|Can we stop with this glasses thing already? It only made sense in the 200Xs.|
Since we're celebrating our need to go out and buy a new calendar today, I thought I'd do a quick post on how our system of numbering days evolved to make this day such a significant one. Most of the world uses the Gregorian calendar, which is a revision of the old Julian calendar, which was a revision of earlier Roman calendars.
The first Roman calendar was probably a lunar calendar. It was made up of 10 months, each lasting the length of a lunar cycle, and a few non-organized winter days were added between each year.
Numa Pompilius organized those winter days into January and February. Did you ever wonder why our months with numeric prefixes - Sept, Oct, Nov, Dec = 7, 8, 9, 10 - are actually our 9th, 10th, 11th and 12th months? The names and numbers used to correspond, until Numa stuck those two new months at the beginning of the year, throwing everything off.
The Julian calendar was the result of Julius Caesar's reform, designed to line the months up with the solar year. It was 365 1/4 days long - 365 days with an extra day every four years. 2012 is one of these leap years with the extra day in February.
That sounds remarkably like the Gregorian calendar, doesn't it? What did Pope Gregory do to change that? It turns out that the solar year is actually about 11 minutes shorter than 365 1/4 days. This meant that over time, the solar season and the calendar would shift slightly, so that solar landmarks like the Spring equinox would have different dates as that 11 minute discrepancy added up each year. Because the Spring equinox was tied so closely to the celebration of Easter, Pope Gregory didn't like that the date would change. To account for this 11 minute error, Gregory proclaimed that instead of every four years being a leap year, leap years would come every four years EXCEPT for century years, but that every fourth century year would remain a leap year.
Confused? Yeah, I just trust my calendar makers to know what's right. Here's to hoping you have a wonderful 2012 - all 366 days of it!