WHY DO THE STARS APPEAR TO MOVE? 199 



hind the hill. We may think of it as setting. When 

 the moon comes up or sets, it just means that we have 

 traveled past it as we dash by objects on a railroad train. 

 It is in the same way that we move past stars of the 

 constellations. Stars seem to move across the sky from 

 east to west, but the earth is really rotating from west 

 to east. Consequently they appear to rise and set. 

 There is one star, however, that does not appear to move. 

 This is Polaris, the North Star. The reason for this is 

 that it is in line with the axis of the earth, as is shown in 

 the demonstration we just performed. Now, because the 

 earth rotates, the stars appear to describe circles around 

 the earth. If the earth is held still while the umbrella 

 is rotated east to west, and you imagine yourself at a 

 fixed spot on the earth, you will readily see the apparent 

 motion of the stars. 



SELF-TESTING EXERCISE 



Select from the following list those words which best fill the blank spaces 

 in the sentences below and arrange the words in proper numerical order. 

 A word may be used more than once. 



always north move spherical 



never south motion earth 



hallucination east movement star 



illusion west rotates equator 



near sun speeds axis 



distant moon revolves poles 



latitude 



The earth in form is a (1) body. It (2) on its (3) 



and (4) around the (5) The axis of the earth points 



towards the (6) (7) which (8) appears to move. All 



the other stars appear to (9) from (10) to (11) during 



the night. But this (12) is really due to the (13) of the 



(14) The fact that we do not see the same stars at different 



seasons is explained by the (15) of the earth to (16) parts 



of the heavens as it revolves around the sun. 



