128 ANSWERS TO PRACTICAL QUESTIONS 



62. Do we see the same stars at different seasons of the 



year ? 



(See Astronomy, pp. 92, 93.) 



63. Why do we not perceive the earth's motion in 

 space ? 



Because all the objects around us partake of its motion. 



64. Did the earth ever shine as a star ? Does it now 

 shine as a planet ? 



The earth, doubtless, shone as a star while it was yet a 

 glowing mass ; now, it reflects the sun's light, like the other 

 planets. 



65. IVJiat is the nebular hypothesis ? 



(See Astronomy, p. 255.) 



66. JVJiat is the cause of the solar spots ? 



(See Astronomy, p. 54.) 



6*7. Would it make the new moon " drier " or " wetter " 

 if the moon's path ran north of, instead of on,, the ecliptic 

 at the time of new moon ? 



The moon's latitude varies from 5 N. to 5 S. (exactly 5 

 8' 47" 9). If the new moon were 5 1ST., this would increase 

 the angle of 72^ (note, p. 30) to 77, and thus make the line 

 joining the moon's cusps more nearly parallel to the horizon. 

 It may be easily seen that whenever the plane of the lunar 

 orbit lies so as to carry the moon past conjunction above the 

 sun, then the crescent is more nearly horizontal ; when below, 

 then it is more nearly vertical. 



68. Under what conditions are we accustomed to trans- 

 fer motion ? 



(See Astronomy, pp. 85, 86.) 



69. Wliy do not the planets twinkle ? 



(See Astronomy, note, p. 207.) 



70. IVliy is the horizon a circle ? 



(See Manual, p. 124, Question 28.) 



7 ! What causes are gradually increasing the length of 



the day ? 



(See Astronomy, notes, pp. 89, 303.) 



