THE MOON 63 



intense brilliancy. The tender blue of the earthly 

 sky has vanished ; it was entirely due to water- 

 vapour, and there is no water here. The sun is too 

 dazzling to behold, and his heat so scorching that no 

 human being could endure it unscreened. He seems of 

 immense size, for around his disc is a glory of extra- 

 ordinary brightness and great extent, which flashes 

 like an aurora borealis. The earth hangs in the 

 sky as a vast disc which goes through its phases 

 and appears dark, partly dark, or wholly bright at 

 different times. She is thirteen times as large as the 

 full Moon seen from the earth, and is almost a 

 fixed object in the lunar heavens. Her edge is fringed 

 with a narrow luminous cloud. The day with its 

 insupportably bright sunlight lasts 27^ earth-days ; 

 the year is about as long as an earth-year. Day and 

 night are nearly equal throughout the year, but the 

 height of the noon-day sun varies according to 

 latitude and season, just as it does upon earth. 



It is a help toward understanding eclipses and other 

 lunar phenomena to form a true mental picture of 

 the sun, moon, and earth. Let the earth be a large 

 marble, one inch in diameter ; then the Moon will be 

 a small pea at a distance of 2\ feet, and the sun a 

 9 foot globe at a distance of 320 yards. A hollow 

 globe as big as the sun, with the earth in the centre, 

 would give ample room for the Moon to revolve at 

 her usual distance. 



If the position of the sun, earth and Moon with 

 respect to one another are noted at a particular date, 

 it will be found that in about eighteen years they will 

 again occupy very nearly the same position. Accord- 



