Chinese New Year Calendrics

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If you’ve worked in the IT field for more than five years, you remember the Y2K bug, and all work associated with it. At the time I was working as a webmonkey/programmer and had to co-ordinate with another programmer who worked with the companies legacy computer system (a DEC/VAX with RMS flat files if you must know). It was our job to make sure all of the programs where the two systems interfaced wouldn’t break when the century changed. Over the next couple months we became friends, and even though we both no longer work there we still talk pretty frequently. Due to the nature of our project we became involved in some calendrics, and I got hooked. Tonight at dinner my 6 year old and wife were trying to understand why some holidays are fixed, and other like Chinese New Year, Easter and Chanukah change so much from one year to the next.

calendars in the ancient days were highly irregular things. However most of them were based on either a lunar, solar or lunisolar calendar. Lunar months are based on the time of one full moon to the next or 29.5 days (29.53059 days for all you sticklers). That creates a problem as days are counted in intergers. So to make things easier they “drop” the half days. Now of course dropping days leads to problems, so they had to figure out a way to get them back in. So they went to a system of alternating 29 and 30 day months. Now the problem lies with how many months to have. If you use 12 months you have too few days (354) and 13 months too many (384). So there still needs to be an adjustment. The Chinese calendar normally has 12 months except during leap year. To calculate when a leap year occurs, you have to count the number of new moons from the winter solstice this year to the winter solstice next year. If there are 13 this is a leap year and you add an extra month. The addition of the extra month is what causes Chinese New Year to “move”.

For all you vocabulary buffs the addition of a leap month or leap day is called intercalation.

Here’s an interesting fact a lot of people don’t know, the first year in the Chinese Calendar is tied to a unique astronomical event. In 1953 BC, the sun, moon, Mercury, Venus, Mars, Jupiter , and Saturn were all visible and in alignment in the sky at sunrise. This was discovered by astronomers at the Jet Propulsion Laboratory (JPL) in 1993 (JPL WEBSITE)

Not bad for a spammer, eh.

BTW that’s a Buff Orpington, thanks DigitalGhost.

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