# Once in Four Century Event! **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [February 29, 2000, 6:47am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185 "2000-02-29T06:47:00Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [February 29, 2000, 6:47am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/1 "2000-02-29T06:47:00Z")
Happy 00 Leap Day! next one in 400 years! * * * and the stars o’erhead were dancing heel to toe ---
**Author:** ![Sylence](https://avatars.discourse-cdn.com/v4/letter/s/b19c9b/32.png) [@Sylence](https://boards.straightdope.com/u/Sylence)\ **Post date:** [February 29, 2000, 7:44am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/2 "2000-02-29T07:44:00Z")
Actually, the next 00 leap year will be in 100 years, not 400. 25 \* 4 = 100. – Sylence * * * If a bird doesn’t sing, I’ll wait until it sings. - Tokugawa Ieyasu ---
**Author:** ![Kamino\_Neko](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kamino_neko/32/34_2.png) [@Kamino\_Neko](https://boards.straightdope.com/u/Kamino_Neko)\ **Post date:** [February 29, 2000, 7:55am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/3 "2000-02-29T07:55:00Z")
> [@](#): > > Originally posted by Sylence: > \*\*Actually, the next 00 leap year will be in 100 years, not 400. > > 25 \* 4 = 100. > \*\* No it won’t. 2100 is not divisible by 400, but is by 100, and thus isn’t a leap year. * * * _Eschew Obfuscation_ ---
**Author:** ![Sylence](https://avatars.discourse-cdn.com/v4/letter/s/b19c9b/32.png) [@Sylence](https://boards.straightdope.com/u/Sylence)\ **Post date:** [February 29, 2000, 8:11am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/4 "2000-02-29T08:11:00Z")
Uh, let’s see here. . . 2000 is a leap year, right? So 2004 would be a leap year. . . then 2008, then 2012. . . eventually 2088, 2092, 2096, 2100. Right? Or am I really missing something? – Sylence * * * If a bird doesn’t sing, I’ll wait until it sings. - Tokugawa Ieyasu ---
**Author:** ![Kamino\_Neko](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kamino_neko/32/34_2.png) [@Kamino\_Neko](https://boards.straightdope.com/u/Kamino_Neko)\ **Post date:** [February 29, 2000, 8:19am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/5 "2000-02-29T08:19:00Z")
What you’re missing is that, with the 400 year exceptions, Centuries aren’t leap years. 1900 wasn’t a leap year, 2000 is, 2100, 2200, and 2300 won’t be. 2400 will. [http://www.mitre.org/research/y2k/docs/LEAP.html](http://www.mitre.org/research/y2k/docs/LEAP.html) > [@](#): > > The Egyptians called it 365 and left it at that. But their calendar got out of step with the seasons, so that after around 750 years of this they were celebrating The Fourth of July in the middle of the winter. But consider the benefits: here in Boston, Massachusetts, there was all that extra room for picnics and blankets at the Esplanade on the frozen Charles River! > > The Romans wised up and added the leap day every four years to get the 365.25 day Julian year. Much better, but notice that this time the year is longer than it ought to be. The small difference between this and the true length of the year caused the seasons to creep through the calendar once again, only slower and in the other direction. After about 23000 years of this, July Fourth would once again fall in mid-winter. > > Fortunately things never reached that sad state. By 1582 the calendar was about ten days out of whack, so Pope Gregory XIII included the correction that’s still in use today. > > If the year is divisible by 100, it’s not a leap year UNLESS it is also divisible by 400. * * * _Eschew Obfuscation_ ---
**Author:** ![Kamino\_Neko](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kamino_neko/32/34_2.png) [@Kamino\_Neko](https://boards.straightdope.com/u/Kamino_Neko)\ **Post date:** [February 29, 2000, 8:21am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/6 "2000-02-29T08:21:00Z")
Sorry. My phrasing there sounded a little rude. It wasn’t meant to be. ---
**Author:** ![MrKnowItAll](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrknowitall/32/87_2.png) [@MrKnowItAll](https://boards.straightdope.com/u/MrKnowItAll)\ **Post date:** [February 29, 2000, 1:20pm UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/7 "2000-02-29T13:20:00Z")
Yet another possible Y2K problem… ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [February 29, 2000, 1:40pm UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/8 "2000-02-29T13:40:00Z")
BTW, this is the first 00 leap year since they started the 400-year rule. * * * “What we have here is failure to communicate.” – Strother Martin, anticipating the Internet. [www.sff.net/people/rothman](http://www.sff.net/people/rothman) ---
**Author:** ![MtnMan](https://avatars.discourse-cdn.com/v4/letter/m/85e7bf/32.png) [@MtnMan](https://boards.straightdope.com/u/MtnMan)\ **Post date:** [February 29, 2000, 2:13pm UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/9 "2000-02-29T14:13:00Z")
MrKnowItAll said: > [@](#): > > Yet another possible Y2K problem… Actually, there is another Y2K problem that many people don’t know about and it is caused (sort of) by the leap year. Unlike most years there are 54 weeks in 2000. The last year with 54 weeks in it was 1972, well before computer use became wide-spread. Obviously there aren’t 54 full weeks, but there are days in 54 separate calendar weeks this year (one day in the first week of the year, one day in the 54th). This is expected to cause problems with some software that will only take input in 53 calendar weeks because programmers didn’t consider the possibility of a 54 week year. Who knows . . . For more information and a much better explanation see[year2000.com](http://www.year2000.com/y2kcurrent1.html) ---
**Author:** ![Sylence](https://avatars.discourse-cdn.com/v4/letter/s/b19c9b/32.png) [@Sylence](https://boards.straightdope.com/u/Sylence)\ **Post date:** [February 29, 2000, 11:14pm UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/10 "2000-02-29T23:14:00Z")
Well, once again I calmly and confidently post the wrong answer. This is why I stay out of GQ and GD. _siiiigggggghhhhhh_ – Sylence * * * If a bird doesn’t sing, I’ll wait until it sings. - Tokugawa Ieyasu ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [March 1, 2000, 1:12am UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/11 "2000-03-01T01:12:00Z")
> [@](#): > > BTW, this is the first 00 leap year since they started the 400-year rule. um, no, actually - it’s the second. The Gregorian calendar came into force (at least in territories that followed the papal bull) the day after October 4, 1582, which became October 14, 1582. Since 1600 is divisible by both 100 and 400, it was a leap year, the first century leap year under the special rule of the Gregorian calendar. Aside from dropping the 10 days, the next time the Gregorian calendar deviated from the Julian calendar was 1700 - divisible by 100, but not divisible by 400, so not a leap year. * * * and the stars o’erhead were dancing heel to toe ---
**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\ **Post date:** [March 1, 2000, 1:01pm UTC](https://boards.straightdope.com/t/once-in-four-century-event/14185/12 "2000-03-01T13:01:00Z")
Sylence, if you haven’t got it by now, check out the Archives: [Why do we have leap years?](http://www.straightdope.com/mailbag/mleapyr.html) for more on the topic than anyone wants to know.