首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Ever since its discovery, Pluto has never really fitted in. After the pale and glowing giant Neptune, it is little more than a c
Ever since its discovery, Pluto has never really fitted in. After the pale and glowing giant Neptune, it is little more than a c
admin
2013-03-27
66
问题
Ever since its discovery, Pluto has never really fitted in. After the pale and glowing giant Neptune, it is little more than a cosmic dust mite, swept through the farthest reaches of the solar system on a planet wildly tilted relative to the rest of the planets. It is smaller than Neptune’s largest moon, and the arc of its orbit is so oval that it occasionally crosses its massive blue neighbor’s path.
For years, it has been seen as our solar system’s oddest planet Yesterday, however, scientists released perhaps the most convincing evidence yet that Pluto, in fact, is not a planet at all. For the first time, astronomers have peered into a belt of rocks beyond Pluto unknown until 10 years ago—and found a world that rivals Pluto in size. The scientists posit that larger rocks must be out there, perhaps even larger than Pluto, meaning Pluto is more likely the king of this distant realm of space detritus than the tiniest of the nine planets.
When discovered in 1930, "Pluto at that point was the only thing(that far)out there, so there was nothing else to call it but a planet," says Mike Brown, an astronomer at the California Institute of Technology in Pasadena. "Now it just doesn’t fit. " In one sense, the question of Pluto’s planetary status is arcane, the province of pocket-protected scientists and sun-deprived pen pushers determined to decide some official designation for a ball of dust and ice 3 billion miles away.
Yet it is also unquestionably something more. From science fair dioramas to government funding, planets hold a special place in the public imagination, and how Pluto is eventually seen—by kids and Congress alike—could shape what future generations learn about this mysterious outpost on the edge of the solar system. The debate has split the astronomical community for decades. Even before the distant band of rocks known as the Kuiper Belt was found, Pluto’s unusual behavior made it suspicious.
Elsewhere, the solar system fit into near families; the rocky inner planets, the asteroid belt, the huge and gaseous outer planets. Pluto, though, was peculiar. With the discovery of the Kuiper Belt—countless bits of rock and ice left unused when the wheel of the solar system first formed—Pluto suddenly seemed to have cousins. Yet until yesterday, it held to its planetary distinction because it was far larger than anything located there.
The rub now is Quaoar(pronounced KWAH-oar), 1 billion miles beyond Pluto and roughly half as large. Named after the creation force of the tribe that originally inhabited the Los Angeles basin, Quaoar forecasts problems for the erstwhile ninth planet, says discoverer Dr. Brown: "The case is going to get a lot harder to defend the day somebody finds something larger than Pluto,"
To some, the problem is not with Pluto, but the definition of "planet. " In short, there is none. To the Greeks, who coined the term, it meant "wanderer," describing the way that the planets moved across the night sky differently from the stars behind them. Today, with our more nuanced understanding of the universe, the word no longer has much scientific meaning.
New York’s Hayden Planetarium caused a commotion two years ago by supposedly demoting Pluto, lumping it with the Kuiper Belt objects in its huge mobile of the solar system. In reality, however, the planetarium was making a much broader statement, says Nell Degrasse Tyson, an astrophysicist there. The textbooks of the future should focus more on families of like objects than "planets. " The discovery of Quaoar strengthens this idea: "Everyone needs to rethink the structure of our solar system," he says. "We’ve just stopped counting planets. "
Still, many are loath to part with the planet Pluto. They note that Pluto, in fact, is distinct from many Kuiper Belt objects. It has a thin atmosphere, for one. It reflects a great deal of light, while most Kuiper Belt objects are very dark. And unlike all but a handful of known Kuiper Belt objects, it has a moon. "Maybe Pluto, then, should be representative of a new class of planets," says Mark Sykes, an astronomer at the University of Arizona in Tucson. "It’s the first example, and we are just beginning to find this category. "
The sentence "In short, there is none. "(Para. 7)can be paraphrased as which of the following?
选项
A、There is no problem with Pluto’s planetary status.
B、There is not much difference between Pluto and other planets.
C、There is yet no scientific definition of the term "planet. "
D、There is no clear distinction between planets and stars.
答案
C
解析
本题考查逻辑推理能力。根据第七段第一、二句可知,对有些人来说,问题不在于冥王星,而在于“行星”的定义,总之,没人能说得清,推知,没人能解释清楚行星的定义。由此可知,C项符合题意。
转载请注明原文地址:https://kaotiyun.com/show/aNmO777K
0
考博英语
相关试题推荐
71.ItwasnotuntilmodernscholarshipuncoveredthesecretofreadingMiddleEnglishthatwecouldunderstandthatChaucer,fa
TheUnitedStatesisacountrymadeupofmanydifferentraces.Usuallytheyaremixedtogetherandcan’tbetoldfromoneanoth
Thediversityoftropicalplantsintheregionrepresentsaseemingly________sourceofrawmaterials,ofwhichonlyafewhaveb
Noothercountryspendswhatwedopercapitaformedicalcare.Thecareavailableisamongthebesttechnically,evenifusedt
ThePakistanipresident,Gen.PervezMusharraf,announcedheretodaythatadelegationofPakistaniofficialswouldflytotheT
Intheearly1960sWiltChamberlainwasoneofonlythreeplayersintheNationalBasketballAssociation(NBA)listedatoverse
Generationgapsarenothingnew.ImperfectcommunicationbetweenagegroupsplaguedtheancientGreeksandcurrentworksalike.
Shegotveryangryand______herclothesaboutintheroom.
DearestScottie:Idon’tthinkIwillbewritinglettersmanymoreyearsandIwishyouwouldreadthislettertwice--bitter
TheworseningcrisisattheFukushimaPowerStationinJapanhasledtoinevitablecomparisonswiththe1986Chernobylnucleard
随机试题
中兴公司2012年有关收支项目的全年累计发生额如下:主营业务收入1892000元、其他业务收入25400元、投资收益31500元、营业外收入1500元、主营业务成本984000元、销售费用326000元、管理费用371000元、财务费用63300
时间序列数据一次差表示的是时间序列数据逐期增长的()
伴有纤维素样坏死的疾病有
概算定额主要是在()适用的定额。
某货代公司接受货主委托,安排一批茶叶海运出口,货代公司在提取了船公司提供的集装箱后,将整箱货交给船公司,同时,货主自行办理了货物运输保险,收货人在目的港拆箱提货时发现集装箱内异味浓重,经查明,该集装箱前一航次所在货物为精萘,致使茶叶受精萘污染。请问,
某物业项目位于沿海城市,总建筑面积达80余万m2,属中高层、高层住宅物业,项目分三期建设,是当地最大的住宅建设项目,也是该市的重点工程倍受当地居民和政府关注。整个小区的建设申报了国家安居示范工程小区,建设单位为把这个项目建设经营好,在项目的立项阶段就选
164,100,68,(),44
Lookatthenotesbelow.Someinformationismissing.YouwillhearatelephonetalkonmakingTVcommercial.Foreachquestion
A.acceptB.unquantifiableC.useD.whatE.purchasedF.consumedG.encouragedH.climbingI.predictablyJ.actually
A.forgeB.tracesC.privateD.fearE.puzzlesF.helpfulG.createsH.free
最新回复
(
0
)