58 ROUND THE YEAR 



or quite covers the sun's disc. We cannot give the 

 apparent diameter of the Moon in any measure 

 except angular measure. It is about |. 720 such 

 Moons would make a belt going all round the horizon. 

 360 such Moons would make an arch passing through 

 the zenith from horizon to horizon. 



There is no comparison between the light of the 

 sun and that of the Moon. If every part of the sky 

 were as bright as a full Moon we should not receive 

 as much light as in full day -light. Wollaston esti- 

 mated that the sun gives out 800,000 times as much 

 light as the full moon. 



The path of the Moon among the constellations 

 can be observed by any one who will take a little 

 trouble. Her motion is sufficiently rapid to cause 

 her place to change visibly in a few hours. How 

 rapid is it? The Moon completes the circle of the 

 heavens in 27^ days. She therefore travels about 

 13 daily on an average, and a little more than 

 her own diameter in an hour. The shifting of 

 the Moon from night to night can be followed 

 in clear weather by making a plan of the con- 

 stellations near her path, and noting upon it the 

 place of the Moon every evening. 



By carefully noting the Moon's path among the 

 stars, it has been found out : 



1. That she keeps very near the zodiac, never 

 departing much more than 5 from the ecliptic, or 

 apparent path of the sun. 



2. That she does not take exactly the same path 

 every time, and does not end exactly where she 



