How are all of the observed properties of stars (Luminosity,

Mass, Radius, Temperature and Spectral Type) related to one another?

This lecture introduces the Herzsprung-Russell Diagram, a plot of

Luminosity versus Temperature for stars that is our most powerful tool

for unlocking the secrets of the stars.

Recorded 2006 January 17 in 1008 Evans Laboratory on the Columbus campus

of The Ohio State University.