CHARTING THE UNIVERSE 



Going out beyond the confines of our immediate 

 star cluster, we find various interesting groups at 

 what might be called gauging our mind to stellar 

 magnitudes moderate distances. 



There is, for example, a neighborly cluster of 

 forty stars in the constellation Taurus, between the 

 Pleiades and the bright yellow star Aldebaran, that 

 Professor Lewis Boss, of Albany, watched with tire- 

 less assiduity for many years, using the proper 

 motions alone, and not the spectrographic method. 

 By laborious calculations he removed one source of 

 error after another, until finally he could assure us 

 that the stars of the Taurus cluster are moving 

 through space together in parallel lines at uniform 

 speed, like a flock of birds. They are 120 light-years 

 (800 million million miles) away; but they passed us 

 at half that distance about 8,000 centuries ago, 

 though the cave man of the period seems to have left 

 no record of the visit. 



Then there is a cluster of seventeen helium stars 

 in Perseus; and another cluster of thirteen stars in 

 the Great Bear, which seem to lie in about the same 

 plane, each cluster pursuing its own independent 

 way, apparently quite unaffected by other stars that 

 may chance to have wandered into the same territory. 



As to the Great Bear cluster, it is rather surprising 

 to learn that of the seven conspicuous stars forming 

 the "big dipper," five are moving uniformly in one 

 direction and the other two with equal uniformity 

 in quite another direction. The familiar figure of the 

 "big dipper" is therefore in part an optical illusion 

 which will not maintain its shape throughout future 



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