6 THE OPEN SKY 



2700 millions of miles farther away from the sun than the 

 earth. 



Each of the twinkling points in the heavens is a sun, shin- 

 ing by its own light. Our sun, if seen from the distance of 

 one of the nearer stars, would appear like a twinkling star. 

 Many of the distant stars are much larger than our sun. 



A STAR CLUSTER 

 This cluster appears as a single star to the eye. 



There is reason to believe that some of them have their 

 families of planets, and that our own solar system is only 

 one of many similar systems that exist throughout space. 



The distances to these suns are so great, however, that 

 their brilliant lights appear little brighter in the evening 

 sky than the flickers of so many candles. The nearest of 

 these stars is probably about 25 thousand billion miles 



