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Archive for February 29th, 2012

Thirty days hath September,
April, June and November;
February has twenty eight alone,
All the rest have thirty-one
Except in Leap Year, that’s the time
When February’s Days are twenty-nine.
  –  Traditional English rhyme

One year ago today…there was no day.  Because today is Leap Day, which only comes once every four years.  Well, almost every four years; centennial years aren’t leap years unless they’re evenly divisible by 400.  In other words, 2000 and 1600 were leap years, but 1700, 1800 and 1900 were not.  It’s that little difference which caused the Julian calendar to creep ahead; the Roman calculations weren’t quite precise enough to determine that one extra day every four years is just a smidgen too much, so in the Julian calendar centennial years are leap years.  The error was ten days when Pope Gregory XIII ordered it corrected in 1582, but eleven when the British Empire adopted his calendar in 1752 (they had added a leap day in 1700 when they shouldn’t have).  By the time Russia adopted it in 1917 the error had increased by two more days (1800 and 1900); that’s why the Russians celebrate Christmas on January 7th.  And if the Russian Orthodox Church doesn’t switch to the Gregorian calendar by 2101, it will then move to January 8th.

Because it doesn’t occur every year, a February 29th birthday is the only one rarer than mine.  What’s that, you say?  What’s special about my birthday?  Well, a study released last year shows that fewer babies are born on Halloween than on any other day of the common year; 11.3% fewer, as it turns out.  So while roughly 1 person in 365 was born on any given day, only about 1 in 411 was born on Halloween.  Even more interestingly, roughly 1 in 347 are born on Valentine’s Day:

Pregnant women are capable of influencing the timing of their babies’ births, according to a study that shows fewer children are born on Halloween…Dr Rebecca Levy of Yale School of Public Health, who led the study, said Halloween’s associations with death, evil and skeletons might subconsciously put women off giving birth.  “The study raises the possibility that the assumption underlying the term ‘spontaneous birth’, namely, that births are outside the control of pregnant women, is erroneous,” Dr Levy told New Scientist magazine.  She added that a connection between the state of mind of pregnant women and hormone levels could explain the link…

Dr Levy and colleagues analysed data from birth certificates for all births in the US that took place within one week on either side of Valentine’s Day and Halloween between 1996 and 2006.  They found the likelihood of women giving birth on Valentine’s Day was on average 5% higher than on other days during the week before or the week after.  It was 3.6% higher for natural, non-induced births and 12.1% higher for Caesarean section births.  The chance of deliveries occurring on Halloween was on average 11.3% lower than during the days in the week before and after.  This broke down to 5.3% lower for natural, non-induced births, and 16.9% lower for Caesareans…

There has been anecdotal evidence from partners of members of the military suggesting that when fathers are due to return from postings away from home close to the date of birth, their babies sometimes “wait” until their return before being born, [and] a 2003 study carried out in Taiwan showed increases in Caesarean births on auspicious days and decreases on inauspicious days of the Chinese lunar calendar.

I wonder if mothers who are scheduled to give birth on February 29th might also unconsciously influence that one way or another, either to give the child a unique birthday or to avoid one that doesn’t come every year.

So, why does February have only 28 or 29 days anyway?  Couldn’t they have just taken one day each from two of the 31-day months and given them to February so she’d have 30 most of the time?  I’ll leave that one to Cecil Adams of The Straight Dope:

…[In] the 8th century BC…a Roman king by the name of Numa Pompilius established the basic Roman calendar.  [Previously] the calendar covered only ten months, March through December…[(which means “tenth month”)]…July was originally called Quintilis, “fifth,” Sextilis was sixth, September was seventh, and so on…3,000 years ago, not a helluva lot happened between December and March.  The Romans at the time were an agricultural people, and the main purpose of the calendar was to govern the cycle of planting and harvesting.  Numa, however…decided it was going to look pretty stupid if the Romans gave the world a calendar that somehow overlooked one-sixth of the year.  So he decided that a year would have 355 days — still a bit off the mark, admittedly, but definitely a step in the right direction.  [This] was the approximate length of 12 lunar cycles, with lots of leap days thrown in to keep the calendar lined up with the seasons.  Numa also added two new months, January and February, to the end of the year.  Since the Romans thought even numbers were unlucky, he made seven of the months 29 days long, and four months 31 days long.  But Numa needed one short, even-numbered month to make the number of days work out to 355.  February got elected.  It was the last month of the year (January didn’t become the first month until centuries later), it was in the middle of winter, and presumably, if there had to be an unlucky month, better to make it a short one…

Some historians say that when Julius Caesar reformed the calendar (and you can see how badly in need of reformation it was), he made February 29 days long (30 in a leap year).  For his work, the month of Quintilis was renamed “July” in his honor.  When his nephew Augustus became emperor, Sextilis was renamed “August” for him, and some say he stole a day from February to make his month as long as Julius’.  Perhaps, but there’s not really any primary evidence for it (like a calendar chart from Julius’ day showing a 29-day common-year February).  What’s important, though, is that the “renaming months after emperors” thing stopped with Augustus; I’d really hate to have been born in the month of Caligu.

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