Recognizing the Stars [417 



the Big Dipper first; after that it is not too difficult, with the aid 

 D a sky map, to find other nearby groups. The best sky-exploring 

 is done away from the bright lights of a big city, and an excellent 

 position from which to do it is flat on your back. It is important 

 not to rush matters by trying to discover or recognize too many 

 :onstellations or stars in a short time. Become really acquainted 

 with one or two before going on to others. 



low Astronomers Study the Stars 



As you explain facts about the stars to a child, he may very 

 well be puzzled. Some of these facts are so fantastic of themselves, 

 iome go counter to "common sense," some contradict what a child 

 nay have taken for granted. How can he be sure that the informa- 

 tion given him is accurate especially as he learns that early 

 studies of the stars led to many incorrect conclusions? 



TELESCOPE AND CAMERA 



It was the telescope that gave tremendous impetus to man'a 

 exploration of the stars. But his observations were still limited 

 intil the camera came along and considerably enhanced the value 

 >f the telescope. A camera can be fastened to the viewing end of 

 i telescope, doing the observer's work more efficiently in some 

 respects. 



The combination of telescope and camera is particularly effective 

 when a driving clock is attached causing the instrument to turn 

 ibout an axis parallel to the axis around which the earth turns, 

 rhe instrument moves at the same speed but in the opposite 

 iirection. Thus a photographic plate may be exposed for several 

 lours, and stars too faint to be seen through the telescope, will 

 register dots on the plate. 



THE VERSATILE SPECTROSCOPE 



Even before the camera was being used by astronomers, 

 lie spectroscope had been invented. To understand how this 

 instrument works requires a knowledge of physics, but even the 

 layman can appreciate the immense usefulness of this instrument* 



