Earth Science 104Earth’s Place in the Cosmos, StructureHistory of AstronomyIntroduction• No lab this week– Must pass lab to pass this class– Instructors will give percent lab grade to one another• Get Lab Manual this week– Do PRELAB 1 before lab next week– Bring manual to lab each weekPeer Led Instruction• Wednesday 5:30 to 7:30 PM• Library—Room 101• Add ES104X—CRN 11870• First Session: October 1, 2008– Do review questions to see if you think it help– Sit in to see if it is for you– Can add before Oct. 8 sessionScales of Space and TimePlanet EarthSphere interactionsAtmosphereBiospherehttp://www.earthscienceeducation.com/creative_science/chemistry_index.htmGeospherehttp://www.miamisci.org/ecolinks/geosphere.htmlTectonic PlatesCrusthttp://earthquake.usgs.gov/learning/glossary.php?term=crustTectonic movementsComplex Interactionshttp://www.msu.edu/~colungag/docs/philosophy.htmHydrologic Cyclehttp://www.mnforsustain.org/water_climate_global_water_cycle_study.htmInternal and external cyclesConvectionEarth’s Structure• Rocky Planet– Silicates– Metals• Melting allowed gravity to separate by density– Metals drawn to center– Silicates dominate the remainder• Oxygen and Silicon most common elements• Combine with other elements to make feldspars, pyroxenes, amphiboles and quartzComposition• Core ~ 3500 km radius• Mantle ~ 2900 km thick• Crust < 100 kmEarth’s Interior Properties• Inner core• Outer core• Lower mantle• Asthenosphere• LithosphereInternal Division• Mantle-Crust boundary is compositional– More silica, less iron, magnesium in crust• Asthenosphere-Lithosphere boundary is based on properties– Asthenosphere is weak, flows– Lithosphere is rigidInterface of spheresNebular Hypothesis of Solar System Formation.Nebular Hypothesis•NEBULA– Rotating cloud of dust and gases – Collapses into solid bodies• Formed our solar system–Sun– Major Planets– Dwarf planets, asteroids and cometsSolar system formed from nebular cloudBig Bang forms all matter• Much more ancient than nebular collapse• “Beginning of the universe”History of Astronomy• Ancient civilizations believed that Earth was at the center of the universe—GEOCENTRIC MODEL• Age of Reason beginning to recognize Sun is center of Solar System—HELIOCENTRIC MODEL• Age of Technology exploring wide reaches of the universeAnaxagoras•5thcentury B.C.• Moon is a sphere lighted by Sunhttp://www-history.mcs.st-andrews.ac.uk/Biographies/Anaxagoras.htmlAristotle•4thcentury BC• Earth is a spherehttp://www.hao.ucar.edu/public/education/sp/images/aristotle.htmlEratosthenes calculatedEarth’s size in ~ 240 BChttp://en.wikipedia.org/wiki/Eratosthenes#Measurement_of_the_EarthPtolemy•2ndcentury AD• Copies of works survive to this day• Translated to Arabic early, to Latin in 13thcenturyPtolemy’s map of Europehttp://archive.ncsa.uiuc.edu/SDG/Experimental/vatican.exhibit/exhibit/full-images/d-mathematics/math21.gifPtolemy’s Solar SystemEpicycle explains retrograde motion• Since thought was Earth is the centerRetrograde motion• Mars usually moves across sky west to east• Occasionally appears to move east to west• Occurs when Earth is ‘passing’ MarsPtolemy’s work• Translated into Latin in 13thcentury• Influenced intellectual thought for centuriesArguments against Heliocentric Model• Earth would fly apart if it rotated on an axis• Moon would be left behind if Earth orbited Sun• Since God created Earth and Sun and all the heavenly bodies, Earth is the center of the
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