MIRACLES OF SCIENCE 



ages. In due course the "pointers," for example, will 

 cease to point to the pole star. But the pole itself 

 is shifting as our little globe wabbles through space, 

 so this does not greatly matter. Some 12,000 years 

 from now Vega will be the pole star, and no pointers 

 will be needed to indicate that brilliant object. 



At far greater distances in space there are groups 

 of stars of the Orion or helium type, which have a 

 characteristic spectrum suggestive of a recent origin. 

 These are sometimes grouped into luminous clouds, 

 like the Pleiades and the diffused nebulosity in Orion. 

 Some of these stars are enormously brilliant. Rigel 

 in Orion, for example, shines at first magnitude. 

 Were it no brighter than our sun it would appear 

 only as a telescopic star of tenth magnitude. 



But while these and sundry other relatively small 

 groups of stars are pursuing their individual flights 

 in one direction or another, their movements 

 gigantic though they seem in the human scale are 

 as minor eddies in the two vast star streams that are 

 moving in opposite directions through the portion of 

 space in which we find ourselves. These two star 

 streams, comprising not less than half a million mem- 

 bers, including most of the brighter stars, have met 

 and mingled like counter-currents in the region of 

 space about us. But their individual members are so 

 far separated that danger of collision is minimized. 



The discovery of these gigantic star streams was 

 made about the yeaf 1904 by the Dutch astronomer 

 Professor Kapteyn, of Groningen, in the course of his 

 laborious microscopic measurements of the loca- 

 tion of about a quarter of a million stars on number- 



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