ORIGIN OF THE WORLD 



There are indeed visible star groups to match each 

 type of nebula, roundish clusters within which 

 thousands of stars are massed (there is a fine example 

 in the constellation Hercules); conical groups; and 

 groups having a linear arrangement like the familiar 

 belt of Orion. 



And as to groups comprising merely two or three 

 stars relatively near together, they positively abound. 

 Recent observation has shown that one star in seven 

 becomes a visual double when viewed through the 

 biggest telescope. Of stars of the Orion type one in 

 three proves to be a double. Then there are multi- 

 tudes of stars that are accompanied by dark compan- 

 ions, the presence of which is revealed only by the 

 spectroscope. 



THE LIFE-STORY OF A STAR 



It would appear, then, that a star is a body which is 

 born out of the cosmical mist of a nebula. The stages 

 of stellar evolution are pretty clearly revealed by the 

 spectroscope. The young star, it would appear, al- 

 though it is incessantly giving out heat, nevertheless 

 contracts so rapidly that it becomes hotter and hotter. 

 Presently it shines with a dazzling white light, as 

 illustrated by the well-known stars Sirius and 

 Procyon, and a host of others. At this stage the 

 spectrum reveals the presence of the light gases, hy- 

 drogen and helium. 



Then the star cools somewhat and becomes yellow- 

 ish in color; and the spectroscope shows the vapors of 

 calcium, iron, and numerous other familiar terrestrial 

 elements. Our sun is a star in the yellow stage; and 



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