Our Earth and Its Fellow Planets [ 397 



Saturn takes twenty-nine and a half of our years to revolve about 

 the sun. Twice during that period the rings are so tilted that only 

 a narrow edge faces the earth. At that stage we cannot see the 

 rings at all through a small telescope; we succeed with a powerful 

 instrument only because of sunlight shining through the rings. 

 When they appear upward or downward, the three rings are 

 distinct. 



It is fascinating to observe the changing aspects of the rings as 

 the shadow of Saturn is thrown on them, and again as the shadow 

 of the rings appears on the planet as a dark, sharply outlined band. 

 They move around the planet at varying speeds the ring nearest 

 Saturn is the fastest; the outer ring, the slowest. 



Saturn is the last of the planets that we can see with the naked 

 eye. It is another of the "giants," second only to Jupiter in size. 

 As in the case of Jupiter, clouds of poisonous gases form bands 

 across the surface of Saturn, but they are much fainter than 

 Jupiter's bands. Despite its great size, Saturn does not appear 

 nearly so brilliant to the naked eye as Jupiter does. Saturn is 

 millions of miles farther away from us. 



Uranus and Neptune Distant Planets 



These planets are so far away from us that only a person with 

 exceptional eyesight can possibly see Uranus without the aid of a 

 telescope, while Neptune is always invisible to the naked eye. 

 Both of these planets resemble Jupiter and Saturn in having 

 clouds of ammonia and methane in their atmosphere. And though 

 they are smaller than Jupiter and Saturn, they are nevertheless 

 classed as giants. 



Uranus is about thirty-two thousand miles in diameter and takes 

 eighty-four of our years to complete its revolution around the sun. 

 Even through a telescope there is little to look for on Uranus. It 

 appears as a small greenish disk with vague belts across the surface. 

 It has four satellites. 



Neptune, as we have seen, is completely invisible except with 

 the aid of a fairly powerful telescope. Still, it has a diameter of 

 about thirty-three thousand miles, and its period of revolving 



