80 NATURE STUDY REVIEW [10:3— Mar., 1914 



started on its journey almost fifty years ago, while the light that 

 reaches us from the interesting little group of stars called the 

 Pleiades, may have started on its journey before Columbus 

 started on his great voyage. 



The stars seem always to us to keep their own place in the 

 heavens, but they are all moving through space just as our sun 

 and its family are doing. However, the stars are so far away that 

 although one may move a million miles a day we would need to 

 make observations upon it for years to detect that it had moved 

 at all. We know that our sun and its planets are moving through 

 space at the rate of about 800 miles per minute. 



Stars also have their youth, middle age and old age. When 

 they are young they are composed of thin gases and shine white 

 or blue; as they mature the gases condense and they shine yellow, 

 like our sun; when the gases become still more condensed they 

 shine red, like Betelgeuze in Orion, which is a very, very old star, 

 and after a time, more years than we can even think about, these 

 stars grow cold and dark and become invisible to us. The spectro- 

 scope shows us that there are many of these vast dead suns, with 

 their fires out, whirling through space. 



. If any of us with especially good eyes were to travel from the 

 Northern to the Southern Polar region, we would be able to see 

 between six and seven thousand stars, although never more than 

 about two thousand at one time. With the aid of the telescope 

 about eight hundred thousand stars have been discovered. But 

 during recent years the skies have been photographed, and thus 

 we have record of about thirty million stars. We usually regard 

 the Milky Way as a band of light across the heavens, but it 

 is really rrade T:p of millions of stars so far away that we cannot 

 see them at all. We can only see the light that comes from them. 



- Before the following lessons are given, the pupils should be 

 instructed how to draw an imaginary line straight from one star 

 to another and to perceive the angle which two lines make when 

 they meet in a certain star. An ordinary ruler, or what is even 

 better, a postal card or other stiff paper with right-angled comers, 

 may be used by holding it between the eyes and the stars to be 

 connected and thus make certain that the imaginary line is straight. 



, Place the diagram as given on the blackboard, but do not add 

 the connecting lines until needed to enable the pupils to find the 

 different stars to be studied. If possible let the blackboard stand 

 so that its edge labelled " East " extends toward the east. 



