科学家发现地球“双胞胎”
<p><span word="Scientists">Scientists</span> <span word="believe">believe</span> <span word="one">one</span> <span word="in">in</span> <span word="five">five</span> <span word="stars">stars</span> <span word="in">in</span> <span word="our">our</span> <span word="galaxy">galaxy</span> <span word="have">have</span> <span word="Earth">Earth</span>-<span word="like">like</span> <span word="planets">planets</span> <span word="orbiting">orbiting</span> <span word="them">them</span>.</p><p><span word="But">But</span> <span word="the">the</span> <span word="ultimate">ultimate</span> <span word="goal">goal</span> <span word="of">of</span> <span word="finding">finding</span> <span word="a">a</span> <span word="world">world</span> <span word="that">that</span> <span word="truly">truly</span> <span word="resembles">resembles</span> <span word="our">our</span> <span word="own">own</span> <span word="has">has</span> <span word="continued">continued</span> <span word="to">to</span> <span word="elude">elude</span> <span word="astronomers">astronomers</span>.</p><p><span word="Now">Now</span> <span word="researchers">researchers</span> <span word="have">have</span> <span word="come">come</span> <span word="a">a</span> <span word="step">step</span> <span word="closer">closer</span> <span word="by">by</span> <span word="finding">finding</span> <span word="Earth">Earth</span>'<span word="s">s</span> <span word="gassy">gassy</span> <span word="twin">twin</span> <span word="in">in</span> <span word="another">another</span> <span word="solar">solar</span> <span word="system">system</span> 200 <span word="light">light</span> <span word="years">years</span> <span word="away">away</span>.</p><p><span word="It">It</span> <span word="orbits">orbits</span> <span word="a">a</span> <span word="dim">dim</span> <span word="red">red</span> <span word="dwarf">dwarf</span> <span word="star">star</span> <span word="at">at</span> <span word="such">such</span> <span word="a">a</span> <span word="close">close</span> <span word="distance">distance</span> <span word="that">that</span> <span word="temperatures">temperatures</span> <span word="on">on</span> <span word="its">its</span> <span word="surface">surface</span> <span word="could">could</span> <span word="be">be</span> <span word="as">as</span> <span word="high">high</span> <span word="as">as</span> 104°<span word="C">C</span> - <span word="too">too</span> <span word="hot">hot</span> <span word="for">for</span> <span word="most">most</span> <span word="forms">forms</span> <span word="of">of</span> <span word="life">life</span> <span word="on">on</span> <span word="Earth">Earth</span>.</p><p><span word="KOI">KOI</span>-314<span word="C">C</span> <span word="is">is</span> <span word="only">only</span> 30 <span word="per">per</span> <span word="cent">cent</span> <span word="more">more</span> <span word="dense">dense</span> <span word="than">than</span> <span word="water">water</span>. <span word="This">This</span> <span word="suggests">suggests</span> <span word="that">that</span> <span word="the">the</span> <span word="world">world</span> <span word="is">is</span> <span word="enveloped">enveloped</span> <span word="by">by</span> <span word="a">a</span> <span word="blanket">blanket</span> <span word="of">of</span> <span word="hydrogen">hydrogen</span> <span word="and">and</span> <span word="helium">helium</span> <span word="hundreds">hundreds</span> <span word="of">of</span> <span word="miles">miles</span> <span word="thick">thick</span>.</p><p><span word="Scientists">Scientists</span> <span word="believe">believe</span> <span word="it">it</span> <span word="may">may</span> <span word="have">have</span> <span word="started">started</span> <span word="life">life</span> <span word="as">as</span> <span word="a">a</span> <span word="mini">mini</span>-<span word="Neptune">Neptune</span> <span word="before">before</span> <span word="some">some</span> <span word="of">of</span> <span word="its">its</span> <span word="atmospheric">atmospheric</span> <span word="gases">gases</span> <span word="were">were</span> <span word="blasted">blasted</span> <span word="away">away</span> <span word="by">by</span> <span word="intense">intense</span> <span word="radiation">radiation</span> <span word="from">from</span> <span word="the">the</span> <span word="parent">parent</span> <span word="star">star</span>.</p><p>'<span word="This">This</span> <span word="planet">planet</span> <span word="might">might</span> <span word="have">have</span> <span word="the">the</span> <span word="same">same</span> <span word="mass">mass</span> <span word="as">as</span> <span word="Earth">Earth</span>, <span word="but">but</span> <span word="it">it</span> <span word="is">is</span> <span word="certainly">certainly</span> <span word="not">not</span> <span word="Earth">Earth</span>-<span word="like">like</span>,' <span word="said">said</span> <span word="lead">lead</span> <span word="astronomer">astronomer</span> <span word="Dr">Dr</span> <span word="David">David</span> <span word="Kipping">Kipping</span> <span word="from">from</span> <span word="the">the</span> <span word="Harvard">Harvard</span>-<span word="Smithsonian">Smithsonian</span> <span word="Centre">Centre</span> <span word="for">for</span> <span word="Astrophysics">Astrophysics</span>.</p><p>'<span word="It">It</span> <span word="proves">proves</span> <span word="that">that</span> <span word="there">there</span> <span word="is">is</span> <span word="no">no</span> <span word="clear">clear</span> <span word="dividing">dividing</span> <span word="line">line</span> <span word="between">between</span> <span word="rocky">rocky</span> <span word="worlds">worlds</span> <span word="like">like</span> <span word="Earth">Earth</span> <span word="and">and</span> <span word="fluffier">fluffier</span> <span word="planets">planets</span> <span word="like">like</span> <span word="water">water</span> <span word="worlds">worlds</span> <span word="or">or</span> <span word="gas">gas</span> <span word="giants">giants</span>.'</p><p><span word="The">The</span> <span word="findings">findings</span> <span word="were">were</span> <span word="presented">presented</span> <span word="at">at</span> <span word="the">the</span> <span word="annual">annual</span> <span word="meeting">meeting</span> <span word="of">of</span> <span word="the">the</span> <span word="American">American</span> <span word="Astronomical">Astronomical</span> <span word="Society">Society</span> <span word="in">in</span> <span word="Washington">Washington</span> <span word="DC">DC</span>.</p><p><span word="To">To</span> <span word="weigh">weigh</span> <span word="KOI">KOI</span>-314<span word="c">c</span>, <span word="the">the</span> <span word="scientists">scientists</span> <span word="used">used</span> <span word="a">a</span> <span word="new">new</span> <span word="technique">technique</span> <span word="called">called</span> <span word="transit">transit</span> <span word="timing">timing</span> <span word="variations">variations</span> (<span word="TTV">TTV</span>), <span word="which">which</span> <span word="only">only</span> <span word="works">works</span> <span word="when">when</span> <span word="more">more</span> <span word="than">than</span> <span word="one">one</span> <span word="planet">planet</span> <span word="orbits">orbits</span> <span word="a">a</span> <span word="star">star</span>.</p><p><span word="The">The</span> <span word="two">two</span> <span word="planets">planets</span> <span word="tug">tug</span> <span word="on">on</span> <span word="each">each</span> <span word="other">other</span>, <span word="slightly">slightly</span> <span word="altering">altering</span> <span word="the">the</span> <span word="time">time</span> <span word="they">they</span> <span word="take">take</span> <span word="to">to</span> <span word="cross">cross</span> <span word="or">or</span> '<span word="transit">transit</span>' <span word="the">the</span> <span word="star">star</span>'<span word="s">s</span> <span word="face">face</span>.</p>
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