VENUS, MAES, AND OTHER WORLDS ABBOT. 167 



the probabilities of intelligent life on the four outer planets can not 

 be regarded as considerable. 



WORLDS AMONG THE STARS. 



As is well known, the stars are but suns and the sun our nearest 

 star. Hence the tremendous temperature which prevails in the sun 

 and prevents us from supposing for a moment that the sun is capable 

 of being an abode for intelligent life, must be regarded as an equally 

 effectual bar against the existence of life upon the other stars. But, 

 just as the sun has a train of planets and satellites which revolve 

 about it, one might assume that the other stars should be similarly 

 attended. To be sure no such planetary trains have been reported 

 by telescopic or spectroscopic observers, but that would not be ex- 

 pected. The distances of the stars are so immense and the disparity 

 of brightness between a body, like the sun, and a body shining by 

 reflected sunlight, like one of the planets, is so enormous that it is 

 not to be supposed that a single one of these supposed starry worlds 

 would be visible even if they existed in almost countless numbers. In 

 illustration of the enormous difference in light-giving powers, it 

 may be remarked that at equal distances the sun would be roughly 

 1,500,000,000 times as bright as the earth. 



The spectroscope, as readers well know, is sometimes capable of 

 indicating the presence of bodies that are invisible to the telescope. 

 Thus there are large numbers of binary and multiple stars in which 

 the components of the system are so close together that the telescope 

 can not see them separately but which, on account of their rotation 

 about a common center, give slight displacements of the spectrum 

 lines owing to motions in their orbits toward and from us in line of 

 sight. It is not even necessary that the component bodies should 

 both be light giving. It has been actually observed in the case of 

 binary stars whose orbits lie in such a plane that the two bodies 

 alternately eclipse one another, that one may be light giving and 

 the other quite dark, yet in the revolution of the light-giving com- 

 ponent around the center its spectrum lines are shifted, and of course 

 a variation in its light is caused when it is partly eclipsed by its com- 

 panion. Without even partially eclipsing the companion, one of these 

 dark bodies may yet, by its gravitational attraction, cause such a 

 rapid motion in the bright star as to indicate its presence by the 

 shifting of spectrum lines. This, however, can only be detected when 

 the dark companion is large enough to produce an orbit of some con- 

 siderable dimensions. 



In the case of our planetary system, the attractions of any and all 

 of the planets are not sufficient to displace the sun appreciably to such 

 spectroscopic observations. Such would probably be the case with 



