The Outer Planets 249 



suitable for habitation, although we have no evidence 

 that any creatures actually live upon them. If in- 

 telligent beings inhabit any of them, they enjoy moon- 

 light from several of the other moons at all times. 

 Jupiter itself would give them both light and heat, and 

 would seem to them much larger than the sun appears 

 to us, although less brilliant. The little satellite discov- 

 ered at the Lick Observatory in California in 1892 is 

 less than 70,000 miles from the surface of Jupiter. 

 Other faint satellites are more than 6,000,000 miles away. 

 The most distant one revolves around Jupiter from east 

 to west, while the rest of them revolve in the direction 

 in which Jupiter rotates, from west to east. 



SATURN 



Saturn, when nearest to us, looks like one of the 

 -brightest stars. As it takes 29-3- years to go around 

 the sun, it moves among the stars only about 1 2 degrees 

 a year. Having once located it, therefore, we can find 

 it at the same month of the following year near the same 

 place, only a little farther to the east. In December, 

 1917, it was low in the east early in the evening, and for 

 several years following 1917 it will be seen in the same 

 direction in winter, appearing later in the evening or 

 later in the season as the years advance. On January 

 31, 1918, it rose as the sun set, and it will rise at sun- 

 set about 13 days later each succeeding year. 



Viewed with a telescope, Saturn, like Jupiter, is seen 

 to be enveloped in clouds. At such a distance from the 

 sun these clouds would condense into liquid or solid 

 substances unless they were receiving heat from the 



