CHAPTER XIIL 



THE GREATEST PLANET. 



MARS is, as we have seen, much smaller than the earth. 

 We now turn to a planet which is very much greater 

 which is, in fact, the greatest of all planets the majestie 

 globe of Jupiter. This superb world far exceeds in bulk 

 any other body in our system, the sun alone excepted. 

 Nay, if all the other planets could be welded into one, 

 their united mass would fall short both in bulk and in 

 weight of the stupendous mass of Jupiter. Our earth has 

 a diameter not one-tenth part that of Jupiter, and the 

 diameter of Jupiter is more than twenty times as great as 

 the diameter of Mars. The path in which the giant planet 

 pursues his stately course is shown in Figure 16, while the 

 inner of the two circles is the orbit of the earth, both 

 drawn to scale. The actual diameter of Jupiter's orbit is 

 about five times that of the earth. It should, however, be 

 noticed that though these orbits are nearly circular, and 

 though I often find it convenient to speak of them as 

 actual circles, yet that when very careful measures are 

 made, they are found to be ellipses instead of circlea 

 Thus, if we take the earth's distance from the sun as 100, 

 the distance of Jupiter from the same centre would be 



