"It is true, as has often been urged, that this theory in its original form, as presented by Olbers, can not be correct. No single explosion of a planet could give rise to the present assemblage of orbits, nor is it possible that even the perturbations of Jupiter could have converted a set of orbits originally all crossing at one point (the point of explosion) into the present tangle. The smaller orbits are so small that, however turned about, they lie wholly inside the larger and can not be made to intersect them. If, however, we admit a series of explosions, this difficulty is removed; and if we grant an explosion at all, there seems to be nothing improbable in the hypothesis that the fragments formed by the bursting of the parent mass would carry away within themselves the same forces and reactions which caused the original bursting, so that they themselves would be likely enough to explode at some time in their later history."[8]
The rival theory of the origin of the asteroids is that which assumes that the planetary ring originally left off from the contracting solar nebula between the orbits of Mars and Jupiter was so violently perturbed by the attraction of the latter planet that, instead of being shaped into a single globe, it was broken up into many fragments. Either hypothesis presents an attractive picture; but that which presupposes the bursting asunder of a large planet, which might at least have borne the germs of life, and the subsequent shattering of its parts into smaller fragments, like the secondary explosions of the pieces of a pyrotechnic bomb, certainly is by far the more impressive in its appeal to the imagination, and would seem to offer excellent material for some of the extra-terrestrial romances now so popular. It is a startling thought that a world can possibly carry within itself, like a dynamite cartridge, the means of its own disruption; but the idea does not appear so extremely improbable when we recall the evidence of collisions or explosions, happening on a tremendous scale, in the case of new or temporary stars.[9]
Coming to the question of life upon the asteroids, it seems clear that they must be excluded from the list of habitable worlds, whatever we may choose to think of the possible habitability of the original planet through whose destruction they may have come into existence. The largest of them possesses a force of gravity far too slight to enable it to retain any of the gases or vapors that are recognized as constituting an atmosphere. But they afford a captivating field for speculation, which need not be altogether avoided, for it offers some graphic illustrations of the law of gravitation. A few years ago I wrote, for the entertainment of an audience which preferred to meet science attired in a garb woven largely from the strands of fancy, an account of some of the peculiarities of such minute globes as the asteroids, which I reproduce here because it gives, perhaps, a livelier picture of those little bodies, from the point of view of ordinary human interest, than could be presented in any other way.
A WAIF OF SPACE
One night as I was waiting, watch in hand, for an occultation, and striving hard to keep awake, for it had been a hot and exhausting summer's day, while my wife—we were then in our honeymoon—sat sympathetically by my side, I suddenly found myself withdrawn from the telescope, and standing in a place that appeared entirely strange. It was a very smooth bit of ground, and, to my surprise, there was no horizon in sight; that is to say, the surface of the ground disappeared on all sides at a short distance off, and beyond nothing but sky was visible. I thought I must be on the top of a stupendous mountain, and yet I was puzzled to understand how the face of the earth could be so far withdrawn. Presently I became aware that there was some one by me whom I could not see.
"You are not on a mountain," my companion said, and as he spoke a cold shiver ran along my back-bone; "you are on an asteroid, one of those miniature planets, as you astronomers call them, and of which you have discovered several hundred revolving between the orbits of Mars and Jupiter. This is the little globe that you have glimpsed occasionally with your telescope, and that you, or some of your fellows, have been kind enough to name Menippe."
Then I perceived that my companion, whose address had hardly been reassuring, was a gigantic inhabitant of the little planet, towering up to a height of three quarters of a mile. For a moment I was highly amused, standing by his foot, which swelled up like a hill, and straining my neck backward to get a look up along the precipice of his leg, which, curiously enough, I observed was clothed in rough homespun, the woolly knots of the cloth appearing of tremendous size, while it bagged at the knee like any terrestrial trousers' leg. His great head and face I could see far above me, as it were, in the clouds. Yet I was not at all astonished.
"This is all right," I said to myself. "Of course on Menippe the people must be as large as this, for the little planet is only a dozen miles in diameter, and the force of gravity is consequently so small that a man without loss of activity, or inconvenience, can grow three quarters of a mile tall."
Suddenly an idea occurred to me. "Just to think what a jump I can make! Why, only the other day I was figuring it out that a man could easily jump a thousand feet high from the surface of Menippe, and now here I actually am on Menippe. I'll jump."
The sensation of that glorious rise skyward was delightful beyond expression. My legs seemed to have become as powerful as the engines of a transatlantic liner, and with one spring I rose smoothly and swiftly, and as straight as an arrow, surmounting the giant's foot, passing his knee and attaining nearly to the level of his hip. Then I felt that the momentum of my leap was exhausted, and despite my efforts I slowly turned head downward, glancing in affright at the ground a quarter of a mile below me, on which I expected to be dashed to pieces. But a moment's thought convinced me that I should get no hurt, for with so slight a force of gravity it would be more like floating than falling. Just then the Menippean caught me with his monstrous hand and lifted me to the level of his face.