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] [Footnote 8: General Astronomy, by Charles A.Young.Revised edition, 1898, p.

372.] 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.