• In-text and reference citations are required for all written responses. 

Question 1: 
Describe the Hertzsprung-Russel diagram. How is it useful in classifying stars? Where do stars tend to cluster on the diagram? Where on the H-R diagram does a star spend most of its life?

Question 2: 
How do we calculate or determine the distances to stars? What units do we use and what are the limitations (if any) of the method used for such calculations?