Marvels of the Universe 



143 



only receive news of her through the rapid 

 waves of hght, which, travelling at the rate 

 of 186,772 mUes a second, arrive on our 

 planet from the moon in a little less than a 

 second and a quarter. 



The perfected methods of modern tele- 

 scopic and photographic exploration can 

 supply us with such precise facts about the 

 earth's companion that our geographers 

 and land surveyors might envy the astro- 

 nomers, for the lunar topography is perhaps 

 better known than that of the terrestrial 

 globe. It must be understood, however, 

 that reference is now made to the hemi- 

 sphere turned towards us, which alone we 

 can see ; the other half of the globe re- 

 maining perpetually hidden from our eyes 

 from the fact that the moon alwa\'s presents 

 the same surface to us. 



Many millions of centuries ago the earth 

 and the moon formed one single confused 

 mass revolving rapidly on itself. This 

 enormous fluid sphere was subject, owing 

 to the attraction of the sun, to formidable 

 tides. Men who have made the science of 

 the formation of worlds their study are of 

 the opinion of Sir George Darwin : viz., that 

 under the combined influence of centrifugal 

 force caused by very rapid rotation and by 

 the solar tides a portion of the surface of 

 the terrestrial globe was detached and con- 

 stituted a single body in space in the form 

 of the Unk of a chain, or a mass of material 

 which afterwards congealed into a ball and 

 became the lunar globe. This event — the 

 birth of the moon — took place about fifty- 

 six million years ago. According to ^Ir. 

 W. H. Pickering, the profound depression of 

 the Pacific Ocean should mark the site of 

 the cradle of the moon. Should such be 

 the case, one is then forced to admit that at 

 the moment of separation the earth was al- 

 ready covered with a solid crust, a condition 

 which appears doubtfu], although the theory 

 of mathematics teaches us that a viscous 

 globe possessing even a thin skin can ex- 

 perience tides as intense as those pre- 

 vailing when it is in a state of complete 

 fluidity. 



VIEW ON THE MOON. 



This view represents the district known as Hygi 

 long diagonal depression, which is thought by some 

 be a forn-iation similar to the supposed canals of Mars. 



nus. 

 astrc 



Note 



