360 NATURE-STUDY REVIEW [14:9— Dec, 1918 



Astronomers tell us that the moon is about one-eightieth the 

 size of the earth. If you were to make a trip around the earth, 

 in the region of the equator, and then repeat your journey again 

 and again for ten times you would have travelled as far as the 

 distance from the earth to the moon, or about 238,840 miles. We 

 usually say about 240,000 miles, as this is an easier number to 

 remember. So you see the moon is really quite far away, and yet 

 it is our nearest heavenly neighbor! Not a very neighborly 

 distance, is it, as we think of neighborly distances in our towns 

 and country-sides? If you were to travel on the fastest express 

 train, and could go a mile a minute, and never stop for any station, 

 or slow up for any grade, you would have to travel for 166 days 

 at this top speed before you reached the moon. And 166 days, 

 remember, is almost half a year! The moon, as you probably 

 already know, travels around the earth once every month, and in 

 a great circle, but not an exact circle. Sometimes the moon's 

 orbit (as this path around the earth is called) lies nearer to the 

 earth than at other times, and so when the moon is in this parti- 

 cular portion of its journey it approaches to within about 210,000 

 miles of us. Still this is not near enough so that we can tell the 

 difference by merely looking at it. It is the astronomers who 

 work these things out for us, using, such very, very hard problems 

 in mathematics, which you and I, I am afraid, would not be able 

 to do. 



Because of its great distance from us the moon seems very small, 

 but I am sure that you will not think that a globe with a diameter 

 of a little over 2,000 miles is very small; and that is the diameter 

 of our moon, or in other words. the distance right through its 

 center from one side to the other. Just remember this when you 

 are next looking at the full moon, and try to imagine how very 

 far away it must be to look no bigger than your tennis ball. Some 

 of the planets (that is the heavenly bodies like our earth) have 

 several moons! But if there are people on such planets, these 

 moons seem to them no larger than many of the bright stars do 

 to us. 



The same surface or side of the moon is turned toward us always, 

 so that when the moon is full we can see the Man in the Moon, 

 or the more beautiful Lady in the Moon, in always the same posi- 

 tions. This surface of the moon that is visible from the earth 

 contains 7,300,000 square miles. It will make these figures more 



