职称英语《理工B》阅读判断历年真题
职称英语《理工B》阅读判断历年真题1
SoManyEarths
TheMilkyWay(银行)containsbillionsofEarth-sizedplanetsthatcouldsupportlife.Thatsthefindingofnewstudy.ItdrawsondatathatcamefromNASAstopplanet-huntingtelescope.
AmechanicalfailurerecentlyputthatKepterspacetelescopeoutofservice.Keplerhadplayedabigroleincreatingacensusofplanetsorbitingsome170,000stars.Itsdatehavebeenhelpingastronomerspredicthowcommonplanetsareinourgalaxy.ThetelescopefocusedonhuntingplanetsthatmighthaveconditionssimilartothoseonEarth.
TheauthorsofastudypublishedinTheProceedingsoftheNationalAcademyofSciencesconcludethatbetween14and30outofevery100starswithamassandtemperaturesimilartotheSunmayhostaplanetthatcouldsupportlifeasweknowit.SuchaplanetwouldhaveadiameteratleastaslargeasEarthsbutnomorethantwicethatbig.Theplanetalsowouldhavetoorbitinastarshabitablezone.Thatswherethesurfacetemperaturewouldallowanywatertoexistasliquid.
Thenewestimateofhowmanyplanetsmightfittheseconditionscomesfromstudyingmorethat42,000starsandidentifyingsuitableworldsorbitingthem.Thescientistsusedthosenumberstoextrapolate(推算)totherestofthestarsthatthetelescopecouldnotsee.
Theestimateisrough,theauthorsadmit.Ifappliedtothesolarsystem,itwoulddefineashabitableazonestartingascloseottheSunasVenusandrunningtoasfarawayasMars.NeitherplanetisEarthlike(althougheithermighthavebeeninthedistantpase).Usingtighterlimitstheresearchersestimatethebetween4and8outofevery100sunlikestarscouldhostanEarth-sizedworld.Theseareonesthatwouldtake200to400daystocompleteayearlyorbit.
Fouroutofevery100sunlikestarsdoesntsoundlikeabignumber.ItwouldmeanhoweverthattheMilkyWaycouldhostmorethanabillionEarth-sizedplanetswithachance