六级考试快速阅读的实战练习（4）
<p> <span word="Our">Our</span> <span word="galaxy">galaxy</span> <span word="is">is</span> <span word="a">a</span> <span word="gigantic">gigantic</span> <span word="agglomeration">agglomeration</span> <span word="of">of</span> <span word="stars">stars</span> <span word="and">and</span> <span word="planets">planets</span> <span word="whose">whose</span> <span word="numbers">numbers</span> <span word="will">will</span> <span word="probably">probably</span> <span word="never">never</span> <span word="been">been</span> <span word="known">known</span>. <span word="Currently">Currently</span> <span word="we">we</span> <span word="estimate">estimate</span> <span word="this">this</span> <span word="number">number</span> <span word="to">to</span> <span word="be">be</span> <span word="about">about</span> <span word="thirty">thirty</span> <span word="billion">billion</span>. <span word="Scientists">Scientists</span> <span word="have">have</span> <span word="estimated">estimated</span> <span word="that">that</span> <span word="the">the</span> <span word="diameter">diameter</span> <span word="of">of</span> <span word="our">our</span> <span word="galaxy">galaxy</span>, <span word="if">if</span> <span word="it">it</span> <span word="were">were</span> <span word="to">to</span> <span word="be">be</span> <span word="traveled">traveled</span>, <span word="would">would</span> <span word="take">take</span> <span word="us">us</span> <span word="about">about</span> <span word="fifty">fifty</span> <span word="thousand">thousand</span> <span word="light">light</span> <span word="years">years</span> <span word="and">and</span> <span word="the">the</span> <span word="thickness">thickness</span> <span word="to">to</span> <span word="be">be</span> <span word="about">about</span> <span word="fifteen">fifteen</span> <span word="to">to</span> <span word="twenty">twenty</span> <span word="light">light</span> <span word="years">years</span>. <span word="We">We</span> <span word="live">live</span> <span word="in">in</span> <span word="small">small</span> <span word="part">part</span> <span word="of">of</span> <span word="the">the</span> <span word="Milky">Milky</span> <span word="Way">Way</span> <span word="Galaxy">Galaxy</span>, <span word="which">which</span> <span word="is">is</span> <span word="referred">referred</span> <span word="to">to</span> <span word="as">as</span> <span word="a">a</span> <span word="solar">solar</span> <span word="system">system</span>. <span word="Our">Our</span> <span word="solar">solar</span> <span word="system">system</span> <span word="is">is</span> <span word="made">made</span> <span word="up">up</span> <span word="of">of</span> <span word="nine">nine</span> <span word="planets">planets</span> <span word="and">and</span> 31 <span word="moons">moons</span>, <span word="which">which</span> <span word="orbit">orbit</span> <span word="the">the</span> <span word="center">center</span> <span word="of">of</span> <span word="galaxy">galaxy</span>. <span word="At">At</span> <span word="the">the</span> <span word="center">center</span> <span word="of">of</span> <span word="our">our</span> <span word="galaxy">galaxy</span> <span word="is">is</span> <span word="our">our</span> <span word="Sun">Sun</span>, <span word="which">which</span> <span word="is">is</span> <span word="approximately">approximately</span> <span word="twenty">twenty</span>-<span word="five">five</span> <span word="thousand">thousand</span> <span word="light">light</span> <span word="years">years</span> <span word="from">from</span> <span word="our">our</span> <span word="solar">solar</span> <span word="system">system</span>. <span word="These">These</span> <span word="nine">nine</span> <span word="major">major</span> <span word="planets">planets</span> <span word="in">in</span> <span word="order">order</span> <span word="from">from</span> <span word="the">the</span> <span word="center">center</span> <span word="are">are</span> <span word="Mercury">Mercury</span>, <span word="Venus">Venus</span>, <span word="Earth">Earth</span>, <span word="Mars">Mars</span>, <span word="Jupiter">Jupiter</span>, <span word="Saturn">Saturn</span>, <span word="Uranus">Uranus</span>, <span word="Neptune">Neptune</span>, <span word="and">and</span> <span word="Pluto">Pluto</span>. <span word="Mercury">Mercury</span> <span word="is">is</span> <span word="the">the</span> <span word="planet">planet</span> <span word="nearest">nearest</span> <span word="to">to</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="As">As</span> <span word="it">it</span> <span word="orbits">orbits</span> <span word="the">the</span> <span word="Sun">Sun</span>, <span word="it">it</span> <span word="does">does</span> <span word="not">not</span> <span word="rotate">rotate</span>, <span word="keeping">keeping</span> <span word="the">the</span> <span word="same">same</span> <span word="face">face</span> <span word="of">of</span> <span word="the">the</span> <span word="planet">planet</span> <span word="toward">toward</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="at">at</span> <span word="all">all</span> <span word="times">times</span>. <span word="This">This</span> <span word="means">means</span> <span word="that">that</span> <span word="one">one</span> <span word="side">side</span> <span word="of">of</span> <span word="the">the</span> <span word="planet">planet</span> <span word="has">has</span> <span word="a">a</span> <span word="continual">continual</span> <span word="burning">burning</span> <span word="day">day</span> <span word="of">of</span> 900 <span word="F">F</span>, <span word="and">and</span> <span word="the">the</span> <span word="other">other</span> <span word="side">side</span> <span word="a">a</span> <span word="continual">continual</span> <span word="night">night</span> <span word="and">and</span> <span word="a">a</span> <span word="deadly">deadly</span> <span word="cold">cold</span> <span word="of">of</span> 450<span word="F">F</span> <span word="below">below</span> <span word="zero">zero</span>. <span word="Mercury">Mercury</span> <span word="is">is</span> <span word="the">the</span> <span word="fastest">fastest</span> <span word="traveling">traveling</span> <span word="of">of</span> <span word="the">the</span> <span word="nine">nine</span> <span word="planets">planets</span> <span word="making">making</span> <span word="one">one</span> <span word="full">full</span> <span word="orbit">orbit</span> <span word="around">around</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="in">in</span> <span word="only">only</span> <span word="eight">eight</span> <span word="days">days</span>. <span word="Life">Life</span> <span word="on">on</span> <span word="mercury">mercury</span> <span word="would">would</span> <span word="be">be</span> <span word="impossible">impossible</span>. <span word="If">If</span> <span word="you">you</span> <span word="could">could</span> <span word="live">live</span> <span word="where">where</span> <span word="the">the</span> <span word="night">night</span> <span word="meets">meets</span> <span word="the">the</span> <span word="day">day</span> <span word="and">and</span> <span word="survive">survive</span> <span word="the">the</span> <span word="extreme">extreme</span> <span word="conditions">conditions</span>, <span word="you">you</span> <span word="would">would</span> <span word="need">need</span> <span word="dark">dark</span> <span word="goggles">goggles</span> <span word="to">to</span> <span word="protect">protect</span> <span word="you">you</span> <span word="eyes">eyes</span> <span word="from">from</span> <span word="the">the</span> <span word="extreme">extreme</span> <span word="light">light</span>. <span word="Mercury">Mercury</span> <span word="has">has</span> <span word="little">little</span> <span word="or">or</span> <span word="no">no</span> <span word="atmosphere">atmosphere</span> <span word="to">to</span> <span word="diffuse">diffuse</span> <span word="the">the</span> <span word="sunlight">sunlight</span>. <span word="You">You</span> <span word="would">would</span> <span word="also">also</span> <span word="weigh">weigh</span> <span word="considerable">considerable</span> <span word="less">less</span> <span word="due">due</span> <span word="to">to</span> <span word="the">the</span> <span word="lack">lack</span> <span word="of">of</span> <span word="gravity">gravity</span>. <span word="A">A</span> <span word="person">person</span> <span word="weighting">weighting</span> 100 <span word="pounds">pounds</span> <span word="on">on</span> <span word="Earth">Earth</span> <span word="would">would</span> <span word="weigh">weigh</span> 27 <span word="pounds">pounds</span> <span word="on">on</span> <span word="Mercury">Mercury</span>. <span word="Looking">Looking</span> <span word="into">into</span> <span word="the">the</span> <span word="night">night</span> <span word="sky">sky</span> <span word="you">you</span> <span word="will">will</span> <span word="notice">notice</span> <span word="Venus">Venus</span>, <span word="the">the</span> <span word="brightest">brightest</span> <span word="star">star</span> <span word="in">in</span> <span word="the">the</span> <span word="sky">sky</span>, <span word="and">and</span> <span word="the">the</span> <span word="second">second</span> <span word="planet">planet</span> <span word="from">from</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="Venus">Venus</span> <span word="can">can</span> <span word="only">only</span> <span word="be">be</span> <span word="seen">seen</span> <span word="at">at</span> <span word="certain">certain</span> <span word="times">times</span> <span word="of">of</span> <span word="the">the</span> <span word="day">day</span> <span word="either">either</span> <span word="at">at</span> <span word="dawn">dawn</span> <span word="or">or</span> <span word="at">at</span> <span word="Sunset">Sunset</span>. <span word="In">In</span> <span word="physical">physical</span> <span word="characteristics">characteristics</span>, <span word="Venus">Venus</span> <span word="is">is</span> <span word="most">most</span> <span word="like">like</span> <span word="earth">earth</span> <span word="with">with</span> <span word="a">a</span> <span word="diameter">diameter</span> <span word="of">of</span> <span word="seven">seven</span> <span word="thousand">thousand</span> <span word="six">six</span> <span word="hundred">hundred</span> <span word="miles">miles</span>, <span word="and">and</span> <span word="gravity">gravity</span> <span word="the">the</span> <span word="same">same</span> <span word="as">as</span> <span word="earth">earth</span>. <span word="It">It</span> <span word="is">is</span> <span word="located">located</span> <span word="a">a</span> <span word="distance">distance</span> <span word="of">of</span> <span word="sixty">sixty</span>-<span word="seven">seven</span> <span word="million">million</span> <span word="miles">miles</span> <span word="from">from</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="and">and</span> <span word="makes">makes</span> <span word="one">one</span> <span word="complete">complete</span> <span word="orbit">orbit</span> <span word="around">around</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="in">in</span> <span word="two">two</span> <span word="hundred">hundred</span> <span word="twenty">twenty</span> <span word="five">five</span> <span word="days">days</span>. <span word="A">A</span> <span word="single">single</span> <span word="day">day</span> <span word="on">on</span> <span word="Venus">Venus</span> <span word="can">can</span> <span word="last">last</span> <span word="up">up</span> <span word="to">to</span> <span word="two">two</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="twenty">twenty</span> <span word="five">five</span> <span word="earth">earth</span> <span word="days">days</span> <span word="due">due</span> <span word="to">to</span> <span word="its">its</span> <span word="slow">slow</span> <span word="rotation">rotation</span>. <span word="The">The</span> <span word="atmosphere">atmosphere</span> <span word="appears">appears</span> <span word="to">to</span> <span word="consist">consist</span> <span word="of">of</span> <span word="mostly">mostly</span> <span word="nitrogen">nitrogen</span> <span word="and">and</span> <span word="carbon">carbon</span> <span word="dioxide">dioxide</span>. <span word="This">This</span> <span word="is">is</span> <span word="due">due</span> <span word="to">to</span> <span word="the">the</span> <span word="lack">lack</span> <span word="of">of</span> <span word="life">life</span> <span word="on">on</span> <span word="the">the</span> <span word="planet">planet</span>. <span word="The">The</span> <span word="best">best</span> <span word="time">time</span> <span word="to">to</span> <span word="view">view</span> <span word="Venus">Venus</span> <span word="comes">comes</span> <span word="every">every</span> <span word="one">one</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="twenty">twenty</span> <span word="years">years</span> <span word="as">as</span> <span word="it">it</span> <span word="passes">passes</span> <span word="between">between</span> <span word="the">the</span> <span word="Earth">Earth</span> <span word="and">and</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="The">The</span> <span word="last">last</span> <span word="time">time</span> <span word="to">to</span> <span word="best">best</span> <span word="view">view</span> <span word="it">it</span> <span word="was">was</span> <span word="on">on</span> <span word="June">June</span> 7, 2004. <span word="Earth">Earth</span>, <span word="the">the</span> <span word="third">third</span> <span word="planet">planet</span> <span word="form">form</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="is">is</span> <span word="our">our</span> <span word="home">home</span> <span word="planet">planet</span>. <span word="Earth">Earth</span> <span word="is">is</span> <span word="the">the</span> <span word="only">only</span> <span word="planet">planet</span> <span word="in">in</span> <span word="our">our</span> <span word="solar">solar</span> <span word="system">system</span> <span word="known">known</span> <span word="to">to</span> <span word="sustain">sustain</span> <span word="life">life</span>. <span word="Under">Under</span> <span word="the">the</span> <span word="layer">layer</span> <span word="of">of</span> <span word="atmosphere">atmosphere</span> <span word="that">that</span> <span word="surrounds">surrounds</span> <span word="the">the</span> <span word="planet">planet</span> <span word="we">we</span> <span word="are">are</span> <span word="able">able</span> <span word="to">to</span> <span word="provide">provide</span> <span word="all">all</span> <span word="the">the</span> <span word="necessary">necessary</span> <span word="components">components</span> <span word="to">to</span> <span word="make">make</span> <span word="life">life</span> <span word="sustainable">sustainable</span>. <span word="Earth">Earth</span> <span word="is">is</span> <span word="the">the</span> <span word="fifth">fifth</span> <span word="larges">larges</span> <span word="planet">planet</span> <span word="in">in</span> <span word="the">the</span> <span word="solar">solar</span> <span word="system">system</span>. <span word="Its">Its</span> <span word="diameter">diameter</span> <span word="is">is</span> <span word="just">just</span> <span word="a">a</span> <span word="few">few</span> <span word="hundred">hundred</span> <span word="kilometers">kilometers</span> <span word="larger">larger</span> <span word="than">than</span> <span word="Venus">Venus</span>. <span word="Earth">Earth</span> <span word="rotates">rotates</span> <span word="on">on</span> <span word="its">its</span> <span word="axis">axis</span> <span word="one">one</span> <span word="complete">complete</span> <span word="revolution">revolution</span> <span word="in">in</span> <span word="a">a</span> <span word="twenty">twenty</span>-<span word="four">four</span> <span word="hour">hour</span> <span word="period">period</span> <span word="and">and</span> <span word="orbits">orbits</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="in">in</span> <span word="three">three</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="sixty">sixty</span> <span word="five">five</span> <span word="days">days</span>. <span word="Mars">Mars</span> <span word="is">is</span> <span word="the">the</span> <span word="fourth">fourth</span> <span word="planet">planet</span> <span word="from">from</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="and">and</span> <span word="is">is</span> <span word="the">the</span> <span word="closest">closest</span> <span word="neighbor">neighbor</span> <span word="to">to</span> <span word="earth">earth</span>. <span word="Every">Every</span> <span word="seventeen">seventeen</span> <span word="years">years</span> <span word="Mars">Mars</span> <span word="reaches">reaches</span> <span word="its">its</span> <span word="closest">closest</span> <span word="point">point</span> <span word="to">to</span> <span word="earth">earth</span> <span word="in">in</span> <span word="its">its</span> <span word="orbit">orbit</span> <span word="around">around</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="at">at</span> <span word="thirty">thirty</span>-<span word="five">five</span> <span word="million">million</span> <span word="miles">miles</span>. <span word="Mars">Mars</span> <span word="is">is</span> <span word="a">a</span> <span word="small">small</span> <span word="planet">planet</span> <span word="that">that</span> <span word="has">has</span> <span word="a">a</span> <span word="red">red</span> <span word="glow">glow</span>. <span word="It">It</span> <span word="makes">makes</span> <span word="one">one</span> <span word="complete">complete</span> <span word="orbit">orbit</span> <span word="around">around</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="in">in</span> <span word="six">six</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="eighty">eighty</span> <span word="seven">seven</span> <span word="days">days</span>. <span word="Oxygen">Oxygen</span> <span word="and">and</span> <span word="water">water</span> <span word="vapor">vapor</span> <span word="have">have</span> <span word="been">been</span> <span word="detected">detected</span> <span word="in">in</span> <span word="the">the</span> <span word="atmosphere">atmosphere</span> <span word="of">of</span> <span word="Mars">Mars</span>, <span word="and">and</span> <span word="a">a</span> <span word="yellowish">yellowish</span> <span word="fog">fog</span> <span word="and">and</span> <span word="clouds">clouds</span> <span word="move">move</span> <span word="around">around</span> <span word="the">the</span> <span word="planet">planet</span> <span word="indicating">indicating</span> <span word="that">that</span> <span word="the">the</span> <span word="planet">planet</span> <span word="has">has</span> <span word="different">different</span> <span word="types">types</span> <span word="of">of</span> <span word="weather">weather</span> <span word="and">and</span> <span word="seasons">seasons</span> <span word="like">like</span> <span word="the">the</span> <span word="earth">earth</span>. <span word="A">A</span> <span word="single">single</span> <span word="day">day</span> <span word="on">on</span> <span word="Mars">Mars</span> <span word="is">is</span> <span word="very">very</span> <span word="much">much</span> <span word="like">like</span> <span word="a">a</span> <span word="day">day</span> <span word="on">on</span> <span word="earth">earth</span> <span word="lasting">lasting</span> <span word="twenty">twenty</span>-<span word="four">four</span> <span word="hours">hours</span> <span word="and">and</span> <span word="thirty">thirty</span>-<span word="seven">seven</span> <span word="minutes">minutes</span>, <span word="however">however</span>, <span word="a">a</span> <span word="year">year</span> <span word="on">on</span> <span word="Mars">Mars</span> <span word="is">is</span> <span word="twice">twice</span> <span word="as">as</span> <span word="long">long</span> <span word="as">as</span> <span word="one">one</span> <span word="year">year</span> <span word="on">on</span> <span word="earth">earth</span>. <span word="Jupiter">Jupiter</span> <span word="the">the</span> <span word="fifth">fifth</span> <span word="planet">planet</span> <span word="from">from</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="gets">gets</span> <span word="its">its</span> <span word="name">name</span> <span word="from">from</span> <span word="the">the</span> <span word="Father">Father</span> <span word="of">of</span> <span word="the">the</span> <span word="Greek">Greek</span> <span word="Gods">Gods</span>. <span word="Jupiter">Jupiter</span>, <span word="which">which</span> <span word="orbits">orbits</span> <span word="four">four</span> <span word="hundred">hundred</span> <span word="eighty">eighty</span>-<span word="three">three</span> <span word="million">million</span> <span word="miles">miles</span> <span word="from">from</span> <span word="the">the</span> <span word="Sun">Sun</span>, <span word="is">is</span> <span word="the">the</span> <span word="biggest">biggest</span> <span word="of">of</span> <span word="all">all</span> <span word="the">the</span> <span word="planets">planets</span> <span word="in">in</span> <span word="our">our</span> <span word="solar">solar</span> <span word="system">system</span>. <span word="It">It</span> <span word="has">has</span> <span word="a">a</span> <span word="diameter">diameter</span> <span word="of">of</span> <span word="eighty">eighty</span>-<span word="nine">nine</span> <span word="thousand">thousand</span> <span word="miles">miles</span> <span word="and">and</span> <span word="a">a</span> <span word="volume">volume</span> <span word="of">of</span> <span word="thirteen">thirteen</span> <span word="times">times</span> <span word="that">that</span> <span word="of">of</span> <span word="earth">earth</span>. <span word="Jupiter">Jupiter</span> <span word="orbits">orbits</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="every">every</span> <span word="twelve">twelve</span> <span word="years">years</span>. <span word="Its">Its</span> <span word="atmosphere">atmosphere</span> <span word="is">is</span> <span word="thousands">thousands</span> <span word="of">of</span> <span word="miles">miles</span> <span word="thick">thick</span> <span word="and">and</span> <span word="is">is</span> <span word="made">made</span> <span word="up">up</span> <span word="of">of</span> <span word="mainly">mainly</span> <span word="hydrogen">hydrogen</span>. <span word="The">The</span> <span word="surface">surface</span> <span word="temperature">temperature</span> <span word="is">is</span> <span word="about">about</span> -205<span word="F">F</span>. <span word="There">There</span> <span word="are">are</span> <span word="no">no</span> <span word="seasons">seasons</span> <span word="on">on</span> <span word="Jupiter">Jupiter</span>, <span word="but">but</span> <span word="it">it</span> <span word="has">has</span> <span word="floating">floating</span> <span word="clouds">clouds</span> <span word="of">of</span> <span word="ammonia">ammonia</span> <span word="and">and</span> <span word="methane">methane</span> <span word="gas">gas</span>. <span word="Jupiter">Jupiter</span> <span word="has">has</span> <span word="a">a</span> <span word="bright">bright</span> <span word="red">red</span> <span word="distinctive">distinctive</span> <span word="spot">spot</span> <span word="that">that</span> <span word="is">is</span> <span word="more">more</span> <span word="than">than</span> <span word="twice">twice</span> <span word="as">as</span> <span word="wide">wide</span> <span word="as">as</span> <span word="Earth">Earth</span>. <span word="This">This</span> <span word="mark">mark</span> <span word="has">has</span> <span word="astronomers">astronomers</span> <span word="puzzled">puzzled</span> <span word="because">because</span> <span word="there">there</span> <span word="is">is</span> <span word="no">no</span> <span word="reason">reason</span> <span word="for">for</span> <span word="the">the</span> <span word="bright">bright</span> <span word="spot">spot</span> <span word="due">due</span> <span word="to">to</span> <span word="the">the</span> <span word="fact">fact</span> <span word="that">that</span> <span word="it">it</span> <span word="does">does</span> <span word="not">not</span> <span word="receive">receive</span> <span word="much">much</span> <span word="Sunlight">Sunlight</span>. <span word="This">This</span> <span word="spot">spot</span> <span word="enables">enables</span> <span word="us">us</span> <span word="to">to</span> <span word="see">see</span> <span word="that">that</span> <span word="Jupiter">Jupiter</span> <span word="has">has</span> <span word="a">a</span> <span word="very">very</span> <span word="fast">fast</span> <span word="rotation">rotation</span>. <span word="One">One</span> <span word="rotation">rotation</span> <span word="is">is</span> <span word="completed">completed</span> <span word="every">every</span> <span word="ten">ten</span> <span word="hours">hours</span>. <span word="The">The</span> <span word="forces">forces</span> <span word="placed">placed</span> <span word="on">on</span> <span word="the">the</span> <span word="planet">planet</span> <span word="due">due</span> <span word="to">to</span> <span word="this">this</span> <span word="quick">quick</span> <span word="rotation">rotation</span> <span word="cause">cause</span> <span word="the">the</span> <span word="clouds">clouds</span> <span word="at">at</span> <span word="the">the</span> <span word="equator">equator</span> <span word="to">to</span> <span word="bulge">bulge</span> <span word="like">like</span> <span word="a">a</span> <span word="tire">tire</span>, <span word="but">but</span> <span word="due">due</span> <span word="to">to</span> <span word="the">the</span> <span word="gravitational">gravitational</span> <span word="forces">forces</span> <span word="of">of</span> <span word="the">the</span> <span word="planet">planet</span> <span word="keep">keep</span> <span word="the">the</span> <span word="clouds">clouds</span> <span word="from">from</span> <span word="being">being</span> <span word="cast">cast</span> <span word="into">into</span> <span word="space">space</span>. <span word="Saturn">Saturn</span>, <span word="even">even</span> <span word="though">though</span> <span word="it">it</span> <span word="is">is</span> <span word="the">the</span> <span word="sixth">sixth</span> <span word="planet">planet</span> <span word="form">form</span> <span word="the">the</span> <span word="Sun">Sun</span>, <span word="it">it</span> <span word="shines">shines</span> <span word="so">so</span> <span word="brightly">brightly</span> <span word="because">because</span> <span word="of">of</span> <span word="its">its</span> <span word="size">size</span>. <span word="Its">Its</span> <span word="diameter">diameter</span> <span word="is">is</span> <span word="seventy">seventy</span>-<span word="one">one</span> <span word="thousand">thousand</span> <span word="five">five</span> <span word="hundred">hundred</span> <span word="miles">miles</span>. <span word="The">The</span> <span word="planet">planet</span> <span word="itself">itself</span> <span word="is">is</span> <span word="golden">golden</span> <span word="in">in</span> <span word="color">color</span> <span word="and">and</span> <span word="is">is</span> <span word="the">the</span> <span word="brightest">brightest</span> <span word="yellow">yellow</span> <span word="star">star</span> <span word="in">in</span> <span word="the">the</span> <span word="night">night</span> <span word="sky">sky</span>. <span word="Saturn">Saturn</span> <span word="makes">makes</span> <span word="one">one</span> <span word="complete">complete</span> <span word="revolution">revolution</span> <span word="on">on</span> <span word="its">its</span> <span word="axis">axis</span> <span word="every">every</span> <span word="ten">ten</span> <span word="hours">hours</span> <span word="and">and</span> <span word="takes">takes</span> <span word="twenty">twenty</span>-<span word="nine">nine</span> <span word="and">and</span> <span word="one">one</span> <span word="half">half</span> <span word="days">days</span> <span word="to">to</span> <span word="complete">complete</span> <span word="one">one</span> <span word="orbit">orbit</span> <span word="around">around</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="The">The</span> <span word="gravitational">gravitational</span> <span word="pull">pull</span> <span word="of">of</span> <span word="this">this</span> <span word="planet">planet</span> <span word="is">is</span> <span word="most">most</span> <span word="like">like</span> <span word="that">that</span> <span word="of">of</span> <span word="Jupiter">Jupiter</span>. <span word="It">It</span> <span word="has">has</span> <span word="a">a</span> <span word="volume">volume</span> <span word="that">that</span> <span word="is">is</span> <span word="eight">eight</span> <span word="hundred">hundred</span> <span word="times">times</span> <span word="that">that</span> <span word="of">of</span> <span word="earth">earth</span>, <span word="but">but</span> <span word="has">has</span> <span word="a">a</span> <span word="volume">volume</span> <span word="that">that</span> <span word="is">is</span> <span word="one">one</span> <span word="hundred">hundred</span> <span word="times">times</span> <span word="lighter">lighter</span> <span word="than">than</span> <span word="earth">earth</span>. <span word="Saturn">Saturn</span> <span word="has">has</span> <span word="two">two</span> <span word="rings">rings</span> <span word="that">that</span> <span word="surround">surround</span> <span word="the">the</span> <span word="planet">planet</span>, <span word="but">but</span> <span word="never">never</span> <span word="touch">touch</span> <span word="it">it</span>. <span word="They">They</span> <span word="are">are</span> <span word="located">located</span> <span word="outside">outside</span> <span word="the">the</span> <span word="atmosphere">atmosphere</span> <span word="and">and</span> <span word="above">above</span> <span word="the">the</span> <span word="equator">equator</span>. <span word="These">These</span> <span word="rings">rings</span> <span word="are">are</span> <span word="only">only</span> <span word="about">about</span> <span word="ten">ten</span> <span word="miles">miles</span> <span word="thick">thick</span>, <span word="which">which</span> <span word="makes">makes</span> <span word="them">them</span> <span word="transparent">transparent</span>, <span word="only">only</span> <span word="being">being</span> <span word="seen">seen</span> <span word="with">with</span> <span word="the">the</span> <span word="use">use</span> <span word="of">of</span> <span word="a">a</span> <span word="telescope">telescope</span>. <span word="The">The</span> <span word="ring">ring</span> <span word="closest">closest</span> <span word="to">to</span> <span word="the">the</span> <span word="planet">planet</span> <span word="is">is</span> <span word="about">about</span> <span word="seven">seven</span> <span word="thousand">thousand</span> <span word="miles">miles</span> <span word="and">and</span> <span word="very">very</span> <span word="thin">thin</span>. <span word="A">A</span> <span word="black">black</span> <span word="band">band</span> <span word="separates">separates</span> <span word="the">the</span> <span word="inner">inner</span> <span word="ring">ring</span> <span word="from">from</span> <span word="the">the</span> <span word="outer">outer</span> <span word="ring">ring</span>, <span word="which">which</span> <span word="is">is</span> <span word="wider">wider</span> <span word="and">and</span> <span word="brighter">brighter</span>. <span word="It">It</span> <span word="is">is</span> <span word="believed">believed</span> <span word="that">that</span> <span word="the">the</span> <span word="rings">rings</span> <span word="are">are</span> <span word="made">made</span> <span word="up">up</span> <span word="of">of</span> <span word="crystals">crystals</span> <span word="of">of</span> <span word="ice">ice</span> <span word="or">or</span> <span word="dust">dust</span> <span word="particles">particles</span>. <span word="Uranus">Uranus</span> <span word="is">is</span> <span word="the">the</span> <span word="seventh">seventh</span> <span word="planet">planet</span> <span word="form">form</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="The">The</span> <span word="name">name</span> <span word="Uranus">Uranus</span> <span word="comes">comes</span> <span word="from">from</span> <span word="Greek">Greek</span> <span word="mythology">mythology</span>. <span word="Uranus">Uranus</span> <span word="was">was</span> <span word="the">the</span> <span word="God">God</span> <span word="of">of</span> <span word="the">the</span> <span word="Heavens">Heavens</span>.〃 <span word="Uranus">Uranus</span> <span word="is">is</span> <span word="situated">situated</span> <span word="one">one</span> <span word="thousand">thousand</span> <span word="seven">seven</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="eighty">eighty</span> <span word="two">two</span> <span word="miles">miles</span> <span word="form">form</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="and">and</span> <span word="completes">completes</span> <span word="one">one</span> <span word="orbit">orbit</span> <span word="around">around</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="every">every</span> <span word="eighty">eighty</span>-<span word="four">four</span> <span word="years">years</span>. <span word="The">The</span> <span word="size">size</span> <span word="of">of</span> <span word="this">this</span> <span word="planet">planet</span> <span word="is">is</span> <span word="four">four</span> <span word="times">times</span> <span word="that">that</span> <span word="of">of</span> <span word="earth">earth</span>, <span word="but">but</span> <span word="has">has</span> <span word="the">the</span> <span word="same">same</span> <span word="force">force</span> <span word="of">of</span> <span word="gravity">gravity</span> <span word="on">on</span> <span word="the">the</span> <span word="surface">surface</span> <span word="as">as</span> <span word="earth">earth</span>. <span word="There">There</span> <span word="are">are</span> <span word="five">five</span> <span word="moons">moons</span> <span word="that">that</span> <span word="orbit">orbit</span> <span word="this">this</span> <span word="planet">planet</span>. <span word="The">The</span> <span word="largest">largest</span> <span word="one">one</span> <span word="is">is</span> <span word="Titania">Titania</span>. <span word="Neptune">Neptune</span>, <span word="the">the</span> <span word="eighth">eighth</span> <span word="planet">planet</span> <span word="from">from</span> <span word="the">the</span> <span word="Sun">Sun</span>, <span word="is">is</span> <span word="invisible">invisible</span> <span word="to">to</span> <span word="the">the</span> <span word="naked">naked</span> <span word="eye">eye</span>. <span word="It">It</span> <span word="is">is</span> <span word="located">located</span> <span word="some">some</span> <span word="two">two</span> <span word="thousand">thousand</span> <span word="seven">seven</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="ninety">ninety</span>-<span word="three">three</span> <span word="million">million</span> <span word="miles">miles</span> <span word="form">form</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="A">A</span> <span word="single">single</span> <span word="orbit">orbit</span> <span word="around">around</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="takes">takes</span> <span word="one">one</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="sixty">sixty</span>-<span word="five">five</span> <span word="yeas">yeas</span> <span word="to">to</span> <span word="complete">complete</span>. <span word="This">This</span> <span word="planet">planet</span> <span word="only">only</span> <span word="receives">receives</span> <span word="one">one</span> <span word="nine">nine</span>-<span word="hundredth">hundredth</span> <span word="of">of</span> <span word="the">the</span> <span word="heat">heat</span> <span word="and">and</span> <span word="Sunlight">Sunlight</span> <span word="as">as</span> <span word="the">the</span> <span word="earth">earth</span>. <span word="Pluto">Pluto</span> <span word="was">was</span> <span word="the">the</span> <span word="ninth">ninth</span> <span word="planet">planet</span> <span word="from">from</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="The">The</span> <span word="name">name</span> <span word="Pluto">Pluto</span> <span word="comes">comes</span> <span word="from">from</span> <span word="the">the</span> <span word="Roman">Roman</span> <span word="God">God</span> <span word="who">who</span> <span word="was">was</span> <span word="the">the</span> <span word="ruler">ruler</span> <span word="of">of</span> <span word="the">the</span> <span word="under">under</span> <span word="world">world</span>. <span word="On">On</span> <span word="Thursday">Thursday</span>, <span word="August">August</span> 24, 2006, <span word="however">however</span>, <span word="the">the</span> <span word="International">International</span> <span word="Astronomical">Astronomical</span> <span word="Union">Union</span> <span word="met">met</span> <span word="in">in</span> <span word="Prague">Prague</span> <span word="voted">voted</span> <span word="finalizing">finalizing</span> <span word="the">the</span> <span word="guidelines">guidelines</span> <span word="of">of</span> <span word="planetary">planetary</span> <span word="classification">classification</span>, <span word="thus">thus</span> <span word="reorganizing">reorganizing</span> <span word="Pluto">Pluto</span> <span word="into">into</span> <span word="a">a</span> <span word="new">new</span> <span word="category">category</span> <span word="of">of</span> <span word="dwarf">dwarf</span> <span word="planet">planet</span>. <span word="Pluto">Pluto</span> <span word="is">is</span> <span word="located">located</span> <span word="three">three</span> <span word="thousand">thousand</span> <span word="six">six</span> <span word="hundred">hundred</span> <span word="and">and</span> <span word="seventy">seventy</span> <span word="million">million</span> <span word="miles">miles</span> <span word="form">form</span> <span word="the">the</span> <span word="Sun">Sun</span>. <span word="It">It</span> <span word="orbits">orbits</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="in">in</span> <span word="total">total</span> <span word="darkness">darkness</span>, <span word="and">and</span> <span word="is">is</span> <span word="about">about</span> <span word="the">the</span> <span word="same">same</span> <span word="size">size</span> <span word="as">as</span> <span word="Mars">Mars</span> <span word="and">and</span> <span word="has">has</span> <span word="a">a</span> <span word="diameter">diameter</span> <span word="two">two</span> <span word="thirds">thirds</span> <span word="that">that</span> <span word="of">of</span> <span word="Earths">Earths</span> <span word="moon">moon</span>. <span word="Due">Due</span> <span word="to">to</span> <span word="the">the</span> <span word="distance">distance</span> <span word="and">and</span> <span word="size">size</span> <span word="of">of</span> <span word="Pluto">Pluto</span>, <span word="it">it</span> <span word="can">can</span> <span word="only">only</span> <span word="be">be</span> <span word="seen">seen</span> <span word="with">with</span> <span word="the">the</span> <span word="use">use</span> <span word="of">of</span> <span word="a">a</span> <span word="twenty">twenty</span>-<span word="inch">inch</span> <span word="telescope">telescope</span>. <span word="Pluto">Pluto</span> <span word="disqualified">disqualified</span> <span word="due">due</span> <span word="to">to</span> <span word="its">its</span> <span word="eccentric">eccentric</span> <span word="orbit">orbit</span> <span word="that">that</span> <span word="crosses">crosses</span> <span word="with">with</span> <span word="Neptune">Neptune</span>. <span word="In">In</span> <span word="addition">addition</span> <span word="to">to</span> <span word="the">the</span> <span word="fact">fact</span> <span word="that">that</span> <span word="it">it</span> <span word="is">is</span> <span word="disproportionately">disproportionately</span> <span word="smaller">smaller</span> <span word="than">than</span> <span word="any">any</span> <span word="of">of</span> <span word="its">its</span> <span word="former">former</span> <span word="counterparts">counterparts</span> <span word="in">in</span> <span word="the">the</span> <span word="solar">solar</span> <span word="system">system</span>, <span word="it">it</span> <span word="does">does</span> <span word="not">not</span> <span word="qualify">qualify</span> <span word="as">as</span> <span word="a">a</span> <span word="planet">planet</span>. <span word="Otherwise">Otherwise</span>, <span word="we">we</span> <span word="might">might</span> <span word="as">as</span> <span word="well">well</span> <span word="qualify">qualify</span> <span word="Plutos">Plutos</span> <span word="moon">moon</span>, <span word="Charon">Charon</span> <span word="as">as</span> <span word="a">a</span> <span word="planet">planet</span>, <span word="thus">thus</span> <span word="making">making</span> <span word="Pluto">Pluto</span> <span word="and">and</span> <span word="Charon">Charon</span> <span word="a">a</span> <span word="binary">binary</span> <span word="planet">planet</span> <span word="system">system</span>. 1. <span word="If">If</span> <span word="we">we</span> <span word="are">are</span> <span word="to">to</span> <span word="travel">travel</span> <span word="from">from</span> <span word="one">one</span> <span word="end">end</span> <span word="of">of</span> <span word="the">the</span> <span word="galaxy">galaxy</span> <span word="circle">circle</span> <span word="to">to</span> <span word="the">the</span> <span word="other">other</span> <span word="at">at</span> <span word="the">the</span> <span word="speed">speed</span> <span word="of">of</span> <span word="light">light</span>, <span word="it">it</span> <span word="would">would</span> <span word="take">take</span> <span word="us">us</span> <span word="fifty">fifty</span> <span word="thousand">thousand</span> <span word="light">light</span> <span word="years">years</span>. 2. <span word="There">There</span> <span word="can">can</span> <span word="not">not</span> <span word="possibly">possibly</span> <span word="be">be</span> <span word="any">any</span> <span word="form">form</span> <span word="of">of</span> <span word="water">water</span> <span word="in">in</span> <span word="Mercury">Mercury</span>. 3. <span word="Venus">Venus</span> <span word="is">is</span> <span word="sharing">sharing</span> <span word="with">with</span> <span word="the">the</span> <span word="earth">earth</span> <span word="similar">similar</span> <span word="diameter">diameter</span>, <span word="similar">similar</span> <span word="gravity">gravity</span> <span word="and">and</span> <span word="similar">similar</span> <span word="rotation">rotation</span>. 4. <span word="The">The</span> <span word="speed">speed</span> <span word="with">with</span> <span word="which">which</span> <span word="Mars">Mars</span> <span word="travels">travels</span> <span word="round">round</span> <span word="the">the</span> <span word="Sun">Sun</span> <span word="is">is</span> <span word="twice">twice</span> <span word="as">as</span> <span word="fast">fast</span> <span word="as">as</span> <span word="that">that</span> <span word="of">of</span> <span word="the">the</span> <span word="earth">earth</span>. 5. <span word="Jupiter">Jupiter</span> <span word="has">has</span> <span word="an">an</span> <span word="atmosphere">atmosphere</span>, <span word="which">which</span>, <span word="unlike">unlike</span> <span word="that">that</span> <span word="of">of</span> <span word="earth">earth</span>, <span word="contains">contains</span> <span word="for">for</span> <span word="the">the</span> <span word="most">most</span> <span word="part">part</span> _____________. 6. <span word="Despite">Despite</span> <span word="the">the</span> <span word="quick">quick</span> <span word="rotation">rotation</span> <span word="of">of</span> <span word="Jupiter">Jupiter</span>, <span word="its">its</span> <span word="clouds">clouds</span> <span word="are">are</span> <span word="still">still</span> <span word="clinging">clinging</span> <span word="to">to</span> <span word="the">the</span> <span word="planet">planet</span> <span word="with">with</span> <span word="the">the</span> <span word="help">help</span> <span word="of">of</span> __________________. 7. <span word="between">between</span> <span word="the">the</span> <span word="inner">inner</span> <span word="ring">ring</span> <span word="and">and</span> <span word="the">the</span> <span word="outer">outer</span> <span word="ring">ring</span> <span word="of">of</span> <span word="Saturn">Saturn</span> <span word="there">there</span> <span word="is">is</span> <span word="a">a</span> ___________________. 8. <span word="Compared">Compared</span> <span word="with">with</span> <span word="that">that</span> <span word="of">of</span> <span word="the">the</span> <span word="earth">earth</span>, <span word="the">the</span> <span word="gravity">gravity</span> <span word="force">force</span> <span word="on">on</span> <span word="the">the</span> <span word="surface">surface</span> <span word="of">of</span> <span word="Uranus">Uranus</span> <span word="is">is</span> _____________. 9. <span word="According">According</span> <span word="to">to</span> <span word="the">the</span> <span word="International">International</span> <span word="Astronomical">Astronomical</span> <span word="Union">Union</span>, <span word="Pluto">Pluto</span> <span word="is">is</span> <span word="no">no</span> <span word="longer">longer</span> <span word="seen">seen</span> <span word="as">as</span> <span word="a">a</span> <span word="planet">planet</span>; <span word="instead">instead</span>, <span word="it">it</span> <span word="should">should</span> <span word="be">be</span> <span word="termed">termed</span> <span word="as">as</span> ________________. 10. <span word="Its">Its</span> <span word="eccentric">eccentric</span> <span word="orbit">orbit</span> <span word="and">and</span> <span word="its">its</span> _____________ <span word="disqualified">disqualified</span> <span word="Pluto">Pluto</span> <span word="as">as</span> <span word="a">a</span> <span word="planet">planet</span>.</p>
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