解開閏年之謎

如果你在2月29日這天出生，那還真是特別。你可以光明正大地“裝嫩”，但也得忍受四年才能過一次真正生日的“悲慘”日子。不過，你可知道閏年是怎么一回事？

Please give February 29 a hearty quadrennial1) welcome. Have a look around， make yourself at home—enjoy it， because there won't be another one along for another four years. Then let me take you on a journey ... into time.

請每四年都向2月29日這一天致以熱情誠摯的歡迎吧。四處走走逛逛，放松自己，不要拘束。好好享受這一天，因?yàn)檫@個(gè)日子得再過四年才會(huì)再度出現(xiàn)。接下來，就讓我?guī)闾ど咸矫貢r(shí)間的旅程。

Why Leap Year? 為什么要有閏年？

Let's start with the basics: the extra day that comes around every four years on February 29 makes it a leap year， meaning those years measure 366 days rather than the usual 365. This keeps the calendar year2) correctly attuned3) to the seasons， and stops them from slipping around4).

Because， you see， the Earth takes the rather fiddly5) sum of 365.256 days to do one complete orbit of the sun. However， it is not the exact orbit figure that is used to calculate a year but the slightly smaller figure of 365.2422 days， because this takes into account the Earth's spin axis， which wobbles6) slightly but significantly over the year.

Having a calendar based on 365 days gets it roughly right， but the inaccuracy over time would eventually mean the seasons would slip， and before you knew it people of the future would soon be having their spring in the winter and their winter in the autumn and so on. For example， if we just had 365 days exactly， after 12 years we would be off by three days.

讓我們從那些基本的概念談起。每四年都會(huì)有一年多出一個(gè)2月29日，這一年就是閏年，也就是說閏年有366天，而不是通常的365天。閏年的出現(xiàn)使日歷上一年的日期與季節(jié)變化保持協(xié)調(diào)，避免了二者偷偷錯(cuò)位的現(xiàn)象發(fā)生。

這是因?yàn)椋闱疲厍蚶@太陽公轉(zhuǎn)一周的精確用時(shí)是365.256天。然而，人們并沒有用這一精確的公轉(zhuǎn)數(shù)據(jù)來計(jì)算一年的長度，而是采用了比它略小的數(shù)據(jù)365.2422天，因?yàn)檫@個(gè)數(shù)據(jù)考慮了地球自轉(zhuǎn)軸的因素——地球自轉(zhuǎn)軸的搖擺雖然輕微，但一年下來造成的影響卻不容忽視(編注：由于引力的影響，地球自轉(zhuǎn)軸的方向會(huì)緩慢地改變)。

雖然以一年365天作為基準(zhǔn)制定而成的歷法在大體上是沒錯(cuò)的，但隨著時(shí)間的推移，不夠精確的那部分最終會(huì)導(dǎo)致季節(jié)的錯(cuò)位。在不知不覺中，未來的人們很快就將在春天度過日歷上的“冬季”，而在冬天度過日歷上的“秋季”等等。舉例來說，如果我們每年都正好有365天，那12年后，我們的時(shí)間就將比實(shí)際時(shí)間落后3天。

Origin of the Gregorian Calendar 現(xiàn)代公歷的起源

In 46 BC Julius Caesar oversaw7) the introduction of the Julian calendar， which incorporated the leap year. But something else was going to be needed to make it more accurate. This became apparent to the Neapolitan doctor Aloysius Lilius who proposed to modify the Julian calendar in 1582. Pope Gregory agreed and soon the Gregorian calendar was introduced. It included leap years and another rule that would cancel some leap years to make it more accurate. That is， a leap year is divisible8) by four， unless it is divisible by 100; however not by 400. This means that 1984 and 2000 were leap years but not 1900.

The calendar basically worked on a 400-year cycle， and the cancelled leap year that is brought back every four centuries gets the adjusted average to just 0.0001 days more than the interval between vernal equinoxes9). The Gregorian calendar will run about half-a-day behind in 4000 years. There was great controversy when the Gregorian calendar was introduced and 11 days were deleted from October 4， 1582 to October 15. People literally thought days of their lives were being stolen.

The Gregorian calendar was eventually adopted by most countries and set the first day of the year at January 1. Some countries， including Germany， already did this， but not， for example， England， which started the year on March 25. England accepted the Gregorian calendar in 1752， although Russia did not accept it until 1918. The Orthodox Church of Russia still maintains the Julian calendar for religious reasons. Experts believe that older civilizations may have tried to keep the calendar tied to lunar phases10).

公元前46年，尤利烏斯·愷撒監(jiān)督引進(jìn)了包含閏年的儒略歷。不過，它還需要增加一些別的內(nèi)容才能更為精確。那不勒斯醫(yī)生阿洛伊修斯·利尤斯意識(shí)到了這個(gè)問題，因此他于1582年提議修訂儒略歷。教皇格里高利批準(zhǔn)了他的提議，不久便頒布了格里高利歷法(譯注：簡稱格里歷，即現(xiàn)在所使用的公歷)。格里歷包含了閏年以及另外一條規(guī)定，這條規(guī)定取消了一些閏年以使格里歷更為準(zhǔn)確，其內(nèi)容為：除了那些能被100整除卻不能被400整除的年份，所有可以被4整除的年份都是閏年(譯注：即通常所說的“四年一閏，百年不閏，四百年再閏”)。也就是說，1984年和2000年都是閏年，但1900年不是閏年。

格里歷大體上以400年為一個(gè)周期，每400年補(bǔ)回的那次閏年使得調(diào)整之后每個(gè)歷年的平均時(shí)長僅比兩次春分之間的時(shí)間間隔長0.0001天。4000年后，格里歷將只比實(shí)際時(shí)間多出大約半天。格里歷最初頒布施行的時(shí)候曾經(jīng)引起過很大的爭議，因?yàn)閺?582年10月4日到10月15日之間的這11天都從日歷上抹去了。那時(shí)的人真的有種生命中的這些時(shí)光被偷走了的感覺。

格里歷最終被大多數(shù)國家采用，并規(guī)定1月1日是一年的開端。包括德國在內(nèi)的一些國家一直是這樣做的，但有的國家并非如此，比如英國把3月25日作為一年之始。英國于1752年開始使用格里歷，而俄羅斯直到1918年才采用。出于宗教原因，俄羅斯的東正教現(xiàn)在用的仍然是儒略歷。專家們認(rèn)為，一些較古老的文明可能已經(jīng)嘗試使用了以月相為基礎(chǔ)的陰歷。

Leap Day 閏日

Roman custom was to insert the extra day at February 24 with following days renumbered. In 2000 the EU said February 29 would be leap day， which the Roman Catholic Church now concurs11) with. Traditionally women may make a marriage proposal to a man on February 29 or any time during a leap year. Tradition dictates12) that if he turns the proposal down he must give a kiss and a silk gown in recompense13).

People born on the special date are sometimes known as Leapers and someone turning 28 on February 29 could claim they are seven. In the Pirates of the Penzance14)， Frederic is not apprenticed15) to a band of pirates until his 21st birthday， but as he was born on February 29， he would have to wait until he was 84. Many born on February 29 have to celebrate a day early.

In the Republic of Ireland babies born on February 29 are to get a pound;70 payment from the Dublin government to celebrate the family. It is thought around 160 payments will be made， based on average daily birth figures.

以往羅馬的慣例是將閏日設(shè)在2月24日，并將其后幾天的日期依次順延。2000年，歐盟宣布將2月29日這一天定為閏日，羅馬天主教會(huì)現(xiàn)在也認(rèn)可了這一做法。依照傳統(tǒng)，女子可以在2月29日或閏年的任意一天向男子求婚。傳統(tǒng)還強(qiáng)行規(guī)定，男子如果拒絕了女子的求婚，必須向?qū)Ψ剿蜕弦晃呛鸵患z袍作為補(bǔ)償。

在這一特殊的日子出生的人有時(shí)被稱為“閏生”，而在2月29日這天年滿28歲的人可以宣稱他們只有7歲。在音樂劇《彭贊斯的海盜》中，弗雷德里克過完第21個(gè)生日就不用給一伙海盜當(dāng)學(xué)徒了，但由于他的生日是2月29日，因此他將不得不等到84歲才能出師。許多在2月29日出生的人只得提前一天慶祝生日。

在愛爾蘭共和國，都柏林政府會(huì)向2月29日出生的嬰兒發(fā)放70英鎊，以示對其家庭的祝賀。根據(jù)日均出生人口數(shù)推算，都柏林政府將在這一天發(fā)放約160筆這樣的禮金。

1.quadrennial [kw#594;#712;dr#603;n#618;#601;l] adj. 四年一次的

2.calendar year: 【天】歷年，即公歷1月1日至12月31日

3.attune [#601;#712;tju#720;n] vt. 使協(xié)調(diào)

4.slip around: 溜走

5.fiddly [#712;f#618;dli] adj. 要求極度精確的

6.wobble [#712;w#594;bl] vi. 搖晃，搖擺

7.oversee [#716;#601;#650;v#601;#712;si#720;] vt. 監(jiān)督；指導(dǎo)

8.divisible [d#618;#712;v#618;z#601;bl] adj. 可除盡的

9.vernal equinox: 春分，春分點(diǎn)。vernal [#712;v#604;#720;nl] adj. 春季的，春天發(fā)生的。equinox [#712;i#720;kw#618;n#594;ks] n. 【天】二分時(shí)刻，晝夜平分時(shí)(指春分或秋分)。文中提過，一年的長度是365.2422天。從地球上看，太陽沿黃道逆時(shí)針運(yùn)動(dòng)，而太陽中心從春分點(diǎn)到春分點(diǎn)所經(jīng)歷的時(shí)間就是365.2422天，這樣的一年被稱為回歸年，也叫太陽年。因此，文中才與兩次春分之間的時(shí)間間隔相比較。

10.lunar phase: 月相

11.concur [k#601;n#712;k#604;#720;(r)] vi. 同意

12.dictate [d#618;k#712;te#618;t] vt. 發(fā)號(hào)施令地規(guī)定，專橫地強(qiáng)加(規(guī)則、條款等)

13.in recompense: 作為補(bǔ)償。recompense [#712;rek#601;mpens] n. 賠償，補(bǔ)償

14.Pirates of the Penzance:《彭贊斯的海盜》。它是一部世界著名的音樂劇，最早于1879年12月在美國紐約第五大道劇院演出，廣受歡迎，至今仍在世界各大劇院上演。

15.apprentice [#601;#712;prent#618;s] vt. 使當(dāng)學(xué)徒，使學(xué)藝

What's More

中國農(nóng)歷的閏年

中國農(nóng)歷又稱為陰歷，每月的天數(shù)依照月相變化而定。一年以12個(gè)月為基準(zhǔn)，大月30天，小月29天，平年一年354或355天，比一回歸年(編注：見注釋9)少約11天。為了與回歸年的時(shí)間相符，每隔2#12316;4年增加一個(gè)月，增加的這個(gè)月為閏月。在哪個(gè)月增加閏月主要依照農(nóng)歷的二十四節(jié)氣來確定。在加有閏月的那一年有13個(gè)月，一年有384或385天，這一年也稱為農(nóng)歷閏年。農(nóng)歷基本上3年一閏，5年二閏，19年七閏。農(nóng)歷的特點(diǎn)在于既重視月相盈虧的變化，又照顧寒暑節(jié)氣。