37 



the monarch of the system will summon it again to make its 

 fiery journey round his throne. 



THE STELLAR UNIVERSE 



1 



The immensity of the Stellar Universe, as we have seen, is 

 beyond our apprehension. The sun is nothing more than a very 

 ordinary star, perhaps an insignificant one. There are stars 

 enormously greater than the sun. One such, Betelgeux, has 

 recently been measured, and its diameter is more than 300 times 

 that of the sun. 



The Evolution of Stars 



The proof of the similarity between our sun and the stars 

 has come to us through the spectroscope. The elements that we 

 find by its means in the sun are also found in the same way in 

 the stars. Matter, says the spectroscope, is essentially the same 

 everywhere, in the earth and the sun, in the comet that visits us 

 once in a thousand years, in the star whose distance is incal- 

 culable, and in the great clouds of "fire-mist" that we call 

 nebulae. 



In considering the evolution of the stars let us keep two 

 points clearly in mind. The starting-point, the nebula, is no 

 figment of the scientific imagination. Hundreds of thousands 

 of nebulas, besides even vaster irregular stretches of nebulous 

 matter, exist in the heavens. But the stages of the evolution of 

 this stuff into stars are very largely a matter of speculation. Pos- 

 sibly there is more than one line of evolution, and the various 

 theories may be reconciled. And this applies also to the theories 

 of the various stages through which the stars themselves pass en 

 their way to extinction. 



The light of about a quarter of a million stars has been ana- 

 lysed in the spectroscope, and it is found that they fall into about 



