Sunday, 26 February 2012

Stuff You Didn't Know You Wanted To Know About Leap Years

As you are probably aware, this week brings us a very special day. Yes folks, in three days' time it will not be March, it will in fact still be February. 29th February to be exact. In honour of this shy little day's appearance, I found out some stuff (6 stuffs to be exact) about leap years.

1. The Earth takes 365 days to complete one circuit around the Sun. Well, in theory yes. In reality it actually takes a bit longer (approximately 0.242199 days longer). This means that the calendar year is a teeny bit shorter than the solar year (5 hours, 48 minutes and 46 seconds shorter to be precise). It's this slight discrepancy between a calendar and solar year that result in 29th February making an appearance every once in a while.

2. If we didn't add this extra day every four years, things would start to get a bit squiffy as the solar and calendar years would become increasingly out of sync with each other. After four years, for example, the calendar year would fall behind the solar year by about a day: after 100 years the difference would grow to around 25 days. This is all fine and dandy until you realise that the seasons  would begin to drift and before you knew it, we'd be having Christmas in summer. Shudder.

3. Working out whether it's a leap year or not is pretty simple: there a few ways you can do it.
Number One - check the calendar. If there's a 29th February, it's a leap year. If there's not, it's not.
(Note - the calendar must be a calendar of the year in question. Doesn't work if it's not)
Number Two - work out whether the year can be evenly divided by 4. If it can, then hey presto it's a
leap year (e.g. 2012 divided by 4 = 503 exactly).
Incidentally, if the year can't be evenly divided by 4, the remainder will tell you how many years it
is since the last leap year (e.g. 2013 divided by 4 = 503 remainder 1).
Number Three - befriend someone who was born in a leap year. When he/she turns a multiple of 4
(e.g. 4, 8, 12, 16, 20, 24 etc), it's a leap year.

4. There are two reasons for a leap year being so called (there are probably more, don't sue me).The first of which is that fixed holidays (such as Christmas) 'leap' forward an extra day during a leap year. The second, and my favourite of the two reasons, is that hundreds of years ago, the extra day had no recognition in English law. Essentially, the day was 'leapt over' and ignored.

5. So you know how I said earlier that a year must be evenly divisible by 4 in order to be a leap year? I lied. In order to keep things in line and chugging along nicely, some clever folks decided to get rid of a leap year every few hundred years. This means that, in order for a century year (1900, 2000, 2100 etc.) to be a leap year, it must be evenly divisible by 400.
2000 divided by 400 = 5 (year 2000 was a leap year)
1900 divided by 400 = 4.75 (year 1900 was not a leap year)

6. 29th February is supposedly the one day when a woman can propose to a man. Apparently this is because in ye olden times people believed that, since the leap day had no legal status (see point 4), it was reasonable to assume that tradition had no status either. Women of ye olden times at once rubbed their hands together with glee as they realised that they could take advantage of this assumption by proposing to their partners and breaking with tradition. Take that, tradition!

If that's whet your appetite and you'd like to find out more, here are some websites:
Time And Date
Leap Year Calculator
Info Please

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