THE NEW COSMOLOGY 



the Milky Way is merely due to the aggregation of a 

 vast number of tiny stars. 



Turning his telescope towards the moon, Galileo 

 found that body rough and earth-like in contour, its 

 surface covered with mountains, whose height could 

 be approximately measured through study of their 

 shadows. This was disquieting, because the current 

 Aristotelian doctrine supposed the moon, in common 

 with the planets, to be a perfectly spherical, smooth 

 body. The metaphysical idea of a perfect universe 

 was sure to be disturbed by this seemingly rough 

 workmanship of the moon. Thus far, however, there 

 was nothing in the observations of Galileo to bear 

 directly upon the Copernican theory; but when an 

 inspection was made of the planets the case was 

 quite different. With the aid of his telescope, Galileo 

 saw that Venus, for example, passes through phases 

 precisely similar to those of the moon, due, of course, 

 to the same cause. Here, then, was demonstrative 

 evidence that the planets are dark bodies reflecting the 

 light of the sun, and an explanation was given of the 

 fact, hitherto urged in opposition to the Copernican 

 theory, that the inferior planets do not seem many 

 times brighter when nearer the earth than when in the 

 most distant parts of their orbits; the explanation 

 being, of course, that when the planets are between 

 the earth and the sun only a small portion of their 

 illumined surfaces is visible from the earth. 



On inspecting the planet Jupiter, a still more striking 

 revelation was made, as four tiny stars were observed 

 to occupy an equatorial position near that planet, and 

 were seen, when watched night after night, to be circling 



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