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?
Lutgens, F. K., & Tarbuck, E. J. (2011). Foundations of earth science (6th ed., Pg.462-464 ). Upper Saddle River, NJ: Prentice Hall.