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
You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 below. Venus in transit June 2004 saw
You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 below. Venus in transit June 2004 saw
admin
2014-11-29
26
问题
You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 below.
Venus in transit
June 2004 saw the first passage, known as a ’transit’, of the planet Venus across the face of the Sun in 122 years. Transits have helped shape our view of the whole Universe, as Heather Cooper and Nigel Henbest explain
A On 8 June 2004, more than half the population of the world were treated to a rare astronomical event. For over six hours, the planet Venus steadily inched its way over the surface of the Sun. This ’transit’ of Venus was the first since 6 December 1882. On that occasion, the American astronomer Professor Simon Newcomb led a party to South Africa to observe the event. They were based at a girls’ school, where - it is alleged - the combined forces of three schoolmistresses outperformed the professionals with the accuracy of their observations.
B For centuries, transits of Venus have drawn explorers and astronomers alike to the four corners of the globe. And you can put it all down to the extraordinary polymath Edmond Halley. In November 1677, Halley observed a transit of the innermost planet, Mercury, from the desolate island of St Helena in the South Pacific. He realised that, from different latitudes, the passage of the planet across the Sun’s disc would appear to differ. By timing the transit from two widely-separated locations, teams of astronomers could calculate the parallax angle - the apparent difference in position of an astronomical body due to a difference in the observer s position. Calculating this angle would allow astronomers to measure what was then the ultimate goal: the distance of the Earth from the Sun. This distance is known as the ’astronomical unit’ or AU.
C Halley was aware that the AU was one of the most fundamental of all astronomical measurements. Johannes Kepler, in the early 17th century, had shown that the distances of the planets from the Sun governed their orbital speeds, which were easily measurable. But no-one had found a way to calculate accurate distances to the planets from the Earth. The goal was to measure the AU; then, knowing the orbital speeds of all the other planets round the Sun, the scale of the Solar System would fall into place. However, Halley realised that Mercury was so far away that its parallax angle would be very difficult to determine. As Venus was closer to the Earth, its parallax angle would be larger, and Halley worked out that by using Venus it would be possible to measure the Sun’s distance to 1 part in 500. But there was a problem: transits of Venus, unlike those of Mercury, are rare, occurring in pairs roughly eight years apart every hundred or so years. Nevertheless, he accurately predicted that Venus would cross the face of the Sun in both 1761 and 1769 - though he didn’t survive to see either.
D Inspired by Halley’s suggestion of a way to pin down the scale of the Solar System, teams of British and French astronomers set out on expeditions to places as diverse as India and Siberia. But things weren’t helped by Britain and France being at war. The person who deserves most sympathy is the French astronomer Guillaume Le Gentil. He was thwarted by the fact that the British were besieging his observation site at Pondicherry in India. Fleeing on a French warship crossing the Indian Ocean, Le Gentil saw a wonderful transit - but the ship’s pitching and rolling ruled out any attempt at making accurate observations. Undaunted, he remained south of the equator, keeping himself busy by studying the islands of Mauritius and Madagascar before setting off to observe the next transit in the Philippines. Ironically after travelling nearly 50,000 kilometres, his view was clouded out at the last moment, a very dispiriting experience.
E While the early transit timings were as precise as instruments would allow, the measurements were dogged by the ’black drop’ effect. When Venus begins to cross the Sun’s disc, it looks smeared not circular - which makes it difficult to establish timings. This is due to diffraction of light. The second problem is that Venus exhibits a halo of light when it is seen just outside the Sun’s disc. While this showed astronomers that Venus was surrounded by a thick layer of gases refracting sunlight around it, both effects made it impossible to obtain accurate timings.
F But astronomers laboured hard to analyse the results of these expeditions to observe Venus transits. Johann Franz Encke, Director of the Berlin Observatory, finally determined a value for the AU based on all these parallax measurements: 153,340,000 km. Reasonably accurate for the time, that is quite close to todays value of 149,597,870 km, determined by radar, which has now superseded transits and all other methods in accuracy. The AU is a cosmic measuring rod, and the basis of how we scale the Universe today. The parallax principle can be extended to measure the distances to the stars. If we look at a star in January - when Earth is at one point in its orbit - it will seem to be in a different position from where it appears six months later. Knowing the width of Earth’s orbit, the parallax shift lets astronomers calculate the distance.
G June 2004’s transit of Venus was thus more of an astronomical spectacle than a scientifically important event. But such transits have paved the way for what might prove to be one of the most vital breakthroughs in the cosmos - detecting Earth-sized planets orbiting other stars.
Questions 14-17
Reading Passage 2 has seven paragraphs, A-G.
Which paragraph contains the following information?
Write the correct letter, A-G, in boxes 14-17 on your answer sheet.
a description of an event which prevented a transit observation
选项
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/gDNO777K
本试题收录于:
雅思阅读题库雅思(IELTS)分类
0
雅思阅读
雅思(IELTS)
相关试题推荐
Whichofthefollowingcouldbetheremainderwhen287isdividedby3?
CENSORSHIP:INFORMATION::
Hitherto,thereisnoevidenceyetthatwoulddefinitivelyprovewhetherornotsomedinosaurswerewarm-blooded,butscient
Onereasonwhyasheep,alesswell-understoodexperimentalsubjectthanthelaboratorymouse,shouldhaveprovedeasier
Diseaseisafluidconceptinfluencedbysocietalandculturalattitudesthatchangediachronicallyinresponsetonewscien
Thedistinctionbetweenmakingartandthinkingandwritingaboutitshouldimplyneitheramutualexclusivenessnorahi
CENSORSHIP:INFORMATION::
Economicscanrenderserviceintheareaofexchange,butitstoolsfindlesspurposewhenappliedtoparadigmsdominated
(Thispassagewaswrittenpriorto1950)Wenowknowthatwhatconstitutespracticallyallofmatterisemptyspa
ThispassageisadaptedfromTheAmericanRepublic:Constitution,Tendencies,andDestinybyO.A.Brownson,1866.Thean
随机试题
政策维持可以区分为()
休克早期的表现有
中年男性,酗酒,呕吐,急腹症。检查左上腹压痛,疑为急性胰腺炎,应测血中哪个酶
林某。男,28岁。狂证日久不愈,面色暗滞而秽,躁扰不安,多言,恼怒不休,甚至登高而歌,妄思离奇,头痛,心悸而烦,舌暗有瘀,少苔,脉弦细。治疗宜
下列装修材料不属于按使用部位和功能分类的是()。
3月1日,某投资者开仓持有3张3月份的恒生指数期货合约多头头寸和2张4月份的恒生指数期货合约空头头寸,其开仓价分别为15125点和15200点,该日结算价分别为15285点和15296点。[2009年11月真题]3月2日,若该投资者继续持有上述头寸,该
多品牌战略的优点有()。
()是指物业管理法规调整物业管理社会关系和社会行为时所形成的相关主体间的权利、义务关系。
下列选项中属于典型紧急事件的是()。
ANSI/IEEE1471-2000是对软件密集型系统的架构进行描述的标准。在该标准中,(1)上这一概念主要用于描述软件架构模型。在此基础上,通常采用(2)描述某个利益相关人(Stakeholder)所关注架构模型的某一方面。(3)
最新回复
(
0
)