HOW TO GET ACQUAINTED WITH CONSTELLATIONS 209 



years; (23) follow different physical laws from those of our own 

 system ; (24) they must be cold bodies. 



VII. When we look into the sky at 8 P.M. in December, we do not 

 see the same constellations that we do at 8 P.M. in June because : 



(25) it is colder weather ; (26) the nights are longer ; (27) the 

 earth has moved halfway around the sun, changing the heavens 

 which we see at night ; (28) the stars have rotated halfway around 

 the North Star. 



VIII. The North Star is : (29) about vertically over the north 

 pole of the earth ; (30) visible to all people on the earth, because 

 of its great distance above the earth; (31) more than two million 

 billion miles from the earth ; (32) also called the Little Bear. 



IX. The light year is : (33) the time it takes light to come to 

 earth from the sun ; (34) the unit of measuring distances of 

 heavenly bodies ; (35) the distance light travels in a year ; (36) about 

 six million million miles. 



X. The Milky Way is: (37) a constellation; (38) a galaxy; 

 (39) a solid heavenly body ; (40) is seen by reflected light just as 

 the moon is. 



THOUGHT QUESTIONS 



1. Why do stars appear to move in a certain direction during 

 the night ? 



2. Why do certain stars appear to change their positions from 

 month to month? 



3. Calculate how long it will take the light from a star selected 

 by yourself to reach the earth ? 



4. Compare an atom of matter and our own solar system. 

 Show how you will use facts, theories, and imagination in making 

 this comparison. 



5. How would you say that future discoveries in astronomy 

 will be made ? 



6. How can we tell the age of a given star? 



7. We say that the axis of the earth points very nearly towards 

 the North Star. Can you explain how, in reality, this statement 

 is very far from the actual fact ? 



REPORTS ON OUTSIDE THINGS THAT I HAVE READ, 

 DONE, OR SEEN 



1. Report upon an article related to some topic discussed in 

 this unit. The article may be from a current number of a science 

 magazine or from some popular science book you have read. 

 H. & w. sci. i 15 



