THE EARTH'S NEAREST NEIGHBORS 41 



FIG. 12. A PHOTOGRAPH OP THE MOON 



This photograph was made about 10 days after new moon. One half of 

 the moon is lighted, as it is always. 1. How much of the lighted half is 

 visible in the picture? 2. The diameter of the moon is about 2,000 miles; 

 estimate the width of the elliptical plain on the right. 3. How wide is the 

 largest ring-shaped elevation that you can see? 



