On This Day

I have come to today's blog post prepared with a little research.
I must confess that I had no idea what I was going to write today. For all I know, nobody cares about this website enough to notice that I'm a day late or something, but I wanted to do something. So I got to thinking about today's date and then the modern calendar system.

The system that I assume we all use (I'm somehow not seeing any readers in Saudi Arabia, Ethiopia, Iran or Afghanistan) is called the Gregorian calendar, named after Pope Gregory VIII (yay for roman numerals at the end of names!) This system has been in use since October 1582. That means that we've been keeping track of the date this way for 434 years, and 105 leap years. Astute mathematicians will notice that this isn't exactly one leap year for every four years. Good observation!

You see, the calendar in use before 1582 gave the year an average length of 365.25 days by adding a leap year every four years. Pope Gregory VIII didn't think two decimal places was good enough. The Catholic church, which measures the date of Easter by the spring equinox, was worried that Easter was drifting, so to speak. Considering there wouldn't be any noticeable difference in Easter's season for quite a while after his lifetime, this makes Pope Gregory VIII rather foresighted, in my opinion.

Anyway, he declared that every exact century would be not a leap year, except for the ones that were multiples of 400. So in 1900 there wasn't a leap year, because centuries are the exception. In 2000 there was a leap year, because every four centuries is an exception to the exception. Incidentally, 2000 was only the second time in the Gregorian calendar that this double-exception was necessary.

The average length of the year is now 365.2425 days, and it's anybody's guess how long it will take for the powers that be to refine that number.

Until next week, let's all be grateful for the time we have.
Ian :)