THE GREATEST PLANET. l8 j 



as Herschel wrote years ago, the resemblance between the 

 earth and Mars appeared to be the most striking analogy 

 in the whole solar system. But a very brief examination 

 of Jupiter shows that we have here a body which, while 

 still a planet, is quite unlike our earth, and still more 



Fig. 17. Comparative Sizes of the Sun and the Planets 



unlike Mars. It becomes, therefore, of special interest to 

 study Jupiter, as it affords an instructive chapter in 

 planetary history. 



The general aspect of the great planet is fortunately 

 within the compass of moderate telescopic power. It has 

 been scrutinized with unintermitting zeal since first 



