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1、1.科学家首次发现系外类地行星CAPECANAVERAL,Fla.Oct30(Reuters)-Forthefirsttime,scientistshavefoundaplanetbeyondthesolarsystemthatnotonlyisthesamesizeasEarth,buthasthesameproportionsofironandrock,akeystepinanongoingquesttofindpotentiallyhabitablesisterworlds.路透社美国佛州卡纳维拉尔角10
2、月30H-科学家首次发现太阳系外存在不但人小与地球类似,而且铁石构成为地球也別无二致的类地行星。这是人类在探索另一个宜居世界的道路上迈出的重要一步。Theplanet,knownasKepler-78b,circlesastarthatisslightlysmallerthanthesunlocatedintheconstellationCygnus,about400lightyearsaway.这颗被命名为Kcplcr-78b的行星围绕天鹅座中一颗比A阳略小的恒星公转,距地球约400光年。Kepler-78b
3、wasdiscoveredlastyearwithNASA'snow-idledKeplerspacetelescope,whichdetectedpotentialplanetsastheycircledinfrontoftheirparentstars,blockingabitoflight.科学家去年使用美国国家航空航天局(NASA)的开普勒天文望远镜发现了这款行星。该望远镜利用行星绕到恒星前方时挡住部分光线来探测行星的存在。ThatmeasurementnotonlyrevealedthatKcplcr
4、-78bwasrelativelysmall,withadiameterjust20percentlargerthanEarth's,butthatitwaspracticallyorbitingonthesurfaceofitshoststa匚这种探测方式不但发现Kepler-78b相对较小,直径仅比地球直径长20%,而且它实际上儿乎是围绕恒星的表面运行。Scientistsdonotknowhowtheplanetsendedupsoclosetotheirhoststars.科学家们还不清楚这颗行星为何如
5、此接近恒星。Whiletheplanet'spresumablymoltensurfaceandsearingtemperaturesmakeitill-suitedforlife,twoindependentteamsofastronomersjumpedattheopportunitytofollowupthediscoverywithground-basedmeasurementstotrytodeterminethedensityofKepler-78b・尽管该行星的疑似液态表面和炽热的温度不适合住命存
6、在,两支独立天文学家团队仍趁机探测了Kepler-78b的密度。Intwopapersinthisweek'sjournalNature,theteamsreportthatnotonlyweretheysuccessful,butthattheycametothesameconclusion:Kepler-78bhasroughlythesamedensityasEarth,suggestingthatitalsoismadeprimarilyofrockandiron・他们本周在《自然》杂志上发表的两篇论文
7、中表示,不仅成功探测了该行星的引力,而几得出结论:Kepler-78b的密度耳地球相仿。这暗示这颗行星也是主耍由岩石和铁构成。Kepler-78bisamongadozenorsorecentlydiscoveredsmallplanetsthatorbitveryclosetotheirparentstars・Kepler-78b,forexample,completesanorbitinjust8.5hours・Kepler-78b是最近人类发现的公转轨道很接近恒星表而的十多颗小行星之一。Kepler-78
8、b公转一周仅需要&5小时。2・Athirdoffoodiswasted,makingitthird-biggestcarbonemitter,U・N・says全球粮食浪费严重••粮农组织LeftoversarepicturedinthefAufdaMuehle*restaurantinthewesternAustrianvillageofSoellJune2,2013.ROME,Sep