ENGR 220 Lecture Notes - Lecture 14: 8 Seconds, Radiography, Photosphere
Document Summary
Sunshine is powered by the fusion of hydrogen into helium in the sun"s core. It takes 100,000 years for light to travel from the sun"s core to the visible surface. Gravitational equilibrium - the balance of pressure and gravity in the sun"s interior. Keeps the core hot and dense enough to release energy through nuclear fusion. Nuclear fusion - the uniting of light atomic nuclei into heavy nuclei, releasing binding energy in the form of gamma ray radiation and other particles. High temperature enable nuclear fusion to happen in the core. At low speeds, electromagnetic repulsion prevents the collision on nuclei. At high speeds, nuclei come close enough for the strong force to bind them together. Sun releases energy by fusing four hydrogen nuclei into one helium nucleus. 2x: two he-3 nuclei fuse to form he-4 (2 p/2 n) releasing 2 extra protons (energy, entire process occurs twice to combine at the end.
