How long can the Sun continue to shine, and what source of energy

does it tap to keep shining? This lecture answers this question by

introducing two important energy sources for stars: Gravitational

Contraction otherwise known as the Kelvin-Helmholz Mechanism, and

Nuclear Fusion. We will show that fusion of 4 Hydrogen nuclei into

a Helium nucleus via the proton-proton chain liberates enough energy

to provide for the Sun's Luminosity needs for about 10 Billion Years.

Recorded 2006 January 19 in 1008 Evans Laboratory on the Columbus campus

of The Ohio State University. Note: the recording mistakenly says

January 18th. Oops.