AST101H1 Lecture Notes - Lecture 17: Radioactive Decay
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AST101H1 Full Course Notes
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Document Summary
Differentiation: light materials rise to the surface. While dense materials fall to the core, gravitational potential energy is converted into thermal energy. Differentiation caused all terrestrial planets to form cores. Only earth and moon have had seismometers on them. The size of core for the rest is inferred from mass distribution of planets and magnetic fields. Planets get their heat from : accretion (gravitational potential energy kinetic energy thermal energy, differentiation (light materials rise, desne fall, gravitational potential energy thermal, radioactive decay (mass contained in nuclei thermal energy) Hot rock weighs less than cooler rock. Hot rock rises and cooler rock falls. This brings head up from the core. A planet"s crust is ridged, so there is no convection there. Heat is conducted through the rock (slower than convection) Infrared light carries energy from surface of planet. Less area per volume means less radiation per volume small planets cool faster.
