky, with or without a telescope. The following is the list of the northern constellations. We have put them in various types to indicate the most important.

The Great Bear, or “Charles’s Wain,” or the “Plough,” as Ursa Major is variously called, is of great value in indicating the pole star, which, when once known, can never be mistaken. This constellation has also been termed the “Dipper,” and is very conspicuous in the northern hemisphere. The three stars form the bear’s tail, or the handle of the “plough”; the others form the body, Charles’s Wain, or “Karl-Wagen,” the German term for peasant’s cart, is represented by the quadrangle forming the cart, and the other three stars are the horses.

The “Pointers” are the two end stars, and if a line be followed northwards from them it will lead close to Polaris, the principal star in the lesser bear. This pole star is of a very great brightness, and peeps out, almost isolated, with a pure lustre. The names of the pointers are Dubhe and Menak. The star at the tail-tip is Benetnasch, then Mizar and Alioth. Megrez and Phad are the remaining pair. We append a rough outline of the bear, for the information of those who have not yet noticed it.

The Lesser Bear is not so important as his elder brother as regards size, but he is very useful to astronomers. He resembles the Great Bear in appearance, but is smaller, and the positions of the stars are inverted. In the cut on page 555 (fig. 629) you see the little bear swinging round the polar star, which is at the tip of the Lesser Bear’s tail, so any one will be enabled to find him if they look for the polar star, and then count the three stars away from it, and the four in the body. The Great Bear’s tail points in the other direction. This movement of the earth’s axis by displacing the equinoctial points, alters the “declination” and “right ascension” of the stars (compare page 473). So Polaris is gradually approaching the actual polar point. In about 200 years he will have got as close as he can, and will then begin to recede from it, and in about 12,500 years after he will reach his most distant point.

Polaris, the Pole Star, was called “Cynosure” by the ancients, and thus we can understand the quotation, “Cynosure of neighbouring eyes,” when a person or object is very attractive. The pole star was the point to which all looked. There are some other very important stars in these constellations. For instance, in—

These stars are also designated by the Greek letters—a, lyrÆ, or the first in the Lyre—that is, Vega; and so on for all, according to rank, as already explained.

Southern Constellations.

We must pass on to the southern constellations, of which there are forty-six; the principal ones are in capital letters:—

We need only describe Orion and Canis Major, the principal groups. The former certainly constitutes the most glorious group, and it is visible to all the world, because the equinoctial passes through it.

Orion, as we have said, can be viewed from either hemisphere, and so can some others; but those marked with an asterisk in the foregoing list are not visible in the latitude of London.

Orion is a very brilliant constellation, and contains two fine stars of the first magnitude, and some of the second. The former are Betelgeux and Rigel. Bellatrix is the third in order. The “belt” is formed of three bright stars, and the sword is visible as five stars just below. Canis Major possesses Sirius, a very fine star (the dog star). Canis Minor has two of the first and second magnitude, and Hydra has one of the first. The Southern Cross is a beautiful constellation, invisible in our latitude, but familiar to sailors in the Southern Seas.

The Stars’ Distance and Magnitude.

When we gaze up into the sky at night, we see the stars twinkling far away, and we may remark here that this twinkling of the stars is due to the atmosphere and the changes in its power of refraction, and of course the star’s light changes its direction. But if we ascend in a balloon into very high and rarefied strata of the air, we will find the twinkling less. We have given the number of the stars according to Flamstead, but the larger the telescope the greater will be the number of stars we shall see, numbers again being too far even for our perfected instruments.

But we can gain some idea of the magnitude of the stars when we consider the distance to arrive at, which is a most difficult task, for figures seem scarcely long enough to count the millions of miles, and no instrument can detect the parallax. Even supposing the parallax to be a very small fraction of a degree we should get a result equalling trillions of miles. No. 61 in Cygni was at one time continually observed by Professor Bessel, and he found that its distance—and it is the nearest star—is sixty-two and a half trillions of miles.

Let us consider what this means. Light comes to us from the sun (91,000,000 of miles) in about eight minutes, and travels at the rate of something like 186,000 miles in a second. But even at that astounding rate the light from the star called 61 Cygni took ten years to reach the earth; and there are stars whose light has never yet reached the earth, although the gleam may have been travelling at 186,000 miles a second for thousands of years. And we may presume that though we still see the light of stars, some of them may be dead, but the light left is still progressing to us through space.

So we must conclude that some stars which look large, as do Vega and Sirius for instance, must be enormous “suns,” a great deal larger than our sun, and the stars are each the centre of invisible systems just as our sun is the centre of the “solar” system. Vega is a tremendous star, and shines with her own light as do all other visible stars; for reflected light, so very visible in the moon, which is close to us, would be quite invisible at such tremendous distances. So we must call these stars “suns,” and may add an apparently astonishing fact, that our own sun is merely one of the stars in the Galaxy, or “Milky Way”!