, NATVBE-STUDY LESSONS. 189 



8. (a) Observe how far the Big Dipper appears to 



move in two hours. (In the long winter 

 evenings you can observe it an hour longer 

 and one does not need to rise very early to 

 see it in the morning.) 

 (d) How many times that apparent distance (its 

 movement in two hours) would complete the 

 circle. 



(c) Hence, infer the number of hours it takes that 



group of stars to make an apparent revolu- 

 tion around the North Star. 



9. (a) Choose another group of stars and observe it in 



a similar manner. 



(d) Infer whether all the stars make apparent, com- 



plete revolutions in twenty-four hours. 



10. Observe the distance from the Big Dipper to the 

 North Star. At the same distance from the North Star, 

 but in the opposite direction, try to make out another 

 group of five or six stars shaped like a W with one of 

 the V's shallower and wider than the other and having 

 the open side towards the North Star. 



This group, often spoken of as the Big W, is called in the sky maps 

 Cassiopeia's Chair. 



11. (a) Compare the brightness of these stars with 



that of the stars in the Big Dipper. 

 (d) Make a map showing their relative position to 

 each other and to the North Star. 



12. With the unaided eye, or by looking over the edge 

 of a ruler, trace a line passing through the North Star 

 from a particular star in the Big W ; for example, the 

 outside one of the sharp "V to the Big Dipper, and find 

 what part of the latter group is opposite that particular 



