THE MOON 



17 



sun's surface are taken. These form a corona, or crown of 

 light, on the surface of the sun that surrounds the black 

 outline of the moon. It must also happen at times that 

 the earth comes between the moon and the face of the sun. 

 If the earth's path lies directly between the two bodies, its 

 shadow wholly obscures the face of the moon for a short 

 time. This is called a total eclipse of the moon. 



HALLEY'S COMET 



One of the most famous visitors from outer space. The small white 

 dots are stars seen through the comet's tail. 



If it were not for the moon, the beauty and variety of 

 our nights would be largely lacking. Moreover, as we shall 

 see later, we should have no tides strong enough to help 

 vessels over the bars into some of our harbors, and to 

 sweep clean our bays, removing the sewage. If the 

 distance of the moon were changed, the height of the 

 tides would be changed, and this would greatly affect our 

 coast towns. 



