lecture_tan35 - Key Concepts: Lecture 35: Life in the...

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Key Concepts: Lecture 35: Life in the Universe: Origin of Life The Drake Equation Radial Velocity Search Life in the Universe – What is life? – How did life arise on Earth? – Are we alone? The Drake Equation – How common are habitable environments? – How do we find Extrasolar Planets? – The number of technological civilizations in the Galaxy – Practicalities of communication and interstellar travel Definition of Life • It can react to its environment • It can grow and take nourishment from its surroundings • It can reproduce - passing along some of its characteristic to its offspring • It has the capacity for genetic change, allowing evolution from generation to generation, mediated by Darwinian selection pressures. Unity of Life on Earth All living things on Earth are composed of organic material (C, H, O, N, P, S) – Carbon is abundant and can form complex string molecules All life on Earth uses replicating strings of These are used to construct amino acids, which link together to form more complex molecules of protein.
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The Origin of Life on Earth Oldest surface rocks found - ~3.8 billion years old “Earth Sterilizing” impacts every ~100,000 years ending about 3.8 billion years ago – Rock vapor from impact circles Earth for months – Oceans are evaporated with each impact First fossils: 3.8 - 3.5 billion years ago – Archaea - cyanobacteria which can live in extreme conditions
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This note was uploaded on 09/07/2011 for the course AST 1002 taught by Professor Dr.haywoodsmith,jr during the Spring '07 term at University of Florida.

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lecture_tan35 - Key Concepts: Lecture 35: Life in the...

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