258 ELEMENTS OF GENERAL SCIENCE 



in the eastern sky at intervals of one year and one month 

 thereafter, and in the western sky at intermediate periods. 

 It can be distinguished from the stars by the fact that it is 

 more brilliant than any fixed star and shines with a steadier 

 light, and a few nights' observation will show that it is 

 moving among the stars. 



261. Saturn. The planet Saturn is a little smaller and 

 somewhat less dense than Jupiter. It has nine and possibly 

 ten satellites, the most remote of which revolves around it in 

 a direction opposite to the others. The thing that distinguishes 



FIG. 129. Saturn 



Three photographs showing the peculiar ring about the planet. Photograph by 

 the Yerkes Observatory 



Saturn from all the other planets is the enormous ring system 

 which surrounds it (fig. 129). The rings have the appearance 

 of being a solid mass ; they are in reality swarms of particles 

 of unknown size (but probably small), which circle around 

 the planet in the plane of its equator and, because of their 

 great numbers, appear solid, just as a cloud floating around 

 a mountain peak appears from a distance to be as solid as 

 the mountain itself. The distance across the outside ring is 

 about 11,000 miles. There is a gap of about 2000 miles 

 between it and the next ring, which is approximately 18,000 

 miles across. This second ring is as bright as the planet 

 itself. Inside it and joining it is a very faint ring about 



