Leap year - SpeedyLook encyclopedia

A leap year is a Année of 366 Jour S instead of 365, i.e. one year including/understanding a February 29th. The term comes from the Latin (a)-sextilis , which means twice “ ((a)) sixth (sextus) ”.

Current rule

Since the introduction of the Gregorian Calendar, is bissextile, the years:

divisible by 4 but nondivisible by 100

divisible by 400

Thus, the year 2004 was bissextile according to the first rule. The year 1900 was not bissextile, because divisible by 100, which goes against the first rule, and nondivisible by 400, which goes against the second. The year 2000 was bissextile because divisible by 400.

The Calendrier Julien, which had course before the Gregorian Calendrier, did not distinguish the ends from centuries (divisible years by 100). One year was bissextile every 4 years, without another exception. The Julien calendar thus had 365,25 days an average year, instead of the 365,2422 Jour S necessary to the terrestrial cycle. What generated the accumulation of ten days of delay into fifteen Siècle S. This delay was corrected by removing days. Introduction of the Gregorian calendar then having to prevent that the error reproduces.

This Gregorian calendar offers according to the stated rules one 365,2425 days year average, which is still a little too long, but generates only one 3 days error in 10 000 years.

The year “0” not existing (this figure was not of use in the Roman numeration still used at the time of the calendar reform), the leap years before “0” are -1,-5,-9… and not -4,-8…

History of the leap years

Intercalated months of the year of Numa

The practice to add a intercalated day in order to make up for lost time taken by the Calendar year on the Solar year goes back to the Romains. Those, before the Julien calendar, used the year known as “of Numa” 355 days, are twelve lunar Mois S. the delay with the solar Calendrier was compensated by intercalated Mois S one duration variable fixed by the Grand Pontiff. This system had been however put out of order at the time of the Civil wars.

The intercalary day of Jules

In 45 before the Christian era, Jules César, then dictator (with the Latin direction of the term) and Grand Pontiff of the Roman République called upon the Greek Astronome Sosigène of Alexandria so that this one regulated the too important shift that one noted between the solar years and civil since the Civil wars. This one created our 365 days year plus one day intercalated every four years (it is necessary to await the Gregorian Calendrier so that the system is even more precise).

This day placed between the 24 and the February 25th. It was thus the “February 24th (a)”. One named this day the February 24th A.D. VI Kal. Mart. , is handle diem sextum Kalendas Martias , which means “the sixth day before the Calendes of March” (the Romans counted the number of days remaining before such or such date in the month, like the calends 1st of the Mois, the nuns the 5 or the 7, according to the months, and the ides the 13 or the 15, according to the months); the “February 24th (a)” thus said quite naturally A.D. (a) VI Kal. Mart. , is handle diem (a) sextum Kalendas Martias : “the sixth day (a) before the calends of March” (“the sixth day (a) before March first”). One year bissextile twice includes/understands the sixth day before March first; “twice sixth” said (a)-sextus ; the suffix - ilis was added to form the adjective bissextilis : “which has twice a sixth (day)”, in order to speak about one (E) anise bissextilis (the word anise “year” is male), “leap year”.

Later, the intercalary day was positioned the 29 of February, as from the moment when the Latin method of calculation of the days was replaced.

February 29th

Since 1980 in France, an small group of people publishes a Journal which appears only the February 29th, called the Candle of the sapper . In 2004, it published its number 7.

The people having incipient a February 29th celebrate usually their birthday the February 28th or the 1^er March the not-bissextile years. It should be noted also that in certain countries, a person born a February 29th is legally the 28. I.e. if Louse had been born a February 29th 1980, it would have 18 years the February 28th 1998. 2008 are one leap year.

February 30th

In 1700, the Sweden tried to use a Julien calendar modified to pass gradually from the Julien calendar to the Gregorian calendar. The process was to reduce gradually a day per annum, during 11 years. Only the year 1700 was thus modified and in 1712 to catch up with the calendar Julien it was necessary to add one day additional in February which became thus doubly bissextile and had a February 30th.

See too

Beats-smg: Kelamė̅jė metā Fiu-vro: Liigaastak Simple: Leap year Zh-min-nan: Lūn-nor Zh-yue: 閏年

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