CHARTING THE UNIVERSE 



movements of those supposedly "fixed" bodies. The 

 seeming fixity of the stars is merely due to their dis- 

 tance. In point of fact they are flying through space, 

 singly, in pairs, in groups, clusters, and swarms, or 

 in vast streams of incomprehensible magnitude. 

 Some of them move upward of 150 miles per second; 

 and the average speed of the very large number 

 hitherto tested, according to Professor W. W. Camp- 

 bell of Lick Observatory, is 20.2 miles per second. 

 Our particular star, the sun, with his attendant 

 planets, moves through space at the rate of about 

 twelve and a half miles per s,econd, making therefore 

 in point of speed, as in the matter of size, a rather 

 poor showing; yet after all shifting our position in 

 space by about 367,000,000 miles each year. 



THE FLIGHT OF SUN AND STARS 



Nothing perhaps shows the wizardry of the 

 modern astronomer to better advantage than his 

 revelations regarding this matter of the movements 

 of the stars. To appreciate the complexity of the 

 problem, we must reflect that the mundane observa- 

 tory shifts its position in virtue of the earth's rota- 

 tion by something like a thousand miles an hour; that 

 the earth wabbles as it whirls and plunges through 

 space at the rate of about nineteen miles per second 

 in order to compass its annual journey about the sun, 

 while at the same time being carried in yet another 

 direction at twelve and a half miles per second by the 

 translational motion of the entire solar system. The 

 net result is that the actual course described in space 

 by the earth is a zigzag spiral, to attempt to conceive 



39 



