ENV100Y5 Lecture Notes - Lecture 3: Interstellar Cloud, Stellar Evolution, Nuclear Fusion
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ENV100Y5 Full Course Notes
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Document Summary
Age of sun and solar system 4. 57ga. Based on models of stellar evolution and dating primitive solar system objects. Based on ages of terrestrial rocks + age of solar system and model of formation. Nebular hypothesis explains the origin of the solar system. Interstellar cloud inherits elements from previous generations of stars. Nuclear fusion begins and the sun forms. Early earth 4. 5 ga was hostile to life. Water molecule has chemical characteristics that support life. Water molecules are polar, bonds with other chemicals. Liquid over a wide range of temperatures. High heat capacity, stabilizes systems against change. Solid less dense than liquid, floating ice insulates water. Surface cooled enough to sustain liquid water. Several hypotheses have been proposed to explain life"s origin. Heterotrophic hypothesis: life originated from inorganic chemicals in the ocean. Panspermia hypothesis: microbes delivered to earth in meteorites. Chemotropic hypothesis: life originated at deep-sea hypothermal vents, first organisms were chemotrophs. Fossil: remnant of long-dead organism, preserved in stone.
