Astronomy:thescienceofthestarsTheuniverseismadeupofstars,planets,andothermatterscatteredthroughoutspace.TheMilkyWayisalargespiralgalaxy（螺旋星系）measuringabout100,000light-yearsacross.Itisabout14billionyearsoldandtakes225millionyearsorsotorotate（旋转）once.Likeallspirals,itcontainsplentyofgasanddust,fromwhichnewstarsareformed.Thedensenucleus（核心）istheoldestpartandhasnogasleftfornewstar.TheSolarsystem1.Mercury(水星)4.Mars（火星）7.Uranus（天王星）2.Venus(金星)5.Jupiter（木星）8.Neptune（海王星）3.Earth(地球)6.Saturn（土星）9.Pluto（冥王星）Oursolarsystemismadeupofthesunandtheobjectsthatorbitit.Theseincludethenineplanets(andprobablymorethannine)andtheirmoons,aswellasasteroids（小行星）,comets,andmeteors（流星）.Thesunistheneareststartotheearth.Itisaglobeofhotgas,mostlyhydrogen（.氢）,andliesatthecenterofoursolarsystem.Itcontainsnosolidmaterial.Starsarelargeballsofhotgasthatproducelightandheatthroughnuclearreactions.OurSunisanaverageyellowstar,butseemsbrightbecauseitissoclose.MercuryTheRomangodofmerchantsandtravellersVenusTheRomangoddessofloveMarsTheRomangodofwarJupiterThekingoftheRomangodsSaturnTheRomangodofseedsandsowingUranusTheGreekgodoftheskyNeptuneTheRomangodoftheseaPlutoTheRomangodofthedeadStarsarelargeballsofhotgasthatproducelightandheatthroughnuclearreactions.OurSunisanaverageyellowstar,butseemsbrightbecauseitissoclose.Planetsarethelargestobjectsthatcirclearoundthestars.Theymayberocky,liketheearth,ormademostlyofgasandliquid,likeJupiter.ThewordplanetisGreekfor"wanderer."Thenamecomesfromthewayplanetsappeartomoveagainstthestarsovertime.Itisthoughtthattheplanetsformedataboutthesametimeasthesun.Astheoriginalcloudofgasanddustcollapsedtoforthesun,somematterwasspunoutintoaflatteneddisk.Overseveralmillionyears,thedustandgasgatheredtogethertoformtheplanetsandmoons.Denserrocksgatherednearthesunandlightergasesfartherout.Ourplanet,theearth,isalargeballofrocksandmetalscoveredwithwaterandsoil.Itbelongstoagroupofnineplanetsthatmovearoundastarcalledthesun.Itissurroundedbyablanketofgasescalledtheatmosphere,hasonemoon,andasfarasweknow,istheonlyplanetthatsupportslife.NASA’sMarsdetector（探测器）,Opportunity,succeededinfindingsignsthatwateronceexistedontheplanet.OpportunitylandedonMarsinJanuary.Scientistsnowbelievethattheplanetcouldoncehavesupportedlife.“Althoughwestillcan’tsaythatlifecouldhaveexistedinthisenvironment,itisnowcertainthattherewaswateronMars,”saidoneofthescientistsworkingontheMarsmission.（任务）HowLifeBeganontheEarthDiscussion:1.Lifeisamysterytoourbeings.Scientistsstudytheoriginoflifebyexplodingspace.Doyoureallythinkspacefightsaremeaningful?Discusstheadvantagesanddisadvantagesofspaceflights.2.Whyistheearththeonlyoneofalltheplanetsonwhichlifecansurvive?Haslifestartedinotherstarsexceptontheearth?Read“HowLifeBeganontheEarth”,thenanswerthefollowingquestions:1.What’sthemainideaofthetext?2.Howmanypartscanthetextbedividedinto?What’sthemainideaforeachpart?Twoparts:Part1(para1):Watermadeitpossibleforlifetobegintodevelop.Part2(para2,3,4):Thedevelopmentoflivingthings.Mainidea:HowlifebeginontheearthReadPart1andanswerquestions:1.Howdidwatercomeintobeingontheearth?2.What’sthesignificanceofthepresenceofwaterontheearth?Itallowedtheearthtodissolveharmfulgasesintooceansandseas.Theexplosionoftheearthproducedwatervapour,whichturnintowaterwhentheearthcooleddown.ReadPart2andanswerquestions:1.Whyweremammalsdifferentfromdinosaurs?Becausetheyproducetheiryoungfromwithintheirbodies.2.Fillinthediagram:Smallplantsinwater1278934562.shellfishandallsortsoffish3.Greenplantsonland4.insects(onland)5.amphibianonlandinwater6.forests7.reptilesonland8.Dinosaursonland9.mammalsonlandRead“HowLifeBeganontheEarth”,fillinthediagramoflife’soriginsandprocess:Harmfulgases1.PlantsintheseasLandplants2.InsectsAmphibiansReptilesDinosaursMammalsincluding3_____________Thehumanbeingswaterlandanimals1.TheBigBangisthetermusedtodescribeahugeexplosionthatscientistsbelievehappenedaround15billionyearsago,creatingouruniverse.NobodyknowswhatcausedtheBigBang,sincewecannotlookbacktoatimebeforeit.Butjustaftertheevent,theuniverseisbelievedtohavebeenaknotoftightlypackedparticlesonlyaboutthesizeofapea.Itstemperaturewastenthousandtrillion,trilliondegreeCelsius.Homework:discussion:1.Whyisthepresenceofplantsimportantforthedevelopmentoflife?2.Istheearthgettingwarmereachyear?Ifso,whateffectswillthishave?What’sthe“greenhouseeffect,”whichsomescientistssaymightdestroyourplant?Willtheburningofcoal,oil,andnaturalgascausetheearthtobecomeadeadplanetlikeVenus?
