29 february - a year bissex...what??

We're using a rather barbaric word this February 29: "leap year". But what does it mean?
A leap year is a year of 366 days, recurring every 4 years, with the month of February comprising 29 days... like today!

But... did you know? 

The origins :

February 29 was invented by the Romans, or rather by Caesar! Indeed, it was this famous emperor who came up with the idea of aligning the calendar with the time taken for the planet earth to rotate around the sun, i.e. 365 days + 1 extra day every 4 years.

But why February, you may ask?

Simply because, at the time, February was the last month of the year!

So... we add 1 day every 4 years, right?

Well, almost...

Caesar's calculations were brilliant, but not quite right...

Then came the Gregorian reform, to realign the calendar with the sun... and that's why the last years of the centuries are not leap years! 

"Yes, the rule is little known, but it does exist: the last years of the centuries are not leap years. By deleting a February 29th every 25 occurrences, we can cancel out the discrepancy observed before the Gregorian reform. So why was 2000 a leap year? It's a question of compensation, this time in the other direction. To align with the solar calendar as closely as possible, only three leap years should be eliminated every 400 years. Hence the idea of keeping the February 29th of years divisible by 400 (1600, 2000, 2400, etc...). Not easy, but effective!

The legend of February 29...

On February 29, women go on the attack! 

Irish legend has it that women can propose to men on this day. And if they refused, they had to give her 12 gloves (to hide the fact that she didn't have a ring on her finger).

Gentlemen, be gallant and say yes :-)