The New Year
Published on Jan 1, 2007 at 12:06 am.
5 Comments.
Filed under calendars.
I had been planning on posting about how arbitrary it is to decide to mark time in orbits of the Sun. But, exactly how you compute that is tough, because there are different ways to compute the year. How do you define a complete orbit? Everything that you use for reference is moving, so what defines an orbit? A complete cycle with respect to the stars, a complete cycle of the seasons, the time between perihelions, or what? But, just as I was about to write all that down, I read Phil’s posting about just that topic! So, instead, I thought that I’d write about the “New Year” itself.
Why do we start the year January 1? It hasn’t always been that way. In ancient times, the length of a year wasn’t really fixed, and it certainly wasn’t in sync with Earth’s orbit. A month was a cycle of the Moon’s phases, usually beginning with the New Moon, but the year had no such easy definition or starting point. Instead, they started a year when something interesting happened. So, when the king died — start a year, when the king has a son — start another year, when the neighboring kingdom invaded, start another year. You get the picture. If you lived in interesting times, years were only a few months long. If you lived in peaceful boring times, years might be dozens of months long. Some of the first calendars to follow regular rules with a defined starting point were developed in Mesopotamia. The Babylonian calendar ran with months defined by the cycle of the Moon, and an extra month tossed in as needed in order for the first month of each year to occur about the time of the Vernal Equinox (when the Sun appears to cross the celestial equator heading from south to north).
The early Roman calendar, from which our current calendar derives, began in March, near the Vernal Equinox, and it ran for ten months. This is where some of the month names come from (September means Seventh month, October means Eighth month, November means Nineth month, and December means Tenth month). Eventually, two more months were added, but the year still began March 1. But, the civil calendar ended at the end of the original calender — the end of December. So, eventually the beginning of the year was switched to January 1. Even so, many people continued to celebrate March 1 as New Year’s Day. Finally, in 46BC, Julius Caesar declared a new calendar, the Julian Calendar, that looked much like our current calendar (and just like it after Augustus’ modifications). The new Julian Calendar began January 1. In typical Roman fashion, the new year was celebrated with a drunken party. Eventually, Christianity became the official religion of the Roman Empire. Church officials declared New Year’s celebrations to be pagan rituals with no religious value, so the celebration was banned. January 1 was no longer the beginning of the year. But, when did the year begin, if not January 1?
Well, that became a problem. Different people began picking different markers as the day to start counting the years. For various legal and historical reasons, they wanted to number the years, but you had to have a specific day to increment the year number. Traditionally that had been New Year’s Day. But, if there were no New Year’s Day, what day did you use to increment the calendar year number? Then, to make matters worse, the Roman Empire fell and was fragmented. By the Dark Ages, each part of Europe was using a different date as New Year’s Day. Some had switched back to March 1. A very few used January 1. Most picked Christmas or Easter. Imagine that. December 24, 783 was followed by December 25, 784! Picking Easter as the New Year Day was even trickier, since the date moved around. Some countries used the Vernal Equinox or Autumnal Equinox, a few used the Winter Solstice, and a few used September 1. So, the very same February 18 could be either February 18, 1217, or February 18, 1218, depending upon what country you were in! As you might suspect, this drives historians absolutely nuts trying to reconcile dates in Medieval records!
But, as Phil points out in his post, even defining a year is tricky. If you define the year as one orbit of the Earth about the Sun with respect to distant stars (the sidereal year), you get a year slightly about 365.26 days. But, if you define a year as an equinox to an equinox, you get about 365.24 days. The difference is because the Earth wobbles on its axis — what physicists call precession. But, the Julian calendar, with a leap year every four years, has an average length of 365.25 days. That doesn’t fit with either astronomical year! The end result was that the seasons were slowly shifting through the calendar, so by the Sixteenth Century, the Vernal Equinox was off by over a week from March 21, when it was supposed to occur. That seemed important to the Catholic Church, since Easter is computed as the Sunday following the Full Moon that occurs after March 21. But, if March 21 were not the equinox, then Easter might be a month off. So, after a concerted effort to figure out a fix, a new calendar was decreed by Pope Gregory XIII. By papal decree, October 4, 1582, was followed by October 15, 1582. That put the Vernal Equinox back on March 21. To make the calendar year closer, we now skip 3 leap years every 400 years. So, leap years occur every four years, except centenial years not divisible by 400 (so leap years were skipped in 1700, 1800, and 1900, but the years 1600 and 2000 had leap years). The same decree for the new calendar, which we call the Gregorian Calendar, also set January 1 as a uniform start date for the year. But, of course, not all countries adopted the new calendar right away. England, for example, did not adopt the new Gregorian Calendar until 1752. So, in the early years of the American colonies, the year began March 1, and we did not change to January 1 being New Year Day until the change to the Gregorian Calendar.
So, you can all all that to Phil’s comments about an arbitary starting day to the year!
And, Happy New Year, everyone.
-Astroprof
Mark Smith on January 1, 2007 at 3:39 pm: 1
Happy New Year 2007
mark_smith
Astroprof’s Page » April Fools’ Day on April 1, 2007 at 8:13 am: 2
[…] If you recall my post about New Year’s Day, January 1 has not always been the start of the year. Many countries started the year at different times. A number of countries started the year at the Vernal Equinox (or March 21 when the equinox was supposed to happen under the calendar). So, one day it would be March 20, 1134, and the next day would be March 21, 1135. Other countries started at Easter, or Christmas, and a few January 1. But, as you can imagine, it is silly to start the year in the middle of the month, so those that started at the equinox or Easter eventually moved towards either March 1 or April 1 as the New Year’s Day. April 1 was closer to the original, so that was more popular. And, often the new year was celebrated by a week and a half of fesitivities, so even starting March 21, the festivities ended April 1. […]
Astroprof’s Page » 2007 –> 2008 on December 31, 2007 at 7:10 pm: 3
[…] The Earth has completed one more trip around the Sun since my last New Year’s posting. So, we increment the calendar by one year. January 1 has not always been the date marking a new year, but today it is. You can read my post from last year for more information on that. […]
MSDN Blog Postings » Happy New Year!!! on January 5, 2008 at 11:43 pm: 4
[…] Happy New Year!!!I spent this New Year ’s Eve at Seattle Center watching Space Needle Fireworks. And software glitch delayed Fireworks show.What a great way to begin the new year for a software professional :). Later I spent some time wondering what New year and January 1st means and read http://en.wikipedia.org/wiki/New_Year and http://astroprofspage.com/archives/585 . So Jan 1st is nothing but an arbitrary orbital marker and It took quite a long time before the adoption of the 1 January as the start of the year became widespread. I am very excited as this year is very significant for Microsoft Dynamics Ax and Enterprise Portal. We are going to unveil the next version this year with a very cool new user experience, powerful ASP.net/AJAX/VS.net development tools ,RAD Development tools for Business applications, seamless setup and deployment options, out of the box Role Centers with customization and adaptability features. Starting with Convergence we will hear more about this new version and expect to see great articles, sample codes and tips-n-tricks about Enterprise portal and Role Centers in this blog regularly. ThanksMeyThis post originated from and is provided by the MSDN Blogs RSS feed. The original post of the article can be found here. […]
Astroprof’s Page » Easter Moon on March 21, 2008 at 6:56 pm: 5
[…] But, adding to the complexity is the calendar itself. Most of Christianity uses the Gregorian Calendar. I wrote a little about the Gregorian Calendar at the beginning of last year. The Gregorian Calendar was imposed by Pope Gregory XIII in 1578 in a measure to shift the calendar so that the Vernal Equinox occurs close to March 21 each year. Under the old Julian Calendar, the year was slightly too long, and the equinox drifted away from March 21 by about 3 days every 400 years. It was about ten days off in 1578 when the switch was made. But, long before the Sixteenth Century, there was a schism in the Catholic Church. The Eastern Orthodox Church did not adopt the new calendar imposed by a Roman Catholic pope. In fact, the Eastern Orthodox Church still has not adopted the Gregorian Calendar for ecclesiastical purposes, still using the Julian Calendar. Thus, March 21 in the Julian Calendar occurs almost two weeks after March 21 in the Gregorian Calendar. So, about half the time, as occurs this year, the Eastern Church’s Easter falls a month after the rest of Christianity’s Easter, falling on April 27 this year. Last year was one of the years in which both the Eastern and Western Churches celebrated Easter on the same date, April 8, 2007. The next time that they will fall on the same date will be April 4, 2010. […]