X THE STARRY HEAVENS 377 



forms and colours. They belong, however, to 

 our Earth, and I must now pass on to the 

 heavenly bodies. 



THE MOON 



The Moon is the nearest, and being the 

 nearest, appears to us, with the single excep- 

 tion of the Sun, the largest, although it is in 

 reality one of the smallest, of the heavenly 

 bodies. Just as the Earth goes round the 

 Sun, and the period of revolution constitutes 

 a year, so the Moon goes round the Earth 

 approximately in a period of one month. 

 But while we turn on our axis every twenty- 

 four hours, thus causing the alternation of 

 light and darkness — day and night — the 

 Moon takes a month to revolve on hers, so 

 that she always presents the same, or very 

 nearly the same, surface to us. 



Seeing her as we do, not like the Sun and 

 Stars, by light of her own, but by the reflected 

 light oiE the Sim, her form appears to change, 

 because the side upon which the Sun shines 

 is not always that which we see. Hence the 



