MIRACLES OF SCIENCE 



the earth's position due to its orbital oscillation 

 about the moon. As already stated the amount of 

 this shift is found to be about 2880 miles. This dis- 

 tance, as computation shows, is about one-eightieth 

 of the moon's distance from the earth. It follows 

 that the mass of the moon is one-eightieth the mass 

 of the earth. 



There are several other methods by which the 

 mass of our satellite is computed. And the results of 

 these other tests are in substantial accordance with 

 this one. There is little doubt, then, that the weight 

 of the moon is thus determined with a considerable 

 degree of accuracy. It is notable, however, that the 

 mass as thus determined is much smaller than would 

 be expected from the moon's size. In point of fact 

 the earth's satellite seems to be composed of a much 

 lighter material than the substance of the earth itself. 

 This seems rather curious, but is not absolutely in- 

 consistent with the older or newer theories of cos- 

 mogony. 



WEIGHING THE SUN 



To find the mass of the sun is a curiously simple 

 problem in arithmetic, provided we take for granted 

 a knowledge of the diameter of the earth's orbit and 

 at the same time disregard the ellipticity of the orbit. 

 Assuming, then, that the earth's distance from the 

 sun is 92,900,000 miles, and that the orbit is approxi- 

 mately circular, a simple computation will show that 

 the earth must traverse the distance of about 

 eighteen and a half miles per second in order to com- 

 plete its journey about the sun in its observed natural 



70 



