THE NEW COSMOLOGY 



The fact that the stars show no parallax had been 

 regarded as an important argument against the motion 

 of the earth, and it was still so considered by the 

 opponents of the system of Copernicus. It had, 

 indeed, been necessary for Aristarchus to explain the 

 fact as due to the extreme distance of the stars; a 

 perfectly correct explanation, but one that implies 

 distances that are altogether inconceivable. It re- 

 mained for nineteenth - century astronomers to show, 

 with the aid of instruments of greater precision, that 

 certain of the stars have a parallax. But long before 

 this demonstration had been brought forward, the 

 system of Copernicus had been accepted as a part of 

 common knowledge. 



While Copernicus postulated a cosmic al scheme that 

 was correct as to its main features, he did not alto- 

 gether break away from certain defects of the\Ptole- 

 maic hypothesis. Indeed, he seems to have retained 

 as much of this as practicable, in deference to the 

 prejudice of his time. Thus he records the planetary- 

 orbits as circular) and explains their eccentricities by 

 resorting to "IKe theory of epicycles, quite after the 

 Ptolemaic method. But no w; ^'course, a much more 

 simple mechanism sufficed to explain the planetary 

 motions^Sffiee-the orbits were correctly referred to 

 the central sun and not to the eartli^ 



Needless to say, the revoHti^ary concepiioji of 

 Copernicus JidjioJL meet witQ immediate.^cceptance. 

 A number of prominent astronomers, however, took it 

 up almost at once, among these being Rhseticus, who 

 wrote a commentary on the evolutions ; Erasmus Rein- 

 hold, the author of the Prutenic tables; Rothmann, 



63 



