472 THE POPULAR SCIENCE MONTHLY. 



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 sys- 

 tem become unstable in too small an orbit, a vast portion of its dilapi- 

 dated 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 hio'h 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 deserv- 

 ing 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 mag- 

 nitude, 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 be- 

 came again close enough to our world to suffer another great dilapida- 

 tion and to give occasion for another gigantic display of meteoric light. 

 It would thus appear that many great luminous exhibitions would at- 

 tend 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 por- 

 tion 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. 



