Happy New Year! Though, it's already a few days ago. Have you ever wondered why the calendar is the way it is? What drove us in the western world to have a 365 day year? Turns out, it’s an interplay between astronomy, religion, and history!
The Most Accurate; The Gregorian CalendarThe calendar we use right now is the Gregorian calendar, so named because it was implemented by Pope Gregory the XIII in 1582. Why would the pope be interested in the calendar?
Well, Easter was traditionally supposed to fall on the Sunday after the first full moon after the Spring Equinox, March 21st. However, it had started slipping later and later behind the solar event. Gregory was worried they were missing Christ’s re-birthday by 10 days. So, he commissioned Italian scientist Aloysius Lilius to fix it and make sure they were on Jesus’ good side.
When they made the switch, the Catholic world jumped forward a full 10 days. And you thought daylight savings was bad. Many non-Catholic countries wouldn’t adopt the Gregorian calendar for hundreds of years still.
Russia switched after their October revolution in 1917, which under the new system, technically began in November.The reason the Gregorian Calendar is more accurate with our solar cycle is because it changed how we approached leap years. It still has a leap year every 4 years, like the Julian Calendar, except for years that are divisible by 100. Except! Except, for years that are divisible by 400.
So, 2000 was a leap year, but 2100 will not be. Why this wonky system for leap years? As it turns out, our revolution around the sun is not a perfect 365 days, but 365 days, 5 hours, 48 minutes and 46 seconds.
Before Julius Caesar became emperor the calendar was all over the place, literally being manipulated by the Roman high priest for political reasons. Sometimes years were lengthened to keep allies in office, sometimes they were shortened to kick rivals out quicker.
Julius Caesar put a stop to that by standardizing the Julian calendar. Introduced in 45 BCE, or what to the romans was 709 as they counted years from the founding of the city of Rome. His calendar had 365 days every year with an extra day every 4.
It still made the average year length 11 minutes and 14 seconds too long, but that wouldn’t be evident until hundreds of years passed. To honor him for reforming the calendar, the Roman senate changed the name of Caesar's birth month to July. They’d honor him again a year later by murdering him on the infamous ides of March.
I always wondered, if Caesar could change the calendar willy nilly, why didn’t he just get rid of March? Way to drop the ball, Caesar. The reason we’re in the year 2015 though and not 2768 is because in 525 Christian Monk Dionysius Exiguus determined that Jesus was born in the Roman year 753, and started counting over again from there. Because of him we get the terms BC for before Christ, and AD, which does not stand for
In the academic and scientific communities, to keep things neutral and welcoming to people of all faiths, you’ll often see the terms BCE and CE for Before Common Era and Common Era.
Of course, the Gregorian Calendar is far from the only calendar in use around the world today! Many calendars from cultures with less pronounced seasons actually rely on the cycles of the moon instead of the Sun. But for predicting the change of seasons, equinoxes, solstices, and when certain constellations will be visible, the Gregorian is the one we prefer for its regularity. At least until 4909, when it’ll be a day ahead.
Have you already blew your New Year's resolution?