Page:Popular Science Monthly Volume 14.djvu/488

472 of a large planet or a vast dark central body presiding over unseen planetary members, but even the corona and the photosphere of a sun. Whenever any of the large members of a solar or of a secondary system become unstable in too small an orbit, a vast portion of its dilapidated mass would be quickly sweeping as innumerable meteors through the atmosphere of the immense primary sphere. This accounts for the incipient brilliancy of the temporary stars, a fact hitherto unexplained, though it is generally admitted, and though it has been recognized by a high authority as a valuable guide in the study of these mysterious phenomena. "The circumstance," says Humboldt, "that nearly all the new stars burst forth at once with extreme brilliancy as stars of the first magnitude, and even with still stronger scintillations, and that they do not appear, at least to the naked eye, to increase gradually in brightness, is in my opinion a singular peculiarity, and one well deserving of consideration." Recent discoveries, though calling for some modification in this statement, detract little from its value; for the three new stars of the present century, though all below the first magnitude, yet showed their greatest effulgence at an early period of their visibility, and afterward exhibited a constant decline. According to the present theory, a rapid weakening of brilliancy in these objects would be an inevitable result: as a large portion of the meteors must have been successively precipitated to the surface of the great central sphere; while the balance assumed a closer array, changing their orbits into circles and forming a solar or a planetary ring.

The most favorable circumstances for such sudden outbursts of light are presented in cases where, in mass and size, the subordinate world is little more than one per cent, of the solar or the primary orb with which it is doomed to incorporate. If, for instance, our moon were caused to revolve so near us that it would be rendered unstable by terrestrial attraction, its dismemberment, though occurring on a large scale, would be confined to the region nearest to the earth. A vast portion of the lunar matter torn from this locality would be hurled to our globe or would fly as innumerable meteors through our atmosphere. But the remainder of our satellite would retire to a greater distance from the earth; and millions of centuries would elapse before it became again close enough to our world to suffer another great dilapidation and to give occasion for another gigantic display of meteoric light. It would thus appear that many great luminous exhibitions would attend the awful paroxysms with which a large planet passes away from the stage of existence in a solar or in a secondary system. Though a small satellite, if fluid, may meet its final doom in an obscure manner, yet, if solid, it would be likely to maintain a planetary form until it came very close to the primary; so that on its dilapidation a large portion of the resulting fragments would sweep through the atmosphere of the latter and call forth a sudden effulgence which in very remote worlds would appear as the transitory glare of a temporary star in the firmament.