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Unformatted text preview: Lecture 8- The Early Earth Environment, and the Origin and Early evolution of Life A. How did life originate-  God or other “supernatural causes” outside of science of scientific study  “Directed panspermia-brought to Earth by intelligent beings, also outside science  Historically: spontaneous generation or vitalism  Panspermia- life originated elsewhere and came to Earth via natural processes, life itself came to Earth  CHEMICAL EVOLUTION- main forces B. Chemical Evolution-  Top down approach- Retrace the rock and fossil record o Fossil record does not tell us exactly how when or where life began but can narrow down to 3.5-3.85 Ga  Bottom-up approach- describe the chemistry of the origin of life C. The Birth of Stars-  Stellar genesis- Proto star system form when a diffuse mass of gas/dust begin to collapse  Near the center, the temperature rises a the density and pressure increase  When the temperature grows hot enough, nuclear reaction begins and the star ignites, then dust particles collide and become larger  Eventually, the larger bodies will become protoplanents and then become planets D. Minor bodies in our solar system-  Asteroids are the leftovers made of metal and rocks and coments are the leftovers...
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This document was uploaded on 04/25/2008.
- Winter '08