THE TRUE GRANDEUR OF THE SUN 233 



of the moon, was a body not vastly greater. Jupiter, of course, 

 was something of a stumbling-block. At five times the distance 

 of the sun, it must be at least a hundred times as far away as 

 the moon ; but though it evidently had an appreciable disk, 

 it was beyond the measuring powers of the instruments of that 

 day and for long after. 



With the sun at four hundred times the distance of the 

 moon, Venus must be nearly a hundred times, and at its brightest 

 it glows like a little moon ; its disk has an apparent diameter 

 of over one minute. It takes only a moment to reckon then 

 that it must be a planet as large as the earth. It is obviously 

 considerably hotter than the earth ; on the other hand, even 

 the greatest telescopes show no clear markings such as we may 

 observe upon the moon ; it is possible it may have a very 

 dense atmosphere and therefore be inhabitable with beings like 

 unto ourselves. 



The fortunate career of Cassini fell amid the charming time 

 of the salons, when women of wit drew around them brilliant 

 coteries of savants, and when the most erudite and accomplished 

 of men did not think it beneath their dignity to clothe knowledge 

 and recent discovery in language so simple as not to seem dull 

 amid the brilliant conversation of that engaging day. A little 

 later Fontenelle, discoverer, with Voltaire, of Newton to France, 

 and knowing like Voltaire how to temper the arid phrases 

 of science with the elegancies of style, caused a polite little 

 rustle in the polite little monde of France by announcing the 

 plurality of worlds. His slender volume is charming reading 

 still. For proclaiming the same fact Bruno had been burned 

 just eighty-six years before. 



A plurality of worlds and our earth in no wise unique 

 this was the new angle from which mankind had now to con- 

 sider the problems of human destiny and the worth of human 

 effort. The earth was not, in all probability, the sole inhabit- 

 able planet even of our system ; it was not unique in size ; 

 it was soon clear that it was, in point of fact, utterly insignificant. 

 Even Galileo's little tubes could measure Jupiter's disk ; at 

 its brightest it is almost as large as that of Venus, and it was 

 now clear that the son of Jove was sixteen times as far away, 

 even at the nearest point which he comes to the earth. If he 

 travelled in the orbit of Hesperus he would be two hundred 



