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Astronomy & Astrophysics
Susan Pfieffer

AST251 JANUARY 9 2012 How did life begin and evolve on earth how did earth form can life exist elsewhere and where How did the earth change rdLife on the universe 3 editionthMidterm feb 13 march 2 essay draft march 19 finalessay 30 final 38 and class is 7wwwastroutorontoca ast251ast251spring what is life complex to simple what consider life and wouldntrecognize life when we see it quite difficult to define life it grows moves replicates so does non life water was described through properties many other things have these properties a lot called waterno definition of life we have a Darwinian definition one capable of evolutionwould have to watch it change over long periodslook for things we already know no life is known outside of earthwhere to look 2 places the solar system bc it is close other planets may have some life microbe mars had liquid water on surface some moons of Jupiter as well extra solar planets most like earth many stars las few years 100 k have been discovered orbiting few have right distance for liquid water and size for good atmosphere really far awayif has all these things are we guaranteed how difficult is it for life to originatewe need a variety of sciences to do so ast earth sci and biothree lines of evidence that make us think life is common organic mol common life originated quickly only after 6 gyr after earth formed almost one tenth of age very high life adaptability gyr 109 myr 106 life is still around and is successful vastly different numbershistorypeople been thinking about it for a long time primitive astronomyBabylonians predict and so did mayans worked without understandingEarly greek philosophers democ 4 elements earth air wind fire and made out of these happened on earth happened elsewhereether
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