AST-1A Chapter Notes - Chapter 11: Nuclear Fusion, Radiation Zone, Chromosphere
Document Summary
Sun generates by slowly contracting in size gravitational contraction. Can only contract very slightly each year: calculations showed that it kept the sun shining for 25 years. Einstein"s theory told us that mass itself contains lots of potential energy. Fatal flaw: earth was far older than 25 million years. Stating the sun shines by converting mass into energy through nuclear fusion. Requires extreme temperatures found deep in the core. Sun was formed 4 billion years ago. Gravitational contraction released the energy that made the suns core hot enough. Sun continues to shine today because it has 2 types of balance: Gravitational equilibrium: the outward push of internal gas pressure and the for fusion inward pull of gravity. Internal pressure balanced gravity keeping it stable in size. Energy balance: between the rate at which fusion released energy and the rate at which the suns surface radiates this energy. Without this balance would not remain steady.
