2012年6月6日，最值得期待的天文現(xiàn)象金星凌日即將精彩上演。金星凌日是一種極為罕見(jiàn)的天象，凌日時(shí)，地球、金星、太陽(yáng)在一條直線上，從地球上可以看到金星像一個(gè)小黑點(diǎn)一樣在太陽(yáng)表面緩慢移動(dòng)。據(jù)悉，我國(guó)大部分地區(qū)都能觀測(cè)到這次凌日的全過(guò)程。如果錯(cuò)過(guò)這一次，就要再等105年。你還猶豫什么？

The Travails1) of Le Gentil 勒讓蒂的辛勤探索

Imagine your country is sending you on a quest to resolve one of the era's biggest questions in science. At this moment in history， the solution， the technology， and the alignment2) of planets have come together. For your part of the mission， all you have to do is record the instant3) when the edge of one small circle touches the edge of a second larger circle.

Such were the fortunate circumstances of Guilliaume Hyacinthe Jean Baptiste Le Gentil. The French astronomer eagerly set sail for India to witness the 1761 transit of Venus， a rare celestial4) alignment in which the silhouette5) of Venus appears to pass directly across the Sun.

Upon Le Gentil's arrival， the intended destination was occupied by hostile English troops， so his ship turned back to sea， where he could not effectively use a telescope. He missed the 1761 transit of Venus. Committed to his task， Le Gentil hung around the Indian Ocean for eight years awaiting the next transit of Venus. He returned to India to view the 1769 transit of Venus， but on the morning of the transit a \"fatal cloud\" momentarily brought brief yet harsh6) weather to the normally placid7) region， and he missed it again! Le Gentil was numb8) with dejection9).

想象一下：國(guó)家派你去探索以解決這個(gè)時(shí)代最大的科學(xué)問(wèn)題之一。在歷史上的這一時(shí)刻，(解決問(wèn)題所需的)方案、技術(shù)和星球的排列都已齊備。而你在這次任務(wù)中所要完成的全部事情，就是在一個(gè)小圓的邊緣切入比它大的另一個(gè)圓的邊緣時(shí)，將這一瞬間記錄下來(lái)。

這正是吉亞姆· 亞森特·讓·巴蒂斯特·勒讓蒂當(dāng)年所處的有利境況。這位法國(guó)天文學(xué)家迫不及待地?fù)P帆前往印度，去見(jiàn)證1761年的金星凌日——一種罕見(jiàn)的天體排列現(xiàn)象。該現(xiàn)象出現(xiàn)時(shí)，金星的黑色輪廓似乎直接穿過(guò)太陽(yáng)。

勒讓蒂到達(dá)印度時(shí)，原定的目的地已被敵對(duì)的英國(guó)軍隊(duì)所占領(lǐng)，他的船只好返回大海，可是望遠(yuǎn)鏡在海上的觀測(cè)效果十分不理想。他錯(cuò)過(guò)了1761年的金星凌日。一心想要完成使命的勒讓蒂在印度洋上漂泊了八年，等待下一次金星凌日的出現(xiàn)。1769年，他返回印度觀測(cè)這一年的金星凌日，可是就在凌日的那天早上，通常都很寧?kù)o的天空突然冒出一片“要命的烏云”，轉(zhuǎn)瞬之間陰云遍布、天昏地暗，時(shí)間雖短卻讓他又一次錯(cuò)過(guò)了時(shí)機(jī)！勒讓蒂絕望到了極點(diǎn)！

Centuries of Intrigue10) 數(shù)百年的吸引力

Transits of Venus occur in pairs eight years apart， with a span of more than a century between each pair. The telescope was in its infancy for the pair of transits prior to Le Gentil's effort. In the early years of the 17th century， Johannes Kepler showed the relationship between a planet's orbital period and its distance from the Sun. Kepler then derived tables of unprecedented11) accuracy that predicted the motions of the planets， including transits of Venus in 1631 and 1639. Poring12) over one such table， the young English astronomer Jeremiah Horrocks caught one of Kepler's mistakes within weeks of the 1639 transit of Venus and mathematically predicted its imminent13) appearance. Horrocks projected14) an image of the 1639 transit of Venus and noted the planet's size and path—the first time in recorded history.

What surprised Horrocks' contemporaries15) most was how small Venus appeared relative to the Sun. Rather than being a disappointment， though， this size discrepancy16) should be recognized as a stunning visual comparison. A planet the size of Earth， Venus' diminutive17) profile highlights the immensity of the distant Sun， which could hold the volume of a million Earths!

Mathematics served science well when Edmond Halley announced one could quantify the distance to the Sun merely by having observers from widely separated locations time the duration of the transit of Venus， which Halley would not live to see. For Venus to slice across the Sun takes about 6 hours， and observers needed to time that event to the second.

金星凌日以兩次凌日為一組，每次間隔八年，而每?jī)山M之間的間隔卻長(zhǎng)達(dá)一百多年。在勒讓蒂觀察之前的那組金星凌日發(fā)生之時(shí)，望遠(yuǎn)鏡的發(fā)展還處于初期。17世紀(jì)初期，約翰尼斯·開(kāi)普勒描述了行星的軌道運(yùn)行周期及其與太陽(yáng)之間的距離的關(guān)系。在此基礎(chǔ)上，開(kāi)普勒得出了一些空前準(zhǔn)確的數(shù)據(jù)表，預(yù)測(cè)了各個(gè)行星的運(yùn)動(dòng)，其中就包括1631年和1639年的金星凌日。一位年輕的英國(guó)天文學(xué)家杰里邁亞·霍羅克斯在仔細(xì)研究了其中一個(gè)表格后，發(fā)現(xiàn)了開(kāi)普勒的一個(gè)錯(cuò)誤，這時(shí)距1639年的金星凌日僅有數(shù)周的時(shí)間，他利用數(shù)學(xué)運(yùn)算預(yù)測(cè)到了凌日的逼近?；袅_克斯用投影法繪制了一幅1639年金星凌日的圖像，并標(biāo)明了金星的大小和運(yùn)行軌跡——這是有史記載以來(lái)的第一次。

最令霍羅克斯同時(shí)代的人感到驚訝的是，金星相對(duì)太陽(yáng)竟顯得那么渺小。然而，這種體積上的差異不應(yīng)成為人們失望的理由，反而應(yīng)當(dāng)被人們視為一種絕妙的直觀比較。金星的大小和地球差不多，金星輪廓的渺小更加反襯出遙遠(yuǎn)的太陽(yáng)的巨大——太陽(yáng)的體積相當(dāng)于一百萬(wàn)個(gè)地球那么大。

數(shù)學(xué)對(duì)科學(xué)有著很好的作用，埃德蒙·哈雷就曾宣布只需用一個(gè)辦法就可以計(jì)算出地球到太陽(yáng)的距離，那就是在廣泛分布的地點(diǎn)讓不同的觀測(cè)者測(cè)定金星凌日的持續(xù)時(shí)間，而這卻是哈雷在世無(wú)法看到的。因?yàn)榻鹦莿澾^(guò)太陽(yáng)需要大約六個(gè)小時(shí)，而觀測(cè)者需要將這一時(shí)間測(cè)定精確到秒(編注：這在當(dāng)時(shí)是無(wú)法做到的)。

Black Drop Effect 黑滴效應(yīng)

Unfortunately， the limitations of the telescopes and other factors gave rise to a hindrance18) called the \"black drop effect\". When the edge of Venus appears just about to touch the inside edge of the Sun， an annoying ligament19) suddenly appears between the well-defined edges. This distortion20) confounded21) the accurate timing of the transit by a few seconds， and Halley's vision of accuracy plummeted22). The effect can be simulated by holding your nearly-pinched thumb and index finger together in front of a bright light. Before they touch， a dark meniscus23) seemingly joins the two digits.

When the 19th century pair of transits rolled around24)， astronomers hoped the new tools of photography could help them to discern25) the exact instant of internal contact， which had been plagued26) previously by the black drop effect. Jules Janssen developed a \"photographic revolver\"， a precursor27) to motion picture cameras， which captured a series of images near the critical moment. Again， ambitious expeditions set out to far-flung28) locales to await and to time the duration of the 1874 and 1882 transits of Venus. Alas， photography proved to have its limitations as well， and the accuracy in practice was again not what Halley had suggested was achievable.

In ensuing29) decades， developments like radar helped astronomers refine the true distance to Venus， and the transit method became a historical artifact. Nonetheless， the 2004 transit of Venus piqued30) the world's curiosity， and for the first time spacecraft could peer at the celestial phenomenon with unprecedented clarity.

遺憾的是，望遠(yuǎn)鏡的局限和其他因素導(dǎo)致了一個(gè)(測(cè)定準(zhǔn)確時(shí)間的)障礙——“黑滴效應(yīng)”。當(dāng)金星邊緣即將碰觸到太陽(yáng)內(nèi)緣時(shí)，原本清晰的邊緣中間會(huì)突然出現(xiàn)一道討厭的韌帶狀黑暈。這一扭曲現(xiàn)象會(huì)給金星凌日的準(zhǔn)確計(jì)時(shí)帶來(lái)幾秒的誤差，這樣一來(lái)，哈雷所預(yù)見(jiàn)的精確性就大打折扣了。這種效應(yīng)可被模擬呈現(xiàn)，你只需將大拇指和食指在強(qiáng)光前似觸非觸地接觸，在這兩根手指碰觸到之前，一道黑色的彎月?tīng)罟鈺炈坪跻褜⒍哌B接起來(lái)。

當(dāng)19世紀(jì)的這組凌日如期發(fā)生時(shí)，天文學(xué)家們希望新的照相儀器能夠幫助他們看清凌日內(nèi)切的精確瞬間，在此之前，這個(gè)問(wèn)題一直深受黑滴效應(yīng)的困擾。朱爾斯·詹森研制出一種“照相旋轉(zhuǎn)裝置”——這應(yīng)該算是電影攝像機(jī)的前身吧——用來(lái)捕捉凌日內(nèi)切前后的一系列圖像。于是，雄心勃勃的探索再次開(kāi)始了，人們前往眾多相隔遙遠(yuǎn)、四處分散的觀測(cè)點(diǎn)，等待著1874和1882年這組金星凌日的到來(lái)，以測(cè)定其精確的持續(xù)時(shí)間。遺憾的是，事實(shí)證明照相技術(shù)也有其局限性，實(shí)踐中的數(shù)據(jù)精確性再次沒(méi)能達(dá)到哈雷設(shè)想能達(dá)到的那種精確性。

在之后的幾十年時(shí)間里，雷達(dá)之類(lèi)的技術(shù)發(fā)展使得天文學(xué)家們能夠修正地球與金星距離的確切數(shù)值，凌日測(cè)距法已成為歷史產(chǎn)物。然而，2004年的金星凌日仍然激起了全世界人們的好奇心，人類(lèi)第一次可以通過(guò)宇宙飛船以前所未有的清晰度觀看這一天文奇觀。

The Future of Transits 金星凌日的前景

While transits of Venus were historically significant， today the spectacle illustrates how astronomers seek to answer one of the biggest questions in modern science: Are there distant worlds capable of sustaining life? A transit of Venus illustrates the method by which astronomers are now searching for planets in the \"habitable zone\" around distant stars. Here on Earth we have a front row seat to a planetary transit on June 5~6， 2012. As we watch the planet Venus pass across the face of the Sun， the Sun's total brightness dips31) by a fraction of a percent. The decrease is not perceptible to the human eye， but it is certainly measurable by sensitive instruments. NASA's Kepler Mission is looking at over 150，000 distant stars simultaneously to detect periodic yet discrete32) dips in stellar brightness， which hint at the presence of companion planets transiting their host stars. Early results from the Kepler Mission suggest there may be over 50 billion planets in the Milky Way， of which 500 million would reside in the so-called habitable zone. A new quest using the transit method has just begun.

在歷史上，金星凌日曾有其重要意義，而在今天，這一奇觀仍能幫助天文學(xué)家嘗試解決現(xiàn)代科學(xué)中的一個(gè)重大問(wèn)題：有沒(méi)有適合生命生存的遙遠(yuǎn)世界？金星凌日可以詮釋天文學(xué)家們現(xiàn)在是運(yùn)用何種方法在遙遠(yuǎn)的恒星周?chē)摹翱删幼А睂ふ倚行堑摹?012年6月5日至6日，我們?cè)诘厍蛏暇涂梢宰谇芭庞欣恢糜^看一場(chǎng)行星凌日的演出。當(dāng)我們看著金星緩緩穿過(guò)太陽(yáng)表面，太陽(yáng)的整體亮度就會(huì)減弱極小一點(diǎn)兒。這種亮度減弱是人的肉眼所看不到的，但通過(guò)精密儀器肯定是可以測(cè)出的。美國(guó)宇航局的開(kāi)普勒計(jì)劃同時(shí)在觀測(cè)超過(guò)十五萬(wàn)顆遙遠(yuǎn)的恒星，以探測(cè)恒星亮度定期卻又短暫的減弱，這種減弱說(shuō)明正有行星穿過(guò)其恒星。開(kāi)普勒計(jì)劃早期監(jiān)測(cè)到的結(jié)果表明，在銀河系中可能存在五百多億顆行星，其中有五億顆可能位于所謂的可居住帶。一種運(yùn)用凌日測(cè)距法而進(jìn)行的新的探索才剛剛開(kāi)始。

Participate in 2012 Transit of Venus 觀測(cè)2012年的金星凌日

The last transit of Venus in our lifetimes occurs June 5~6， 2012， with the date and time dependent on your location. With some preparation， you can safely witness the 2012 transit of Venus yourself.

Popular \"eclipse shades\" are useful， but because the one-arc33) minute diameter of Venus is near the limit of the human eye's capability， the best views will be filtered and magnified. Experienced observers can use solar filters over the large， front end of their telescopes， or project an image onto a surface. A rear screen projection is a favored viewing technique， allowing a group of people to gather around the projected image while enclosing the path of the Sun's rays. Be safe， but seize the opportunity.

Unlike Le Gentil， a \"fatal cloud\" should not doom you. The beleaguered34) astronomer would have marveled at the capacity of our population to rally around his longtime objective， regardless of weather. If inclement35) weather occurs， or if you are in the zone where the transit is not visible， you can watch webcasts of the 2012 transit of Venus broadcast live from atop the Big Island of Hawaii.

The 2012 transit of Venus is also an opportunity to celebrate the Sun and marvel at its magnificence. During the preceding several years the Sun has been at a low point in its 11-year cycle of activity. However， as it rises from the depth of visual dullness， you will likely be able to see through filtered telescopes some emerging solar features like sunspots36).

As the 2012 transit of Venus concludes， envision how the 2117 and 2125 pair of transits might differ from our seemingly modern events. What new inventions or unforeseeable changes in world culture will transform the 22nd century experience? We will have to wait 105 years to find out， which is more incentive not to miss this last transit of Venus in our lifetimes.

我們這一生所能見(jiàn)到的最后一次金星凌日發(fā)生在2012年6月5日至6日，具體日期和時(shí)間取決于你所處的地理位置。做點(diǎn)兒準(zhǔn)備，你就可以親眼安全觀測(cè)到2012年的金星凌日。

常用的“觀測(cè)日食的減光裝置”都可以使用，但由于金星1弧分的視直徑(編注：1弧分是1弧度的60分之一)已幾乎接近人類(lèi)視力的極限，必須經(jīng)過(guò)過(guò)濾和放大方可得到最佳觀測(cè)結(jié)果。有經(jīng)驗(yàn)的觀測(cè)者可在望遠(yuǎn)鏡較大的前端放置陽(yáng)光過(guò)濾裝置，或者將圖像投射到一個(gè)平面上。使用背投式投影是一種很好的觀測(cè)方法，它可以使一群人圍在一起觀看投射的影像而又能遮擋太陽(yáng)光線。(觀測(cè)時(shí))既要注意安全，又要抓住時(shí)機(jī)。

和勒讓蒂不同的是，現(xiàn)在即使有一片“要命的烏云”也不會(huì)讓你有扼腕嘆息之感。如果那位倒霉的天文學(xué)家看到我們那么多人能夠聚集在一起無(wú)視天氣狀況也能觀看他長(zhǎng)期期待的目標(biāo)，肯定會(huì)驚嘆不已。如果遭遇惡劣天氣或者身處觀測(cè)不到凌日的區(qū)域，你還可以觀看從夏威夷大海島上空發(fā)出的2012年金星凌日的網(wǎng)絡(luò)現(xiàn)場(chǎng)直播。

2012年的金星凌日也是一個(gè)禮贊太陽(yáng)、仰慕太陽(yáng)光輝的大好時(shí)機(jī)。在先前的幾年時(shí)間里，太陽(yáng)一直處于其11年活動(dòng)周期的低點(diǎn)。然而，一旦它從視覺(jué)疲勞的深淵中升起，你就會(huì)通過(guò)過(guò)濾的望遠(yuǎn)鏡觀測(cè)到諸如太陽(yáng)黑子之類(lèi)的新出現(xiàn)的太陽(yáng)特征。

在2012年金星凌日結(jié)束之時(shí)，可以設(shè)想一下2117和2125年那組凌日將會(huì)和我們目前看似比較現(xiàn)代的事件有何不同。又有什么新發(fā)明或者什么無(wú)法預(yù)見(jiàn)的世界文化變革將會(huì)改變?nèi)祟?lèi)22世紀(jì)的凌日體驗(yàn)?zāi)兀课覀儗⒉坏貌坏却?05年才可以揭曉答案，這也更加促使我們不要錯(cuò)過(guò)我們今生最后一次的金星凌日。

1.travail [#712;traelig;ve#618;l] n. 艱苦勞動(dòng)，辛勤努力

2. alignment [#601;#712;la#618;nm#601;nt] n. 成一直線；直線排列；隊(duì)列

3.instant [#712;#618;nst#601;nt] n. 瞬息，頃刻，剎那；(某一)時(shí)刻

4.celestial [s#601;#712;lesti#601;l] adj. 天的，天空的，天上的

5.silhouette [#716;s#618;lu#712;et] n. (淺色背景上的)黑色輪廓像

6.harsh [hɑ#720;#643;] adj. 嚴(yán)酷的，嚴(yán)峻的

7.placid [#712;plaelig;s#618;d] adj. 寧?kù)o的，平靜的

8.numb [n#652;m] adj. 麻木的；失去感情的

9.dejection [d#618;#712;d#658;ek#643;n] n. 沮喪，情緒低落，泄氣

10.intrigue [#618;n#712;tri#720;ɡ] n. 吸引力

11.unprecedented [#652;n#712;pres#618;dent#618;d] adj. 無(wú)前例的，空前的，前所未聞的；絕無(wú)僅有的

12.pore [p#596;#720;(r)] vi. 專(zhuān)心閱讀；鉆研(over)

13.imminent [#712;#618;m#618;n#601;nt] adj. 臨近的；即將發(fā)生的；逼近的

14.project [pr#601;#712;d#658;ekt] vt. 作……的投影線(或圖)；用投影法制作(地圖、天體圖等)

15.contemporary [k#601;n#712;tempr#601;ri] n. 同時(shí)代的人；(幾乎)同年齡的人

16.discrepancy [d#618;s#712;krep#601;nsi] n. 差異，不符合，不一致

17.diminutive [d#618;#712;m#618;nj#601;t#618;v] adj. 極小的，小型的，超常微小的

18.hindrance [#712;h#618;ndr#601;ns] n. 起妨礙作用的人(或事物)；阻礙者；障礙物

19.ligament [#712;l#618;ɡ#601;m#601;nt] n. 維系物，聯(lián)結(jié)物，紐帶

20.distortion [d#618;#712;st#596;#720;#643;n] n. 扭歪，扭曲，變形

21.confound [k#601;n#712;fa#650;nd] vt. 混淆

22.plummet [#712;pl#652;m#618;t] vi. (價(jià)格、水平等)驟然下跌，徒然變差

23.meniscus [m#601;#712;n#618;sk#601;s] n. 彎月形物，新月形物

24.roll around: 規(guī)律發(fā)生

25.discern [d#618;#712;s#604;#720;n] vt. 識(shí)別，區(qū)別

26.plague [ple#618;ɡ] vt. <口> 使煩擾，困擾

27.precursor [pri#720;#712;k#604;#720;s#601;(r)] n. (從中產(chǎn)生變化的)產(chǎn)物母體，前身，前體

28.far-flung: 分布廣的；覆蓋面大的；遙遠(yuǎn)的

29.ensue [#618;n#712;sju#720;] vi. 接著發(fā)生

30.pique [pi#720;k] vt. 激起，引起(好奇心或興趣)

31.dip [d#618;p] vi. 下降；(尤指短暫或小幅度地)減少

32.discrete [d#618;#712;skri#720;t] adj. 分離的，互不連接的；不相關(guān)聯(lián)的

33.arc [ɑ#720;k] n. 弧

34.beleaguered [b#618;#712;li#720;ɡ#601;d] adj. 身陷困境的

35.inclement [#618;n#712;klem#601;nt] adj. 險(xiǎn)惡的；嚴(yán)寒的；狂風(fēng)暴雨的

36.sunspot [#712;s#652;nsp#594;t] n. 【天】(太陽(yáng))黑子