EXERCISE 2

The Milky Way galaxy consists of a disk of stars roughly 30,000 
parsecs across and about 300 parsecs thick, and a bulge at its center 
roughly 3,000 parsecs in diameter. The distance between us and our 
nearest neighbors, the Alpha Centauri system, is about 1.3 parsecs. 
Estimate the number of stars in the Milky Way galaxy. Be sure to state 
the assumptions and steps in your reasoning.