NATS 1740 Study Guide - Radiation Zone, Photosphere

• School: York University
• Department: Natural Science
• Course: NATS 1740
• Professor: Patrick Hall

Document Summary

Gravitational contraction the sun generates energy by slowly contracting in size: gravitational contraction provided the energy that heated the core of the sun as the sun was forming, gravitational contraction stopped when fusion began. Fusion the fusion of hydrogen into helium is how the sun produces energy to keep its temperature and pressure high enough to resist gravity: the sun is powered by nuclear energy, so the sun shines. Gravitational equilibrium the outward push of pressure balances the inward pull of gravity: weight of upper layers of sun compresses lower layers; high density and high temperature yield high pressure high enough to support sun"s mass. Energy balance energy provided by fusion maintains the pressure by keeping the temperature high, replacing the energy the sun is radiating away: energy gradually escapes sun"s core as photons random walk by scattering from one particle to another.