HEAVENLY BODIES 473 



and a south pole on which snow appears during the different seasons 

 of the year. There are two moons, one of which travels so fast that 

 it goes around Mars three times a day. The planet is surrounded 

 with a blanket of air probably much thinner than our own. Mars is 

 covered over with a network' of long, dark, thin lines called canals. 

 It is believed that these canals are caused by water and vegetation 

 growing on the surface of Mars, as the red appearance of the planet 

 is supposed to be due to great stretches of desert land. 



Jupiter. Jupiter is the largest of all the planets. It is more than 

 1300 times larger than our earth. Jupiter has eight moons, four 



FIG. 364. The planet Jupiter. The ringed planet Saturn. 



small ones and four large ones. The four large ones may be 

 seen with a small telescope. 



Saturn. Saturn is one of the most beautiful planets in the 

 heavens. It is surrounded by three rings of gaseous vapor of which 

 the middle and broadest one is probably about 10,000 miles wide. 

 The planet changes position so that the rings may be seen more 

 easily at certain times. 



Uranus and Neptune. Further out in space is the planet Uranus 

 which has four moons. Beyond Uranus lies the planet Neptune with 

 only one moon. Neptune is almost in utter darkness, for it is so 

 far from the sun it receives little of its light. 



The Small Planets. (Asteroids.) Beyond Mars there are a 

 number of very tiny planets, so small that the diameter of the 



