496 SOLAR SYSTEMS OTHER THAN OUR OWN. 



twenty-one and a half, so that the squares of their periodical times are very 

 iiear in the same proportion with the cubes of their distance from the cen- 

 ter of Mars, which evidently shows them to be governed by the same law 

 of gravitation that influences the other heavenly bodies.' 



"This was expressly written to cast ridicule upon the astronomers of his. 

 day, and now about one hundred and fifty years afterwards it becomes- 

 numbered among the established fticts of science." — Boston Journal of Chem- 

 istry. 



SOLAR SYSTEMS OTHER THAN OUR OWN. 



We know a great number of stars which are accompanied by smaller 

 stars, moving around them like the earth around the sun. These systems, 

 which are now numbered by hundreds, have been so carefully observed that 

 we have been able to calculate the orbits and periods of the planets, brilliant 

 or opaque, which compose them. 



It is, then, no longer on mere hypothesis that we can speak of solar sys- 

 tems other than our own, but with certainty, since we already know a great, 

 number, of every order and of every nature. Single stars should be consid- 

 ered as suns anologaus to our own, surrounded by planetary worlds. Double 

 stars, of which the second star is quite small, should be jDlaced in the same 

 class, for this second star may be an opaque planet reflecting only the light 

 of the large one, or a planet still giving out heat and light. Double stars 

 of which the two components give the same brightness are combinations of 

 two suns around each of which may gravitate planets invisible from this 

 distance; these are worlds absolutely different from those of our system, for' 

 they are lighted up by two suns, sometimes siraultaneous, sometimes succes- 

 sive, of different magnitudes, according to the distances of these planets from 

 each of them; and they have double years, of which the winter is warmed 

 by a supplementary sun, and double days of which the nights are illumina- 

 ted, not only by moons of different colors, but also by a new sun, a sun of 

 night. 



Those brilliant points which sparkle in the midnight sky, and which 

 have, during so many ages, remained as mysteries in the imagination of our 

 fathers, are therefore veritable suns, immense and mighty, governing, in 

 the parts of space lighted by their splendor, systems different from that of 

 which we form a part. The sky is no longer a gloomy desert; its ancient 

 solitudes have become regions peopled like those in which the earth is loca- 

 ted; obscurity, silence, death, which reigned in these far-off distances, have 

 given place to light, to motion, to life ; thousands and millions of suns pour 

 in vast waves into space the energy, the heat, and the diverse undulations, , 

 which emanate from their fires. All these movements follow each other, in- 

 terfere, contend, or harmonize, in the maintenance and incessant development 

 of universal life. — Camille Flammarion, in Popular Science Monthly for 

 JNovember. 



