ENV100Y5 Lecture 4: ENV100 - 04 - Earth as a Planet II
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ENV100Y5 Full Course Notes
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Age of sun and solar system: ~ 4. 57 ga (billion years) Age of earth: ~ 4. 54 ga (billion years) Based on models of stellar evolution and dating of primitive solar system objects. Based on ages of terrestrial rocks + age of solar system + models of solar system formation. The older rocks could"ve been damaged - could"ve been completely wea away. Come from a previous older rock that has been eroded. Oldest rock is 4 ga old acasta gneiss. The nebular hypothesis* explains the origin of the solar system. Interstellar (between stars) cloud inherits elements from previous generations of stars. The solar nebula: early in solar system history. Differentiation - to separate into its different components (denser part in the middle, lighter part on the edges) When you have a large enough body/characteristics of planets: Clear orbit around them by attracting objects around them gravitationally. Earth didn"t have an atmosphere so no protection; no ozone layer which protects from uv.
