The moon is so very much nearer to us than any other heavenly body that
we have a remarkable knowledge of it. In Fig. 14 you have a photograph,
taken in one of our largest telescopes, of part of its surface. In a
sense such a telescope brings the moon to within about fifty miles of
us. We should see a city like London as a dark, sprawling blotch on the
globe. We could just detect a Zeppelin or a Diplodocus as a moving speck
against the surface. But we find none of these things. It is true that a
few astronomers believe that they see signs of some sort of feeble life
or movement on the moon. Professor Pickering thinks that he can trace
some volcanic activity. He believes that there are areas of vegetation,
probably of a low order, and that the soil of the moon may retain a
certain amount of water in it. He speaks of a very thin atmosphere, and
of occasional light falls of snow. He has succeeded in persuading some
careful observers that there probably are slight changes of some kind
taking place on the moon.
[Illustration: FIG. 17.--A MAP OF THE CHIEF PLAINS AND CRATERS OF THE
MOON