闰年

公历 现时世界普遍采用的公历是格列高里历，它的前身是儒略历。根据儒略历的规定，每4年有1个闰年，闰年为366日，其余3年(称为平年)各有365日。公元年数能被4除得尽的是闰年。儒略历1年平均长365.25日，比实际公转周期的365.2422日长11分14秒，即每400年约长3日。 教宗格列高里十三世于1582年宣布改历，改变置闰规则。公元年数被4除尽的是闰年，但如被100除得尽而被400除不尽的则不是闰年。这样的做法可在400年中减少3个闰年。在格列高里历下，400年中有97个闰年(每年366日)及303个平年(每年365日)，所以每年平均长365.2425日，与公转周期的365.2422日十分接近。 公元2000年是闰年吗？ 根据公历的置闰规则，2000被4及400整除，所以公元2000年是闰年。但1700，1800及1900因不被400整除，所以不是闰年。 For a day that comes rarely to the calendar, Google has doodled a rare two-in-one doodle that commemorates not only the leap day but also the 220th birth anniversary of the Italian composer Gioachino Rossini. Since the leap years and leap days are usually associated with frogs, the leaping ambhibians, the Google doodle on February 29 has a number of frogs, all four of them. The doodle is inspired by Gioachino Antonio Rossini's famous 1816 comic opera The Barber of Seville (Il barbiere di Siviglia), one of the most performed operas. Of the four frogs in the scene, one is at the piano and the soprano is the only one leaping. The barber frog is Figaro and the frog getting a shave is Count Almaviva (Characters created by French playright Pierre Beaumarchais and The Barber of Seville is one of the three Figaro plays penned by him

Rossini's other famous operas include William Tell (1829), Semiramide (1823) and Cinderella (1817). Gioachino Rossini was born on February 29, 1792 (died November 13, 1868). The possibility of someone's birthday falling on February 29 is 1 in 1461 (as four years including a leap year have 1461 days in total) that in turn calculates to a mere 0.068 per cent chance.
The Gioachino Rossini leap year Google doodle is the third leap year doodle in Google's history. The previous two were put up on 2004 and 2008. There was no leap day doodle in the year 2000.
By our calculations this is the 1314th Google doodle since the first ever on for the Burning Man Festival back on August 30, 1998.




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#Google doodle#Google#Gioachino Rossini#Leap year#Leap day#29 Fenruary#Internet#Opera

动物园“青蛙配套” 配合闰年跳一跳

（2012-02-29）

动物园希望借观察动物生命周期，不管是大人或小孩，能从中提升大家对这些生物的认识及体会大自然的奇妙。

　　今年逢四年一次的闰年（leap year），新加坡动物园取“leap”跳跃之意，推出“青蛙配套”，希望借着此配套的推出为本地生物多样性造势，引起公众的兴趣，尤其是在原始两栖动物方面。
　　公众将能根据“青蛙配套”（Frog Kit）提供的手册及蝌蚪食物，亲身体验照料10只蝌蚪的过程，见证蝌蚪在这过程中的有趣变化。
　　动物园希望借观察动物生命周期，不管是大人或小孩，能从中提升大家对这些生物的认识及体会大自然的奇妙。
　　“青蛙配套”在试用期间，已分发给几所国际及本地学校，并收到良好反馈。加拿大国际学校更是成功将配套中所有的蝌蚪，照料成活蹦乱跳的青蛙后，将它们放生至动物园。
　　由于小学的科学教学大纲也包括动物生命周期，动物园希望学校能在接下来几个月，购买此配套。
　　此活动属全球活动“跳出绝种危机”（Leaping Ahead of Extinction）之一，有兴趣购买“青蛙配套”的公众，可拨电63608657或电邮至xinli.yap@wrs.com.sg，售价为25元。