It comes every four years without fail. (Well, kinda.) Some people literally mark their calendars in anticipation; others find the whole affair to be impossibly boring. But, whether we like it or not, there’s nothing that we can do to stop it. It’s nearly as certain an occurrence as Christmas visitors overstaying their welcome. Obviously, the quadrennial event to which I am referring is… leap year! If you were thinking that I was talking about the Olympics or presidential elections, you may now repent.
Few things necessitate the warning “Nerd alert!” more than discussions of leap year. Speaking of nerds, NPR is doing a whole series on the topic! In any case, a “common year” is 365 days – plus six hours or so. This extra ¼ of a day over the course of a year is why we have leap years. Feel free to point the finger at the people who created calendars during the past few thousand years without accounting for those “extra” hours.
What would happen if we didn’t account for these hours? According to the Smithsonian Institution, our seasons would eventually be thrown off so much that summer would be in December instead of June! Of course, global warming will eventually do the same thing, so there is that…
That’s not all. The Smithsonian also helps us understand why leap year is not every four years (despite what I suggested above):
“By adding a leap day every four years, we actually make the calendar longer by over 44 minutes. Over time, these extra 44+ minutes would also cause the seasons to drift in our calendar. For this reason, not every four years is a leap year. The rule is that if the year is divisible by 100 and not divisible by 400, leap year is skipped. The year 2000 was a leap year, for example, but the years 1700, 1800, and 1900 were not. The next time a leap year will be skipped is the year 2100.”
In short, we add a 366th day to the Gregorian calendar – which is a slight improvement over the Julian calendar – so as to synchronize the astronomical year with the calendar year. This process of inserting another day is known as “intercalation”. Thus, the technical name for leap year is “intercalary year”. (It’s also called a “bissextile” year, but that moniker makes immature men far too giddy.)
Another solution to this major astronomical problem is to add a 13th lunar month to the lunisolar Hebrew calendar, called Adar Aleph. This addition happens seven times every 19 common years so as to prevent the calendar year from causing seasons to shift. Then there is the as-yet-to-be-adopted Hanke-Henry Permanent Calendar, which adds an entire week to December every six years. That calendar also does away with time zones. There are other permutations, but I don’t want to lose the remaining three people who are still reading at this point.
Needless to say (though I’ll say it anyway), we can’t discuss this hot topic without addressing the elephant in the intercalary room: leap year birthdays. Common years are 52 weeks – plus one day. Thus, if your birthday occurs on a Wednesday, it will generally be on a Thursday the following year. However, during a leap year, your birthday “skips” or “leaps” a day, meaning that it would occur on Friday rather than on Thursday. What does this mean for those who were born on February 29th?
In the original Juian calendar, two days were considered February 24th, so there was no February 29th. The ancient Romans fancied this “solution”, as did the British right up to 1750.) Today, of course, most people recognize February 29th given that the Gregorian calendar is the most world’s most widely used civil calendar. Unfortunately, those who are born on that date don’t get to claim that they’re younger than they actually are – at least once they become responsible adults. But who are we kidding? Those folks will never be responsible adults.
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