天文学英文版PPT资料 (5)

UniverseEighthEditionRogerA.Freedman•WilliamJ.KaufmannIIICHAPTER3EclipsesandtheMotionoftheMoonHW2–Chapter2QuizDUEFriday9/10@5PMReadingAssignment:Chapter4(forMonday9/13)Exam1:ScheduledforWednesday9/22(moreinfolater)iClickers:Aftertoday,ifyouforgetyouriClicker,youwillnotreceiveparticipationcreditfromasign-insheet!3-1WhyweseetheMoongothroughphases3-2WhywealwaysseethesamesideoftheMoon3-3Thedifferencesbetweenlunarandsolareclipses3-4Whynotalllunareclipsesaretotaleclipses3-5WhysolareclipsesarevisibleonlyfromcertainspeciallocationsonEarth3-6HowancientGreekastronomersdeducedthesizesoftheEarth,theMoon,andtheSunByreadingthischapter,youwilllearnThephasesoftheMoonoccurbecauseA.theEarthcastsashadowontheMoon.B.theMooncastsashadowontheEarth.C.itispossibletoseeonlypartoftheilluminatedsideofthemoondependingonitspositioninitsorbit.D.ofyourlocationonEarth.E.peopleseetheMoonfromdifferentplacesontheEarth.Q3.2ThephasesoftheMoonoccurbecauseA.theEarthcastsashadowontheMoon.B.theMooncastsashadowontheEarth.C.itispossibletoseeonlypartoftheilluminatedsideofthemoondependingonitspositioninitsorbit.D.ofyourlocationonEarth.E.peopleseetheMoonfromdifferentplacesontheEarth.A3.2IfthephaseoftheMoonisfullonthefirstdayofspringinthenorthernhemisphere,whereistheMoonlocatedonthecelestialsphere(seediagram)?A.summersolsticeB.wintersolsticeC.vernalequinoxD.autumnalequinoxE.thezenithQ3.4IfthephaseoftheMoonisfullonthefirstdayofspringinthenorthernhemisphere,whereistheMoonlocatedonthecelestialsphere(seediagram)?A.summersolsticeB.wintersolsticeC.vernalequinoxD.autumnalequinoxE.thezenithA3.4WhyistheMoonareddishcolorduringatotallunareclipse?A.LightsfromcitiesontheEarthilluminateit.B.Itisanopticalillusioncreatedbytheeclipse.C.RedlightpassesthroughtheEarth’satmosphereandthenilluminatestheMoon.D.LightfromMarsdimlyilluminatestheMoon.E.Lunardustreflectsthesunlight.Q3.10WhyistheMoonareddishcolorduringatotallunareclipse?A.LightsfromcitiesontheEarthilluminateit.B.Itisanopticalillusioncreatedbytheeclipse.C.RedlightpassesthroughtheEarth’satmosphereandthenilluminatestheMoon.D.LightfromMarsdimlyilluminatestheMoon.E.Lunardustreflectsthesunlight.A3.10Atotalsolareclipseoccursonthefirstdayofsummerinthenorthernhemisphere.WhatmustbetrueabouttheMoon’slocationonthecelestialsphereonthatday?A.Itmustbeatthevernalequinox.B.Itmustbeattheautumnalequinox.C.Itmustbenorthofthecelestialequator.D.Itmustbesouthofthecelestialequator.E.Noneoftheabove.Q3.5Atotalsolareclipseoccursonthefirstdayofsummerinthenorthernhemisphere.WhatmustbetrueabouttheMoon’slocationonthecelestialsphereonthatday?A.Itmustbeatthevernalequinox.B.Itmustbeattheautumnalequinox.C.Itmustbenorthofthecelestialequator.D.Itmustbesouthofthecelestialequator.E.Noneoftheabove.A3.5LunarPhases:ThephasesoftheMoonoccurbecauselightfromtheMoonisactuallyreflectedsunlight.AstherelativepositionsoftheEarth,theMoon,andtheSunchange,weseemoreorlessoftheilluminatedhalfoftheMoon.LengthoftheMonth:TwotypesofmonthsareusedindescribingthemotionoftheMoon.Withrespecttothestars,theMooncompletesoneorbitaroundtheEarthinasiderealmonth,averaging27.32days.TheMooncompletesonecycleofphases(oneorbitaroundtheEarthwithrespecttotheSun)inasynodicmonth,averaging29.53days.TheMoon’sOrbit:TheplaneoftheMoon’sorbitistiltedbyabout5°fromtheplaneoftheEarth’sorbit,orecliptic.KeyIdeasThelineofnodesisthelinewheretheplanesoftheMoon’sorbitandtheEarth’sorbitintersect.ThegravitationalpulloftheSungraduallyshiftstheorientationofthelineofnodeswithrespecttothestars.ConditionsforEclipses:Duringalunareclipse,theMoonpassesthroughtheEarth’sshadow.Duringasolareclipse,theEarthpassesthroughtheMoon’sshadow.Lunareclipsesoccuratfullmoon,whilesolareclipsesoccuratnewmoon.EithertypeofeclipsecanoccuronlywhentheSunandMoonarebothonorverynearthelineofnodes.Ifthisconditionisnotmet,theEarth’sshadowcannotfallontheMoonandtheMoon’sshadowcannotfallontheEarth.KeyIdeasUmbraandPenumbra:Theshadowofanobjecthastwoparts:theumbra,withinwhichthelightsourceiscompletelyblocked,andthepenumbra,wherethelightsourceisonlypartiallyblocked.LunarEclipses:DependingontherelativepositionsoftheSun,Moon,andEarth,lunareclipsesmaybetotal(theMoonpassescompletelyintotheEarth’sumbra),partial(onlypartoftheMoonpassesintotheEarth’sumbra),orpenumbral(theMoonpassesonlyintotheEarth’spenumbra).KeyIdeasSolarEclipses:Solareclipsesmaybetotal,partial,orannular.Duringatotalsolareclipse,theMoon’sumbratracesoutaneclipsepathovertheEarth’ssurfaceastheEarthrotates.Observersoutsidetheeclipsepathbutwithinthepenumbraseeonlyapartialsolareclipse.Duringanannulareclipse,theumbrafallsshortoftheEarth,andtheouteredgeoftheSun’sdiskisvisiblearoundtheMoonatmideclipse.TheMoonandAncientAstronomers:AncientastronomerssuchasAristarchusandEratosthenesmadegreatprogressindeterminingthesizesandrelativedistanceso