526 



SCIENCE OF HOME AND COMMUNITY 



gravity is so small that a ball player could bat a baseball a 



half mile. 



The moon represents the last state to which the heavenly 



bodies may come. It is the stage which the earth and the 

 other planets will probably reach many thou- 

 sands of years hence. 



Eclipses. When the sun shines on the earth 

 and moon, a long shadow is thrown out on the 

 side of these bodies away from the sun. This 

 shadow is in the form of a cone extending out 

 many thousands of miles, indeed farther than 

 the distance between the earth and the moon. 

 When the earth is between the sun and moon 

 (figure 209), the moon at certain times passes 

 into this shadow and so is eclipsed. This 

 shadow is big enough so that the moon may be 

 entirely covered. When the moon is between 

 the earth and the sun, it sometimes happens 

 that the moon's shadow falls on some part of 

 the earth and this causes an eclipse of the sun. 

 This part of the moon's shadow is very 

 small, less than two hundred miles in diameter, 

 so that the sun is eclipsed for only a small part 

 of the earth at any one time. These eclipses 

 can be foretold many years ahead with great 

 exactness. 



Planets. The earth is one of a group of 

 eight planets, all of which revolve around 

 the sun in the same direction. The four 

 brightest of these that can be easily seen are 

 Jupiter, Venus, Mars, and Saturn. The 

 other three are Mercury, Uranus, and Nep- 

 tune. At first sight these look like stars ; yet 



two differences may be easily noticed. In the first place, 



the planets do not twinkle ; and in the second, if the planets 



FIG. 209. How 

 eclipses of the 

 sun and moon 

 take place. 



