180 



THE NATIONAL GEOGRAPHIC MAGAZINE 



Uranus 



• • Mercury 



Venus 



• -- 

 Earth 



Moon 



Statute Miles 



Drawn by Albert H. Bumstead 



CHART SHOWING THE; RELATIVE SIZE OE THE SUN, MOON, AND MAJOR PLANETS 



The stupendous size of the sun in comparison with the several members of its planetary 

 family is emphasized by the distance of the moon from the earth as here plotted on the face 

 of the sun. The differences in their sizes play peculiar tricks of gravity. A hundred pounds 

 would weigh 2,764 pounds on the sun, 252 pounds on Jupiter, 36 pounds on Mars, and 16 

 pounds on the moon. Spots on the face of the sun are often six times the diameter of the 

 earth, and prominences frequently reach so far into space that they would completely envelop 

 our moon if they started from the earth (see also page 166). 



tensive than the most advanced astrono- 

 mer dares think or else these stars will 

 run clear through it and out into God only 

 knows where, unless they shall sooner 

 pass close enough to some bigger star that 

 can tame them. 



THE MILKY WAY 



Called the Silver River of Heaven by 

 the Japanese, pronounced by the ancient 

 mycologists the dust stirred up by Per- 

 seus as he hastened to the rescue of An- 

 dromeda, the Milky Way sweeps in a 

 vast circle around the celestial sphere. 

 Herschel said it might be likened to a 

 great grindstone. It is made up of mil- 

 lions of small stars that cannot be sepa- 

 rated without optical aid. 



This great star stream, coursing its 

 way around the heavens, in a sweep that 



may require as much as two hundred 

 million years for its circuit, seems to 

 have captured the vast majority of the 

 folk of the universe, and is flowing in 

 unending procession onward and on- 

 ward. Here it branches and flows around 

 an island in space ; there it is crossed by 

 a bridge of blackness ; at another place 

 it is narrow, as though passing through 

 a gorge ; and elsewhere it widens out as 

 though flowing through an alluvial valley. 



Composed of great clusters of multi- 

 tudinous suns, many of the individual 

 members vastly larger than our own, one 

 who looks upon the Milky Way can feel, 

 with Buchanan Read, that the stars that 

 are faintest to us may to diviner vision 

 be the noblest of them all. 



Nor is it easy to neglect those wonder- 

 ful objects of the sky, the nebulae, those 



