All Wound Up

I like time. If I wake up in the middle of the night, the first thing I do is check the time to orient myself. I am consistently early to events. I place a (probably unhealthy) meaning upon numbers and dates and cycles. Time is such a beautiful way of organization.

So I find leap day a little annoying. First of all, 29 is a prime number. I can’t do anything with that. February should be regularly getting 30 days anyway; take one back from July and August. Second, it’s embarrassing that we can’t have a more accurate calendar have to insert “make up days” every few years. It feels very sloppy.

It’s actually anything but that, however. When Pope Gregory XIII began his calendar reform in the sixteenth century, it was because the calendar we were using (the Julian calendar) had drifted far off from the solar observations. The Roman calendar followed a mix of lunar and solar observations. Intercalary days or months would occasionally be called to adjust as needed. In 45 BC, Julius Caesar established the Julian calendar which consistently treated a year as 365 days. However, a solar rotation is 365 days, 6 hours. Over the centuries, that difference adds up, so he also included a rule for leap years: one leap day every four years.

But over time, the small differences of this calendar from the solar rotation also became noticeable. The Julian calendar drifted from the solar rotation by about three days every 400 years. The Council of Trent in 1545 called for a reform the calendar that would set the date of the spring equinox to what it had been at the time of the First Council of Nicaea in 325 and that a new calendar prevent “drift” and allow for accurate scheduling of Easter.

Pope Gregory XIII consulted astronomers and mathematicians to create a calendar that would align our human methods of time-keeping with the movement of the planet—the first day of spring would be on the spring equinox, the first day of summer would be on the summer solstice, etc. The pope released the new calendar on Feb. 24, 1582 in the papal bull “Inter gravissimas” (“Among the Most Serious”).

The Gregorian calendar first removed 10 days of “drift” that had occurred due to the Julian calendar. In the Catholic world, people went to bed on Oct. 4, 1582 and woke up on Oct. 15, 1582. (It would take centuries for some countries to adopt the new calendar and dating system. Greece adopted it in 1923.)

Next, the Gregorian calendar revised the rules for a leap year: a leap year would fall in years divisible by 4 unless divisible by 100 unless divisible by 400. So turns of the century do not have a leap day unless the year is divisible by 400 (1800-no leap day, 1900-no leap day, 2000-leap day, 2100-no leap day). This weird exception to an exception makes the average calendar year 365.2425 days long, more closely approximating the 365.2422-day solar year determined by the Earth's revolution around the sun. This means the Gregorian calendar is only off by about one day every 3,030 years.

Another correction was the calculation of Easter. Because the calendar had fallen away from actually observance of lunar or solar calendars, the date of Easter was being calculated by differing charts. Pope Gregory clarified that the date of Easter would be based off the new March 21 (spring equinox) as well as Paschal charts. Since Easter is determined by the Sunday after the first full moon after the spring equinox, it requires both solar and lunar calendars. (This is because Easter is tied to Passover, and the Jewish faith determines the date of Passover by a lunisolar calculation: the 14th of Nisan, the beginning of Passover, is the full moon of the first month of spring.) Orthodox Churches still use the Julian dating system in order to determine the date of Easter, often falling a week or two off from the Gregorian date. This year, the Orthodox will celebrate Easter a full 35 days later, on May 5.

You would think given my unsettledness with leap days would mean I’m not fond of the Easter calculation of Easter. But I love it. I love a moveable feast and the reason for its determination. I like that the date itself isn’t as important has the season and the corresponding feasts and the placement of the sun and moon. Because it’s not about the date that Christ died or even the date He rose, it’s about the time spent experiencing the death and resurrection with Him.

All this to say, measuring time is a human construct, like any form of measurement is. We try to exact order. And I like order. Order is beautiful and rhythmic and ties us together. But it can be tricky. And our methods can be flawed. Or improved upon with better science and math. Maybe one day we’ll find a calendar that accounts for tidal acceleration and doesn’t need leap days and still has Easter fall after the spring equinox. Only time will tell.