12 EXPERIMENTAL GENERAL SCIENCE 



about the sun, in connection with the tilting of the earth's axis, 

 causes the seasons (152). 1 The axis is so directed in space 

 that first one pole and then the other is brought nearer to the 

 sun. When one pole is toward the sun, the parts of the earth 

 near it have summer and the opposite region has winter. 

 Spring and autumn are the seasons between, when neither pole 

 is nearer the sun. It is the inclination of the earth's axis, 

 also, that causes the sun to be higher in our sky in summer than 

 in winter. The sun does not really move north and south as 

 the seasons change but only appears to do so because of the 

 apparent change in the earth's axis. 



Practical Exercises 



1. Identify as many constellations as you can. 



2. Locate the Pole Star. 



3. Examine a star map and find the names of the brighter stars. 



4. Find out from the almanac where the planets are located in the 

 sky at this time of the year, and identify the brighter ones. 



5. Make a drawing showing the positions of the axis of the earth with 

 reference to the sun during each of the four seasons. 



6. Look for the "earthshine" at the next new moon. 



7. The moon goes around the earth in a direction the reverse of the 

 sun's apparent motion, that is, from west to east. Can you account 

 for the fact that the moon usually rises nearly an hour later each 

 evening? 



8. How long is a day on the moon? 



1 The references are to other sections in this book where the subject 

 under discussion is further mentioned. The student is urged to consult 

 all such references as an aid to the proper understanding of the subject. 



