We all know that leap years fall every four years, anyone born on February 29th gets special treats, and that on leap day women are encouraged to propose.
But have you ever wondered why we actually have leap years? Are they just a weird tradition we’ve made up for an excuse for free stuff?
Nope. Leap years are actually pretty important, and play a key role in keeping seasons and our calendars working properly.
This feeds into how years are calculated. One year is measured as the time between the beginning of spring and the next time spring occurs – which is technically not 365 days (as we all tend to think), but 365 days, five hours, 48 minutes and 45 seconds.
That exact figure has been rounded up to 365 days and one quarter by philosophers trying to keep things simple.
And so, to make years easy to keep track of and not have to deal with a quarter of a day every year, every four years we have to add on an extra day to the calendar. Because four quarter days makes one full day. Get it?
If we just ignored that awkward quarter of a day and had a 365 day year, the months would slowly shift in time with the sun, until eventually June would be winter.
Now, leap years are any year that can be divisible by four. Apart from century years, which must be divisible by 400.
And if you’re wondering why February drew the short straw, there’s a (slightly unfair) reason.
It’s because of Julius Caesar and the later Roman Emperor, Caesar Augustus. The calendar created by Julius Caesar left February with 30 days, July (named after Julius) with 31, and August with 29.
But when Augustus came into power, he wanted his month, August, to have more days. So he added two days to his month, taking one from February.And so, every four years we have February 29 – leap day. It’s important.