Happy New Year! 新年快樂 (xīn nián kuài lè)!

Today marks the start of the Year of the Dragon! To celebrate this, I have a guest post from shuripentu, who has previously guest posted here on the subject of the Mid-Autumn Festival. Last year I posted a brief introduction to the Chinese lunisolar calendar, which led to my asking her to do another guest post for this New Year. Shuri is a Canadian of Chinese descent, and a great fan of calendrical systems, mathematics, and footnotes.

Now over to Shuri...

A while back, my mother and I were discussing the Chinese calendar^[1], and I happened to mention that the Hong Kong Observatory has some useful Gregorian-Chinese conversion tables. "What does the Observatory have to do with it?" asked Mum.

The involvement of an observatory in setting a calendar may seem odd to those of us who are used to the purely arithmetically defined Gregorian calendar: the number of days in a year, and the way those days are divided into months, is set by a simple numerical algorithm. That the Gregorian year remains closely synchronised with the actual solar year^[2] is entirely due to the well-chosen numbers involved in the algorithm: there is no need to track the position of the sun or moon, or attempt to match any solar event – an equinox or solstice, say – with any particular Gregorian day.

The Chinese calendar, however, is defined almost entirely by astronomical events, and therefore requires the accurate and precise prediction of when these events will occur. The core requirement of the Chinese calendar is that each month must begin with the day (starting at midnight in Beijing – for astronomical calendars, location is crucial^[3]) containing the new moon. Now if, for example, the moment of a new moon occurs very close to midnight, then correctly determining whether the new month begins on the previous day or the next requires a very good astronomical model, and an error would result in the lengths of both months, and the numbering of all the days in the second month, being incorrect.

Like most calendars, the Chinese calendar aims to remain in sync with the solar year. In order to do so, it divides the solar year into 24 segments called solar terms, each corresponding to 15° of solar longitude. The odd-numbered terms are minor solar terms, and the even-numbered ones are major solar terms. Then, to compute the number and arrangement of the months (of which there are either 12 or 13) in a Chinese calendar year, the following rules are applied:

• The 22nd solar term, 冬至 (Dōng Zhì/"Winter Solstice"), always begins on a day contained in Month 11.
• If there are 13 new moons between a winter-solstice-to-winter-solstice period, then one of those new moons is the start of a leap month. The leap month is selected by finding the first month in this period which does not contain the first day of a major solar term.
• The leap month is given the same number as the month that preceded it; it is a second go at the same month, if you will. For example, the upcoming Chinese calendar year contains 13 months, and the months are numbered: 1, 2, 3, 4, 4 again, 5, 6, 7, 8, 9, 10, 11, 12.^[5]

I find the generational differences in the use of the Chinese calendar interesting. My grandparents now use the Gregorian calendar for everyday things, but still celebrate their birthdays according to the Chinese calendar^[7]; I'm not sure they even know their Gregorian birthdays offhand. (I'd certainly need to look it up, whereas I do know their Chinese birthdays.) My parents, on the other hand, celebrate their birthdays according to the Gregorian calendar, and it's their Chinese birthdays that would need looking up. However, my grandparents don't know offhand what their Chinese zodiac signs^[8] are – it's apparently something their generation didn't pay much attention to – whereas my parents most certainly do. (And nowadays the zodiac signs are everywhere: as cheap trinkets, as not-so-cheap trinkets, and incorporated into all sorts of personalised gubbins.) So while the use of the Chinese calendar as an actual calendar has fallen away, the use of it to provide an aspect of personal identity has increased.

And finally, since this is a food blog, here is the foodstuff which I most strongly associate with Chinese New Year: the traditional tray of sweets.

[Image: A circular tray of sweets, divided into sections, sitting on a red tablecloth.]

On either side of the tray are bowls containing dried seeds of some sort – the internet suggests watermelon. In the centre of the tray are 利是糖 (lì shì táng, which translates roughly as "lucky money candy", since the wrappers resemble the red envelopes in which monetary gifts are given), the one true candy for Chinese New Year. It's just your average boiled sweet really, but you've got to have them, and I think there's only the one company that produces them; they must rake in the profits every winter. I can't identify the rest of the things in that tray, except for the single slice of dried lotus root (it's the thing that resembles a wagon wheel above and to the left of the sweets), but they'll mostly be dried fruits and nuts and suchlike, and they'll all be deliciously sugar-laden.

¹ Disclaimer: I have spent almost all of my life living in non-Chinese-majority countries, so my experiences of things Chinese predominantly reflect my family's particular views and traditions and may therefore be extremely idiosyncratic.

² In this post, I use "solar year" to specifically mean the tropical year, "lunar month" to specifically mean the synodic month, "day" to specifically mean a civil day, and "midnight" to specifically mean local civil midnight.

³ The pedant in me notes that it is not strictly necessary for an astronomical calendar to take location^[4] into account, but I have yet to meet one that does not do so. That way lies wailing and gnashing of teeth.

⁴ The super-pedant in me clarifies that I of course meant location on this planet. Which is Earth. (For now.)

⁵ Note, however, that due to the variable length of the lunar month (presently ranging between 29.27 to 29.84 days, with an average of 29.53 days^[6] – and besides, it is never an integral number of days anyway), the number of days in a Chinese calendar month varies from month to month and year to year. In the above example from 2012-13, the first round of Month 4 has 30 days, but the second round of Month 4 – the leap month – only has 29 days. Next year, Month 4 will have 29 days again, and the year after that, Month 4 will have 30 days.

⁶ Dershowitz, Nachum, and Edward M. Reingold, Calendrical Calculations, 3rd edn (Cambridge: Cambridge University Press, 2008), p. 193. Much of my understanding of the Chinese calendar, and calendrical systems in general, is indebted to this inimitable work; any errors in my understanding are entirely my fault.

⁷ I'd never considered it until now, but the extremely variable nature of the Chinese calendar creates a lot of edge-case birthdays, and I wonder how people with them handle it. For example, any given Chinese calendar month will sometimes have 30 days, but some years it'll only have 29 days – what do people born on the 30th of the month do? I figure they probably just celebrate on the 29th, or the 1st of the next month, but I don't actually know. And leap years don't insert single leap days but entire leap months – and it's not always in the same place either! How do people cope? I should probably ask.

⁸ According to my father – and this is backed up by at least one website on Chinese astrology – the change in zodiac sign occurs not at Chinese New Year as commonly believed, but at the 1st solar term, 立春 (Lì Chūn/"Start of Spring"), which occurs around 4 February. This isn't something most people will know, though, unless they have consulted (or are) a Chinese astrologer.