In which I explain the Hertzprung-Russel diagram

Here’s a powerpoint animation that explains the Hertzprung-Russel diagram, step by step. The Hertzprung-Russel diagram is one of those great organizational schemes, like the Periodic Table, that manage to have great predictive and associative power.  It’s not perfect (neither is the Periodic Table), but it CAN explain a great number of things about stars.