THE MOON 57 



persons of strong imagination are always hoping to 

 find some connection between the Moon and the 

 weather. 1 



The rule which governs the position of the Moon's 

 cusps and bright edge is easily stated, though it is 

 not so easily explained. Imagine a great circle drawn 

 across the star-sphere, passing through the centres of 

 both sun and Moon. That circle will nearly coincide 

 with the zodiac, and it may be taken as the edge of 

 a circular plane in which the earth lies. The centre 

 of the bright edge of the Moon and the centre of 

 the line joining her cusps will be found always to 

 lie in that great circle ; the bright edge being turned 

 towards the sun. 



When the Moon is almost new, she presents a bright 

 crescent, enclosing a faintly illuminated surface, which 

 we call the new Moon in the arms of the old. The 

 light thus faintly reflected cannot come direct from 

 the sun, nor is the Moon self-luminous ; it is reflected 

 from the earth. At new Moon the Moon is between 

 the sun ajid the earth, and the earth appears full to 

 the Moon, reflecting its maximum of sunlight upon 

 the Moon. At half-moon the " earth-shine " is much 

 fainter, for then only half the earth's disc, as seen 

 from the Moon, is illuminated. 



What is the apparent size of the Moon ? Very 

 nearly the same as the apparent size of the sun. At 

 eclipses of the sun, we see that the Moon very nearly 



1 In some p^s of the country the belief is that when the 

 Moon holds the mouth of her cup uppermost it will be fine, but 

 that it will rain if the cup seems to be turned upside down. 



