ORIGIN OF THE WORLD 



detail the principles of world-building made familiar 

 through Lockyer's famous meteoric theory of side- 

 real cosmogony. 



THE ORIGIN OF SPIRAL NEBULAE 



If, then, we give at least provisional recognition to 

 the spiral nebula as the "Mother of Worlds/' a ques- 

 tion naturally arises as to how this interesting struc- 

 ture itself came into being. 



Professor Moulton answers this question in de- 

 tail. He tells us that what we now view as a spiral 

 nebula was aforetime (let us say a million or a hun- 

 dred million years ago) a gaseous star, not particu- 

 larly different from millions of others that exist in the 

 sky to-day, or for that matter from our sun itself. 



But it chanced that in its progress through space 

 this star flew in a direction which brought it ultimate- 

 ly in the neighborhood of another star. Unless the 

 scheme of the universe is something quite different 

 from what we now imagine, this must happen in 

 course of time to every stellar body. All the stars are 

 moving, and their rate of speed in some measured 

 instances exceeds 100 miles per second. They are 

 moving in different directions, in groups, clusters, 

 pairs, or. singly, and it would seem inevitable that 

 their paths must cross. , 



It will not often happen, in all probability, that 

 two stars will meet head on. But they may exert a 

 tremendous mutual influence without actually collid- 

 ing. A German astronomer named Roche made, half 

 a century ago, a famous estimate to the effect that if 

 two stellar bodies of equal size approach each other 



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