Bulletin Q&A Article; Published 1-21-24:
My friend belongs to the Serbian Orthodox Church and they celebrated Christmas on January 7th. Can you explain?
Well actually, the Orthodox Churches do celebrate Christmas on December 25th, but some of them use a different calendar. Most of the world uses the Gregorian calendar, but some of the Orthodox Churches have retained the Julian calendar for celebrating religious feasts and rites. To address this question, we need to look at a little bit of history and a little bit of science.
In about 45 BC, the solar calendar was very far out of sync with the Roman civic calendar. This prompted Julius Caesar to create a new calendar. At that time it was believed that the length of a solar year was 365.25 days. And so Caesar created his new calendar, the Julian calendar, with 365 days with an extra day added every fourth year, what we call leap year. It was a vast improvement.
In the year 325 AD, the Council of Nicea established the movable date of Easter based on a solar-lunar formula. It was determined that Easter would be celebrated on the first Sunday after the first full moon after the vernal (spring) equinox. In 325 AD the vernal equinox would have been on March 21st according to the Julian calendar in effect at the time. It turns out that the length of a solar year was later more accurately determined to be 365.2422 days. It doesn’t seem like much of a difference, but, in effect, too many leap days were being added to the Julian calendar. There was approximately one too many extra days added every hundred years. Fast forward to the papacy of Pope Gregory XIII in the 16th century. Because of the extra leap days that were added over the years, the calendar was once more getting out of sync with the seasons. The vernal equinox was occurring on about March 11th, instead of the 21st, and this was affecting the date of Easter. In 1582, Pope Gregory issued a papal bull establishing a new calendar with a minor change and a major correction. The minor change to the Gregorian calendar was the elimination of the leap day in three of every four century years. For example the year 2000 was a leap year, but 1700, 1800, and 1900 were not leap years. The major correction made in the calendar was the removal of ten days to get everything back in sync. Thursday, October 4, 1582 was followed by Friday, October 15, 1582. This meant that the Julian calendar and the Gregorian calendars immediately disagreed by ten days with another three days of difference added every four hundred years. The pope had no authority outside the Church to change the calendar but many saw the benefit of the changes. The Orthodox Churches that had been separated from Rome were suspicious, and reluctant to follow along. Today, most countries have gradually adopted the Gregorian calendar. It is interesting to note that in North America, the Spanish and French colonies switched to the new calendar immediately, but as a British colony, we didn’t make the switch until 1752. Because of the delay, we had to add eleven days instead of ten to catch up. It must have been terribly confusing in those intervening years.
And that brings us to where we are today. The Julian and Gregorian calendars currently disagree by thirteen days. Many of the Orthodox Churches celebrate Christmas on December 25th according to the Julian calendar which corresponds to January 7th in the more commonly used Gregorian calendar.
There are also discrepancies on the date for celebrating Easter, but that is a slightly different, and more complicated, issue. Maybe that can be addressed in another article closer to Easter.