2024剑桥雅思讲义Labelling_a_Diagram 1.docx

ZQ国国PaSSaHe1TheLayersoftheSunConsidertheearth,themoon,andalltheotherplanetsinoursolarsystem.Thinkaboutthemassthatallthoseobjectsmusthavewhentheyarealladdedtogether.Counter-intuitively,addedalltogethertheyaccountforonly0.2%ofthetotalmassofthesolarsystem.Thesunmakesuptheremaining99.8%ofallthemassinthesolarsystem!Thesunisthecenterofthesolarsystemandthelargestobjectinthesolarsystem.OursunisastarthatprovideslightandheatandsupportsalmostalllifeonEarth.Thesunisasphere,butunliketheearthandthemoonzitisnotsolid.Mostatomsinthesunexistasplasmazorafourthstateofmattermadeupofsuperheatedgaswithanelectricalcharge.Oursunconsistsalmostentirelyoftheelementshydrogenandheliumzandbecausethesunisnotsolid,itdoesnothaveadefinedouterboundary.Itdoes,however,haveadefiniteinternalstructure.Thereareseveralidentifiablelayersofthesun:Thecoreistheinnermostorcentrallayerofthesun.Thecoreisplasmazbutmovessimilarlytoagas.Itstemperatureisaround27milliondegreesCelsius.Inthecore,nuclearreactionscombinehydrogenatomstoformhelium,releasingvastamountsofenergyintheprocess.Theenergyreleasedthenbeginstomoveoutwardztowardstheouterlayersofthesun.Justoutsidethecoreistheradiativezone,whichhasatemperatureofabout7milliondegreesCelsius.Theenergyreleasedinthecoretravelsextremelyslowlythroughtheradiativezone.Particlesoflightcalledphotonscanonlytravelafewmillimetersbeforetheyhitanotherparticleinthesun,areabsorbedandthenreleasedagain.Itcantakeaphotonaslongas50millionyearstotravelallthewaythroughtheradiativezone.Surroundingtheradiativezoneistheconvectionzone.Here,hotmaterialfromnearthesun'scenterrises,coolsatthesurface,andthenplungesbackdownwardtoreceivemoreheatfromtheradiativezone.Thismovementhelpstocreatesolarflaresandsunspots.Thesefirstthreelayersmakeupwhatwewouldactuallycall"thesun".Thenextthreelayersmakeupthesun'satmosphere.Ofcourse,therearenosolidlayerstoanypartofthesun,sotheseboundariesarefuzzyandindistinct.Thevisiblesurfaceofthesunisknownasthephotosphere.Thisistheregionofthesunthatemitssunlight.It'salsooneofthecoolestlayersofthesun-onlyabout6700oC.Lookingataphotographofthesun'ssurface,youcanseethatithasseveraldifferentcolors:oranges,yellowandredszgivingitagrainyappearance.Wecannotseethiswhenweglancequicklyatthesunasoureyescan'tfocusthatquicklyandthesunistoobrightforustolookatformorethanabriefmoment.Lookingatthesunforanylengthoftimecancauseblindness,sodon'ttryit!Sunlightisemittedfromthesun'sphotosphere.AfractionofthelightthattravelsfromthesunreachesEarth.Ittravelsaslightinarangeofwavelengths,includingvisiblelight,ultraviolet,andinfraredradiation.Visiblelightisallthelightwecanseewithoureyes.Wecan'tseeultravioletorinfraredradiation,buttheireffectscanDD国BIstillbedetected.Forexample,sunburniscausedbyultravioletradiationwhenyouspendtoomuchtimeinthesun.Thechromosphereisthezoneabout2,000kilometersthickthatliesdirectlyabovethephotosphere.Thechromosphereisathinregionofthesun'satmospherethatglowsredasitisheatedbyenergyfromthephotosphere.Temperaturesinthechromosphererangefromabout4000oCtoabout10,000oC.Jetsofgasfireupthroughthechromosphereatspeedsupto72,000kilometersperhour;reachingheightsashighas10,000kilometers.Theoutermostlayerofthesunzandtheoutermostpartofitsatmosphere,iscalledthecorona.Itisthesun'shaloor"crown".Ithasatemperatureof2to5milliondegreesCelsiusandismuchhotterthanthevisiblesurfaceofthesunzorphotosphere.Thecoronaextendsmillionsofkilometersintospace.Ifyoueverhavethechancetoseeatotalsolareclipse,youwillbeabletoseethesun'scorona,shiningoutintospace.Toconclude,inthesun'score,nuclearfusionreactionsgenerateenergybyconvertinghydrogentohelium,andtherestofthesunisheatedbythemovementofthisenergyoutwardfromthecore.Lightenergyfromthesunisemittedfromthephotosphere,andittravelsthroughspace,andsomeofitreachestheearth.ThesunisthesourceofalmostalltheenergyonEarthandsunlightpowersphotosynthesis,aswellaswarmingandilluminatingourEarth.Adaptedfrom:https:en.wikibooks.orq/Wiki/HiqhSChOOlEarthSCienCe/TheSUcSS国IELTSADVANTAGEDailySkillsClinic:LabellingaDiagramPracticeQuestions1-4Labelthediagrambelowwiththenamesofthelayersofthesun.ChooseNOMORETHANTWOWORDSfromthereadingpassageforeachanswer.