42 FIRST YEAR COURSE IN GENERAL SCIENCE 



since Galileo looked at the moon with his first telescope 

 more than three hundred years ago. 



35. Eclipses of the Sun. As the light from the sun 

 cannot pass through the moon, there is always a dark space 

 or shadow stretching away from the moon on the side oppo- 

 site the sun. When the moon comes directly between the 

 sun and the earth, this shadow sometimes reaches the 

 earth and a solar eclipse occurs. 



As the moon is a sphere, the shadow is cone-shaped, and 

 where it touches the earth, it makes a round or an oval 

 shadow spot, just as a cloud between the earth and the sun 

 casts a shadow on the ground. The shadow is less than 170 

 miles in diameter where it falls upon the earth. The sun is 

 completely hidden from people who are on the part of the 

 earth where the shadow falls. 



When a total eclipse of the sun occurs, darkness comes 

 on suddenly, for the daylight lasts as long as even a small 

 portion of the sun is visible. When the last crescent of the 

 sun has disappeared, it is as dark as night and stars are 

 visible. 



The outside gaseous portion of the sun, the corona, is 

 never seen except at a solar eclipse, because its light is so 

 much fainter than the light of the rest of the sun. During 

 a total solar eclipse, the corona shines out around the dark 

 moon with a beautiful, soft, pearly light, sometimes tinted 

 pale green or rose color. 



36. Eclipses of the Moon. In a lunar eclipse the earth 

 is between the sun and the moon. The shadow is then cast 

 by the earth and it is much larger than the shadow made by 

 the moon in a solar eclipse. Instead of making a dark spot 

 upon the moon, it may cover the whole moon. As the 

 moon enters the shadow space, a portion of the moon is 

 darkened while the rest of the moon is as bright as usual. 

 At this time the form of the earth is shown in the curved 

 edge of the shadow. We "see our own shadow." In a 



