ASTR100 (Spring 2006) Introduction to Astronomy Earth as a Living PlanetExtra Credit OpportunitiesA Word About the Greenhouse EffectWhat unique features of Earth are important to human life?Slide 5Slide 6Slide 7The Carbon Dioxide CycleSlide 9Slide 10The ThermostatThese unique features are intertwined…How is human activity changing our planet?Dangers of Human ActivityGlobal WarmingCO2 ConcentrationSlide 17Modeling of Climate ChangeConsequences of Global WarmingWhat can we do about it?What makes a planet habitable?Slide 22Planetary DestinyASTR100 (Spring 2008) Introduction to Astronomy Jovian Planet SystemsA Different Kind of PlanetJovian Planet CompositionJovian Planet FormationSlide 28Differences in Jovian Planet FormationDensity DifferencesSlide 31Sizes of Jovian PlanetsSlide 33What are jovian planets like on the inside?Interiors of Jovian PlanetsInside JupiterComparing Jovian InteriorsJupiter’s Magnetic FieldAurora on JupiterAurorae on SaturnWhat is the weather like on jovian planets?Jupiter’s AtmospherePlanet colorsSlide 44PowerPoint PresentationJupiter Winds and StormsJupiter’s Great Red SpotWeather on Jovian PlanetsQuiz!ASTR100 (Spring 2006) Introduction to AstronomyEarth as a Living PlanetProf. D.C. RichardsonSections 0101-0106Extra Credit OpportunitiesThe first 10 astronomy-related posts to the course discussion board or blog.Existing posts will earn retroactive credit and not count against the 10.Maximum 3 points per student.Comments/replies can count too!Homework #6.5 on MasteringAstronomy.com.Not due for a couple of weeks.Ask me an astronomy question in class, right now!A Word About the Greenhouse EffectThe “greenhouse” part is misleading:A real greenhouse works by heating and trapping the air inside the structure.The same principle explains why the inside of a car gets hot so fast on a sunny day.The greenhouse “effect” is trapping of heat by the air (atmosphere) itself.No glass needed!What unique features of Earth are important to human life?1) Surface liquid water.2) Atmospheric oxygen.3) Plate tectonics.4) Climate stability.What unique features of Earth are important to human life?1) Surface liquid water.2) Atmospheric oxygen.3) Plate tectonics.4) Climate stability.Earth’s distance from the Sun and moderate greenhouse effect make liquid water possible.What unique features of Earth are important to human life?1) Surface liquid water.2) Atmospheric oxygen.3) Plate tectonics.4) Climate stability.PHOTOSYNTHESIS (plant life) is required to make high concentrations of O2, which produces the protective layer of O3.What unique features of Earth are important to human life?1) Surface liquid water.2) Atmospheric oxygen.3) Plate tectonics.4) Climate stability.Plate tectonics are an important step in the carbon dioxide cycle.The Carbon Dioxide Cycle1. Atmospheric CO2 dissolves in rainwater.2. Rain erodes minerals that flow into the ocean.3. Minerals combine with carbon to make rocks on ocean floor.The Carbon Dioxide Cycle4. Carbonate rocks carried down into the mantle by subduction.5. Rocks melt in mantle and outgas CO2 back into atmosphere through volcanoes.What unique features of Earth are important to human life?1) Surface liquid water.2) Atmospheric oxygen.3) Plate tectonics.4) Climate stability.The CO2 cycle acts like a thermostat for the Earth’s temperature.The ThermostatIf Earth heats up a bit, increased rainfall dissolves more CO2, reducing greenhouse effect.If Earth cools down a bit, decreased rainfall dissolves less CO2, building up greenhouse gas.Everything is OK if swings are slow and small…These unique features are intertwined…Plate tectonics creates climate stability.Climate stability allows liquid water.Liquid water is necessary for life.Life is necessary for atmospheric oxygen.More?How is human activity changing our planet?Dangers of Human ActivityHuman-made CFCs in the atmosphere destroy ozone, reducing protection from UV radiation.Human activity is driving many other species to extinction.Human use of fossil fuels produces greenhouse gases that can cause global warming.Global WarmingEarth’s average temperature has increased by 0.5°C in the past 50 years.The concentration of CO2 is rising rapidly.An unchecked rise in greenhouse gases will eventually lead to global warming.CO2 ConcentrationGlobal temperatures have tracked CO2 concentration for the last 500,000 years.Antarctic air bubbles indicate the current CO2 concentration is at its highest level in at least 500,000 years.CO2 ConcentrationMost of the CO2 increase has happened in the last 50 years!Modeling of Climate ChangeComplex models of global warming suggest that the recent temperature increase is indeed consistent with human production of greenhouse gases.Consequences of Global WarmingMelting of polar ice.More extreme weather.Rising sea levels.QuickTime™ and aH.264 decompressorare needed to see this picture.What can we do about it?Reduce greenhouse emissions by improving energy efficiency, especially car gas mileage.Invest in alternative energy sources.Bury the CO2.What makes a planet habitable?Located at an optimal distance from the Sun for liquid water to exist.What makes a planet habitable?Large enough for geological activity to release and retain water and atmosphere.Planetary DestinyEarth is habitable because it is large enough to remain geologically active, and it is at the right distance from the Sun so oceans could form.ASTR100 (Spring 2008) Introduction to AstronomyJovian Planet SystemsProf. D.C. RichardsonSections 0101-0106A Different Kind of PlanetBigger and more massive.Lower density, different composition.Rings.Numerous moons.Jovian Planet CompositionJupiter and SaturnMostly H and He gas.Some hydrogen compounds, metal, rock.Uranus and NeptuneMostly hydrogen compounds: water (H2O), methane (CH4), ammonia (NH3).Some H, He, metal, and rock.Why the difference?Jovian Planet FormationBeyond the frost line, planetesimals could accumulate ICE.H compounds are more abundant than rock/metal so jovian planets got bigger and acquired H/He atmospheres.Jovian Planet FormationThe jovian cores are very similar: solid masses of about 10 Earths.The jovian differences are in the amount of H/He gas accumulated.Why did that amount differ?Differences in Jovian Planet FormationTIMING: the planet that forms earliest