God's glory in the heavens/A Journey Through Space

by William Leitch

Structure of Milky Way.

I

A JOURNEY THROUGH SPACE.

We are accustomed to survey the universe from the stand point of our globe, and, consequently, as far as the mere evidence of sense is concerned, all else appears little compared to man's abode; and so great is the mastery of sense over reason, that, for ages, man resisted the conclusive force of the latter. It was an agreeable delusion, that the whole universe centred in man; and when Galileo was persecuted by papal authority, the motive may perhaps as much be traced to human pride, as to orthodox zeal. The whole subsequent history of astronomy is, simply, the record of the way in which man has been brought to his level, as far, at least, as his dignity depends on the abode in which he dwells. But the grand lesson of astronomy is, that man's true dignity does not consist in the mere outward and physical. The more that the discoveries of astronomy make this world shrink into insignificance, the more amazing is the view we obtain of man's spiritual dignity. It is the immensity of the universe, contrasted with the humble abode of man, that brings out most strikingly the value of the human soul, as redeemed by the death of the Cross. When you attempt to plumb the depths of space, or number the orbs of heaven, your feeling is, How little is man! And, yet, how great, when measured by the price of his redemption! How little are worlds and systems to a God-loving spirit! The holy breathings of one devout heart, give to God more glory than the loudest anthems of the heavenly hosts. And the starry firmament has not been created in vain, while it teaches this great truth to all spiritual intelligences. There is something that urges us to find some use or adaptation for all God's works, but we too often restrict the nature of the use; and unless we find some physical adaption, we think that we have failed. Is it not use enough for the innumerable hosts of heaven to be the silent teachers of immortal spirits, emphasising the great redemptive act, and proclaiming that, in the estimate of heaven, there is nothing greater than the soul of man? The deeper we penetrate into the abyss of space, the more will we comprehend the significance of the inquiry, "What shall it profit a man, though he gain the whole world, and lose his own soul? or what shall a man give in exchange for his soul?"

Though the facts and deductions of astronomy sufficiently bring out the immensity of the universe, as contrasted with our world, still it is difficult to realise the truth; our thoughts will obstinately cling to our globe, and the images of grandeur will still be, our terrestrial seas and mountains. Let us, however, attempt to escape from the narrow confines of our globe, and see it, as others see it, from a different point of view. Let us take a nearer survey of other orbs and systems, and see what impressions they produce, as compared with that received from the platform of the earth.

But what vehicle can we avail ourselves of for our excursion? Must we be altogether dependent on the fairy wings of imagination, or can we derive aid from some less ethereal agencies? It was long the fond wish of man to soar above this terrestrial scene, and visit other planets. In the infancy of physical science, it was hoped that some discovery might be made that would enable us to emancipate ourselves from the bondage of gravity, and, at least, pay a visit to our neighbour the moon. The poor attempts of the aeronaut have shewn the hoplessness of the enterprise. The success of his achievement depends on the buoyant power of the atmosphere, but the atmosphere extends only a few miles above the earth, and its action cannot reach beyond its own limits. The only machine, independent of the atmosphere, we can conceive of, would be one on the principle of the rocket. The rocket rises in the air, not from the resistance offered by the atmosphere to its fiery stream, but from the internal reaction. The velocity would, indeed, be greater in a vacuum than in the atmosphere, and could we dispense with the comfort of breathing air, we might, with such a machine, transcend the boundaries of our globe, and visit other orbs.

Instead, however, of torturing our imagination to conceive of a rocket device, which would eclipse the performances of all flying machines, let us take one of nature's rockets as the material aid to our imaginary flight. Let us follow the course of some comet in its wanderings across our system. A rocket, held fast, with its fiery stream directed against a strong wind, very well represents the telescopic appearance of a comet, when in the neighbourhood of the sun. The luminous particles shoot out from the nucleus of the comet, precisely as the sparks issue from the rocket-tube, and they are thrown back as a strong wind would throw back the fiery stream of the rocket.

The sector or fan, so well seen in the comet which lately (1861) burst upon us with such astonishing brilliancy, is the form which the gush of luminous particles assumes under some unknown repelling power. The revolution of the comet is determined by the laws of gravitation, but there are perplexing movements in the tail and nucleus, which likely will receive an explanation from this rocket-like action.

We have, however, to do at present, not with the theory of the constitution of the comet, but with its character, as a vehicle for surveying the solar system. We may be pardoned in using it as a vehicle for our imagination, when some advocates for the plurality of inhabited worlds have gravely argued, that the most ethereal comets may have their inhabitants—that even each particle may have its adhering element of life. An inexorable logic has driven them to this conclusion, from the assumed position, that the very matter of planets, apart from their proved adaptation, implies life. The densest comet would afford but insecure footing to beings of almost spiritual essence, as the matter of which it is composed must be so light that the atmosphere of our earth is as lead compared to it. But we shall overlook this difficulty, and venture, in thought, to follow the fortunes of some cometic wanderer. The difficulty of reaching some suitable comet, is lessened by the consideration that the comet may come to us. It has been surmised that the above comet touched at our earth, as one of its stations, in its line of transit across the system. The surmise needs corroboration, but it is quite a legitimate one. There is no physical reason why we should not pass through the tail of a comet without ever knowing it. The phosphorescent light, seen by Mr Hind, and noticed by others, may have had no connexion with the matter of the comet; but still, it is possible that we may have been immersed in this cometary medium, without any appreciable effects being produced.

The great advantage of the comet, as a convenient vehicle for an excursion, is, that it gives near, as well as extensive views of the system. The drawback of our own globe is, that it always keeps at the same distance, or nearly so, from all the bodies of the system; so that, although it is constantly moving onwards, we are kept at such a distance, that we see but little change in the celestial scenery. It is like an excursion steamer constantly sailing, in a narrow circuit, round a buoy moored in the middle of a wide lake. The view of the surrounding scenery never changes, and the minute objects of the landscape are never seen. The comet, on the other hand, is like the steamer that sails up the whole length of the lake on one side, and comes down along the other. Every object is seen minutely, and from different points of view. Most comets, too, rise above the plane of the solar system, so that we may have a clear view of the relation of one planet to the other. The early misconception, as to the arrangement of the solar system, arose chiefly from the circumstance that, from the position of the earth, we see it in section, not in plan. When two armies meet, it is difficult for the one to comprehend the dispositions of the other, and hence the plan, sometimes resorted to, of employing balloons, to enable the one party to look down from above upon the position taken up by the other. The orbit of the comet is, in like manner, usually so situated, that it commands such a view of the solar system; and the sun and its surrounding planets are seen as distinctly as the central body of an army, with all its outlying forces, is seen from the balloon. Comets, however, occasionally move on the same level with the planets, and it is from a comet with such an orbit that the best view can be obtained of them individually. The comet may, in this case, come so close that the planetary orbs may be caught in the sweep of its tail. A planet may, at one time, be seen so large as to cover most of the celestial hemisphere; at another, so minute as to appear but a point of light in the dark concave.

Then, again, let us consider the rate at which the comet travels. This is by no means an equable one. Sometimes it moves so slowly, that a child might keep up with it; at another, it speeds round with lightning velocity. It is like a coach going down a declivity without a drag. It increases its velocity till it comes to the bottom of the hill, and the momentum acquired carries it up the opposite side, till it gradually slackens and assumes a snail's pace. The comet approaching the sun is going down hill, and when it reaches the nearest point it wheels round, and then ascends till its speed is gradually arrested. It is reined in by the sun, from which there are invisible lines of force dragging it back; and, if its momentum be not too great, it is effectually checked and brought back to pursue its former course. Most frequently, however, its course is so impetuous that all the strength of the sun, in reining back, avails nothing. It breaks loose, like a fiery steed from its master; speeds off into space, and is heard of no more. We shall, first, follow the fortunes of one of the more tractable comets, or those that remain permanent members of the solar system, performing their revolutions regularly round the sun. Of these there are six whose orbits are well determined.

Let us enter the cometary vehicle at some point beyond the confines of the solar system; and Halley's comet makes an excursion three hundred millions of miles beyond Neptune—the most distant planet in the system. Here the comet is a globular mass, lazily floating along like a filmy cloud in the heavens. It is on its way to the sun, and we shall suppose that the planets are so many stations on the line. When we near Neptune, his attraction is powerfully felt. The sun would have us go straight on, but our motion is so slow, and the sun so distant, that Neptune readily drags us out of our course. Here we may discover objects that have escaped the keen eye of astronomers. No astronomer has ever detected more than one satellite; but we may well suppose that this arises, not from their non-existence, but from their invisibility at such a distance. As planets recede from the sun, distance from the centre of light is compensated for, in some measure, by the number of satellites. If the day wants brilliancy, the loss is made up by the magnificence of the moonlight scenery. There are probably crowds of moons studding the Neptunian skies, and giving cheering light when the tiny sun has set—the sun being only a thousandth part as large as it appears from our globe. It is not improbable that Neptune has rings like Saturn. Some astronomers have pretty confidently asserted that they have sometimes got glimpses of a ring. The rings may be invisible, not merely from distance, but from the dimness of the matter of which they are composed. The dark ring of Saturn would not be seen by the best telescope at the distance of Neptune. When we alight on the surface of Neptune, we find a little more difficulty in locomotion. A man who weighs twelve stones on the earth, would here weigh sixteen stones; and having this additional weight, with the same muscular strength, difficulty of movement would necessarily be the result. This does not arise from the density of the planet, but from its superior mass. So far from the matter being dense, it is on the whole no heavier than water. This, however, is on the supposition that we see the solid surface of the planet. What we see, however, may be only an envelope far above the surface of the nucleus, which may have a much greater density. Though the sun has dwindled down to one-thousandth its size, its light is by no means so dim as might be supposed. We have a proof of this in the case of eclipses. If the most slender crescent be left uncovered by the moon, the diminution of light is by no means startling. It is only at the moment of totality that the dread effects of an eclipse are produced. We can conceive of the Neptunians thriving very well, notwithstanding their stinted supply of light; and we can suppose that all unpleasant effects might be completely obviated, by having the pupil of the eye enlarged, and the sensibility of the retina increased. The diminution of heat would be more difficult to endure, but, with a properly constituted atmosphere, and with the central heat of the planet itself, we can have no difficulty in conceiving of its being inhabited. The human frame proves how low a temperature is compatible with the functions of life. In this climate, the sinking of the temperature ten degrees below the freezing-point, is more keenly felt than a sinking of twenty degrees below zero during a Canadian winter. The reaction of the vital powers seems to come more into play at very low temperatures, and hence the wide range through which life is possible.

The next station is Uranus, but the interval between is vast. The stage from the one orbit to that of the other is about one-third of the whole journey to the sun. In a railway train, running at the ordinary speed, this distance could not be done under less than six thousand years; so that, if the train started at the creation of man, it would not have yet reached this first station on the way to the sun. The planets, however, are closer as you approach the sun, just as on a railway the stations become more numerous as you approach the metropolis. In our cometary vehicle, the speed is always increasing, so that, although slow as a railway train at first, it soon acquires immensely greater speed as it rushes on towards its distant goal. The comet of Halley, though starting so far beyond the verge of the system, takes only about forty years to reach the sun. The railway train, going always at the same rate, would take 10,000 years from the remotest orbit of the system to the centre.

With our increased velocity, Uranus has less influence in drawing us out of our course. Here we find numerous satellites. Sir William Herschel discovered six, but only four have been detected by others. It is, however, highly probable that the number is greater even than that assigned by Herschel. In Uranus, as far as weight is concerned, we would find ourselves more at home than in any other planet. Our power of locomotion would be very much the same as here. The most notable fact connected with Uranus is, that his satellites revolve in a direction the opposite to that of all the planets and satellites of the solar system. The nebular hypothesis is very much founded upon the uniformity of the system in this respect; and this breach of uniformity presents a rather baffling discrepancy.

Our next stage is somewhat shorter than the last, still the interval between Uranus and Saturn is immense; but when we reach this station, we have only a third of our journey before us. Here we are in danger of being completely drawn out of our course, the attraction of the planet being so powerful. Its size is such that it could contain within its sphere 772 terrestrial globes. It is, however, as light as cork; and the consequence is, that standing on its surface, you do not feel yourself dragged down by its attraction; you feel no material difference, in this respect, between it and our own globe. An opportunity is now afforded of inspecting the mystery of the rings. You will probably discover many more rings, or, rather, what appears a single ring will be found to consist of many smaller ones. You can see through the dusky ring, and have an opportunity of detecting its nature. You will find it to be different from vapour or gas, and to consist of meteorites of considerable size, though, at the distance of the earth, it would appear as if you were looking through a cloud of fine dust. It is probable, also, that you will find the brighter rings to be of a similar nature, though the bodies of which they are composed may be larger and more closely packed together. The rings have, not without reason, been suspected to be rows of satellites, so closely crowded together that they appear to be one solid body. This accounts for the occasional appearance of divisions, and their subsequent obliteration. On none of the planets will the heavens present so grand a spectacle. The rings, shining with the lustre of the moon, will constantly arch the heavens. From the effect of perspective, the arch will appear broadest at the summit, and gradually to taper towards the horizon. The eight moons, some of them threading the outline of the ring, will be seen in different phases in the sky ; the stars will be seen setting behind the bright bars, and re-appearing in the dark spaces between.

We next reach Jupiter, nearly midway between Saturn and the sun. It was here that Lexell's comet got entangled in the satellites, and was thrown quite out of its course by the overpowering attraction of the planet. A proof was, on this occasion, afforded of the almost ethereal constitution of the comet. While the comet was driven about at the mercy of every body it met, it had no power whatever to disturb the course of the smallest bodies it came in with; and the mass of the heavenly bodies is determined by this power of disturbing other bodies. In the case of the comets, no disturbing power has been detected, and no mass can be assigned to them. How stupendous an object must Jupiter have appeared to an eye in Lexell's comet, when it swept through its satellites. The disc must have covered a great part of the heavens as a brilliant canopy, and the rotation would be distinctly sensible, as some marked cloud would be seen appearing at one edge of the disk, and, in five hours, disappearing at the other. Jupiter is by far the largest planet in the system. His dimensions are such, that it would take 1491 terrestrial globes to equal it. The density is, however, only that of water, so that the increased weight of objects on its surface, is not so great as might be supposed. A man's weight would be little more than doubled.

In setting out again on our journey, we might expect a new station by halving the distance between Jupiter and the sun, as this process served us in the case of our last two stages. We are so far successful, that we find not one large planet, but thousands of small ones. We have, from the earth, discovered only seventy-one, but, in all probability, there are many yet to be discovered; there may be thousands too small to be detected. In sweeping through the zone of asteroids, we are like a ship threading her way through innumerable icebergs, large and small. Like icebergs, they cross one another's path, and probably sometimes unite, so as to form a more conspicuous object—thus accounting for the fact, that asteroids have been discovered in localities which were scrutinised with the utmost care a little before, and were found not to exist. It is easy to understand how two bodies, invisible from their smallness, should become a notable object when united. Let us step on one of these miniature worlds, no larger than an English county. With our present muscular strength, we could easily clear the broadest rivers and the loftiest spires—our bodies being literally lighter than a feather. We could readily keep up with the rotation of the asteroid, and prevent the sun from setting. We could have all climates at command. We could withdraw to the polar regions during the heat of the day, and return to the torrid zone to spend the evening. Cyclopean structures might be raised, compared to which, the pyramids of Egypt would be but mole-hills. The very globe itself might be tunnelled and split up, so that contending parties might have little worlds of their own to live in. The imagination can thus easily revel in the wildest fancies, if we exchange the normal conditions of life for extreme physical suppositions. This zone of asteroids serves as the boundary between the two distinct groups of planets. The planets which we have already visited have all distinctive characters, and a family likeness. They are characterised by their greater size and their remarkable lightness. The outer planets may Le compared to wood,while those within the zone of asteroids are more allied to metals in density.

But our fiery chariot is now, on account of its proximity to the sun, experiencing strange internal commotions. The globular mass is now elongated towards the sun, the nucleus being situated near the foremost end, and as we approach still nearer, the nucleus is thrown into a state of wild excitement. A jet of bright luminous matter rises from it, similar in shape to a bat-wing gas-burner; and, in other respects, this fan of light is not unlike a jet of gas. It is sometimes seen to dance like a gas-burner when there is water in the pipe. The whole comet seems for a moment or two to be extinguished, and then suddenly flashes out with its former brilliancy. This excited action increases in intensity, till the comet reaches its nearest point to the sun, and it is only after the comet has emerged from the rays of the sun, that it has attained its maximum brilliancy. The motion of the comet, and the increase of brilliancy, is sometimes so rapid, that it appears to burst all at once, as in the case of the recent comet (1861), upon an astonished world.

As our vehicle now advances with such rapidity, and as the stations are now very close to one another, we shall take but a cursory glance at each body as we advance. The first of the heavy planets is Mars, and on his surface we can readily descry the circle of snow at the poles, and the general outlines of his continents. The Earth next appears with its surrounding blue atmosphere. Her continents and oceans are seen dimly down through the openings in the clouds that float in her atmosphere. Belts more or less distinct, corresponding to the trade-winds, will also be detected. We pass, in rapid succession, Venus, Mercury, and Vulcan; and we probably find that Vulcan is only one of innumerable asteroids that form a zone between Mercury and the sun. At last we reach the goal, and find ourselves in close proximity to the sun. Conceive of our sun expanding, so as nearly to fill the whole concave of the sky, and we shall have some conception of a comet's approach to it; and, in their daring course, comets sometimes almost graze its surface. Here the diamond would flash into flame like gunpowder, and the hardest metals would, in an instant, be volatilized, so intense must be the heat. Here, too, we may closely survey those mysterious rose-coloured flames, seen in total eclipses, that have so puzzled observers. Through the luminous envelope we see down into these perforations, which appear as dark spots from the earth. These minute specks are now seen to be gulfs, down which the earth could be projected with the greatest ease; and so capacious is the sun, that it could engulf all the planets of the system, and yet shew no appreciable difference in size. Millions of meteorolites and comets have probably been engulfed already, and yet millions more would not visibly enlarge the furnace.

To understand the relative position of the stations at which we have stopped in our excursion, it is necessary to assign a scale. If, then, we call the distance of the earth to the sun one mile, the distance of Neptune will be thirty miles; and our nearest neighbour, the moon, will only be four yards from us. To expand this scale to represent the reality, we have only to keep in mind that a railway train, going at the rate of thirty miles an hour, and travelling day and night, would take twenty thousand years to go straight across the whole breadth of the solar system.

But, after all, this journey is nothing more than a morning drive to the houses of a few friends in the neighbouring streets. We have still an expedition before us, which may be compared to the crossing of the Atlantic, or a voyage to China. We have not yet really left home, and now that we propose going abroad, what vehicle shall we take to aid us in our flight to other systems? The comet is all too slow for our purpose. We must have something still more subtle and swift. The only physical agency that can serve our purpose is a ray of light. On a ray of light we may reach the moon in a single second, and the sun in eight minutes. Instead of taking twenty thousand years, like the railway train, to cross the solar system, it would require only eight hours. Let us suppose, then, that, with the ethereal vehicle of light we are to start upon a journey far beyond the solar system, where shall be our first resting-place? Alpha Centauri is the nearest of the stars whose distance has been well determined; but with all the spiritual swiftness of light, we can reach it only in three years and a quarter. We are separated from the planets by an interval that may be compared to the breadth of a river; but an expanse like the Atlantic Ocean, separates us from the nearest of the fixed stars. The smallest stars visible to the naked eye can probably be reached by a ray of light only in about fourteen years; and the smallest stars, visible in the largest reflectors, would probably require a journey of four thousand years.

Let us now start from the star on which we have gained a footing, for a position from which we may look down upon the group of fixed stars to which our sun belongs. Having gained this position, we find that the sun is part of the Milky Way, which lies like a bright ring before us, with perhaps a tendency to the spiral structure; the cleft in the galaxy corresponding to a coil of the spiral. To expand this ring to its true dimensions, we must remember that a ray of light would probably take a thousand years to speed across its whole breadth. But from our position we find that the Milky Way, with its millions of stars is not the only luminous disc. The whole heavens are studded over with similar patches of light or nebulse which, on closer inspection, are found to be firmaments, consisting, like the Galaxy, of innumerable stars. They may appear as single, hazy stars, but they are the combined light of countless hosts. These groups are separated by gulfs which it would require millions of years for a ray of light to traverse.

As we in thought travel from firmament to firmament, we see new forms constantly presented to our view. Each firmament has some bond of unity, and, generally, a symmetrical structure. However much they differ, a tendency to the spiral structure may be discovered. One cannot look at the figures of the spiral nebulæ without having suggested the idea of vast vortices, in which streams of stars are hastening on to some grand consummation. There is nothing fixed or final in the heavens; all things are passing through cycles of decay or revivification. As there are silent molecular changes going on in the most solid masses on the earth's surface, so these suns, which to a mind of superior grasp may appear as only single particles of which the nebula is the mass, are in constant motion in the galaxy to which they belong.

But where are we to stop? Are we to assume that the firmament or resolvable nebula is the last step? or, are we to look for some higher unity, under which these groups may be subsumed? Speculations connected with the indestructibility of force, have led to the idea that all the worlds and system which astronomy has revealed, are included within one vast sphere of definite dimensions, and consisting of the ethereal medium through which light, heat, electricity, and gravity are propagated. But are we to accept this definite sphere as the sum of the physical universe? Overwhelmingly vast it may appear to us, but shall we limit the creative power of the Infinite to a sphere which, compared to the infinitude of space, is as a mote in the sunbeam? But then the metaphysical question arises—and the ultimate problems of physics always merge in metaphysical questions — What is space? Is it an objective reality, or a subjective condition of thought? We cannot enter on this mare magnum of controversy, but we must advert to the curious correlations of time and space brought out by the laws of light.

From the simple law, that light requires time to travel from one point to another, it follows, that we see everything in the past. In the case of very distant objects, this leads to startling results. For every event in the past history of the world, there is a corresponding point in space, and if we were situated on a star at that point, we would, on looking down upon the earth, see the corresponding event transacted. For example, if we took up our position in a star, to which light would take six thousand years to travel from this globe, we would witness the scenes of paradise, and the roll of the world's history would unfold itself to our eyes. If the course of events appeared too slow, we could hasten it, in any degree, by gliding swiftly towards the earth, along the course of the rays. If we could accomplish the journey in an hour, the history of six thousand years would be condensed into that period. The schoolmen defined eternity as punctum stans, and the propagation of light gives a startling illustration of their meaning. We can arrest the flow of time by continued motion. Suppose our world is the illuminated dial of a clock, that the hand is at twelve o'clock, and that the machinery is faithfully doing its duty; we have only to take up our position in a star that moves from the earth as rapidly as the rays from the dial, in order to arrest the hand for ever at that hour. To one who is stationary, the hand makes its ordinary revolution; but one who moves away with the rapidity of light, sees it perfectly fixed. Nay, it is possible to turn back the hand, as in the case of the dial of Ahaz. In a star moving away from the earth more rapidly than the light, a person would see the hands gradually move in the reverse order, from twelve to eleven o'clock, and so on. By moving in the direction opposite to that of the light, centuries might be concentrated into hours, and hours into seconds. Had we unlimited powers of locomotion, we would not be under the necessity of reading unintelligible and prosaic accounts of campaigns and battles in the past history of our country; it would only be necessary to wing our way to some star where the light from the seat of war is just arriving, and leisurely watch the actual progress of events.

These curious relations of space and time, as linked together by the laws of light, sufficiently show how the properties of matter may aid the spirit, in a future state of being, in obtaining a wide and comprehensive view of the works and the providence of God. Matter and force, as far as we know, are indestructible, and time itself, the most perishable, in one sense, of all things, is, in another, indestructible too. It can be recalled, as we have seen, and forced again to do duty, by repeating the events of the past.

When we step from planet to sun, from sun to system, and from system to firmament, we are ascending the rounds of the ladder that leads up to the Infinite; and this is the great end of the book of God in the heavens. But a hard-featured philosophy comes, and tells us that we cannot know the Infinite, that the notion we form is merely a synthesis of finites, that no number of finites can ever make an infinite; and that this arises from the very limits of thought. This is true, if it means merely that we cannot construe to our minds the image of an infinite ladder, by indefinitely increasing the rounds of it; but surely we can know a thing, though we cannot draw a definite picture of it to the eye or the imagination. We can, in like manner, know the Infinite and the Eternal, though we cannot construe to our minds either infinite duration or infinite space. The African on the banks of the Niger may be altogether ignorant of its source and termination; but would it be right, on that account, to deny that he has any knowledge of the river? It would be equally wrong to deny that we can know God, merely on the ground that we do not and cannot grasp His Infinite attributes.