Mars and the Minor Planets 243 



FIG. 146. Mars in 1916. Photograph of drawings made by 

 Dr. Percival Lowell. 



seen from there it might appear half as large as the 

 moon viewed from the earth. 



Is Mars inhabited ? If any planets besides the earth 

 are inhabited, Mars and Venus are probably the ones; 

 for the others are believed to be either too hot or too 

 cold for living things to exist on them. Even when near- 

 est to us, Mars's distance is too great for us to see upon 

 the planet, with the very best telescopes, so small an 

 object as the largest of our living creatures an elephant 

 or a whale. Even the largest building in the world could 

 not be seen at such a distance. Yet things have been 

 seen on Mars which some astronomers consider the 

 result of the work of intelligent creatures. 



The equator of Mars is inclined to the plane of its 

 orbit 24 degrees and 50 minutes, so that it should have 

 seasons just as the earth has. When its north pole is 

 turned away from the sun, that part of the planet be- 

 comes covered with a white substance, which has been 

 supposed to be snow or ice. This cap shrinks on the 

 coming of the Martian spring, and then lines may be 



