CAS AS 100 Chapter Notes - Chapter 24: Rare Earth Hypothesis, Galactic Habitable Zone, Star System
19 May 2016
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Document Summary
Astrobiology the modern science of life in the universe. *earth, venus, and mars have been exchanging rock for billions of years. Because organic molecules have been found on meteorites and comets, this tells us that the building blocks of life can survive in space and maybe life originated there and then came to earth. Cambrian period occurred about 542 million years ago and is when life began to diversify. Three basic requirements for life: source of nutrients from which to build living cells, energy to fuel the activities of life, like sunlight, chemical reactions, or from the heat of earth itself, liquid water. *mars and europa are the most likely to contain life. Methane is quickly destroyed by ultraviolet light from the sun so its presence on mars means that it is being continually released from the martian surface. Amount of methane varies regionally on mars and with the martian seasons.
