THE EARTH'S NEAREST NEIGHBORS 



43 



total lunar eclipse the moon is in the shadow more than an 

 hour, while in a solar eclipse the sun is hidden only a few 

 minutes at the longest. 



Eclipses of the moon are much more frequently seen than 

 solar eclipses. The moon is visible to people on half the 

 earth at one time, so when a lunar eclipse occurs, many of 

 the earth's inhabitants may see it. In a solar eclipse, how- 

 ever, the shadow spot covers only a small portion of the 

 earth and a solar eclipse is visible only to those within this 

 small area. 



Astronomers can predict with great exactness the times at 



FIG. 13. LUNAR AND SOLAR ECLIPSES 



1. Compare the shadows cast by the earth and the moon. 2. Why is 

 there this difference? 3. From what portion of the earth, as shown in this 

 figure, is the lunar eclipse visible? 4. The solar eclipse? 5. In which of 

 these portions do the larger number of people live? 



which eclipses will occur, and almanacs give the dates of 

 eclipses for the current year. 



37. Telescopes. There are two reasons why a telescope 

 enables one to see an object better than is possible with the 

 unaided eye. The light which makes a body visible is re- 

 ceived through a small opening in the front of the eye, 

 called the pupil. When the eye is placed at the eyepiece of 

 a telescope, it receives all the light that falls upon a lens, 

 some inches in diameter, at the other end of the telescope. 

 Thus more light than usual is brought to the eye and the 



