COSMIC EXCHANGE OF MATTER AND LIFE 431 



It follows that even a relatively small body crashing through 

 the enclosing crust would produce a terrific eruption. When a 

 pair of bodies comparable in grandeur with the sun came 

 together, the effect of course would be tremendous. It would 

 resemble an explosion, and the matter they contained would 

 be blown about over an area that would be considerable, 

 measured even by stellar spaces. If this process were continued 

 over extended periods of cosmic time, the result would be a 

 more or less even distribution of the different materials or 

 elements of which the suns are composed. It would produce 

 precisely the condition of more or less kinship of constitution 

 which the spectroscope has revealed. 



It is evident that the number of relatively near approaches 

 of the suns would be immensely greater than the number of 

 actual collisions.* If we conceive the suns in general as pro- 

 vided with satellites like our own, the effect of this nearing of 

 the suns would be a constant planetary exchange. Thus, for 

 example, suppose that our sun and alpha Centauri should come 

 rather closely together, they might not collide ; they might be 

 moving too swiftly to form a binary system. They still might 

 approach near enough so that our sun would rob alpha Centauri 

 of an outer planet or so, or alpha Centauri might rob our system 

 of Neptune or Uranus. 



Lively minds may, if they like, picture the stellar dance 

 as a sort of endless Virginia Reel, with the suns flinging 

 off their partners and taking new suns in a continual round. 

 Just as we conceive the particles of musk or the particles of 

 smoke diffusing through the air of a room perforce of the in- 

 cessant movement, collision, and rebound of the particles of air, 

 so we might in imagination portray the planets as diffusing 

 through space, going on from one sun to another, to the end of 

 the world. The cosmic processes are leisurely ; but time is long. 



In yet another way the binary systems might easily lose their 

 satellites simply by means of their mutual attraction one upon 

 the other. It is easy to see that when a planet or satellite 

 swept between a pair of suns, its orbit would be straightened 

 out more or less, with the result that the planet would pursue a 

 path extremely elliptical, or else go shooting away into space. 

 With a speed sufficient, they would of course go travelling on 

 until they came within the sphere of influence of another system. 1 

 1 T. J. J. See, The Evolution of Stellar Systems. 



