The dating of the Greek Passover, or Pascha, has plagued theologians for centuries. While other Christians in the West are finishing all their chocolate eggs, for some people Easter is coming – seemingly once again.

By George Sapounidis

Orthodox Christians in some countries, including Greece and Cyprus, celebrate Easter later than most Western countries.

It may seem trivial or… bizarre. But it’s not meant to confuse everyone. It’s all for mathematical reasons.

Mathematics, did you say? My ears just twitched. If you’re not a numbers guy like me, who has a PhD (Pizza Hut Delivery) on the subject, you might as well say: Enough already! Why not just pick a day and be done!

It is complicated!

It mainly comes down to the fact that those who adhere to Greek orthodoxy espouse the calendar devised by Julius Caesar – the Roman general turned dictator – versus the calendar modified by the Pope… Gregory, i.e. then the leader of the Roman Catholic Church. Hmm… come to think of it, they are both Romans!

The fundamental problem that anyone creating a calendar has to face is the fact that it takes the Earth just over 365 days to complete one complete revolution around the sun. Specifically, it takes 365.24219 days. We are talking now!

So if you build a calendar with only 365 days, the seasons will very slowly drift apart with the months. Eventually, Christmas would appear in the middle of summer – chaos!

Enter Caesar! The Julian calendar was a reform of the previous Roman calendar, which was a messy hodgepodge. It came into effect on January 1, 46 BC. AD by edict. It was designed with the help of Greek mathematicians (yes!) and Greek astronomers (yes!) like Sosigenes of Alexandria.

But things were still a little off. There was a leap day every four years, which turned out to be an overcorrection. The average year now had 365.25 days, just over 365.24219. By the 1570s, these slight differences had added up. The calendar was now out of sync with the solar year by about ten days.

Enter Pope Gregory! In 1577 he appointed a commission to solve the problem. It took five years, but they finally found a solution: First, let’s just eliminate those extra 10 days and get back on schedule. Faded away!

Next, let’s modify the leap year system. We will have leap years every four years except the centenary years which are not divisible by 400. So there is a leap year in 2000, but not in 1900 or 1800 or 1700. In summary, the contemporary pope decreed ( not dictated… big difference) that the ten days following October 4 would simply not exist. The next day would be… October 15th.

In other words, the decree was: “Pfft. These 10 days? You will never miss them.

Thereafter, a new calendar would come into effect that would better align the months with the Earth’s journey around the sun. This would correct a mismatch in the ancient Roman calendar, first put in place by Caesar, which caused the months to regularly fall out of step with the seasons.

The current Gregorian calendar, with its complex dance of leap days and leap years, seems utterly unremarkable to those of us in the Western world today. It has a bunch of quirks. Our months are unequal, about 31 days, about 30, plus the monstrosity of February.

By the way, leap days aren’t the only problem for timekeepers. We also have leap seconds to contend with. But that’s a story for another day.

Oh yes, the food! Greeks around the world traditionally eat lamb roasted on a barbecue spit and tsoureki, a sweet Easter bread. They also break their fast with a traditional soup called magiritsa, made with lamb, rice and dill before the main feast begins on Sunday.

And the eggs… oblong spheres filled with hard-boiled egg yolk painted blood red are used as ruthless weapons in a valiant round-table take-no-prisoners challenge to see who can beat the eggs of other invited opponents. No lame milk chocolate in Orthodoxy!

All this to say that Greek Easter can sometimes fall on the same day as Western Easter. It’s not done on purpose and is not meant to confuse anyone. But only by pure and improbable coincidence.
Don’t like math?

I wish you a happy Greek Easter!
Καλό Πάσχα! Καλή Ανάσταση!

George Sapounidis is a Greek-Canadian mathematician who is also a musician, bridging Greek culture with many other cultures in his work.