EPSC 221 Lecture Notes - Outer Core, Lead, Cosmic Ray
28 Oct 2012
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Document Summary
A brief history of the earth: the origin of our solar system and planets. Large explostion sebt all maters at incredible speed. Debrits start to cool dowm the milky way galaxy forms cloud starts to contract under influence of gravity. Nebular hypothesis : a rotating cloud of dusts and gas forms in the milkey way. Matter in the middle accumulate to form the. End of gravitationnal heating disk around sun cools, condenses. Planetesimals (km-scale) form and start to collide and grow. Lighter elements preferentially blown away from inner planets. Outer giants icy core, mostly gas: the early earth. Earth forms just slightly more than 4. 5 billion years ago (fig a) Giant impact by mars-size body ~ 50 million years after formation forms moon energy from impact and radioactive heat cause partial melting of earth which causes differenitation. Melting permits differentiation lighter elements( hydrogen) rise to surface, denser elements sink to center (pb, fe) (fig b)
