THE EARTH 5 



Venus, has one or more smaller bodies revolving around 

 it. These bodies are called satellites or moons. The 

 earth has one of these moons, and Saturn has the greatest 

 number, ten in all. In addition to its ten satellites 

 Saturn has several concentric, bright rings surrounding 

 it and revolving about it (Figure 2). When Saturn 

 is situated so as to show the broad side of the rings, - 



FIG. 3. 



once in fifteen years, it is in its brightest phase and is 

 a wonderful sight through the telescope (Figure 3). 



Planetoids and Comets. Besides the planets and 

 their satellites there are in the solar system about six 

 hundred planetoids or asteroids. These are solid bodies 

 much smaller than the planets, revolving in orbits be- 

 tween Mars and Jupiter. Within the limits of the solar 

 system are also comets heavenly bodies consisting 

 of a head, with a very bright spot gradually shading into 

 a less luminous portion, and a tail or streamer (Figure 4). 

 Some of the comets seem to have regular paths about the 

 sun, making their appearance at regular intervals, and 

 must be considered a part of the solar system; others 

 appear as occasional visitors, never to return. 



