532 



SCIENTIFIC RECREATIONS. 



SATURN. 



We now come to the most curious of all the planets Saturn, which 

 is an immense globe surrounded by a beautiful bright ring, or rather series 



of rings, and attended by eight 

 moons. He appears to possess 

 much the same constitution as 

 Jupiter, but enveloped in an even 

 denser atmosphere than the latter. 

 Saturn's diameter is about nine 

 times greater than the earth ; he 

 revolves on an inclined axis in 

 Fig. 590. Satum. about ten hours, and has sea- 



sonal alternations of unequal length. His year is about thirty of ours (10,759 

 days). The most striking phenomena in connection with Saturn are his 

 rings. 



Saturn's rings are supposed to be a close agglomeration of stars, or 

 satellites, revolving around the planet and encircling him in a belt. The 

 rings are apparently broad and flat and thin, resembling roughly the horizon 

 of a globe. 



The globe of the planet is not exactly in the centre of the rings, which 

 have been measured, and are approximately as below : 



Diameter of exterior ring . . , 169,000 miles. 



Diameter of interior ring . . . 124,000 



Diameter of innermost . .. ... 100,000 ., 

 Interval between innermost ring and Saturn 19,000 ., 

 Intervals between the rings . . 18,000 



Thickness of the rings ... 130 



Breadth of the rings . . . ; . 37,ooo 



Fig 591. Saturn's rings at Equinox. 



The rings were first recognised as such by Huyghens in 1659, but 

 Galileo had- remarked the curious appearance the planet presented. Cassini 

 confirmed Huyghens' discovery, and found that the ring was duplicated, and 



Mr. Ball made the same discovery. 

 The two outermost rings are very 

 bright, the inner ring being darker 

 and partially transparent, for the 

 ball of Saturn can be perceived 

 through it. 



But the rings are not always 



S P lainl >' SCen ' m the Agoing 



diagram. Sometimes they appear 

 as a mere line of light on each side of the planet, as shown in fhe margin. 

 This occurs at the time of the equinox (fig. 591). By degrees, however,. 



Fig. 593-Enlarging ring. 



