It’s New Year’s Eve. I know I should be excited about this (and I am definitely looking forward to a friend’s party tonight), but I’ve always struggled to find meaning in this particular holiday.

It’s not like we’re celebrating a specific event—like the 4^th of July or the resurrection. We’re not celebrating a honored person—such as George Washington, or St. Valentine. We’re not even marking an astronomical event. The winter solstice was ten days ago on December 21.

Rather, our celebration is based purely on the calendar being what it is. So, why do we celebrate January 1 as the start of a new year?

After all, the Jews don’t. While the first month of the Jewish calendar is Nissan (the month of Passover in the spring), the Jewish New Year occurs in early fall, during Tishri, and that’s when the date changes. (The dates count back to the creation of the world, considered to be the year 1, based on a literal translation of Genesis. We’re currently in the year 5771.)

The Chinese don’t either. For the last 5,600 years, the Chinese new year has begun on the second new moon after the winter solstice.

The Greeks, and then the Romans, had a lunar calendar with ten months and some winter days left over. (That’s where many of our month names come from.) Things were pretty flexible, and various rulers took advantage of that, adjusting the calendar to fit their political aspirations. The first day of the year varied as well, landing on March 15, May 1, and probably July 1. The Romans may have been the first to establish January 1 as the start of the year in 153 BC, although that’s not proven.

Julius Caesar is credited with devising the modern calendar in 46 BC as a reform to the Roman calendar. It was based on there being 365¼ days in a solar year, and it started on January 1.

However, with the rise of Christianity, New Year’s Day didn’t stay fixed at the beginning of January. The Church was upset about the wild pagan parties that traditionally ushered in the new year, so the date was moved around a bit. Throughout the Middle Ages, March 1, March 25, December 25, and the Saturday before Easter were all considered New Year’s Day at some point. January 1 reasserted itself by 1600 AD, although England and Italy didn’t endorse it until around 1750.

Meanwhile, the Julian calendar proved a success for quite a while, but eventually problems arose. It seems there aren’t exactly 365½ days per year—it is actually eleven minutes shorter. Over the years, those eleven minutes per year added up until the calendar was off by ten whole days. This was a major concern for the church in assigning a date to Easter. So, in the 16^th century, the Gregorian calendar was created to fix this problem (by dropping occasional leap years). Although the reform was introduced by Pope Gregory XIII in 1582, there was quite a bit of resistance to this change, and some countries continued to use the Julian calendar well into the 20^th century. In fact, some Orthodox churches still use it for a liturgical calendar to this day. They therefore celebrate the new year on their January 1, which is our January 14.

And where do we get the year 2011 from?

Fifteen hundred years ago, Dionysius Exiguus (a Russian monk who lived around 500 AD) had the bright idea to base the number of the calendar year on the birth of Jesus. That’s great… except we don’t know exactly when He was born. Some scholars fix the date before 4 BC while others argue for 6 AD. Dionysius made an educated guess and we’re still living with the results.

With all these adjustments, calculations, and what amounts to guesswork on the part of the calendar creators, the fact that January 1, 2011 starts tomorrow is really pretty arbitrary. Still, I’m happy to have the day off, and it sure makes a good excuse for a party tonight!