THE HEAVENS.—Amédée Guillemin
What are the heavens? Where the shores of that limitless ocean; where the bottom of that unfathomable abyss?
What are those brilliant points—those innumerable stars, which, never dim, shine out unceasingly from the dark profound? Are they sown broadcast—orderless, with no other bond save that which perspective lends to them? Or, if not immovable, as we have so long imagined, if not golden nails fixed to a crystal vault, whither are they bound? And, finally, what are the parts assigned to the sun, our earth, and all the earths attendant on the glorious orb of day in this tremendous concert of celestial spheres—this sublime harmony of the universe?
These are magnificent problems of which the most fertile imagination would have in vain attempted the solution, if, for the greater glory of the human mind, astronomy—first born of the sciences—had not at length come to our aid.
How wonderful is the power of man! Chained down to the surface of the earth, an intelligent atom on a grain of sand lost in the immensity of a space, he invents instruments which multiply a thousand-fold his vision, he sounds the depths of the ether, gauges the visible universe, and counts the myriads of stars which people it; next, studying their most complicated movements, he measures exactly their dimensions and the distances of the nearest of them from the earth, and next deduces their masses; then, discovering in the seeming disorder of the stellar groupings real bonds of union, he at last evolves order from apparent confusion.
Nor is this all. Rising by a supreme flight of thought to the most abstract speculations, he discovers the laws which regulate all celestial movements, and defines the nature of the universal force which sustains the worlds.
Such are the fruits of the unceasing labors of twenty generations of astronomers. Such the result of the genius and of the patient perseverance of men who have devoted themselves for two thousand years to the study of the phenomena of the heavens. The Chaldean shepherds were, they say, the first astronomers. We can well believe it. Dwelling in the midst of vast plains, where the mildness of the seasons permitted them to pass the night in the open air, where the clear sky unfolded before them perpetually the most glorious scenes, they ought to have been, and they were, contemplative astronomers. And all of us would be what they were did not the rigor of our climate and our variable atmosphere so often prevent us observing the heavens; and did not, moreover, the turmoil and cares of civilized life deprive us of the necessary leisure.
Nothing is more fitted to elevate the mind toward the infinite than the pensive contemplation of the starry vault in the silent calm of night. A thousand fires sparkle in all parts of the sombre azure of the sky. Varied in color and brilliancy, some shine with a vivid light, perpetually changing and twinkling; others, again, with a more constant one—more tranquil and soft; while very many only send us their rays intermittently, as if they could scarce pierce the profundity of space.
To enjoy this spectacle in all its magnificence, a night must be chosen when the atmosphere is perfectly pure and transparent—one neither illuminated by the moon, nor by the glimmer of twilight or of dawn. The heavens then resemble an immense sea, the broad expanse of which glitters with gold dust or diamonds.
In presence of such splendor, the senses, mind and imagination are alike inthralled. The impression gathered is an emotion at once profound and religious, an indefinable mixture of admiration, and of calm and tender melancholy. It seems as if these distant worlds, in shining earthward, put themselves in close communication with our thoughts.
At a first glance at the starry firmament the stars seem pretty regularly distributed; nevertheless, look at that whitish, undecided, vapory glimmer which girdles the heavens as with a belt. It is the Milky Way.[1] As we approach the borders of this star-cloud in our inspection, the stars appear more and more crowded together, and most of them so small that the eye can scarcely distinguish them. The accumulation of stars in the direction of the Milky Way is more especially visible when we examine the heavens with the aid of a powerful telescope.
The Milky Way itself is nothing more than an immensely extended zone of stars, that is, of suns, since each star, from the most brilliant to the faintest, is a sun.
Here, then, is an immense group, a gigantic assemblage of worlds, which seems to embrace all the universe, if it be true that the greater number of the scattered stars situated out of the Milky Way nevertheless form part of it. In reality, this multitude of millions of suns is divided into numerous and distinct groups, and those into others still more restricted in number, each composed of two or three suns.
What breadth of space does each of these groups occupy? What is the measure of the space which holds them all? The most powerful imagination in vain attempts to answer these questions intelligibly; here numbers fail us.
Let us add—a fact well proved, and one which will seem strange to many—
Our sun himself is a star of the Milky Way.
In examining attentively every part of the starry vault, a keen eye perceives here and there whitish spots resembling little clouds. One would say they were so many patches detached from the Milky Way, from which, however, they are often very distinct and very distant. The telescope discovers by thousands those cloud-patches, these—to give them their astronomical name—Nebulæ.
It was formerly imagined that each of these star-clouds was nothing more than an accumulation of stars, very close together, and very numerous—so many Milky Ways lying outside our own, and for the most part so distant that the most powerful instruments were able only to distinguish a confused glimmering. One of the most important observations of modern times, however, has shown that many of these nebulæ, including the most glorious one in our northern hemisphere—that in the sword-handle of Orion—are but masses of glowing gases.
Others, again, of these cloud-like masses—cloud-like by reason of their distance—show us, faintly shining on a background of apparent nebulæ, brilliant stars, larger no doubt, or more brilliant, than their fellows, and some of these objects called “Star-Clusters,” which are nearest to us, are among the most glorious objects revealed to us by our telescopes.
Let us attempt now to conceive what fearful distances separate these archipelagoes of worlds from our own!
Unfathomable abysses whose unspeakable depths the most powerful telescopes increase indefinitely! Profound, endless, bottomless, but lighted up by millions of suns!
Such appears to us the universe from the natural observatory where we are placed. But to obtain a more complete idea of its constitution, of the infinite variety of its members, we must descend from those regions, where the sight and mind are lost, to a group, nearer to us, and therefore more accessible to the investigations of man—to that group, or system, of which the earth forms part.
Of this the sun is the centre.
Round this focus of light and heat, but at various distances, revolve more than a hundred secondary bodies—Planets, some of which are accompanied by smaller ones—Satellites. Not self-luminous, they would be invisible to us, if the light, which they receive from the sun, were not reflected toward the earth, making them also appear as luminous points spread over the celestial vault like so many stars. Such would be the appearance of the earth seen in space, at a distance sufficiently great.
A common character distinguishes all the celestial bodies that form part of this group—the Solar System—from the multitude of other stars. For while the suns, composing what is called the Sidereal Universe, are situated at distances seemingly infinite, the bodies composing the group of which we speak are relatively much nearer the earth, are, in fact, our neighbors.
What results from this double fact? Two very simple consequences, easily understood.
The first is, that the stars do not undergo any sensible change of position in the starry vault. Their distance is such that they appear actually at rest in the depths of space; hence the term Fixed Stars—now abandoned, because a minute and elaborate study of their relative positions has established the fact that the stars really do move in the remote regions of the heavens. The apparent immobility of which we have spoken, and which is one of their characteristics, is evidenced by the uniformity of appearance preserved for centuries by the artificial groups of stars, to which the name of Constellations has been given.
Now, it is otherwise with the bodies that revolve round our sun: they are near enough to the earth to allow of their displacements in space being perceived in short intervals of time. Traveling, by virtue of their proper motions along the starry vault, distances which appear greater as their own distance from us is less, these bodies received at the outset the name they have since retained—Planets, or Wandering Stars.
It is thus that, when we stand in the middle of an extensive plain, we judge distant objects—those that border the horizon—to be immovable; while we instantly perceive the slightest change of place in the near ones. It is true that when we ourselves move, the real movements become complicated with the apparent movements, but the former must be distinguished, if we wish to have an exact idea of the actual course traveled. This complication of the apparent movements of the planets—a necessary consequence of the movement of the earth—is one of the most striking testimonials to the reality of the latter; but it must also be added, that this was precisely the stone of stumbling of ancient astronomy until the time—and that not long ago—when the real movements were made known. Movements of rotation, movements of revolution, around the common centre, the duration of these movements, distances, forms and dimensions, distribution of light and heat, all change in passing from one planet to another. And yet, marvelous thing, the same laws govern, all in such a way that the unity of plan is not less marked than the astonishing variety of the phenomena.
One circumstance common to all the bodies of the solar system forcibly strikes the imagination. It is, that these enormous masses—these globes, many of which are much heavier than the earth, and lastly, the earth itself—are not only suspended in space, but move through the ether with velocities truly stupendous.
Imagine yourself a spectator, standing immovable in space. A luminous body appears in the distance, little by little you see it approach and increase in size; its immense circumference, which exceeds a hundred thousand leagues, is in rapid rotation, which makes each point on its periphery travel through nine miles a second. The globe itself passes before you, carried through space with a velocity twenty-four times greater than that of a cannon-ball. In such a way Jupiter would appear to you traveling in its orbit. This headlong course would banish it forever to the most remote regions of the visible universe, if it were not subdued and held by the powerful attraction of a globe a thousand times larger than its own—by the sun himself. Not only does astronomy show, by undeniable proofs, the reality of these marvelous movements—not only has she arrived at the knowledge of their invariable constancy, at least during thousands of centuries; but she has found in their very rapidity the cause of the stability of all the celestial bodies.
If there is difficulty in imagining such masses freely circulating in the ether, how much more are we impressed when we consider that these rapid movements are not confined to the planets; and when we look upon the sun with all his retinue as moving in an orbit yet unknown, himself attracted no doubt by a more powerful sun, or by a group of suns! All the stars which by reason of their infinite distances appear immovable, move in different directions; and we shall see later, that if these movements are performed with extreme slowness, the slowness is apparent only. In reality, these are the most rapid celestial movements that we know of.
Thousands of centuries will be necessary before these immense sidereal voyages are accomplished. Their vast periods are to the length of our year what the dimensions of the earth are to the distances of the stars; and, according to the happy expression of Humboldt, they make of the universe an eternal timekeeper. Thus, in the contemplation of celestial phenomena, the idea of infinite duration impresses itself on the mind with the same irresistible power as the idea of the infinity of space.