Our Earth and Its Fellow Planets [ 381 



When the sun is overhead, every bit of air and dust catches its 

 light and scatters it. Thus in the daytime the air is brighter than 

 the starlight and prevents it from shining through to us. 



Stars appear to twinkle because we see their light through an 

 unsteady atmosphere. The fact that there are no collisions of 

 heavenly bodies is explained by the force of gravitation, which 

 makes the stars, planets, and moons move around each other in 

 fixed paths, or "orbits." They pull and tug at their neighbors, but 

 the net effect is to hold all in place rather than pull them off 

 course. 



We cannot fly to the stars though we sometimes feel we can 

 reach up and almost touch them because they are really millions 

 of miles away. Up to now no one has penetrated beyond the mere 

 six miles of air that surround our earth. 



THINGS ARE Nor WHAT THEY SEEM 



The youngster who observes the heavens appears to be 

 easily learning a number of facts. He watches the sun rise in the 

 east and move across the sky until it sinks in the west. He sees 

 the moon gradually disappear each month, then gradually return 

 to view. When he can see it, he knows it rises and sets, as the sun 

 does. He may notice that the stars, too, seem to travel from east 

 to west across the sky. 



But these are apparent happenings. Our children have the 

 benefit of centuries of study by people who questioned what their 

 eyes perceived; and before a child is ten, he usually begins to 

 learn at school some of the facts discovered by the astronomers. 

 He is taught that much of what appears to be the behavior of the 

 heavenly bodies is actually the result of our earth turning on its 

 axis and revolving around the sun; and that the moon is a sphere 

 that reflects the light of the sun and revolves around the earth in a 

 period of about twenty-nine days. 



Yet, even while they are learning, today's children are being 

 exposed to a new type of fantasy that is likely to become confusing 

 even to parents. Science fiction and television depict people racing 

 in rocketships from one planet to another; they describe distant 



