1 66 Trees, Stars, and Birds 



of our* solar system, and our entire solar system is so 

 small a part of the whole universe that blotting it out of 

 existence would be only like wiping a speck of star dust 

 from the sky. Well has the poet Emerson said : "If 

 the stars should appear one night in a thousand years, 

 how would men believe and adore; and preserve for 

 many generations the remembrance of the city of God 

 which had been shown." 



The work of astronomers. In the vast voids of space 

 between the heavenly bodies there is no air, and across 

 them no sounds can pass. In them all is darkness and 

 silence, and there the cold is of an intensity not known 

 on earth. Nothing comes to us across this space ex- 

 cept waves of light and heat and the mysterious force 

 of gravitation, which all material bodies exert on each 

 other. Yet from the information gained from these 

 sources, astronomers have measured the distances to 

 some of the stars, learned that certain of them are 

 young and others old, and calculated the weights of 

 the sun, moon, and many other heavenly bodies. By 

 countless observations and by careful thought and 

 long computations they have learned the secrets of the 

 universe and have built them into a system so wonderful 

 and so complete that of it the philosopher Laplace has 

 said : " Contemplated as one grand whole, astronomy 

 is the most beautiful monument of the human mind, 

 the noblest record of its intelligence." 



