天文学英文版PPT资料 (11)

UniverseEighthEditionRogerA.Freedman•WilliamJ.KaufmannIIICHAPTER10OurBarrenMoonOnlinequizzesfromChapters9and10dueMonday10/18OnlineQuizfromChapter11dueWednesday10/20HWUpdateSomeareasoftheMoonarerelativelysmooth,whereasotherareasareheavilycratered.ThisisbecauseA.meteorsdidnotstriketheflatareasbecausetheyareintheEarth’sshadow.B.weatheringhassmoothedpartsoftheMoon.C.platetectonicshasrecycledpartsofthelunarcrust.D.insomeplaceslavaflowshavecoveredoveroldercraters,leavingasmoothersurface.E.tidalforcesbetweentheEarthandMoonsmoothedpartsoftheMoon.Q10.4SomeareasoftheMoonarerelativelysmooth,whereasotherareasareheavilycratered.ThisisbecauseA.meteorsdidnotstriketheflatareasbecausetheyareintheEarth’sshadow.B.weatheringhassmoothedpartsoftheMoon.C.platetectonicshasrecycledpartsofthelunarcrust.D.insomeplaceslavaflowshavecoveredoveroldercraters,leavingasmoothersurface.E.tidalforcesbetweentheEarthandMoonsmoothedpartsoftheMoon.A10.4TheastronautfootprintontheMoonshowninthisphotographwillprobablyA.existfor10,000yearsbecausethereisverylittleweatheringontheMoon.B.existfor10,000yearsbecausetheMoon’ssurfaceishardanddurable.C.existfor10,000yearsduetoerosionfromwindinthetenuouslunaratmosphere.D.existfor10,000yearsduetobombardmentbylargenumbersofmeteors.E.BothCandDarecorrect.Q10.1TheastronautfootprintontheMoonshowninthisphotographwillprobablyA.existfor10,000yearsbecausethereisverylittleweatheringontheMoon.B.existfor10,000yearsbecausetheMoon’ssurfaceishardanddurable.C.existfor10,000yearsduetoerosionfromwindinthetenuouslunaratmosphere.D.existfor10,000yearsduetobombardmentbylargenumbersofmeteors.E.BothCandDarecorrect.A10.1KeyIdeasAppearanceoftheMoon:TheEarth-facingsideoftheMoondisplayslight-colored,heavilycrateredhighlandsanddark-colored,smooth-surfacedmaria.TheMoon’sfarsidehasalmostnomaria.Virtuallyalllunarcraterswerecausedbyspacedebrisstrikingthesurface.ThereisnoevidenceofplatetectonicactivityontheMoon.KeyIdeasInternalStructureoftheMoon:MuchofourknowledgeabouttheMoonhascomefromhumanexplorationinthe1960sandearly1970sandfrommorerecentobservationsbyunmannedspacecraft.AnalysisofseismicwavesandotherdataindicatesthattheMoonhasacrustthickerthanthatoftheEarth(andthickestonthefarsideoftheMoon),amantlewithathicknessequaltoabout80%oftheMoon’sradius,andasmallironcore.KeyIdeasTheMoon’slithosphereisfarthickerthanthatoftheEarth.Thelunarasthenosphereprobablyextendsfromthebaseofthelithospheretothecore.TheMoonhasnoglobalmagneticfieldtoday,althoughithadaweakmagneticfieldbillionsofyearsago.KeyIdeasGeologicHistoryoftheMoon:Theanorthositiccrustexposedinthehighlandswasformedbetween4.3and4.0billionyearsago.Aneraofheavybombardmentformedthemariabasinsbetween4.0and3.8billionyearsago,andthemarebasaltssolidifiedbetween3.8and3.1billionyearsago.TheMoon’ssurfacehasundergoneverylittlechangeoverthepast3billionyears.KeyIdeasMeteoroidimpactshavebeentheonlysignificant“weathering”agentontheMoon.TheMoon’sregolith,orsurfacelayerofpowderedandfracturedrock,wasformedbymeteoriticaction.Allofthelunarrocksamplesareigneousrocksformedlargelyofmineralsfoundinterrestrialrocks.Thelunarrockscontainnowaterandalsodifferfromterrestrialrocksinbeingrelativelyenrichedintherefractoryelementsanddepletedinthevolatileelements.KeyIdeasOriginoftheMoon:ThecollisionalejectiontheoryoftheMoon’soriginholdsthattheproto-EarthwasstruckbyaMars-sizedprotoplanetandthatdebrisfromthiscollisioncoalescedtoformtheMoon.ThistheorysuccessfullyexplainsmostpropertiesoftheMoon.TheMoonwasmolteninitsearlystages,andtheanorthositiccrustsolidifiedfromlow-densitymagmathatfloatedtothelunarsurface.Themarebasinswerecreatedlaterbytheimpactofplanetesimalsandfilledwithlavafromthelunarinterior.TidalinteractionsbetweentheEarthandMoonareslowingtheEarth’srotationandpushingtheMoonawayfromtheEarth.