Astronomy for Amateurs

their spectrum. These stars are older than the first, and the ruddy ones, such as Antares, Betelgeuse, α of Hercules, are still older; several of them are variable, and are on their way to final extinction. The Heavens afford us a perennial store of treasure, wherein the thinker, poet or artist can find inexhaustible subjects of contemplation. You have heard of the celestial jewels, the diamonds, rubies, emeralds, sapphires, topazes, and other precious[Pg 67] stones of the sidereal casket. These marvels are met with especially among the double stars. Our Sun, white and solitary, gives no idea of the real aspect of some of its brothers in Infinitude. There are as many different types as there are suns! Stars, you will think, are like individuals: each has its distinct characteristics: no two are comparable. And indeed this reflection is justified. While human vanity does homage to Phœbus, divine King of the Heavens, other suns of still greater magnificence form groups of two or three splendid orbs, which roll the prodigious combinations of their double, triple, or multiple systems through space, pouring on to the worlds that accompany them a flood of changing light, now blue, now red, now violet, etc. In the inexhaustible variety of Creation there exist Suns that are united in pairs, bound by a common destiny, cradled in the same attraction, and often colored in the most delicate and entrancing shades conceivable. Here will be a dazzling ruby, its glowing color shedding joy; there a deep blue sapphire of tender tone; beyond, the finest emeralds, hue of hope. Diamonds of translucent purity and whiteness sparkle from the abyss, and shed their penetrating light into the vast space. What splendors are scattered broadcast over the sky! what profusion! [Pg 68] To the naked eye, the groups appear like ordinary stars, mere luminous points of greater or less brilliancy; but the telescope soon discovers the beauty of these systems; the star is duplicated into two distinct suns, in close proximity. These groups of two or several suns are not merely due to an effect of perspective—i.e., the presence of two or more stars in our line of sight; as a rule they constitute real physical systems, and these suns, associated in a common lot, rotate round one another in a more or less rapid period, that varies for each system. One of the most splendid of these double stars, and at the same time one of the easiest to perceive, is ζ in the Great Bear, or Mizar, mentioned above in describing this constellation. It has no contrasting colors, but exactly resembles twin diamonds of the finest water, which fascinate the gaze, even through a small objective. Its components are of the second and fourth magnitudes, their distance = 14″[6]. Some idea of their appearance in a small telescope may be obtained from the subjoined figure (Fig. 17). Another very brilliant pair is Castor. Magnitudes[Pg 69] second and third. Distance 5.6″. Very easy to observe. γ in the Virgin resolves into two splendid diamonds of third magnitude. Distance, 5.0″. Another double star is γ of the Ram, of fourth magnitude. Distance, 8.9″. Fig. 17.—The double star Mizar. And here are two that are even more curious by reason of their coloring: γ in Andromeda, composed of a fine orange star, and one emerald-green, which again is accompanied by a tiny comrade of the deepest blue. This group in a good telescope is most attractive. Magnitudes, second and fifth. Distance, 10″. β of the Swan, or Albireo, referred to in the last chapter, has been analyzed into two stars: one [Pg 70]golden-yellow, the other sapphire. Magnitudes, third and fifth. Distance, 34″. α of the Greyhounds, known also as the Heart of Charles II, is golden-yellow and lilac. Magnitudes, third and fifth. Distance 20″.[7] α of Hercules revolves a splendid emerald and a ruby in the skies; ζ of the Lyre exhibits a yellow and a green star; Rigel, an electric sun, and a small sapphire; Antares is ruddy and emerald-green; η of Perseus resolves into a burning red star, and one smaller that is deep blue, and so on. These exquisite double stars revolve in gracious and splendid couples around one another, as in some majestic valse, marrying their multi-colored fires in the midst of the starry firmament. Here, we constantly receive a pure and dazzling white light from our burning luminary. Its ray, indeed, contains the potentiality of every conceivable color, but picture the fantastic illumination of the worlds that gravitate round these multiple and colored suns as they shed floods of blue and roseate, red, or orange light around them! What a fairy spectacle must life present upon these distant universes! [Pg 71] Let us suppose that we inhabit a planet illuminated by two suns, one blue, the other red. It is morning. The sapphire sun climbs slowly up the Heavens, coloring the atmosphere with a somber and almost melancholy hue. The blue disk attains the zenith, and is beginning its descent toward the West, when the East lights up with the flames of a scarlet sun, which in its turn ascends the heights of the firmament. The West is plunged in the penumbra of the rays of the blue sun, while the East is illuminated with the purple and burning rays of the ruby orb. The first sun is setting when the second noon shines for the inhabitants of this strange world. But the red sun, too, accomplishes the law of its destiny. Hardly has it disappeared in the conflagration of its last rays, with which the West is flushed, when the blue orb reappears on the opposite side, shedding a pale azure light upon the world it illuminates, which knows no night. And thus these two suns fraternize in the Heavens over the common task of renewing a thousand effects of extra-terrestrial light for the globes that are subject to their variations. Scarlet, indigo, green, and golden suns; pearly and multi-colored Moons; are these not fairy visions, dazzling to our poor sight, condemned while here below to see and know but one white Sun? [Pg 72] As we have learned, there are not only double, but triple, and also multiple stars. One of the finest ternary systems is that of γ in Andromeda, above mentioned. Its large star is orange, its second green, its third blue, but the two last are in close juxtaposition, and a powerful telescope is needed to separate them. A triple star more easy to observe is ζ of Cancer, composed of three orbs of fifth magnitude, at a distance of 1″ and 5″; the first two revolve round their common center of gravity in fifty-nine years, the third takes over three hundred years. The preceding figure shows this system in a fairly powerful objective (Fig. 18). Fig. 18.—Triple star ζ in Cancer. [Pg 73] In the Lyre, a little above the dazzling Vega, ε is of fourth magnitude, which seems a little elongated to the unaided eye, and can even be analyzed into two contiguous stars by very sharp sight. But on examining this attractive pair with a small glass, it is further obvious that each of these stars is double; so that they form a splendid quadruple system of two couples (Fig. 19): one of fifth and a half and sixth magnitudes, at a distance of 2.4″, the other of sixth and seventh, 3.2″ distant. The distance between the two pairs is 207″. Fig. 19.—Quadruple star ε of the Lyre. In speaking of Orion, we referred to the marvelous star θ situated in the no less famous Nebula, below[Pg 74] the Belt; this star forms a dazzling sextuple system, in the very heart of the nebula (Fig. 20). How different to our Sun, sailing through Space in modest isolation! Be it noted that all these stars are animated by prodigious motions that impel them in every direction. Fig. 20.—Sextuple star θ in the Nebula of Orion. There are no fixed stars. On every side throughout Infinity, the burning suns—enormous globes, blazing centers of light and heat—are flying at giddy speed toward an unknown goal, traversing millions of miles each day, crossing century by century such vast spaces as are inconceivable to the human intellect. [Pg 75] If the stars appear motionless to us, it is because they are so remote, their secular movements being only manifested on the celestial sphere by imperceptible displacements. But in reality these suns are in perpetual commotion in the abysses of the Heavens, which they quicken with an extraordinary animation. These perpetual and cumulative motions must eventually modify the aspect of the Constellations: but these changes will only take effect very slowly; and for thousands and thousands of years longer the heroes and heroines of mythology will keep their respective places in the Heavens, and reign undisturbed beneath the starry vault. Examination of these star motions reveals the fact that our Sun is plunging with all his system (the Earth included) toward the Constellation of Hercules. We are changing our position every moment: in an hour we shall be 70,000 kilometers (43,500 miles) farther than we are at present. The Sun and the Earth will never again traverse the space they have just left, and which they have deserted forever. And here let us pause for an instant to consider the variable stars. Our Sun, which is constant and uniform in its light, does not set the type of all the stars. A great number of them are variable—either periodically, in regular cycles—or irregularly. [Pg 76] We are already acquainted with the variations of Algol, in Perseus, due to its partial eclipse by a dark globe gravitating in the line of our vision. There are several others of the same type: these are not, properly speaking, variable stars. But there are many others the intrinsic light of which undergoes actual variations. In order to realize this, let us imagine that our Earth belongs to such a sun, for example, to a star in the southern constellation of the Whale, indicated by the letter ο, which has been named the "wonderful" (Mira Ceti). Our new sun is shining to-day with a dazzling light, shedding the gladness of his joyous beams upon nature and in our hearts. For two months we admire the superb orb, sparkling in the azure illuminated with its radiance. Then of a sudden, its light fades, and diminishes in intensity, though the sky remains clear. Imperceptibly, our fine sun darkens; the atmosphere becomes sad and dull, there is an anticipation of universal death. For five long months our world is plunged in a kind of penumbra; all nature is saddened in the general woe. But while we are bewailing the cruelty of our lot, our cherished luminary revives. The intensity of its light increases slowly. Its brilliancy augments, and finally, at the end of three months, it has recovered its former splendors, and showers its bright beams upon our[Pg 77] world, flooding it with joy. But—we must not rejoice too quickly! This splendid blaze will not endure. The flaming star will pale once more; fade back to its minimum; and then again revive. Such is the nature of this capricious sun. It varies in three hundred and thirty-one days, and from yellow at the maximum, turns red at the minimum. This star, Mira Ceti, which is one of the most curious of its type, varies from the second to the ninth magnitudes: we cite it as one example; hundreds of others might be instanced. Thus the sky is no black curtain dotted with brilliant points, no empty desert, silent and monotonous. It is a prodigious theater on which the most fantastic plays are continually being acted. Only—there are no spectators. Again, we must note the temporary stars, which shine for a certain time, and then die out rapidly. Such was the star in Cassiopeia, in 1572, the light of which exceeded Sirius in its visibility in full daylight, burning for five months with unparalleled splendor, dominating all other stars of first magnitude; after which it died out gradually, disappearing at the