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1、ZQ国国PaSSage1TheLayersoftheSunConsidertheearth,themoon,andalltheotherplanetsinoursolarsystem.Thinkaboutthemassthatallthoseobjectsmusthavewhentheyarealladdedtogether.Counter-intuitively,addedalltogethertheyaccountforonly0.2%ofthetotalmassofthesolarsystem.Thesunmakesuptheremaining99.8%ofallthemassinthe
2、solarsystem!Thesunisthecenterofthesolarsystemandthelargestobjectinthesolarsystem.OursunisastarthatprovideslightandheatandsupportsalmostalllifeonEarth.Thesunisasphere,butunliketheearthandthemoon,itisnotsolid.Mostatomsinthesunexistasplasma,orafourthstateofmattermadeupofsuperheatedgaswithanelectricalch
3、arge.Oursunconsistsalmostentirelyoftheelementshydrogenandhelium,andbecausethesunisnotsolidzitdoesnothaveadefinedouterboundary.Itdoes,howevehaveadefiniteinternalstructure.Thereareseveralidentifiablelayersofthesun:Thecoreistheinnermostorcentrallayerofthesun.Thecoreisplasma,butmovessimilarlytoagas.Itst
4、emperatureisaround27milliondegreesCelsius.Inthecore,nuclearreactionscombinehydrogenatomstoformhelium,releasingvastamountsofenergyintheprocess.Theenergyreleasedthenbeginstomoveoutward,towardstheouterlayersofthesun.Justoutsidethecoreistheradiativezone,whichhasatemperatureofabout7milliondegreesCelsius.
5、Theenergyreleasedinthecoretravelsextremelyslowlythroughtheradiativezone.Particlesoflightcalledphotonscanonlytravelafewmillimetersbeforetheyhitanotherparticleinthesun,areabsorbedandthenreleasedagain.Itcantakeaphotonaslongas50millionyearstotravelallthewaythroughtheradiativezone.Surroundingtheradiative
6、zoneistheconvectionzone.Here,hotmaterialfromnearthesunscenterrises,coolsatthesurface,andthenplungesbackdownwardtoreceivemoreheatfromtheradiativezone.Thismovementhelpstocreatesolarflaresandsunspots.Thesefirstthreelayersmakeupwhatwewouldactuallycallthesun.Thenextthreelayersmakeupthesunsatmosphere.Ofco
7、urse,therearenosolidlayerstoanypartofthesun,sotheseboundariesarefuzzyandindistinct.Thevisiblesurfaceofthesunisknownasthephotosphere.Thisistheregionofthesunthatemitssunlight.Itsalsooneofthecoolestlayersofthesunonlyabout6700oC.Lookingataphotographofthesunssurface,youcanseethatithasseveraldifferentcolo
8、rs:oranges,yellowandreds,givingitagrainyappearance.Wecannotseethiswhenweglancequicklyatthesunasoureyescantfocusthatquicklyandthesunistoobrightforustolookatformorethanabriefmoment.Lookingatthesunforanylengthoftimecancauseblindness,sodonttryit!Sunlightisemittedfromthesunsphotosphere.Afractionoftheligh
9、tthattravelsfromthesunreachesEarth.Ittravelsaslightinarangeofwavelengths,includingvisiblelight,ultravioletandinfraredradiation.Visiblelightisallthelightwecanseewithoureyes.Wecantseeultravioletorinfraredradiation,buttheireffectscanQD国IELTSADVANTAGEstillbedetected.Forexample,sunburniscausedbyultraviol
10、etradiationwhenyouspendtoomuchtimeinthesun.Thechromosphereisthezoneabout2,000kilometersthickthatliesdirectlyabovethephotosphere.Thechromosphereisathinregionofthesunsatmospherethatglowsredasitisheatedbyenergyfromthephotosphere.Temperaturesinthechromosphererangefromabout4000oCtoabout10z000oC.Jetsofgas
11、fireupthroughthechromosphereatspeedsupto72,000kilometersperhour,reachingheightsashighas10,000kilometers.Theoutermostlayerofthesun,andtheoutermostpartofitsatmosphere,iscalledthecorona.Itisthesunshaloorcrown.Ithasatemperatureof2to5milliondegreesCelsiusandismuchhotterthanthevisiblesurfaceofthesun,orpho
12、tosphere.Thecoronaextendsmillionsofkilometersintospace.Ifyoueverhavethechancetoseeatotalsolareclipse,youwillbeabletoseethesunscorona,shiningoutintospace.Toconclude,inthesunscore,nuclearfusionreactionsgenerateenergybyconvertinghydrogentohelium,andtherestofthesunisheatedbythemovementofthisenergyoutwar
13、dfromthecore.Lightenergyfromthesunisemittedfromthephotosphere,andittravelsthroughspace,andsomeofitreachestheearth.ThesunisthesourceofalmostalltheenergyonEarthandsunlightpowersphotosynthesis,aswellaswarmingandilluminatingourEarth.Adaptedfrom:https:en.wikibooks.ora/Wiki/HiahSChOOlEarthSCienCe/TheSUnQD
14、国后Questions1-4LabelthediagrambelowWiththenamesofthelayersofthesun.ChooseNOMORETHANTWOWORDSfromthereadingpassageforeachanswer.Afteryou,vetriedthesequestions,checkyouranswerswiththefollowingvideo.Questions5-9CompleteeachsentencewiththecorrectendingA-Ifromtheboxbelow.WritethecorrectletterA-Iinboxes5-9o
15、nyouranswersheet.NBnotallletterswillbeused.S. Thevastmajorityofthetotalmassofthesolarsystemisaccountedforby.T. Thereisnofixedouteredge.U. Thecoreproducesenergywhich.O.Ourplanetonlyreceives.Q.Onekindoflightemittedbythesun,which.A.canbeseeninthephotosphere,isaformOfsuperheatedgas.V. isextremelyhotandu
16、sedtocreatehydrogen.W. isinvisibletohumanszcandamageourskin.X. movesataveryslowpacethroughtheareasurroundingit.Y. asmallproportionofthelightwhichthesunemits.Z. sunspots,whicharethethirdlayerofthesunzsatmosphere.AA. thebiggestsingleobjectinthesolarsystem,whichisthesun.BB. theplanetsandtheirmoons.CC. tothesunduetothefactthatitismo
