HOW TO GET ACQUAINTED WITH CONSTELLATIONS 203 



called " pointers." They point to the polar star, Polaris. 

 The position of these and other constellations differs with 

 the season. As the earth moves along its orbit to new 

 positions in the heavens, the stars overhead at 8 P.M. will 

 vary greatly at different times of the year. If you observe 

 the Big Dipper in early evening as soon as visible, and 

 again the same evening three or four hours later, you can 

 see that its position in the heavens changes. 



How to Tell Some of the Constellations. We can 

 easily find a number of the constellations if we know the 

 position of the Big Dipper and the Little Dipper. A 

 study of any good star map will show you that if you 

 follow the pointer of the Big Dipper to the North Star 

 and then continue about an equal distance beyond, 

 you will see a little to the right a constellation whose 

 bright stars roughly form the letter W. This is the 

 constellation Cassiopeia. If you go from the pointer 

 to Polaris and turn at right angles and travel nearly twice 

 the distance, you will come to a very bright red star, called 

 Capella. From the pointer at the open end of the bowl 

 draw a straight line to the handle side of the bowl one- 

 third of the distance down from the rim of the bowl and 

 continue in the same direction to a bright star which 

 is twice as far from the North Star as the bowl of the 

 Dipper is. This is Arcturus in the constellation Bootes. 

 Arcturus is a first-magnitude star 500 times as large as our 

 sun and gives a white light. We have already seen that it 

 takes about 40 years for its light to reach the earth. 



By studying the star maps shown on pages 204 and 205, 

 you can locate a number of the more common constella- 

 tions such as Orion, with its three-starred belt, and the 

 bright stars Rigel and Betelgeuse ; the Twins ; the Great 

 Dog Star, Sirius, which is the brightest star in the sky; 

 and many others. Remember that the maps made for 

 use here show you the situation in the sky during the 



