Enjoy the leaping day

I'm sure most of you will know this, but I've just realized that there's an extra day tacked on to the end of February this year. That's because 2008 is a leap year. So we get an extra day of February this year.

But what exactly is a leap year? I remember from my school days that it's added to the calendar every four years because a solar year is actually 365.25 days long...so we need an extra day to compensate. But that seems so simple. Surely we can find a more detailed (and impressive) explanation. So I consulted Wikipedia which rarely lets me down. And it looks like I was right.

However, some exceptions to this rule are required since the duration of a solar year is slightly less than 365.25 days. Years which are divisible by 100 are not leap years, unless they are also divisible by 400, in which case they are leap years. For example, 1600 and 2000 were leap years, but 1700, 1800 and 1900 were not. Going forward, 2100, 2200, 2300, 2500, 2600, 2700, 2900, and 3000 will not be leap years, but 2400 and 2800 will 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.

Now that's something that I want to have handy to be able to pull out at a moment's notice, just to impress people. Wikipedia is good for stuff like that.

So what else of interest can we find out about a Leap Year?

Here are a few more items, also from the lengthy Wikipedia entry:

- In the English speaking a world, it is a tradition that women may propose marriage only on leap years. 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. 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. Because men felt that put them at too great a risk, the tradition was in some places tightened to restricting female proposals to the modern leap day, 29 February, or to the medieval leap day, 24 February. 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.' 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."

- In Greece, it is believed that getting married in a leap year is bad luck for the couple. Thus, mainly in the middle of the past century, couples avoided setting a marriage date in a leap year.

- A person born on February 29 may be called a "leapling". In common years they usually celebrate their birthdays on 28 February or 1 March.

- For legal purposes, their legal birthdays depend on how different laws count time intervals. In Taiwan, for example, the legal birthday of a leapling is 28 February in common years, so a Taiwanese leapling born on February 29, 1980 would have legally reached 18 years old on February 28, 1998.

- In some situations, March 1 is used as the birthday in a non-leap year since it then is the day just after February 28.

- There are many instances in children's literature where a person's claim to be only a quarter of their actual age turns out to be based on counting only their leap-year birthdays. A similar device is used in the plot of the Gilbert and Sullivan operetta The Pirates of Penzance.

And finally, just to liven up this post a bit, I found an article from PatriotLedger.com in Boston that explains how to leap properly, including a video on the right way to leap presented by a member of the Boston Ballet.

Enjoy.