400 ] Our Earth and Its Fellow Planets 



of the moon terms concerned with facts rather than fancy. As he 

 grows older he may have the exciting dream of going to the moon 

 by rocketship; being the nearest of the heavenly bodies, the moon 

 is the first that scientists hope to reach. 



WHAT MAKES "THE MAN IN THE MOON" 



A powerful telescope gives spectacular results when it is 

 trained on the moon, but we can still learn many things about its 

 surface by observing it with field glasses or a small telescope. Con- 

 spicuous even to an unaided eye are the large dark spots we like 

 to associate with a man's face, a rabbit, and other fancies. 



Through a telescope we can see these spots better. They are 

 craters great circular depressions. Some are fifty miles or more in 

 diameter, with walls thousands of feet high; others are small pits 

 without walls. Many astronomers believe the craters were formed 

 by volcanoes, but others suggest that large meteors falling upon 

 the moon created them. 



PHASES OF THE MOON 



The dark spots give further emphasis to the fact that the 

 moon (like the planets) has no light of its own; the brilliance of 

 the moon is all reflected light. And because it borrows its light 

 from the sun, the moon has ' 'phases" that range from crescent to 

 "first quarter" to "full" to "last quarter" to crescent again. With 

 light of its own the moon would not be so changeable. 



What Produces the Phases: To understand the phases, we must 

 keep in mind several facts: The sun is ninety-three million miles 

 from our earth. The moon is a mere 240,000 miles from us. The 

 moon revolves around the earth, as the earth revolves around the 

 sun. But whereas the earth takes a year to make its revolution the 

 moon requires only a month for its journey. (The word "month" 

 is derived from "moon.") 



We cannot see the moon at all when it comes between us and 

 the sun, for the side of the moon that faces the earth then reflects 

 no light. When we are able to see a thin sliver of light on its edge, 

 which now faces the sun, we call it the crescent or "new" moon. 



