The Evolution 



of the Universe 



Some measure of the size and organization of the 

 universe is to be gained by considering the earth as 

 a starting point. The earth is one of nine planets 

 revolving around the sun. Approximately 8,000 

 miles in diameter, the earth weighs roughly 

 6,600,000,000,000,000,000,000 tons (6.6 X 10-^). The 

 sun is about 3,000 times more massive. Compared 

 with other stars, our sun is of only moderate size. 

 It is part of a tremendous aggregation of stars known 

 as a galaxy. The galaxy in which we live is only one 

 of the myriads that comprise the universe. Our 

 galaxy is lens-shaped and contains about 100 billion 

 stars (Robertson, 1956) and great masses of inter- 

 stellar dust and gas concentrated in the edge por- 

 tions (Westerhout, 1959). The total mass of our 

 galaxy is about 70 billion times that of the sun, 94 

 per cent consisting of stars, the remaining 6 per cent 

 consisting of interstellar gas and dust. The chief 



