Our Earth and Its Fellow Planets [ 401 



About a week later, when the moon has moved a quarter of the 

 way around its orbit, we can see half of its bright side (first 

 quarter) . 



In another week the moon is opposite the sun, and appears full, 

 for we can see all of its bright side. (During this period the moon 

 rises about sunset and remains in the sky all night.) Still another 

 week brings the moon three-quarters of the distance of its orbit 

 and we again see half of the bright side (third quarter). The moon 

 goes through all these phases each month. 



It happens that the moon rotates on its axis in just the same 

 time that it revolves about the earth, with the result that the same 

 face is always turned towards us! No one has ever seen the other 

 side the intriguing ' 'hidden side" of the moon. 



WHAT WE WILL FIND ON THE MOON 



If the time comes when we can shoot in a rocketship to the 

 moon, we shall have to take oxygen tanks along; there is no air on 

 this planet-like heavenly body. The territory to be explored will 

 be far less than on the earth, for the moon's diameter is only 2,160 

 miles in contrast to the earth's 7, 91 8-mile diameter. 



We probably would not regret the small size, for there is a 

 terrible sameness about the moon's landscape. Rocks, rocky plains, 

 and rocky mountains are on all sides of us. No trees, flowers, or 

 even grass break the monotony and no birds or other animals give 

 life to the scene. If we clap our hands to break the eerie quiet, we 

 still hear nothing! without air there can be no sound waves. 



Knowing as we do that the force of gravitation on the moon is 

 low compared with that of our earth, we check our weight. 

 Whereas on earth we weighed 120 pounds, we are now just twenty 

 pounds only a sixth of our accustomed weight! In this feather- 

 weight condition we find that we can get around with great strides. 

 So we climb easily over the moutains, dome-shaped hills, and 

 mountain-ringed plains. We have no worries about weather for 

 the moon, being without moisture, has no clouds, rain, snow, or 

 wind. 



