INTERCALATION

Higgledy piggledy,
Emperor Julius
Looked at the calendar,
Saying, “Oh, my!

“If we add one Dies
Intercalarius,
We won’t have winter
Show up in July!”

Today is that rarest of days in the civil calendar: Leap Day, the intercalary day inserted once every four years (except on centennial years not evenly divisible by 400, thanks to Pope Gregory).

That extra day is necessary because the solar year is slightly longer than 365 days. A calendar year has to have a whole number of days, which means that without the occasional intercalation, you eventually end up with the seasons becoming unlinked from the months. Winter in July, that sort of thing. Thus, Leap Day.

The Hebrew calendar doesn’t bother with leap days. Since it is a lunisolar calendar - the months are determined by the moon’s phases while the year is based on the solar year - an entire month is inserted when necessary. That works out to seven leap years every nineteen years. (In case you’re interested, this year (5772) is not a leap year, but last year was.)

I have heard that, in some jurisdictions, it is next to impossible to get a driver’s license with the February 29 date on it. Whether that’s a software issue or a credibility issue, who can say? But it affects the 0.068% of the population - one in every 1461 - that manages to arrive on the planet right on the intercalary day.

How ’bout that for a Useless Observation?