Jan 1, 2012

The Calendar

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!

15 comments:

  1. Never realized Sept, Oct, Nov, Dec corresponded to a number. I think it would have been more logical to put January and February as the last two months of the year.

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  2. Wow... I never knew about the Sept, Oct, Nov, Dec prefixes, followed by Jan and Feb being the two newest months.

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  3. "Confused?" Yup! but fascinating though!

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  4. interesting read... and we can't forget of all the other calendars of the world!

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  5. Or only 360 day according to the mayans. Just joking that stuff is dumb :)

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  6. Very insightful. I feel a little more prepared for jeopardy if I'm ever a constestant.

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  7. Definitely, Vulcan. I obviously did Gregorian because that's the one most of us are celebrating the new year of, but just clicking through the wiki article (http://en.wikipedia.org/wiki/List_of_calendars) is super interesting. ...Or maybe I just have weird interests.

    Oh yeah BragonDorn, how could I forget? =D Not a bad idea for a post in the vague, general future, so I might steal it!

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  8. Very interesting stuff, didn't know it was so complicated

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  9. I knew some of this, but the rest was quite interesting...Thanks!

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  10. I love reading the history of the western/Gregorian calendar. Nice post!

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  11. yeah.. ive always wondered about the sept, oct, nov, and dec thing.. thanks for clearing it up!

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  12. Thank You! I hope you have a wonderful year too!

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Discuss!