詳解rmonthi e中秋節(jié)文稿

Chapter8:Chapter8:Lunarphases,and1MisconceptionsMisconceptionsabouttheQuestion:RightorTheMoonisonlyvisibleatTheMoonislargerneartotheTheMoonisthebiggestonthe15thofthe8thlunarmonth(i.e.中秋節(jié)).WealwaysseethesamesideoftheTheMoondoesnotTheMoondoesnotproducelight.ItislitbyThereisadarksideofthe28.1TheMoon’s??TheMoon’sorbitisalmost8.1TheMoon’s??TheMoon’sorbitisalmostperiod(恆星周期theonce=27.3Theorbitinclinesbyonly5totheEarth’sMoonalwaysappearsneartheecliptic(黃道?4?self-sameas?self-sameasthesidereal?WealwaysseethesamehalfoftheMoonfromthe5668.2Phase8.2Phasecycle(月相之循環(huán)7上弦凸?jié)u滿蛾眉上弦凸?jié)u滿蛾眉滿Newmoon新漸暗蛾眉?xì)?下弦AsimpleAsimplewaytodeterminethetimeof9siderealperiod(siderealperiod(恆星周期):27.3synodicperiod朔望周期29.58.3Tides8.3Tides(潮汐ConsidertheEarth-Moonsystem.ConsidertheEarth-Moonsystem.TheEarth(togetherwithseawater)isalsofallingfreelyunderthegravityoftheMoon(butitneverhitstheMoon).ThesideoftheEarthclosesttotheMoonfeelsastrongerforcethanthecentre,andthecentrefeelsastrongerforcethantheopposite???relativetothe?relativetothecentreoftheEarth,theinforcepullwaterintobulgesonbothsidesoftheEarthalongtheEarth-Moonline?Twohigh?AlthoughtheMoon’sgravitationalforceonusissmall(~0.0003%thatoftheEarth’s),thetidescannotbeneglected.Thereare?AlthoughtheMoon’sgravitationalforceonusissmall(~0.0003%thatoftheEarth’s),thetidescannotbeneglected.Therearesimilareffectsfromthebutonlyhalfthemagnitude,becausetheSunismuchfartherawayfromtheEarth??SomeexamplesSomeexamplesofToloHighLowBayofImage:BayofImage:Image:WikimediaTidesareaffectedbygeography.Themaximumtidaldifferencedependsonthelocation.MontSaint-MontSaint-~15mbetweenhighandlow(明報(bào)(明報(bào)新聞圖片Springtides(朔Springtides(朔望潮Theword“spring”doesnotrefertotheseason!Neaptides(弦潮Note:highandlowtidesrefertothelevelofwatercomparedtoothertimeinthesameday.Springandneaptidesrefertothetidalshiftcomparedtoothertimeinthemonth.?Thereisfrictionbetweenwaterbulgessea??frictionalforceslowsdown?Thereisfrictionbetweenwaterbulgessea??frictionalforceslowsdowntherotationofself-the0.001secondper?millionyearsagotheEarth’sdaywas22TheEarth’sgravitationalforceontheMoonalsohastidaleffectstoelongatetheMoon??let’sassumethattheMoonusedtorotatetheMoontheMoonisthereisfrictioninsidetheEnergy?increaseduntil?increaseduntilitisalmostthesameastheMoon’sorbitalperiodtidalcoupling(潮汐耦合):thealwaysshowsthesamefacetowardsTheMoonTheMoonissometimesbiggerontheImage:WikimediaSuper??Thetidal??ThetidalbulgesattracttheTheMoonisaccelerated,itsdistancetotheEarthincreasesslowly(~3cm/year).8.4Eclipses(月食與日食On8.4Eclipses(月食與日食OnthecelestialspheretheMoon’sorbitandtheeclipseintersectattwopointscallednodes(交點(diǎn)).Foreverymonth,theMooncrosseseachnodeonce.WhenboththeSunandtheMoonareclosetothenodes,theSun,theEarthandMoonalignalmostonastraightline???AneclipseThesenodesarejusttheintersectionsoftheMoon’sorbitThesenodesarejusttheintersectionsoftheMoon’sorbitandtheplaneoftheEarth’sorbit.Whenaneclipseoccurs,thenodallinepointsatornearlyattheLunar??Lunar??TheMoonenterstheEarth’sshadowTheEarth’sshadowhastwoparts:umbra(本影):NolightfromtheSuncanthisalmosttotalpenumbra(半影partialSunlightscatteredSunlightscatteredfromEarth’satmospheregivesthetotallyeclipsedMoonitsreddishcolor.TotallunarTheMoonenterstheumbracompletely;onlysunlightscatteredTotallunarTheMoonenterstheumbracompletely;onlysunlightscatteredbytheEarth’satmospherecanTheMoonappearsredanddimbecause???Partialeclipse(偏食?Partialeclipse(偏食umbraTheMoononlyenters?TheMoonPenumbraeclipse(半影食enterstheSolareclipse日食TheMoon’sshadowfallsonSolareclipse日食TheMoon’sshadowfallsontheTheMoon’sumbralshadowisatmostabout270km??diameteroftheEarth~13,000Peopleintheumbralshadowcanseeatotalsolar(日全食)atthesameAstheEarthrotates,theshadowsweepsapathoftotaleclipseontheEarthTotaleclipseonlylastsforafewminutesateachlocationontheEarth???Total?ObserversTotal?ObserversinthepenumbraoftheMooncanonlyapartialsolareclipse(日偏食ShadowofShadowofthe(Image:Mir;(takenfromtheMirspacestation,11AugAnnulareclipse(Annulareclipse(日環(huán)食):TheMoonistoofartheEarthtocovertheSunAnnularAnnularAnnularsolareclipseinHongKong,AnnularsolareclipseinHongKong,backin2012Image:Saroscycle沙羅周期Saroscycle沙羅周期BecauseoftheprecessionoftheMoon’sorbit,theSun,theandMoondonotreturntothesamerelativepositionsafter1Theyreturntothesamerelativepositionevery18years11.3??Thisperiod??ThisperiodiscalledtheSarosrepetitio