114 ANSWERS TO PRACTICAL QUESTIONS 



22. Do we ever see the sun where it really is ? 



(See Astronomy, p. 114.) 



Both refraction and aberration of light change the apparent^ 

 place of the sun. 



23. " At Edinburgh) Scotland, there are times when 

 the sun rises at 3% o'clock A.M., and sets at 8^ o'clock 

 P.M., and the twilight lasts the entire night. 9 ' When and 



why is this ? 



(See Astronomy, p. 116.) 



The latitude of Edinburgh is 55 57'. Any place north of 

 48 33' will have twilight at midnight in midsummer ; for 90 

 23 27' (the sun's declination) 18 3 (at which twilight ceases) 

 = 48 33'. The hours named in the problem are the times for 

 the rising and setting of the sun at Edinburgh at the summer 

 solstice. 



24. Which is the longest day of the year ? 



(See Astronomy, p. 99.) 



The summer solstice points out the longest day of the year. 



25. Ts the moon nearer to us ivlien it is at the horizon , 

 or at the zenith ? 



(See Astronomy, p. 124.) 



The moon is nearer to ur, when it is at the zenith than 

 when it is at the horizon. 



26. How many solar eclipses ivould happen each year 

 if the orbits of the sun and the moon ^vere in the same 

 plane ? 



(See Astronomy, p. 138.) 



In that case a solar eclipse would occur every new moon. 



27. Is there any heat in moonlight ? 



(See Astronomy, p. 125.) 



28. Can ive see the moon during a total eclipse ? 



(See Astronomy, p. 146.) 



29. WTiicJi of the planets are repeating a portion of the 

 earth's history ? 



Spectrum Analysis renders it possible, perhaps probable, 

 that Jupiter and Saturn, and, may be, Uranus and Neptune, 



