174 



EARTH AND HEAVENLY BODIES 



Activity 118. How can the North Star (Polaris) and 

 some of the common northern star groups be lo- 

 cated from the Great Dipper? 



Select the star map of the northern skies for the month 

 in which you are observing. Locate the Great Dipper (Ursa 

 Major) and then locate it in the evening skies by observa- 

 tion. Find the two stars in the bowl of the dipper on the 

 side away from the handle and carefully observe the distance 

 between them. 



On your star map imagine a line drawn through these 

 two stars and follow it in the direction of the upper one a 



Courtesy Mount Wilson Observatory 



FIG. 286. THE MILKY WAY 



Note that the illustration is made of a number of photographs 

 pieced together. 



distance equal to about five times the distance between them. 

 You should arrive at the last star in the handle of the Little 

 Dipper. This is Polaris, the North Star. When you have 

 located it on the star map, make the observation in the eve- 

 ning skies. You may have to look sharply to see Polaris, as 

 it is not an extremely bright star. 



The Little Dipper can be located from Polaris. Notice that 

 the bowl of the Little Dipper seems always to be pouring 

 into the bowl of the Great Dipper. 



Cassiopeia, the Queen's Chair, can be located from the 

 Great Dipper by passing a line from a point in the middle 

 of its handle through the Pole Star and continuing as far 

 on the other side as Polaris is from the Great Dipper. Ob- 

 serve this on the map and then in the evening skies. 



Draco, the Dragon, always curls jts tail down between 

 the two Dippers. Locate it in this way on the star map and 

 then find it in the evening sky. 



In your notebook write a summary paragraph telling of 

 your experiences in making the observations required in 

 this investigation. 



OTHER INVESTIGATIONS WHICH YOU CAN MAKE 



1. How can one make a star finder? See American Boy's 

 Engineering Book by Bond or The Book of Stars by Collins. 



2. How can a planisphere be made ? See Our Physical 

 World by Downing. 



3. How may the heavenly bodies be photographed? See 

 The Book of Stars by Collins. 



4. How may a simple telescope be made ? See The Book of 

 Stars by Collins or The Boys' Own Books of Great Inven- 

 tions by Darrow. 



5. How may a reflecting telescope be made? See Amateur 

 Telescope Making, edited by Ingalls. 



NOTE: This is a painstaking exercise and should be under- 

 taken only by a group that is willing to put in long hours 

 of careful and difficult work. It is, however, a project which, 

 once completed, will yield many hours of fruitful returns. 



READINGS WHICH WILL HELP ANSWER THE 

 PROBLEM QUESTIONS 



How many stars can you see on a clear, moonless 

 night? Have you ever gone out under the open sky, 

 on a clear and moonless night, and tried to count 

 the stars? If you have, no doubt you found the task 

 a difficult one. The stars seem scattered like tiny 

 points of light in great profusion over the heavens. 

 Their number seems countless. But one of the first 



Courtesy Mount Wilson Observatory 



FIG. 287. SPIRAL NEBULA VIEWED EDGEWISE 



Notice that it is shaped much like a watch. Our galaxy is some- 

 what similar in shape. 



things everyone must learn when he begins a study 

 of the heavens is that things are not always as they 

 seem. The stars visible to the naked eye from the 

 north pole to the south- pole have been counted, and 

 the number is approximately 6,000. But since only 

 half this number is above the horizon at any mo- 

 ment and since the haze in the atmosphere near the 

 horizon prevents faint stars there from being seen, 

 only about 2,000 stars are visible at one time. Of 

 course there are many more than 6,000 stars. Through 

 an opera glass at least 100,000 stars can be seen, and 

 our largest telescopes show millions of them. 



Neither are the stars the tiny, twinkling points of 

 light they seem to be. They seem so only because 

 of their great distances from the earth. With the ex- 

 ception of our sun, the nearest star (Alpha Centauri) 



