# Encyclopedia

.A leap year (or intercalary year) is a year containing one extra day (or, in the case of lunisolar calendars, a month) in order to keep the calendar year synchronized with the astronomical or seasonal year.^ Leap year days in febuary?
• WikiAnswers - How many days are in a leap year 10 January 2010 11:57 UTC wiki.answers.com [Source type: General]

^ Go there at http://en.wikipedia.org/wiki/Leap_year Let's read what Wikipedia says about Leap Year and Leap Day: "A leap year (or intercalary year) is a year containing one or more extra days (or, in the case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year.
• CLICKING ON THE WEB: Leap Day is past but Leap Year bounds ahead 10 January 2010 11:57 UTC hometownsource.com [Source type: General]

^ Days ia a leap year?
• WikiAnswers - How many days are in a leap year 10 January 2010 11:57 UTC wiki.answers.com [Source type: General]

.For example, in the Gregorian calendar (common calendar), February in a leap year has 29 days instead of the usual 28, so the year lasts 366 days instead of the usual 365. Because seasons and astronomical events do not repeat in a whole number of days, a calendar that had the same number of days in each year would, over time, drift with respect to the event it was supposed to track.^ Most years have 365 days, but a leap year has 366 days.

^ So this year for example you would have one extra day and 5 seconds added to February.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

^ Well, take 365.25 (the quarter day is for the leap year) and multiply by 28 years ...
• 28 year Calendar! 10 January 2010 11:57 UTC qbx6.ltu.edu [Source type: General]

.By occasionally inserting (or intercalating) an additional day or month into the year, the drift can be corrected.^ By occasionally inserting (or intercalating) an additional day or month into the year, the drift can be corrected.
• Leap Year Math | Googol Learning 10 January 2010 11:57 UTC www.googolpower.com [Source type: General]
• CLICKING ON THE WEB: Leap Day is past but Leap Year bounds ahead 10 January 2010 11:57 UTC hometownsource.com [Source type: General]
• Why Do We Have Leap Year? | Raising A Family 10 January 2010 11:57 UTC www.raisingafamily.net [Source type: General]

^ By occasionally inserting an additional day into the year, the drift can be corrected.

^ Add an additional day once every four years to correct the drift.
• Inside MyFax: A MyFax Leap Year 10 January 2010 11:57 UTC blog.myfax.com [Source type: General]

.A year that is not a leap year is called a common year.^ The year in which this occurs, is called a Leap Year.
• Leap Day and Leap Year at Holiday Insights 10 January 2010 11:57 UTC www.holidayinsights.com [Source type: FILTERED WITH BAYES]

^ A year which is not a leap year is called a common year.
• Leap Year Math | Googol Learning 10 January 2010 11:57 UTC www.googolpower.com [Source type: General]
• Leap year - How and when it happens, February 08 - 2GB.com 10 January 2010 11:57 UTC www.2gb.com [Source type: General]
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]
• CLICKING ON THE WEB: Leap Day is past but Leap Year bounds ahead 10 January 2010 11:57 UTC hometownsource.com [Source type: General]
• Why Do We Have Leap Year? | Raising A Family 10 January 2010 11:57 UTC www.raisingafamily.net [Source type: General]

^ Values are: 0 = the year IS NOT a leap year (and therefore is a common year).
• jewish_leap_year (am) Detail (jwleapyr.js) 10 January 2010 11:57 UTC www.humphreys.org [Source type: FILTERED WITH BAYES]

## Gregorian calendar

.In the Gregorian calendar, the current standard calendar in most of the world, most years that are evenly divisible by 4 are leap years.^ If a year is divisible by 4 and by 100, it is not a leap year unless it is also divisible.
• Leap Year | Today's issues | Guardian Unlimited 10 January 2010 11:57 UTC chef-girl.net [Source type: News]

^ Unlike the Gregorian calendar, 2006 was a leap year in the Chinese calendar.
• Leap Year in Other Calendars 10 January 2010 11:57 UTC www.timeanddate.com [Source type: General]

^ However, if it is evenly divisible by 4 and also evenly divisible by 100 and not further evenly divisible by 400, then it is not a leap year.
• How To Calculate Leap Years with Perl | Perl 10 January 2010 11:57 UTC www.willmaster.com [Source type: General]

.In each leap year, the month of February has 29 days instead of 28. Adding an extra day to the calendar every four years compensates for the fact that a period of 365 days is shorter than a solar year by almost 6 hours.^ So this year for example you would have one extra day and 5 seconds added to February.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

^ In fact that takes 365.24 days.
• Topper Shutt's Blog: Leap Year 10 January 2010 11:57 UTC www.wusa9.com [Source type: General]

^ ISO/ESPP Holding Period--365 Days or 12 Months?
• Leap Year and ISOs - The NASPP Blog 10 January 2010 11:57 UTC www.naspp.com [Source type: General]

.However, some exceptions to this rule are required since the duration of a solar year is slightly less than 365.25 days.^ However, the length of an actual year is 365.2425 days.
• Leap year: What is it and when does it happen? 10 January 2010 11:57 UTC www.windows.ucar.edu [Source type: General]

^ In common years, the calendar has 365 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The solar year is about 11 minutes less than 365 days in length.
• List of Leap Years 10 January 2010 11:57 UTC www.buzzle.com [Source type: FILTERED WITH BAYES]

.Years that are evenly divisible by 100 are not leap years, unless they are also evenly divisible by 400, in which case they are leap years.^ Unfortunately, this is not the case in 2100 because it isn't divisible by 400 so it is not a leap year!

^ If a year is divisible by 4 and by 100, it is not a leap year unless it is also divisible.
• Leap Year | Today's issues | Guardian Unlimited 10 January 2010 11:57 UTC chef-girl.net [Source type: News]

^ Every year divisible by 4 is a leap year But every year divisible by 100 is NOT a leap year Unless the year is also divisible by 400, then it is still a leap year.
• February 29, 2008 Is Leap Day! | Scholastic.com 10 January 2010 11:57 UTC www2.scholastic.com [Source type: General]

[1][2] .For example, 1600 and 2000 were leap years, but 1700, 1800 and 1900 were not.^ (That means 1600 was a leap year, but not 1700, 1800 and 1900.
• Leaping Lizards, It’s Leap Year! at Ray Fowler .org 10 January 2010 11:57 UTC www.rayfowler.org [Source type: FILTERED WITH BAYES]

^ Don't forget, 1900, 1800, and 1700 were each not leap years.
• ITinfo: Feb 29: A Leap Year Computer Snag? 10 January 2010 11:57 UTC itrain.org [Source type: General]

^ Thus, 1600 was a leap year; 1700, 1800, and 1900 were not, but 2000 will be.
• Leap Year FAQ 10 January 2010 11:57 UTC incompetech.com [Source type: News]

.Similarly, 2100, 2200, 2300, 2500, 2600, 2700, 2900 and 3000 will not be leap years, but 2400 and 2800 will be.^ List of Leap Years in 2200 .
• List of Leap Years 10 January 2010 11:57 UTC www.buzzle.com [Source type: FILTERED WITH BAYES]

^ This means that the year 2000 was a leap year and 2400 will also be one, but 1800 and 1900 were not leap years, and the years 2100 , 2200 , and 2300 will not be leap years either ...
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ So the year 2000 was a leap year, but the years 2100, 2200 and 2300 will not be.

.By this rule, the average number of days per year will be 365 + 1/4 − 1/100 + 1/400 = 365.2425, which is 365 days, 5 hours, 49 minutes, and 12 seconds.^ Each year actually includes, besides the 365 days, an extra 5 hours, 49 minutes and 12 seconds.

^ This results in an average year of 365.24 days.
• Catholic Calendar Leap Year Page 10 January 2010 11:57 UTC www.easterbrooks.com [Source type: News]

^ If it was .6 seconds per year the day would have lengthen by 1 minute and 40 seconds since 1820.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

.The Gregorian calendar was designed to keep the vernal equinox on or close to March 21, so that the date of Easter (celebrated on the Sunday after the 14th day of the Moon—i.e.^ "The Gregorian calendar was designed to keep the vernal equinox on or close to March 21, so that the date of Easter (celebrated on the Sunday after the 14th day of the Moon that falls on or after 21 March) remains correct with respect to the vernal equinox.
• CLICKING ON THE WEB: Leap Day is past but Leap Year bounds ahead 10 January 2010 11:57 UTC hometownsource.com [Source type: General]

^ It also dropped several days from the caled several days from the calendar so that the vernal equinox was brought back to March 21.
• The Calendar, Leap Years and the Year 2000 AD 10 January 2010 11:57 UTC chemistry.csudh.edu [Source type: FILTERED WITH BAYES]

^ This new version was designed with the goal of keeping the vernal equinox on or close to March 21.
• Inside MyFax: A MyFax Leap Year 10 January 2010 11:57 UTC blog.myfax.com [Source type: General]

a .full moon—that falls on or after March 21) remains correct with respect to the vernal equinox.^ The dropping of 10 days from the calendar made the Vernal Equinox fall on March 21.
• Leap Year Isn't a Bust - Ted Pedas, YSU Planetarium Lecturer 10 January 2010 11:57 UTC www.farrellareaschools.com [Source type: General]

^ "The Gregorian calendar was designed to keep the vernal equinox on or close to March 21, so that the date of Easter (celebrated on the Sunday after the 14th day of the Moon that falls on or after 21 March) remains correct with respect to the vernal equinox.
• CLICKING ON THE WEB: Leap Day is past but Leap Year bounds ahead 10 January 2010 11:57 UTC hometownsource.com [Source type: General]

^ This may not seem like a lot, but over the course of centuries it added up, until in the 16th century, the vernal equinox was falling around March 11 instead of March 21.
• Leap Year Explained — Infoplease.com 10 January 2010 11:57 UTC www.infoplease.com [Source type: General]

[3] .The vernal equinox year is about 365.242374 days long (and increasing).^ In the long term, it is accurate to about one day in 2500 years.
• Leap Year in Other Calendars 10 January 2010 11:57 UTC www.timeanddate.com [Source type: General]

^ In common years, the calendar has 365 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The length of the vernal tropical year is 365.24237 days.
• Leap years and leap seconds : Time fact files : Astronomy & time : Explore online : NMM 10 January 2010 11:57 UTC www.nmm.ac.uk [Source type: FILTERED WITH BAYES]

.The marginal difference of 0.000125 days between the Gregorian calendar average year and the actual year means that, in around 8,000 years, the calendar will be about one day behind where it is now.^ Compared with the Gregorian calendar, which errors by one day in about every 3226 years, the Iranian calendar needs a one-day correction in about every 141,000 years.
• Leap Year in Other Calendars 10 January 2010 11:57 UTC www.timeanddate.com [Source type: General]

^ Everyone understands that the Gregorian calendar will be off by about a day in 3000 years or so.
• Leap Year FAQ 10 January 2010 11:57 UTC incompetech.com [Source type: News]

^ You can have one day a year."
• February 29@Everything2.com 10 January 2010 11:57 UTC everything2.com [Source type: General]

.But in 8,000 years, the length of the vernal equinox year will have changed by an amount that cannot be accurately predicted (see below).^ But in 8,000 years, the length of the vernal equinox year will have changed by an amount which cannot be accurately predicted (see below).
• CLICKING ON THE WEB: Leap Day is past but Leap Year bounds ahead 10 January 2010 11:57 UTC hometownsource.com [Source type: General]

^ The solar year, the time it take the sun to appear directly over the equator (Vernal Equinox) and then re-appear takes a bit over one year.
• Topper Shutt's Blog: Leap Year 10 January 2010 11:57 UTC www.wusa9.com [Source type: General]

^ The only hitch is that the current calendar may need an overhaul a few thousand years from now due to the changing length of the year at the equator.
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

.Therefore, the current Gregorian calendar suffices for practical purposes, and the correction suggested by John Herschel of making 4000 a non-leap year will probably not be necessary.^ Unlike the Gregorian calendar, 2006 was a leap year in the Chinese calendar.
• Leap Year in Other Calendars 10 January 2010 11:57 UTC www.timeanddate.com [Source type: General]

^ The purpose of a leap year is to align the calendar year with the astronomical year.
• What's the point of leap year? 10 January 2010 11:57 UTC ask.yahoo.com [Source type: General]

^ According to the Gregorian calendar, there are 3 rules to calculate if it is leap year or not a leap year.
• Teaching About Leap Year 2008: Classroom Activities to Explain the Extra Day in February 10 January 2010 11:57 UTC classroom-activities.suite101.com [Source type: News]

 . This graph shows the variations in date and time of the June Solstice due to unequally spaced 'leap days' rules.^ Improve ] Unlike a normal year a leap year is 366 days due to the fact that a year is acually 365.25 days in a normal year so ever time a year goes by it adds up like 365.25 then 365.50 then 365.75 then finally 366 then back around. WikiAnswers - How many days are in a leap year 10 January 2010 11:57 UTC wiki.answers.com [Source type: General] ^ Since the tropical year is 365.242190 days long, a leap year must be added roughly once every four years (four times the fractional day gives ). Leap Year -- from Eric Weisstein's World of Astronomy 10 January 2010 11:57 UTC scienceworld.wolfram.com [Source type: FILTERED WITH BAYES] ^ Fact: In 1288, Scotland established Leap Day as a time when a woman could propose marriage to a man. 11 Things: Leap year - SFGate 10 January 2010 11:57 UTC articles.sfgate.com [Source type: News] See Iranian calendar to contrast with a calendar based on 8 leap days every 33 years.

#### Algorithm

This algorithm determines leap years on the proleptic Gregorian calendar, which includes leap years before the official inception in 1582.
Pseudocode to determine whether a year is a leap year or not:
```if year modulo 400 is 0
then is_leap_year
else if year modulo 100 is 0
then not_leap_year
else if year modulo 4 is 0
then is_leap_year
else
not_leap_year
```
A more direct algorithm:
```if (year modulo 4 is 0) and (year modulo 100 is not 0) or (year modulo 400 is 0)
then is_leap_year
else
not_leap_year
```
.The three terms in the more direct algorithm may be grouped either way, [(4 and not 100) or 400] or [4 and (not 100 or 400)], as shown by the following truth table.^ For this reason, the following years are not leap years: 1700, 1800, 1900, 2100, 2200, 2300, 2500, 2600 This is because they are evenly divisible by 100 but not by 400.
• Method to determine whether a year is a leap year 10 January 2010 11:57 UTC support.microsoft.com [Source type: General]

^ While that might work, it adds more complexity to the algorithm and makes it harder to follow.
• Leap year and the Zune - And now it's all this 10 January 2010 11:57 UTC www.leancrew.com [Source type: General]

^ DAY BY DAY Day by day, O dear Lord, Three things I pray: To see Thee more clearly, Love Thee more dearly, Follow Thee more nearly, Day by day.
• A New Day ; Leap Year 10 January 2010 11:57 UTC 216.117.216.152 [Source type: Original source]

.If a year is divisible by 400 (400 = T) then it is also divisible by 100 (100 = T) and 4 (4 = T), so TFT, FTT and FFT are not in the truth table.^ "A century year, that is, a year which ends in two zeroes 1800 , 1900 , 2000 , etc., is not a leap year unless it is also evenly divisible by 400.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ Expressed in pseudocode:  If ((year modulo 4 is 0) and (year modulo 100 is not 0)) or (year modulo 400 is 0) Then   leapYear = true  Else   leapYear = false  End if .

^ However, if it is evenly divisible by 4 and also evenly divisible by 100 and not further evenly divisible by 400, then it is not a leap year.
• How To Calculate Leap Years with Perl | Perl 10 January 2010 11:57 UTC www.willmaster.com [Source type: General]

.Similarly, if a year is not divisible by 400 (400 = F) but is divisible by 100 (100 = T) then it is also divisible by 4 (4 = T), so FTF is not in the table.^ "A century year, that is, a year which ends in two zeroes 1800 , 1900 , 2000 , etc., is not a leap year unless it is also evenly divisible by 400.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ In this calendar, every fourth year is a leap year except century years that are not divisible by 400.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ The Gregorian reform to the calendar altered the rule for determining if a year should be a leap-year by stating that centenary years should only be leap-years if they were divisible by 400.
• The Calendar, Leap Years and the Year 2000 AD 10 January 2010 11:57 UTC chemistry.csudh.edu [Source type: FILTERED WITH BAYES]

4 100 400 (4 and not 100) or 400 4 and (not 100 or 400)
T T T T T
T T F F F
T F F T T
F F F F F

### Leap day

A pocket calendar from the year 2008 showing February 29
.February 29 is a date that usually occurs every four years, and is called leap day.^ How many days are in a leap year?
• WikiAnswers - How many days are in a leap year 10 January 2010 11:57 UTC wiki.answers.com [Source type: General]

^ A year which has a February 29 is, by definition, a leap year .
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ Why is every fourth year called a 'leap year?'
• What year is the next leap year? 10 January 2010 11:57 UTC www.funtrivia.com [Source type: General]

.This day is added to the calendar in leap years as a corrective measure, because the earth does not orbit around the sun in precisely 365 days.^ A leap year has 366 days, vs a non-leap year which has 365.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

^ When does leap year occur?
• Time, Weights, and Measures - When Does Leap Year Occur?: Science Fact Finder 10 January 2010 11:57 UTC www.enotes.com [Source type: FILTERED WITH BAYES]

^ Leap year days in febuary?
• WikiAnswers - How many days are in a leap year 10 January 2010 11:57 UTC wiki.answers.com [Source type: General]

.The Gregorian calendar is a modification of the Julian calendar first used by the Romans.^ This calendar was used before the Gregorian calendar was adopted.
• The Leap Year and Leap Day - February 29 10 January 2010 11:57 UTC www.timeanddate.com [Source type: News]
• CodeProject: Is it Leap Year? ....Using Javascript.. Free source code and programming help 10 January 2010 11:57 UTC www.codeproject.com [Source type: General]
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ We use the Gregorian Calendar today.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

^ Besides the Julian and Gregorian calendars, what other calendars have been used?
• Time, Weights, and Measures - When Does Leap Year Occur?: Science Fact Finder 10 January 2010 11:57 UTC www.enotes.com [Source type: FILTERED WITH BAYES]

.The Roman calendar originated as a lunisolar calendar and named many of its days after the syzygies of the moon: the new moon (Kalendae or calends, hence "calendar") and the full moon (Idus or ides).^ Here’s the history: The Romans originally had a 355-day calendar.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

^ The Roman calendar had 355 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ Later, when Julius Caesar reformed the calendar, and instituted the practice of an additional day every four years, he decreed the sixth day before the Kalendae of March be doubled.
• The Old Joel on Software Forum - Leap Year Date Problems 10 January 2010 11:57 UTC discuss.fogcreek.com [Source type: General]

.The Nonae or nones was not the first quarter moon but was exactly one nundinae or Roman market week of nine days before the ides, inclusively counting the ides as the first of those nine days.^ Today is one of those days.
• Collider 10 January 2010 11:57 UTC www.collider.com [Source type: FILTERED WITH BAYES]

^ Instead of having a single leap day every four years (as we do now) the Egyptians allowed the one-quarter day accumulate.
• humor To Leap Or No?: The Story of Leap Year - Humor Computers & Internet 10 January 2010 11:57 UTC www.bytebackonline.com [Source type: General]

^ Each 29.5-day cycle amounted to one month, and the first versions counted only 10 months in a year.
• Leaping Lizards, It’s Leap Year! at Ray Fowler .org 10 January 2010 11:57 UTC www.rayfowler.org [Source type: FILTERED WITH BAYES]

.In 1825, Ideler believed that the lunisolar calendar was abandoned about 450 BC by the decemvirs, who implemented the Roman Republican calendar, used until 46 BC. The days of these calendars were counted down (inclusively) to the next named day, so February 24 was ante diem sextum Kalendas Martii ("the sixth day before the calends of March") often abbreviated a.^ After 100 years, the calendar would be off by about 24 days.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ This calendar was used before the Gregorian calendar was adopted.
• The Leap Year and Leap Day - February 29 10 January 2010 11:57 UTC www.timeanddate.com [Source type: News]
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ The Roman calendar had 355 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

d. VI Kal. Mar. .The Romans counted days inclusively in their calendars, so this was actually the fifth day before March 1 when counted in the modern exclusive manner (not including the starting day).^ The Roman calendar had 355 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The modern 365-day calendar is based on the time it takes for the Earth to revolve around the sun.
• Leap year trips up computers - MassLive.com 10 January 2010 11:57 UTC www.masslive.com [Source type: News]

^ Every second year, the Roman calendar included an > extra month called Mercedonius of 22 or 23 days to keep up with the > solar year.

[4]
.The Republican calendar's intercalary month was inserted on the first or second day after the Terminalia (a.^ Rome had been following a calendar that first had 10 months of 304 days.
• Leap Year Isn't a Bust - Ted Pedas, YSU Planetarium Lecturer 10 January 2010 11:57 UTC www.farrellareaschools.com [Source type: General]

^ Every second year, the Roman calendar included an > extra month called Mercedonius of 22 or 23 days to keep up with the > solar year.

^ Leap years, in which we add a day every 4 years, don't account completely for the discrepancies between reality and our arbitrary calendar Every so often, a second has to be added.
• Zune chokes on leap-year bug - Macworld Forums 10 January 2010 11:57 UTC forums.macworld.com [Source type: FILTERED WITH BAYES]

d. VII Kal. Mar., February 23). The remaining days of Februarius were dropped. .This intercalary month, named Intercalaris or Mercedonius, contained 27 days.^ A leap year (or intercalary year) is a year containing one or more extra days (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronized with the astronomical or seasonal year.
• Leap Year Math | Googol Learning 10 January 2010 11:57 UTC www.googolpower.com [Source type: General]

^ Therefore, the Romans introduced an extra month at no additional charge called Mercedonius, which contained 22 or 23 days and was added every second year.
• humor To Leap Or No?: The Story of Leap Year - Humor Computers & Internet 10 January 2010 11:57 UTC www.bytebackonline.com [Source type: General]

^ "Year containing some intercalary period, especially a Gregorian year having a 29th day of February instead of the standard 28 days.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

.The religious festivals that were normally celebrated in the last five days of February were moved to the last five days of Intercalaris.^ Do you celebrate on the last day of February, because that's when you were born???
• Honor Society of Leap Year Day Babies 10 January 2010 11:57 UTC feb29.leapyearday.com [Source type: General]

^ Science Videos More Science Videos » We all know that February is a funny month -- every four years it has one extra day (February 29) instead of the normal 28 days.
• HowStuffWorks "How could the year 2000 be a leap year when 1900 was not?" 10 January 2010 11:57 UTC science.howstuffworks.com [Source type: News]

^ Linguistics also play a part here - why “leap?” The proper term for the inserted day apparently is an “intercalary day”, but it results in all celebrated festivals “leaping” one day forward .

.Because only 22 or 23 days were effectively added, not a full lunation, the calends and ides of the Roman Republican calendar were no longer associated with the new moon and full moon.^ The Roman calendar had 355 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ Therefore, as the hours accumulated over the centures, an extra day was occasionally added to the calendar, and over time the practice became more or less official.
• Leap Year Trivia, Leap Day Fun Facts & History 10 January 2010 11:57 UTC www.chiff.com [Source type: General]

^ Every second year, the Roman calendar included an > extra month called Mercedonius of 22 or 23 days to keep up with the > solar year.

.The Julian calendar, which was developed in 46 BC by Julius Caesar, and became effective in 45 BC, distributed an extra ten days among the months of the Roman Republican calendar.^ Julius caesar created the modern calendar in 46 bc, which is distinct from the astronomer’s Julian calendar .
• leap year : Java Glossary 10 January 2010 11:57 UTC mindprod.com [Source type: FILTERED WITH BAYES]

^ Julius Caesar added 30 and 31 days to consecutive months.
• List of Leap Years 10 January 2010 11:57 UTC www.buzzle.com [Source type: FILTERED WITH BAYES]

^ The Roman calendar had 355 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

.Caesar also replaced the intercalary month by a single intercalary day, located where the intercalary month used to be.^ A leap year (or intercalary year) is a year containing one or more extra days (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronized with the astronomical or seasonal year.
• Leap Year Math | Googol Learning 10 January 2010 11:57 UTC www.googolpower.com [Source type: General]

^ The Gregorian calendar is closely based on the Julian calendar, which was introduced by Julius Caesar in 45 BC. The Julian calendar featured a 12-month, 365-day year, with an intercalary day inserted every fourth year at the end of February to make an average year of 365.25 days.
• Leap Year Explained — Infoplease.com 10 January 2010 11:57 UTC www.infoplease.com [Source type: General]

^ February was further despoiled by Augustus Caesar who also purloined a day so as to make `his' month, August, also have 31 days.
• The Calendar, Leap Years and the Year 2000 AD 10 January 2010 11:57 UTC chemistry.csudh.edu [Source type: FILTERED WITH BAYES]

.To create the intercalary day, the existing ante diem sextum Kalendas Martii (February 24) was doubled, producing ante diem bis sextum Kalendas Martii.^ The leap day is inserted in the days of Ayyam-i-ha , a period of intercalary days devoted to fasting preparations, hospitality, charity and gift-giving from February 26 to March 1.
• Leap Year in Other Calendars 10 January 2010 11:57 UTC www.timeanddate.com [Source type: General]

^ "Year containing some intercalary period, especially a Gregorian year having a 29th day of February instead of the standard 28 days.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

^ February 29 LEAP Year - LEAP Day © 1995-2008 Leap Day (February 29th) @ February 29 LEAP Year - LEAP Day (an extra day / 24 hours / 1440 minutes / 86,400 seconds) Why???
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

.Hence, the year containing the doubled day was a bissextile (bis sextum, "twice sixth") year.^ Therefore, the Romans introduced an extra month at no additional charge called Mercedonius, which contained 22 or 23 days and was added every second year.
• humor To Leap Or No?: The Story of Leap Year - Humor Computers & Internet 10 January 2010 11:57 UTC www.bytebackonline.com [Source type: General]

^ So every 400 years, we DON'T NOT add the extra day (double negative intended).
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ So, if calendar years contained 365 days they would drift from the actual year by about 1 day every 4 years.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

.For legal purposes, the two days of the bis sextum were considered to be a single day, with the second half being intercalated, but common practice by 238, when Censorinus wrote, was that the intercalary day was followed by the last five days of February, a.^ A person born on February 29 may we call a leapling and none leap years these people celebrate their birthdays on the last day of February or the first day of March.
• What Is a Leap Year Video – 5min.com 10 January 2010 11:57 UTC www.5min.com [Source type: FILTERED WITH BAYES]

^ But if there's a February 29 between the two dates, the day of the week "leaps" forward an extra day: January 1, 2009, will be on a Thursday (instead of Wednesday).
• February 29, 2008 Is Leap Day! | Scholastic.com 10 January 2010 11:57 UTC www2.scholastic.com [Source type: General]

^ Still not exact, but the calendar year won't vary by more than a day from its current place in the seasonal (astronomical) year in two hundred centuries - close enough for practical purposes.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

d. VI, V, IV, III and pridie Kal. Mar. (which would be those days numbered 24, 25, 26, 27, and 28 from the beginning of February in a common year), i.e. the intercalated day was the first half of the doubled day. All later writers, including Macrobius about 430, Bede in 725, and other medieval computists (calculators of Easter), continued to state that the bissextum (bissextile day) occurred before the last five days of February.
.Until 1970, the Roman Catholic Church always celebrated the feast of Saint Matthias on a.^ The reform was accepted, immediately in most Roman Catholic countries, more gradually in Protestant countries, and in the Eastern Church the Julian calendar was retained into the 20th cent.
• Leap Year FAQ 10 January 2010 11:57 UTC incompetech.com [Source type: News]

^ St Matthias moves (for Roman Catholics) from Feb 24 to Feb 25.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ Feast day (alternate) of Pope St Hilarius , 46 th Roman Catholic pope , from 461 to 468 ; commemorated today or February 28 .
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

d. VI Kal. .Mar., so if the days were numbered from the beginning of the month, it was named February 24 in common years, but the presence of the bissextum in a bissextile year immediately before a.^ In common years, the calendar has 365 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ There are 29 days this year in the month of February.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

^ In a leap year an extra day is added to the month of February.
• This is Leap Year - Marriage - Families.com 10 January 2010 11:57 UTC marriage.families.com [Source type: General]

d. VI Kal. Mar. shifted the latter day to February 25 in leap years, with the Vigil of St. Matthias shifting from February 23 to the leap day of February 24. Other feasts normally falling on February 25–28 in common years are also shifted to the following day in a leap year (although they would be on the same day according to the Roman notation). .The practice is still observed by those who use the older calendars.^ Many countries, especially in Asia still use such calendars.
• The Leap Year and Leap Day - February 29 10 January 2010 11:57 UTC www.timeanddate.com [Source type: News]

^ So, still, there are some who, in this way, are "born out of due time," through the Holy Spirit's use even of the preacher's weakness and apparent failure.
• A Leap Year Sermon 10 January 2010 11:57 UTC www.spurgeon.org [Source type: Original source]

^ (Footnote: The Russian Orthodox Church still uses the Julian calendar.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

## Julian, Coptic and Ethiopian calendars

.The Julian calendar adds an extra day to February in years evenly divisible by four.^ In common years, the calendar has 365 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The 1/4 part adds up to a whole day every four years.
• WikiAnswers - Why is there a leap year 10 January 2010 11:57 UTC wiki.answers.com [Source type: General]

^ This extra day is added to the calendar on February 29th.
• NIST Time and Frequency FAQ 10 January 2010 11:57 UTC tf.nist.gov [Source type: FILTERED WITH BAYES]

.The Coptic calendar and Ethiopian calendar also add an extra day to the end of the year once every four years before a Julian 29-day February.^ A year which has a February 29 is, by definition, a leap year .
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ By adopting a leap year with an extra day every four years, the calendar year would drift much less.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ So every 400 years, we DON'T NOT add the extra day (double negative intended).
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

.This rule gives an average year length of 365.25 days.^ This results in an average year of 365.24 days.
• Catholic Calendar Leap Year Page 10 January 2010 11:57 UTC www.easterbrooks.com [Source type: News]

^ And that gives us an average of 365.24225 days per year over a 4.000 year period.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ If a leap day is added every fourth year, the average length of the calendar year is 365.25 days.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

.However, it is 11 minutes longer than a real year.^ Some years are longer than others.
• ok50.com | Top 50 Leap Year Facts, our Leap Year feature is full of ideas and offers to get your man! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

^ The Romans however, still based months on the moon cycles which was 11 days off of the actual year and they ended up 80 days off on their schedule.
• The Leap Year Demystified | Popular Science 10 January 2010 11:57 UTC www.popsci.com [Source type: General]

^ We've made the calendar year longer than it ought to be.
• Calendars and Leap Years | Loren on the Art of MATLAB 10 January 2010 11:57 UTC blogs.mathworks.com [Source type: General]

.This means that the vernal equinox moves a day earlier in the calendar every 131 years.^ This means that the calendar will not be off by a full day until the year 4915 A.D. .
• Catholic Calendar Leap Year Page 10 January 2010 11:57 UTC www.easterbrooks.com [Source type: News]

^ After every 128 years, that was a full day.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ In common years, the calendar has 365 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

## Revised Julian calendar

.The Revised Julian calendar adds an extra day to February in years divisible by four, except for years divisible by 100 that do not leave a remainder of 200 or 600 when divided by 900. This rule agrees with the rule for the Gregorian calendar until 2799. The first year that dates in the Revised Julian calendar will not agree with those in the Gregorian calendar will be 2800, because it will be a leap year in the Gregorian calendar but not in the Revised Julian calendar.^ In this calendar, every fourth year is a leap year except century years that are not divisible by 400.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ A year which has a February 29 is, by definition, a leap year .
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ By adopting a leap year with an extra day every four years, the calendar year would drift much less.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

.This rule gives an average year length of 365.242222… days.^ This results in an average year of 365.24 days.
• Catholic Calendar Leap Year Page 10 January 2010 11:57 UTC www.easterbrooks.com [Source type: News]

^ And that gives us an average of 365.24225 days per year over a 4.000 year period.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ The length of a seasonal year is 365.24219878 days (more or less).
• Calendars and Leap Years | Loren on the Art of MATLAB 10 January 2010 11:57 UTC blogs.mathworks.com [Source type: General]

This is a very good approximation to the mean tropical year, but because the vernal equinox year is slightly longer, the Revised Julian calendar does not do as good a job as the Gregorian calendar of keeping the vernal equinox on or close to March 21.

## Chinese calendar

.The Chinese and Korean calendars are lunisolar, so a leap year has an extra month, often called an embolismic month after the Greek word for it.^ 'Leap Year Day was added to the calendar when February was the last month of the year.
• babyworld - your baby - special events - leap year babies 10 January 2010 11:57 UTC www.babyworld.co.uk [Source type: General]

^ The years that are not leap years are called common years.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ A year which is not a leap year is called a common year.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

.In the Chinese calendar the leap month is added according to a complicated rule, which ensures that month 11 is always the month that contains the northern winter solstice.^ According to the Gregorian calendar, there are 3 rules to calculate if it is leap year or not a leap year.
• Teaching About Leap Year 2008: Classroom Activities to Explain the Extra Day in February 10 January 2010 11:57 UTC classroom-activities.suite101.com [Source type: News]

^ Sometimes, however, a "leap month" is added to keep the calendar from drifting.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ 'Leap Year Day was added to the calendar when February was the last month of the year.
• babyworld - your baby - special events - leap year babies 10 January 2010 11:57 UTC www.babyworld.co.uk [Source type: General]

.The intercalary month takes the same number as the preceding month; for example, if it follows the second month (二月) then it is simply called "leap second month" (simplified Chinese: 闰二月traditional Chinese: 閏二月pinyin: rùn'èryuè).^ A Leap Year (or intercalary year) is a year containing one or more extra days (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year.
• 2008 A Leap Year | Eyedea Lab 10 January 2010 11:57 UTC www.eyedealab.com [Source type: FILTERED WITH BAYES]

^ The second change was to reform the calendar to prevent slippage in the future; and we use that same calendar system today, called the Gregorian.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ Leap into the unknown: Simply clear your diary and leave the day wide open to do whatever the mood takes you - and enjoy!
• February 29th: Your leap-year day extravaganza - Telegraph 10 January 2010 11:57 UTC www.telegraph.co.uk [Source type: General]

## Hebrew calendar

.The Hebrew calendar is also lunisolar with an embolismic month.^ A Leap Year (or intercalary year) is a year containing one or more extra days (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year.
• 2008 A Leap Year | Eyedea Lab 10 January 2010 11:57 UTC www.eyedealab.com [Source type: FILTERED WITH BAYES]

^ The solar year does not have a whole number of lunar months either, so a lunisolar calendar must have a variable number of months in a year.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ The Hebrew calendar is lunar, and it periodically inserts extra months to make up the shortfall.
• Calendars and Leap Years | Loren on the Art of MATLAB 10 January 2010 11:57 UTC blogs.mathworks.com [Source type: General]

.This extra month is called Adar Alef (first Adar) and is added before Adar, which then becomes Adar Bet (second Adar).^ After 3 years, such a lunar calendar would be off by a whole month, so the Assyrians added an extra month from time to time to keep their calendar in synchronization with the seasons.
• HP OpenVMS systems - Year 2000 10 January 2010 11:57 UTC h71000.www7.hp.com [Source type: FILTERED WITH BAYES]
• Leap Year Explained 10 January 2010 11:57 UTC www.edu-cyberpg.com [Source type: FILTERED WITH BAYES]

^ This extra day was added to the month of February because it was the shortest month in the year already.
• Leap Year History & Cartoon Fun from Brownielocks. 10 January 2010 11:57 UTC www.brownielocks.com [Source type: General]

^ These six hours added up to roughly one full extra day every four years, so it was tacked on to the end of February, every so-called bissextile year.
• Leap year babies forever young 10 January 2010 11:57 UTC www.canada.com [Source type: News]

.According to the Metonic cycle, this is done seven times every nineteen years (specifically, in years 3, 6, 8, 11, 14, 17, and 19).^ A leap month is added 7 times out of every 19 years.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ Since the Jewish holidays are supposed to be season-related (they were originally harvest festivals), the calendar adjusts by adding a whole month about every three years - actually, 7 times every 19 years.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ The Jewish calendar is based on a lunar cycle - that is, each month is based on the interval, about 29 or 30 days, from new moon to new moon - so it's short by about 11 days per solar year.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

.In addition, the Hebrew calendar has postponement rules that postpone the start of the year by one or two days.^ You can have one day a year."
• February 29@Everything2.com 10 January 2010 11:57 UTC everything2.com [Source type: General]

^ What Year and day are we in according to the 360 Calendar?
• Bible Prophecy Calendar: 360 day/year 10 January 2010 11:57 UTC www.360calendar.com [Source type: FILTERED WITH BAYES]

^ In common years, the calendar has 365 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

.These postponement rules reduce the number of different combinations of year length and starting days of the week from 28 to 14, and regulate the location of certain religious holidays in relation to the Sabbath.^ This year it only has 28 days.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

^ The length of the year is 365.242199 days.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ Stuff not related to Leap Year Day .
• Leap Year Revolution : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]
• Mystery of Leap Year solved! : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]

.In particular, the first day of the Hebrew year can never be Sunday, Wednesday or Friday.^ The astronomical year, the time taken for the Earth to complete its orbit around the Sun, is about 365.242 days, or, to a first approximation, 365.25 days.
• leap year (calendar) -- Britannica Online Encyclopedia 10 January 2010 11:57 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ "Leap Year Day" babies will never have a "Golden Birthday" !
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

^ Leap Year Day will also be Shrove Tuesday in 2028, and Ash Wednesday in 2096.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

This rule is known in Hebrew as "lo adu rosh" (לא אד"ו ראש), i.e. "Rosh [ha-Shanah, first day of the year] is not Sunday, Wednesday or Friday" (as the Hebrew word adu is written by three Hebrew letters signifying Sunday, Wednesday and Friday). Accordingly, the first day of Pesah (Passover) is never Monday, Wednesday or Friday. This rule is known in Hebrew as "lo badu Pesah", which has a double meaning — "Pesah is not a legend", but also "Pesah is not Monday, Wednesday or Friday" (as the Hebrew word badu is written by three Hebrew letters signifying Monday, Wednesday and Friday).
One reason for this rule is that Yom Kippur, the holiest day in the Hebrew calendar, must never be adjacent to the weekly Sabbath (which is Saturday), i.e. it must never fall on Friday or Sunday, in order not to have two adjacent Sabbath days. However, Yom Kippur can be on Saturday.
.Years consisting of 12 months have between 353 and 355 days.^ Years are 354 or 355 days.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ Each year consists of 12 lunar months.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ The Jewish calendar is based on a lunar cycle - that is, each month is based on the interval, about 29 or 30 days, from new moon to new moon - so it's short by about 11 days per solar year.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

.In a k'sidra ("in order") 354-day year, months have alternating 30 and 29 day lengths.^ Month lengths also differ from Gregorian; 6×31 then 5×30 then 29 or 30 days.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ Years are 354 or 355 days.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ Leap Year Day February 29 .
• Leap Year Revolution : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]
• Mystery of Leap Year solved! : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]

.In a chaser ("lacking") year, the month of Kislev is reduced to 29 days.^ Leap Year Day February 29 .
• Leap Year Revolution : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]
• Mystery of Leap Year solved! : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]

^ There are 29 days this year in the month of February.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

^ February 29 LEAP DAY - LEAP YEAR .
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

.In a malei ("filled") year, the month of Cheshvan is increased to 30 days.^ The Jewish calendar is based on a lunar cycle - that is, each month is based on the interval, about 29 or 30 days, from new moon to new moon - so it's short by about 11 days per solar year.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ The original Roman 355 day calendar had an extra 22-day month every few years to maintain the correct seasonal changes.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]
• ok50.com | It's Leap Year... & You Know What That Means! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

^ A Leap Year (or intercalary year) is a year containing one or more extra days (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year.
• 2008 A Leap Year | Eyedea Lab 10 January 2010 11:57 UTC www.eyedealab.com [Source type: FILTERED WITH BAYES]

.13-month years follow the same pattern, with the addition of the 30-day Adar Alef, giving them between 383 and 385 days.^ This month gives us an extra day this year.
• Career Coach: Leap Year Thoughts about Time | AWN | Animation World Network 10 January 2010 11:57 UTC www.awn.com [Source type: General]

^ The Jewish calendar is based on a lunar cycle - that is, each month is based on the interval, about 29 or 30 days, from new moon to new moon - so it's short by about 11 days per solar year.
• The Straight Dope: Why do we have leap years? 10 January 2010 11:57 UTC www.straightdope.com [Source type: General]

^ The original Roman 355 day calendar had an extra 22-day month every few years to maintain the correct seasonal changes.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]
• ok50.com | It's Leap Year... & You Know What That Means! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

## Islamic calendar

.The observed and calculated versions of the Islamic calendar do not have regular leap days, even though both have lunar months containing 29 or 30 days each in no apparent order.^ Month lengths also differ from Gregorian; 6×31 then 5×30 then 29 or 30 days.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ February 29 LEAP DAY - LEAP YEAR .
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

^ Leap-Month Cycles of the 360-day Calendar of the Prophets .
• Bible Prophecy Calendar: 360 day/year 10 January 2010 11:57 UTC www.360calendar.com [Source type: FILTERED WITH BAYES]

.However, the tabular Islamic calendar used by Islamic astronomers during the Middle Ages and still used by some Muslims does have a regular leap day added to the last month of the lunar year in 11 years of a 30-year cycle.^ Likewise, the 'normal' 360-day year of the Prophetic Calendar adds a 30-day leap month at regular intervals, with that year having 3 9 0 days.
• Bible Prophecy Calendar: 360 day/year 10 January 2010 11:57 UTC www.360calendar.com [Source type: FILTERED WITH BAYES]

^ The solar year does not have whole number of days, but a calendar year must have a whole number of days.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ The last leap second was added Dec.
• Leap Year birthdays pose some dilemmas, some funLeap Year birthdays pose some dilemmas, some fun on Feb. 29» The Commercial Appeal 10 January 2010 11:57 UTC www.commercialappeal.com [Source type: News]

Leap months in the Islamic calendar were prohibited in year 10 AH or 632 CE, both in Muhammad's Farewell Sermon and in two verses of the Qur'an revealed in year 10 AH:
.
The number of months with Allah has been twelve months by Allah's ordinance since the day He created the heavens and the earth.^ The rotation of the earth around its own axis relative to the sun is the basis for our day, the rotation of the earth around the sun defines the year, and the rotation of the moon around the earth relative to the sun defines the month (at least it did originally).
• Calendars and Leap Years | Loren on the Art of MATLAB 10 January 2010 11:57 UTC blogs.mathworks.com [Source type: General]

^ (A "Golden Birthday" is when your age matches the number of the day of the month you were born on.
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

^ The earth has used the Gregorian calendar since 1582 with an error of 27 seconds that adds up to one day every 3,236 years.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

.Of these four are known as sacred; That is the straight usage, so do not wrong yourselves therein, and fight those who go astray collectively as they fight against you collectively.^ So you must collect those books.
• Glenn Beck and his crazy 5,000 Year Leap - Crunchy Con 10 January 2010 11:57 UTC blog.beliefnet.com [Source type: General]

^ It's just nice to run into those who see it that way rather than the usual majority who say "Oh you poor thing!
• A PERSONAL BIO OF 10 January 2010 11:57 UTC www.raenelldawn.com [Source type: FILTERED WITH BAYES]

^ Be finicky – they’ll try harder to please you in four years.
• All I Need To Know About Leap Year Birthdays, « Funny Jokes 10 January 2010 11:57 UTC jokesfunny.wordpress.com [Source type: FILTERED WITH BAYES]

.But know that Allah is with those who are pious.
Verily the transposing (of a prohibited month) is an addition to Unbelief: The Unbelievers are led to wrong thereby: for they make it lawful one year, and forbidden another year, of months forbidden by Allah and make such forbidden ones lawful.^ Make it one year in four."
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ After 3 years, such a lunar calendar would be off by a whole month, so the Assyrians added an extra month from time to time to keep their calendar in synchronization with the seasons.
• Leap Year Explained 10 January 2010 11:57 UTC www.edu-cyberpg.com [Source type: FILTERED WITH BAYES]

^ Everyone just cares about making the most money the fastest way possible, and whether their profits one year are higher than the previous year.
• By the Numbers - February 2009: Wish It Were A Leap Year Edition — Autoblog 10 January 2010 11:57 UTC www.autoblog.com [Source type: General]

The evil of their course seems pleasing to them. .But Allah guideth not those who reject Faith.^ If there are those who get all chilled by the mention of the Christian faith, then don't read it if it offends you.
• Amazon.com: Customer Reviews: 5000 Year Leap: 30 Year Anniversary Edition with Glenn Beck Foreword 10 January 2010 11:57 UTC www.amazon.com [Source type: General]

^ For those who love taking giant leaps of faith in trying to put all the pieces together in one sitting!
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

(Qur'an 9:36-37)

## Calendars with leap years synchronized with Gregorian

.The Indian National Calendar and the Revised Bangla Calendar of Bangladesh organise their leap years so that the leap day is always close to February 29 in the Gregorian calendar.^ A year which has a February 29 is, by definition, a leap year .
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ There is 1 extra day in a leap year, on Feb 29.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

^ Leap day occurs to synchronize the solar year with the calendar year.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

This makes it easy to convert dates to or from Gregorian.
.The Bahá'í calendar is structured such that the leap day always falls within Ayyám-i-Há, a period of four or five days corresponding to Gregorian February 26 – March 1. Because of this, Baha'i dates consistently line up with exactly one Gregorian date.^ What exactly is a leap day?
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ Without the leap year correction, every four years the calendar year falls behind the seasons by one day.
• Calendars and Leap Years | Loren on the Art of MATLAB 10 January 2010 11:57 UTC blogs.mathworks.com [Source type: General]

^ February 29 LEAP DAY - LEAP YEAR .
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

The Thai solar calendar uses the Buddhist Era (BE), but has been synchronized with the Gregorian since AD 1941.

## Hindu calendar

.In the Hindu calendar, which is a lunisolar calendar, the embolismic month is called adhika maasa (extra month).^ The original Roman 355 day calendar had an extra 22-day month every few years to maintain the correct seasonal changes.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]
• ok50.com | Top 50 Leap Year Facts, our Leap Year feature is full of ideas and offers to get your man! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]
• ok50.com | It's Leap Year... & You Know What That Means! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

^ The Babylonians had a lunar calendar, but found they had to add extra months to get the calendar back in sync with the seasons.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

^ The solar year does not have a whole number of lunar months either, so a lunisolar calendar must have a variable number of months in a year.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

.It is the month in which the sun is in the same sign of the stellar zodiac on two consecutive dark moons.^ The rotation of the earth around its own axis relative to the sun is the basis for our day, the rotation of the earth around the sun defines the year, and the rotation of the moon around the earth relative to the sun defines the month (at least it did originally).
• Calendars and Leap Years | Loren on the Art of MATLAB 10 January 2010 11:57 UTC blogs.mathworks.com [Source type: General]

.Adhika maasa occurs once every two or three years, compensating for the approximately eleven fewer days per year in twelve lunar months than the solar calendar.^ The solar year does not have whole number of days, but a calendar year must have a whole number of days.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ The Calendar Year is about 11 days shorters than the Seasonal Year.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ Leap day occurs to synchronize the solar year with the calendar year.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

.Thus, Hindu festivals tend to occur within a given span of the Gregorian calendar.^ The links below show the calendars with the days dropped when the change to the Gregorian calendar occurred: The Gregorian calendar was first adopted in Italy, Poland, Portugal and Spain in 1582.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ Thus, the year 2800 will be a leap year in the Gregorian calendar but not in the Soviet calendar.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

.For example: the No Moon during Diwali festival tends to occur between October 22 and November 15. Buddhist calendars in several related forms (each a simplified version of the Hindu calendar) are used on mainland Southeast Asia in the countries of Cambodia, Laos, Thailand, Myanmar (formerly Burma) and Sri Lanka.^ In the Gregorian calendar, which is the calendar used by most modern countries, the following rules decide which years are leap years: Every year divisible by 4 is a leap year.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ Why are there no leap year days in the 13 Moon Calendar?
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ Wed, October 15, 2008 (No comments) .
• Happy Leap Year | Sovereign Grace Church 10 January 2010 11:57 UTC www.sovgracefairfax.org [Source type: FILTERED WITH BAYES]

The Hindu Calendar also known as Vikram Samvat is used in Nepal as National Calendar. .All the official work is done based on this calendar.^ All of the calendars mentioned above are known as solar calendars, because their length is based on the revolution of the earth around the sun.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

The calendar followed in some parts of South India (mainly in Tamil Nadu) is solar. .It has a leap year every four years.^ "Leap year every fourth year" rule.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ From what I have heard it happens every four years, but I can't remember when the last leap year was.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

^ Like thousands across the country, Matthew was born on a Leap Day -- those extra 24 hours that extend February calendars once every four years.
• Leap Year birthdays pose some dilemmas, some funLeap Year birthdays pose some dilemmas, some fun on Feb. 29» The Commercial Appeal 10 January 2010 11:57 UTC www.commercialappeal.com [Source type: News]

## Iranian calendar

.The Iranian calendar also has a single intercalated day once in every four years, but every 33 years or so the leap years will be five years apart instead of four years apart.^ Without the leap year correction, every four years the calendar year falls behind the seasons by one day.
• Calendars and Leap Years | Loren on the Art of MATLAB 10 January 2010 11:57 UTC blogs.mathworks.com [Source type: General]

^ On leap year it has 29.That 1/4 day that is not counted every year is made up on leap year which is every four years.
• Leap year? - Yahoo! Answers 10 January 2010 11:57 UTC answers.yahoo.com [Source type: General]

^ "Every year divisible by 4 is a leap year.
• Time (leap year??) - comp.lang.ruby | Google Groups 10 January 2010 11:57 UTC groups.google.com [Source type: FILTERED WITH BAYES]

.The system used is more accurate and more complicated, and is based on the time of the March equinox as observed from Tehran.^ From Roman times until the second half of the Second Millennium, the Julian Calendar was used, more or less accurately, through the bulk * of Christendom; it was then superseded over a period by the Gregorian Calendar.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

^ The Calendar FAQ says that the Islamic Calendar relies on an observed full moon; except that Saudi Arabia and neighbours now use one based on an accurate calculation of whether Sun or Moon sets first on the 29th of a month.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

.The 33-year period is not completely regular; every so often the 33-year cycle will be broken by a cycle of 29 or 37 years.^ Every 4 years, we have a Feb 29.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ Date: Thu, 1 Sep 2005 05:37:33 +0900 Local: Wed, Aug 31 2005 4:37 pm Subject: Re: Time (leap year??
• Time (leap year??) - comp.lang.ruby | Google Groups 10 January 2010 11:57 UTC groups.google.com [Source type: FILTERED WITH BAYES]

^ Other leap years facts The Gregorian calendar has a 400 year long cycle and the calendars have the same week days -- February 29, 2008 is a Friday and February 29, 2408 is a Friday.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

[citation needed]

## Long term leap year rules

.The accumulated difference between the Gregorian calendar and the vernal equinoctial year amounts to 1 day in about 8,000 years.^ After 100 years, the calendar would be off by about 24 days.
• What exactly is a leap year? - Yahoo!7 Answers 10 January 2010 11:57 UTC au.answers.yahoo.com [Source type: General]

^ It would take 3,000 years for the Gregorian calendar to gain one whole day.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The Calendar Year is about 11 days shorters than the Seasonal Year.
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

This suggests that the calendar needs to be improved by another refinement to the leap year rule: perhaps by avoiding leap days in years evenly divisible by 8,000.
.(The most common such proposal is to avoid leap years in years evenly divisible by 4,000.[5] This is based on the difference between the Gregorian calendar and the mean tropical year.^ In common years, the calendar has 365 days.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The years that are not leap years are called common years.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ A year must be evenly divisible by 4 to be considered a leap year.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

.Others claim, erroneously, that the Gregorian calendar itself already contains a refinement of this kind.^ Rome changed to the Gregorian Calendar in 1582, Britain and Colonies in 1752 (other places changed at various dates from 1582 to perhaps 1924).
• Merlyn - Leap Years - J R Stockton 10 January 2010 11:57 UTC www.merlyn.demon.co.uk [Source type: FILTERED WITH BAYES]

[6])
.A system of 128-year-based leap years has been proposed,[7] and it can be adopted directly without any modification to current leap year calculations until the year 2048 because no year between now and 2048 is divisible by 128. This rule gives a mean year of 365 + 1/4 − 1/128 = 365.2421875 days, which is 365 days, 5 hours, 48 minutes and 45 seconds, or one second short of the mean tropical year.^ Leap year in the past was just another day until Feb.
• Daily Herald | Leap Year babies tell their stories 10 January 2010 11:57 UTC www.dailyherald.com [Source type: General]

^ "Every year divisible by 4 is a leap year.
• Time (leap year??) - comp.lang.ruby | Google Groups 10 January 2010 11:57 UTC groups.google.com [Source type: FILTERED WITH BAYES]

^ Re: second Leap Day.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

However, there is little point in planning a calendar so far ahead because over a timescale of tens of thousands of years the number of days in a year will change for a number of reasons, most notably:
1. Precession of the equinoxes moves the position of the vernal equinox with respect to perihelion and so changes the length of the vernal equinoctial year.
2. Tidal acceleration from the sun and moon slows the rotation of the earth, making the day longer.
.In particular, the second component of change depends on such things as post-glacial rebound and sea level rise due to climate change.^ You understand, acknowledge and agree that we have the right to delete, re-format and/or change your Postings in any manner that we may determine (although you will not be responsible for any such changes made).
• Leap Year Trailer | SPIKE 10 January 2010 11:57 UTC www.spike.com [Source type: General]
• Leap Year - Theatrical Trailer | SPIKE 10 January 2010 11:57 UTC www.spike.com [Source type: General]

^ Notice of material changes will be posted on the Site's homepage and/or will be provided by e-mailing you or notifying you upon login about these changes; the form of such notice is at our discretion.
• Leap Year Trailer | SPIKE 10 January 2010 11:57 UTC www.spike.com [Source type: General]
• Leap Year - Theatrical Trailer | SPIKE 10 January 2010 11:57 UTC www.spike.com [Source type: General]

^ We will post or display notices of material changes on the Site and/or e-mail you or notify you upon login about these changes; the form of such notice is at our discretion.
• Leap Year Trailer | SPIKE 10 January 2010 11:57 UTC www.spike.com [Source type: General]
• Leap Year - Theatrical Trailer | SPIKE 10 January 2010 11:57 UTC www.spike.com [Source type: General]

.We can't predict these changes accurately enough to be able to make a calendar that will be accurate to a day in tens of thousands of years.^ The only hitch is that the current calendar may need an overhaul a few thousand years from now due to the changing length of the year at the equator.
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

^ So, if calendar years contained 365 days they would drift from the actual year by about 1 day every 4 years.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ In many calendars, this is done by adding to a common year of 365 days, an extra day ( leap day or intercalary day ): this makes a leap year of 366 days.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

.In the English speaking world, it is a tradition that women may propose marriage only on leap years.^ Greek couples still believe this old superstition as one in five couples bound for marriage wait until the Leap Year passes before exchanging vows.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The only hitch is that the current calendar may need an overhaul a few thousand years from now due to the changing length of the year at the equator.
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

^ But now they got 4 years to fix this problem I can only say, “Thank god it’s no leap year” .
• Zune Freeze Result of Leap Year: Microsoft | Gadget Lab | Wired.com 10 January 2010 11:57 UTC www.wired.com [Source type: General]

.While it has been argued that the tradition was initiated by Saint Patrick or Brigid of Kildare in 5th century Ireland, it is dubious as the tradition has not been attested before the 19th century.^ It is believed this tradition was started in 5th century Ireland when St.Bridget complained to St. Patrick about women having to wait for so long for a man to propose.
• ok50.com | Top 50 Leap Year Facts, our Leap Year feature is full of ideas and offers to get your man! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

^ Apparently this tradition began in the 5th century with an obscure, upstart Irish priest named St. Bridget.
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

^ This tradition originates in Ireland in the 5th century, when St. Bridget convinced St. Patrick to allow one day that a woman could propose.
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

[8] .Supposedly, a 1288 law by Queen Margaret of Scotland (then age five and living in Norway), required that fines be levied if a marriage proposal was refused by the man; compensation ranged from a kiss to £1 to a silk gown, in order to soften the blow.^ The drink was often accompanied by a marriage proposal from a woman to a man.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

^ The man may, of course, refuse but, by tradition, he should soften the blow by providing a kiss, one pound currency and a pair of gloves (some sources say a silk gown).
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ A document from 1288 shows that Scotland passed a law allowing ladies to propose marriage on Leap Day.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

[9] Because men felt that put them at too great of a risk, the tradition was in some places tightened to restricting female proposals to the modern leap day, February 29, or to the medieval leap day, February 24.
.According to Felten: "A play from the turn of the 17th century, 'The Maydes Metamorphosis,' has it that 'this is leape year/women wear breeches.'^ Once I get based the fact that the movie is basically saying women have to sit and patiently wait to be proposed to…or they can wait until Leap Year and propose themselves.
• Amy Adams 'Leap Year' trailer: More than just another witless rom-com? Or...not? | EW.com 10 January 2010 11:57 UTC popwatch.ew.com [Source type: FILTERED WITH BAYES]
• Amy Adams 'Leap Year' trailer: More than just another witless rom-com? Or...not? | EW.com 10 January 2010 11:57 UTC popwatch.ew.com [Source type: FILTERED WITH BAYES]

^ The Scots (the Celts with kilts) were a little more on the ball and in 1288 passed a law that permitted women to propose to a man of their choice and marry in a "leap year".
• LET'S HEAR IT FOR LEAP YEAR! 10 January 2010 11:57 UTC www.squidoo.com [Source type: General]

^ "A century year, that is, a year which ends in two zeroes 1800 , 1900 , 2000 , etc., is not a leap year unless it is also evenly divisible by 400.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

.A few hundred years later, breeches wouldn't do at all: Women looking to take advantage of their opportunity to pitch woo were expected to wear a scarlet petticoat—fair warning, if you will."^ Even the trailer ticks all the boxes, and gives away a fair bit (also, you can apparently drive from Cardiff to Dublin), but when looking at the talent involved this becomes something else.
• Leap Year - Cinema, Movie, Film Reviews - Review by entertainment.ie | Entertainment.ie Ireland 10 January 2010 11:57 UTC entertainment.ie [Source type: FILTERED WITH BAYES]

^ And on MSNBC's "ZeitGeist," Willie Geist takes advantage of the extra day to pander to you with new video of a cute baby polar bear and other diversions.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

^ Look Before You LEAP YEAR I'd want one Take it back +13 Share: Facebook Twitter email .
• Shirt.Woot : Derby #30: Leap Year 10 January 2010 11:57 UTC shirt.woot.com [Source type: News]

[10]
.In Denmark, the tradition is that women may propose on leap day February 24 and that refusal must be compensated with 12 pairs of gloves.^ Leap Year was the traditional time that women could propose marriage.
• ok50.com | Top 50 Leap Year Facts, our Leap Year feature is full of ideas and offers to get your man! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

^ Leap Year Day February 29 .
• Leap Year Revolution : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]
• Mystery of Leap Year solved! : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]

^ February 29 LEAP DAY - LEAP YEAR .
• LEAP YEAR - LEAP DAY @ February 29 10 January 2010 11:57 UTC www.mystro.com [Source type: General]

.In Finland, the tradition is that if a man refuses a woman's proposal on leap day, he should buy her the fabrics for a skirt.^ It is believed this tradition was started in 5th century Ireland when St.Bridget complained to St. Patrick about women having to wait for so long for a man to propose.
• ok50.com | Top 50 Leap Year Facts, our Leap Year feature is full of ideas and offers to get your man! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

^ Granted, it doesn’t look nearly as bad as Confessions of a Shopaholic , but it’s not much better, and the premise is typically frogballs heinous: She goes to Wales or something, where it’s apparently cool to propose to a man on Leap Day.
• Leap Year Trailer | Pajiba - Scathing Reviews for Bitchy People 10 January 2010 11:57 UTC www.pajiba.com [Source type: FILTERED WITH BAYES]

^ Also, to celebrate leap day , you can either propose to your beau (if you're a woman) or try out the Project Leap Year Web site, which gives you the opportunity to share your leap-day dreams.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

.In Greece, it is believed that getting married in a leap year is bad luck for the couple[citation needed].^ There is a Greek superstition that claims couples have bad luck if they marry during a leap year.
• ok50.com | Top 50 Leap Year Facts, our Leap Year feature is full of ideas and offers to get your man! 10 January 2010 11:57 UTC www.ok50.com [Source type: General]

^ "There is a Greek superstition that claims couples have bad luck if they marry during a leap year.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ Greek couples still believe this old superstition as one in five couples bound for marriage wait until the Leap Year passes before exchanging vows.
• Once Upon A Leap Year 2008 | Lifescript.com 10 January 2010 11:57 UTC www.lifescript.com [Source type: General]

.Thus, mainly in the middle of the past century, couples avoided setting a marriage date in a leap year.^ Now we have a Leap Year date problem.
• You Had Me At EHLO... : Exchange Server 2007 and leap year day Feb 29 2008... 10 January 2010 11:57 UTC msexchangeteam.com [Source type: General]

^ Thus 2000 was a leap year, 1900 was not.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

^ Apparently one in five engaged couples in Greece will avoid planning their wedding during a leap year."
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

## Birthdays

.A person born on February 29 may be called a "leapling" or a "leaper" [11].^ I wish I was born on February 29 .
• Leap Year Revolution : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]
• Mystery of Leap Year solved! : LEAP THIS 10 January 2010 11:57 UTC www.cafepress.com [Source type: General]

^ "In the comic operetta The Pirates of Penzance , Frederic, born on February 29, was not apprenticed to a band of pirates until his 21st birthday , in theory until he is 84 years old.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ Maybe you dazzle us with a startling treatment of the words "February 29".Maybe you sloganeer: "People born on leap day do it one-quarter as often."
• Shirt.Woot : Derby #30: Leap Year 10 January 2010 11:57 UTC shirt.woot.com [Source type: News]

In common years they usually celebrate their birthdays on February 28 or March 1.
For legal purposes, legal birthdays depend on how local laws count time intervals. For example, in Taiwan, in common years, the legal birthday of a leapling is February 28, so a Taiwanese leapling born on February 29, 1980, legally reaches 18 years old on February 28, 1998.
.
If a period fixed by weeks, months, and years does not commence from the beginning of a week, month, or year, it ends with the ending of the day which precedes the day of the last week, month, or year which corresponds to that on which it began to commence.^ And while we're at it, leap day aside, exactly why DOES February have only 28 days when some months have thirty one?
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

^ Therefore, even though this year 2000 ends in '00', it remains a leap year , and today is the added leap day.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ The solar year does not have whole number of days, but a calendar year must have a whole number of days.
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

.But if there is no corresponding day in the last month, the period ends with the ending of the last day of the last month.^ We have Julius and Gregory to thank for Friday's leap day, the extra day that's periodically tacked onto the month of February.
• The science of leap time - Cosmic Log - msnbc.com 10 January 2010 11:57 UTC cosmiclog.msnbc.msn.com [Source type: General]

^ Why are there no leap year days in the 13 Moon Calendar?
• *�*  Wilson's Almanac free daily ezine | Book of Days | February 29 | Leap Year Day bissextile intercalation Sadie Hawkins Day February 29 10 January 2010 11:57 UTC www.wilsonsalmanac.com [Source type: General]

^ There is no need of any set period for this all-important matter; time, is no element in the case.
• A Leap Year Sermon 10 January 2010 11:57 UTC www.spurgeon.org [Source type: Original source]
• A Leap Year Sermon  -- C. H. Spurgeon 10 January 2010 11:57 UTC www.biblebb.com [Source type: Original source]

[12]
In some situations, March 1 is used as the birthday in a non-leap year since it is the day following February 28.
.Technically, a leapling will have fewer birthdays than their age in years.^ I have one for you, last year Chrysler had fewer recalls than any of the big six sales leaders - GM, Toyota, Ford, Chrysler, Honda, and Nissan.
• By the Numbers - February 2009: Wish It Were A Leap Year Edition — Autoblog 10 January 2010 11:57 UTC www.autoblog.com [Source type: General]

.This phenomenon is exploited when a person claims to be only a quarter of their actual age, by counting their leap-year birthdays only.^ On the "off" years I actually have two birthdays.
• Daily Herald | Leap Year babies tell their stories 10 January 2010 11:57 UTC www.dailyherald.com [Source type: General]

^ I actually don’t have a lot to say about this quadrennial idiosynracy, other than to say that I feel badly for those people who only get a birthday one year our of every four.
• Happy Leap Year | Sovereign Grace Church 10 January 2010 11:57 UTC www.sovgracefairfax.org [Source type: FILTERED WITH BAYES]

^ They delight in announcing whenever possible, my leap age and the fact that I turned 10 the same year as my daughter and I turn 11 the same year as my son.
• Daily Herald | Leap Year babies tell their stories 10 January 2010 11:57 UTC www.dailyherald.com [Source type: General]

In Gilbert and Sullivan's 1879 comic opera The Pirates of Penzance, Frederic the pirate apprentice discovers that he is bound to serve the pirates until his 21st birthday rather than until his 21st year.

## References

1. ^ Royal Observatory, Greenwich: Leap years
2. ^ USNO (U.S. Naval Observatory): Leap Years
3. ^ E.G. Richards, Mapping time: The calendar and its history, p. 240, ISBN 0-19-282065-7.
4. ^ Thomas Hewitt Key, Calendarium (1875)
5. ^ Google search for 4000-year rule.
6. ^ The Straight Dope with 4000-year rule
7. ^ Julian Date Calculator
8. ^ The Privilege of Ladies by Barbara Mikkelson
9. ^ Virtually no laws of Margaret survive. Indeed, none concerning her subjects are recorded in the twelve volume Acts of the Parliaments of Scotland (1814–75) covering the period 1124–1707 (two laws concerning young Margaret herself are recorded on pages 424 & 441–2 of volume I).
10. ^ The Bissextile Beverage - WSJ.com
11. ^ Hall, Christina (2008-02-29), "Leap year babies hop through hoops of joy, pain of novelty birthday" (), Detroit Free Press, retrieved 2008-02-29
12. ^ Article 121 of the Civil Code Part I General Principles of the Republic of China in effect in Taiwan

# Simple English

A leap year comes once every four years. It is a year in which an extra day is added to the Gregorian calendar which is used by most of the world.

An ordinary year has 365 days. A leap year has 366 days. The extra day is added to the month of February. In an ordinary year, February has 28 days. In a leap year, it has 29 days. This extra day is called a leap day.

In a leap year, January, April, and July, all start on the same day of the week.

In a leap year, February starts and ends on the same day.

A leap year can always be evenly divided by four. For example, 2008 is a leap year. But a year is not a leap year if it can be evenly divided by 100, but cannot also be evenly divided by 400. This is why 1700, 1800, and 1900 are not leap years, but 2000 was.

We have leap years because instead of 365 days, the Earth really takes a few minutes less than 365-1/4 days (365.24219) to go completely around the Sun.

Without leap years, the seasons would start one day earlier on the calendar every four years. After 360 years, spring (which usually begins on March 21) would begin on December 21 (which is when winter presently begins).

A number of countries use a lunar calendar (based on the moon). They have leap years when they add an extra lunar month. Different calendars add the extra month in different ways.

# Citable sentences

Up to date as of December 24, 2010

Here are sentences from other pages on Leap year, which are similar to those in the above article.