254 



THE GUIDE TO NATURE 



to be eclipsed by this system. Neither 

 Saturn nor its rings shine by their own 

 light ; they look bright only because 

 they are illuminated by the light of the 

 sun, and therefore they cast a shadow 

 in space. As the satellite entered the 

 shadow of the inner edge of the dusky 

 ring it grew steadily fainter, until, 

 when it entered the shadow of the 

 bright ring B, it completely disap- 

 peared. Evidently the ring B is more 

 opaque than either C or A. 



It is now definitely known that the 

 rings are a great flattened swarm of 

 little particles, each one of which re- 



jects in the sky. Were he on the 

 equator of the planet he would see 

 them only as a bright, narrow line, 

 spanning the heavens from the east to 

 the west, for there he would view them 

 exactly edgewise. But were he to 

 journey northward, he would see them 

 apparently widen until they formed a 

 most brilliant band across the sky. 

 The apex of this wonderful arch would 

 sink lower in the heavens as he pressed 

 on, until, when he reached a latitude 

 of sixty-three degrees north of Saturn's 

 equator, the uppermost edge of A 

 would sink below the south horizon 



£>OL)T>+ 



Figure 4. The orbits of the seven inner satellites of Saturn, and the positions of the bodies at 

 9 P. M., December 1. as seen in an inverting telescope. The time given with each moon is the time 

 occupied by it in completing the circuit of its orbit. 



volves around Saturn as a separate 

 little moon. Those on the inner edge 

 of the Dusky Ring make the circuit 

 in five hours and fifty minutes, while 

 those on the outer edge of A, on ac- 

 count of their greater distance from 

 the planet, require twelve hours and 

 five minutes for a single revolution. 



Thus the ring by no means turns 

 as a solid mass around Saturn and it 

 can, in fact, be shown mathematically 

 that it would be impossible for it to 

 do so. No known substance could 

 stand one-hundredth part of the strain 

 to which such a solid, turning ring 

 would be subjected, without being torn 

 in pieces. The particles of the Dusky 

 Ring are much more scattered than 

 those of the ring A, while those of 

 the wide, middle swarm are the most 

 closely packed of all. 



To an observer on Saturn, could an 

 observer exist there, the rings would 

 appear by far the most wonderful ob- 



and he would lose sight of the rings- 

 altogether. 



But this beautiful arch would only be 

 seen by him while the sun was shining 

 on the north side of the rings. During 

 one-half of the long Saturnian year, 

 which is nearly thirty times as long 

 as ours, the dark sides only of the 

 myriad of particles would be turned 

 toward him. The rings would then be 

 recognized merely as an opaque band, 

 hiding from his view a large part of 

 the heavens. Indeed from the intens- 

 ity of the shadow which the rings are 

 seen by us to cast upon the ball of the 

 planet, it seems probable that they are 

 sufficiently opaque to obscure the light 

 of the sun itself. If this is so then the 

 imaginary inhabitant while in certain 

 latitudes would be subjected to a total 

 eclipse of the sun which would continue 

 without intermission for more than five 

 years. 



Saturn has ten satellites of which the 



