248 Trees, Stars, and Birds 



FIG. 149. A photograph of Jupiter. 



dark earth or rock. Do you think there was ever a 

 time when there was nothing solid about the earth? 



Satellites of Jupiter. The first heavenly bodies dis- 

 covered after the invention of the telescope were four 

 satellites of Jupiter. They are farther from Jupiter 

 than our moon is from the earth. The smallest of them 

 is about the size of our moon. With field glasses you 

 should see them. Perhaps only three will be visible at 

 the time you look, the other being behind or in front of 

 the great planet, so that it does not show ; or two of the 

 satellites may be so close together that they will appear 

 as one. The satellites seem to be close to the planet 

 and in a straight line. Besides these four satellites 

 Jupiter has five others, so small that they were not dis- 

 covered until recent years, and possibly some that have 

 not yet been seen by any one on the earth. 



It is quite improbable that anything could live on 

 Jupiter, but some of its four large satellites may be 



