CHAPTER SIXTEEN 



SHOOTING STARS 



SHOOTING stars are no 

 more like real stars than 

 skyrockets are like the 

 earth. They are small, dark 

 bodies moving through space, 

 and we do not see them until 

 they enter the earth's atmos- 

 phere. Then the friction 

 caused by their rapid motion 

 through the air heats them 

 so that they glow and are 

 bright for an instant, and 

 then disappear. On a clear 

 night a number of shooting 

 stars may be seen by ob- 

 servers on any part of the 

 earth. As the same ones 

 are not visible at stations 

 far apart, the whole number 

 entering the earth's atmos- 



- , 



P here ever Y *4 hours must 



be many millions, and they 

 have probably been falling 



in this number for many millions of years. Being so 

 small, they burn out or are reduced to dust before 

 reaching the solid earth, and cannot be distinguished 

 from dust derived from other sources. By melting 

 large quantities of snow in the arctic regions, men have 

 obtained dust which they believed to have come partly 



254 



FIG. 152. The trail of a meteor. 

 The great nebula of Orion is seen 

 in the background. 



