22 FIRST YEAR COURSE IN GENERAL SCIENCE 



revolution around the sun causes changes of position which 

 are apparent from month to month. The motions of the 

 stars are always apparently westward, .because the earth's 

 motion around the sun is eastward. 



12. The Solar System. The sun is a moderate-sized 

 star, very much nearer to us than any other star. There 



FIG. 4. THE SIZE OF THE SUN COMPARED WITH THE DISTANCE 

 FROM THE EARTH TO THE MOON 



Imagine the earth at the center of the sun's sphere and the moon 

 revolving around the earth on the circle within. Measure from E to M. 



1. What fraction of the radius of the sun is the distance from E to M? 



2. If E to M is 240,000 miles, what is the diameter of the sun? 3. At the 

 rate of 1,000 miles a day, how long would it take the earth to travel across 

 the sun's disk? 



are other bodies, called planets, revolving about the sun; 

 and other smaller bodies, called satellites, revolving about 

 some of the planets. The sun and the planets with their 

 satellites make up the solar system. 



While the planets are revolving around the sun, they and 

 their satellites are rotating upon their axes, each body having 

 a definite period or time of rotation. 



