Planetary Science

  1. Astrobiology and the Search for Life
    1. Defining Life
      1. Characteristics of Life
        1. Metabolism
          1. Reproduction
            1. Evolution
              1. Organization
              2. Challenges in Definition
                1. Alternative Biochemistries
                2. Requirements for Life
                  1. Liquid Water
                    1. Properties of Water
                      1. Alternative Solvents
                      2. Essential Elements
                        1. Carbon
                          1. Hydrogen
                            1. Nitrogen
                              1. Oxygen
                                1. Phosphorus
                                  1. Sulfur
                                  2. Energy Sources
                                    1. Sunlight
                                      1. Chemical Energy
                                        1. Geothermal Energy
                                      2. The Habitable Zone
                                        1. Circumstellar Habitable Zone
                                          1. Definition and Limits
                                            1. Factors Affecting Boundaries
                                              1. Continuously Habitable Zone
                                              2. Galactic Habitable Zone
                                                1. Location in the Galaxy
                                                  1. Supernova Rates and Metallicity
                                                    1. Stellar Density
                                                  2. Potential Habitats in the Solar System
                                                    1. Mars
                                                      1. Past Habitability
                                                        1. Present-Day Potential
                                                          1. Subsurface Environments
                                                          2. Europa
                                                            1. Subsurface Ocean
                                                              1. Energy Sources
                                                                1. Chemical Gradients
                                                                2. Other Icy Moons
                                                                  1. Enceladus
                                                                    1. Ganymede
                                                                      1. Callisto
                                                                      2. Titan
                                                                        1. Surface Lakes and Chemistry
                                                                          1. Prebiotic Chemistry
                                                                        2. Biosignatures
                                                                          1. Atmospheric Gases
                                                                            1. Oxygen
                                                                              1. Methane
                                                                                1. Phosphine
                                                                                  1. Other Potential Gases
                                                                                  2. Surface Reflectance
                                                                                    1. Vegetation Red Edge
                                                                                      1. Seasonal Variations
                                                                                      2. Temporal Variations
                                                                                        1. Seasonal Changes
                                                                                          1. Diurnal Variations
                                                                                        2. The Drake Equation and Fermi Paradox
                                                                                          1. Drake Equation Parameters
                                                                                            1. Star Formation Rate
                                                                                              1. Fraction with Planets
                                                                                                1. Habitable Planets per System
                                                                                                2. Implications for Extraterrestrial Life
                                                                                                  1. Fermi Paradox Explanations
                                                                                                    1. Great Filter
                                                                                                      1. Rare Earth Hypothesis

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                                                                                                  8. Exoplanets and Other Planetary Systems

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                                                                                                  10. Planetary Exploration and Instrumentation