So, what the hell is the deal with leap years, anyway? Forget all the crappy traditions and stupid shit on TV. Why is there even a leap year in the first place?
Well, the truth is that time is the single most important thing to the modern mind and yet it is probably the thing we suck at the most. Because time is relative and also complicated. Because our two main sources of relative time – the sun and the seasons – don’t exactly jibe in the way we humans would prefer them to. Because basically, Western Europeans just got lazy and said, “Fuck it. Let’s just add a day every once in a while and call it happy.”
But let’s start with what we think we know about time. Our calendar and watches all agree: there are twenty four hours in a day, which is defined by the time it takes the Sun to rise twice as seen on Earth. 365 of those days combine to make a year, which more or less relates to the time it takes the Earth to revolve around the Sun.
It is more or less true that a day is 24 hours. Why 24? Why not, say, 10, a number we seem to like a lot in the first place? Well, one theory has it that the ancient Babylonian method of counting on one’s fingers was essentially base-12 and only because there’s that many segments of your four non-thumb fingers. But I’ll leave that for you to read on your own.
As for the year? Well, that’s where our problem lies. You see: the ancients basically took the day, which was well-understood, and counted up the number of them that worked out to a year, based on the sun’s return to the same point in the sky. This is what is known as a tropical or solar year.
But right off the bat, they knew they were slightly off. About 1/4 of a day off, to be more specific. 365.2422 to be entirely too specific about it. Because the Sun, Earth and Stars don’t really give a rat’s ass about our counting system. In fact, if you track the Earth’s travel 360 degrees around the Sun using the only accurate model – basing it on the Earth’s position relative to certain fixed stars – you end up with a very different number, which is known as the sidereal year.
So, who invented the leap year? None other than Julius Caesar. Previously, Roman calendars used a 22 day month every other year. But to keep things more in line, Caesar opted for a single additional day every fourth year, to be added to month of Februarius. That’s February for us.
And nothing’s changed since the time of Caesar because we procrastinate a lot. And because every four years, its fun to tell this story over again.