406 ] Recognizing the Stars 



its glare is reduced so that you can watch it briefly without ill 

 effect. At this time it appears to grow larger; but if you roll a 

 sheet of paper into a tube and look through it, the sun will resume 

 its usual size. The "change" of size is one of nature's interesting 

 illusions. 



SPOTS ON THE SUN 



If you look at the sun through a telescope equipped with a 

 specially darkened filter, you may observe some dark spots on its 

 bright yellow surface, possibly grouped in pairs or clusters. You 

 would see them apparently moving across the disk a short distance 

 each day as the sun turns on its axis. 



These "sunspots" would appear very tiny in your telescope, but 

 in reality each one of them might be as large as our earth or 

 larger. The earth is a mere speck compared to the sun, which 

 requires twenty-five of our days to complete a turn on its axis and 

 has a mass 332,000 times greater than that of the earth! 



What Sunspots Are: A sunspot is believed to begin in a column 

 of gas that rises from far below the surface of the sun. This column 

 is pushed upward to the surface by energy supplied by its own 

 heat. This expended energy results in a shallow layer of gas at the 

 top of the column. The top layer is cooler than its surroundings 

 and therefore appears darker. 



The number and frequency of sunspots vary, but they have a 

 way of increasing and gathering in larger groups for several years, 

 then becoming less and less frequent until the sun is quite clear of 

 them. On the average, about eleven years elapse between one 

 period of great spottedness to the next. 



Tracing the Influence of Sunspots: There has naturally been a 

 great deal of speculation about the possible effects of sunspots on 

 our earth. Occasionally scientists have thought they could trace a 

 connection between "storms" on the sun and stormy weather on 

 the earth. However, observers in the United States Weather 

 Bureau have not yet succeeded in tracing any direct influence of 

 sunspots on our storms. 



