The Original Asian Zodiac 4: The Lunisolar Calendar


Lunisolar Calendar

It’s been awhile, but I remember playing my music on one of these cassettes as a very young girl.  Nowadays, you can’t even find these ribbon cassettes anymore.  Give it a few more decades and nobody will know what they were used for.  In the relatively short time that it took for a technology to become obsolete, it’s no wonder that we no longer use the lunisolar calendar for much of anything, even though it works very well, and is still relevant.

The lunisolar calendar is very old.  It’s so old that most people don’t even know how it works.  Even if they do, they don’t know where the names came from, or even what it means.  That’s to be expected.  It’s been around for a very long time.  It’s so old, most folks don’t even know what the word Tết means, or what, if anything, it has to do with the New Year.

oneIt’s pretty much the same all over the world.  Everyone knows the names of the days of the week, but many don’t know what those names mean.  Monday is moon day.  Tuesday is Tyr’s day.  Wednesday is Wodin’s day.  Thursday is Thors’ day.  Friday is Frige’s day.  Saturday is Saturn day, and Sunday is sun day.

That’s because these names are ancient.  We know it was before the advent of Christianity because otherwise, we would surely have seen Jesus day, or Mary day, or John, Luke, or Matthew days.  But no.  They were mostly Nordic gods with a planet and the moon thrown into the mix for luck.

As I have stated, even though everyone calls the Asian calendar a lunar calendar, it’s actually a lunisolar calendar.  We Viets call it Lịch âm dương which means yin-yang calendar because, you know, we all that and a bag of chips.  LOL.

Well, there is a lot more than that.

The Equinox Tuổi

After the change from a purely Metonic cycle calendar, we still used the  lunar month as the basic unit of measuring months but went on the track of following one spring equinox to the next.  It may sound like the western’s tropical year, but there is a slight distinction.  We do track the equinox, but only to determine the Tuổi, which we celebrate with a designated holiday called the new year Tết Holiday Celebration.

See, this is so damn cool because most people have no idea why we call our age a tuổi, nor do they have a clue why each new year, every single Vietnamese person’s age increases by one year.

girlhandonchinThis means that when someone is asking you mấy tuổi? which means how old are you? They aren’t asking you how long you’ve been on this Earth.  They were asking you how many New Year Tết celebrations you’ve been alive to experience. 

Nobody gives a shit what month you were born in unless he was your resident astrologer, in which case, he would absolutely NOT ask you for your tuổi.  He would ask you for the minute, hour, day, month, and year of your birth.

For the general public, that’s TMS (too much sharing).  if you were alive after the first of the new year, you automatically got one year older.  End of story.

This is not that disruptive except if you were born in the last month of the previous year.  You would be barely one month old, but would be considered two years old, as the new year passes.  This is because the Vietnamese confers the 9 months 10 days inside the womb as the real age of the baby, and assigns a full year as the age of the child at birth.

You come out of your mom, all wet and sticky, and BOOM, you’re a brand new one-year-old.  Then, when the new year comes, since everyone gets a new year bump in age, so does your poopy one-month-old ass.  It’s quite annoying actually.  I know because it happened to me.  I was, for a very short amount of time, a two-year-old newborn.

The Solstice Niên Kỳ

The second part of the calendar has to do with the solar aspects of the lunisolar calendar.  We call those the Niên, which follows the solar year, from one December solstice to the next, and therein lies the problem of time drift.

lime slicesTo try and mitigate the drift issue, we split up the Niên into 24 even slices.  We call the slices tiết khí, which literally means time-spans of chi, or time-slices of chi. After 24 Tiết, you get one Tết.

And that’s why we call Vietnamese New Year, Tết.

For each time-span, there is a set amount of chi attributed to it.   You see, my ancient peeps were really not measuring the duration of time, but rather the unit of chi, because as we have demonstrated, time speeds up and slows down, depending on gravity’s effects on the Earth as it approaches the sun, or recedes from the sun (see my previous post The Original Asian Zodiac 3: The Math…It’s Always the Math for more details on Kepler’s second law).  So even back then, they knew that time was not constant, but they figured out that we are always gonna get the same amount of chi, regardless.

It’s an ancient word, going back to the days when my ancestors were still measuring volumes of chi per time slices, using the Metonic cycle.  The Chinese people don’t call New Year Tết because…well, I don’t think they were that concerned with measuring chi.

To be honest, I don’t know why we Viets were preoccupied with the chi either, but we were, so we did, and that’s how we retained the word Tết because it was an important culmination of the 24 chi units in the year.  Does that make sense?

If you understand, then you are a smarter cookie than me because to be honest, I still have a hard time separating the two, but you know…I’m just a blonde taobabe and my ancestors–they wielded the tao to manage their existence.  I can barely manage drinking my coffee without spilling it on my shirt.

Anyhoo, back to time slices.


There are 24 solar slices that divide the solstices and equinoxes into equal sections of 15° each time slice.  The Earth travels around the sun in an elliptical path that is fairly close to being circular, so to make it easier to understand, here is a circular diagram of the niên kỳ, which means year cycle, with each slice delineated in 15 degrees each.

The diagram is read counter-clockwise starting with 315° since this is the location of  the first day of spring, ie New Year Tết, and the designation of the new Tuổi.

girl-image-transparent-anime-girlEach slice has a name.  The names are supposed to be generalizations of the various effects and happenings of the solstices and the equinoxes. 

No definitions are given for any names because well duhhh…doesn’t everybody know what Kinh Trập means?  It means larvae dance!

My first reaction be like…Huh?

But that’s because unlike many people, I can’t keep a plant alive to save my life.  For farmers, it’s very obvious.  For us, not so much.  So I did us non-farmers a favor and gave a brief description of each term, just to be clear what the heck it is the words are trying to generalize.


Solar Slices/ Tiết Khí English Việt Meaning Date
315° Spring Begins Lập xuân Spring starts and the cycle begins anew. Feb 4
330° Water Dances Vũ thủy Vũ means water and thủy means water, so it means water-water.  However, Vũ also means dance, so Water Dances works too. Light drizzle and mists of rain begins to fall. Feb 19
345° Insects Awaken Kinh trập Larvae and tiny bugs hatch and squirm around everywhere. March 5
Mid-Spring Xuân phân The March Equinox begins. March 21
15° Crystal Clear Thanh minh Clear blue skies are in the forecast. April 5
30° Grain Showers Cốc vũ Americans don’t have the word for Grain Showers, but it is the rains that fall in tiny droplets, like grains, that allow for actual grain seedlings to grow without being pounded into the ground. April 20
45° Summer Begins Lập hạ Summer commences, with all its bright fanfare. May 6
60° Cloudburst Tiểu mãn Small summer cloudbursts, sudden downpours, which quickly dissipates. May 21
75° Pleiades Emerges Mang chủng When the Pleiades emerge, you still have time to take care of the fields. Tua rua thì mặc tua rua, mạ già ruộng ngấu, không thua bạn điền* June 6
90° June Solstice Hạ chí The longest day of the year is mid June. Đêm tháng năm chưa nằm đã sáng, ngày tháng mười chưa cười đã tối** June 21
105° Balmy Tiểu thử Gentle warm tropics beach weather. July 7
120° Sultry Đại thử The heat intensifies at this time; stifling, hot and humid. July 23
135° Start of Autum Lập thu Autumn has begun. Aug 7
150° Temperate Xử thử The weather becomes milder, nights get cooler. Aug 23
165° White Dew Bạch lộ Also known as the Clinging Rain. Early morning humidity transforms into milky autumn dew. Bạch lộ vi sương thu khí thâm*** Sept 8
180° Mid-Autum Thu phân September equinox marks the mid-autumn point. Sept 23
195° Cold Dew Hàn lộ Days get cooler, night gets chilly. Oct 8
210° Dew Point Sương giáng Fog appears. Once air temperature reaches the dew point, fog will form. Oct 23
225° Winter Starts Lập đông Winter begins Nov 7
240° Snow Flurries Tiểu tuyết The first flurries of snow start to appear. Nov 22
255° Blizzard Đại tuyết Blizzards cause thick layers of snow on the world below. Dec 7
270° Mid-Winter Đông chí December solstice marks the mid-winter. Dec 22
285° Light Freeze Tiểu hàn Light freeze Jan 6
300° Frigid Cold Đại hàn The coldest time of the year. Hard freeze. Jan 21
  • *Tua rua thì mặc tua rua, mạ già ruộng ngấu, không thua bạn điền:  Tua Rua is the Vietnamese word for the Pleiades Constellation.  The ancient saying roughly means:  Who gives a shit about the appearance of the Pleiades in the sky.  Even if you haven’t had the chance to finish work on your rice paddies, no worries.  You still have plenty of time to catch up to your neighbors.
  • **Đêm tháng năm chưa nằm đã sáng, ngày tháng mười chưa cười đã tối:  You barely got the chance to lie down at night in the fifth month, and it’s already morning.  You haven’t even had the chance to laugh in the daylight of the tenth month, and it’s already dark.
  • ***Bạch lộ vi sương thu khí thâm:  White vapor condenses to dewfall, which transforms into murky fog.

This then leads me to the Sexagenary Cycle.

Sexagenary Cycle


I did say I was going to talk about the sexagenary cycle that the Asian calendar utilized, so this is the perfect time to introduce it.  It is only an introduction because I need to separate out the two parts of the sexagenary cycle into the decimal and the duodecimal system.

The decimal system is a system that uses 10 digits as the base count and increases by powers of 10.  It is called base 10.  We call the base 10 Thiên Can, or Heaven.  In the Asian calendar system, there are ten Thiên Can, also known as Branches.

The duodecimal system is a system that uses 12 digits as the base count and increases by powers of 12.  It is called base 12.  We call the base 12 Địa Chi, meaning Earth.  There are 12 Địa Chi, also known as Stems, in the calendar, and they are very well-known.

Remember the Chinese restaurant placemats I was talking about?  Well, those animals are these animals.

So here is my souped up Can Chi Wheel in my two favorite colors.

Can Chi, aka Thiên Can Địa Chi


The zodiac animals occupy the Địa Chi Stems on the wheel, and the ten Thiên Can Branches cycle through them.  There is a lot of dense information regarding the Branches and Stems, but I will push it to the next posting because this post is getting much longer than a post should get.  I always have to remind myself that I’m not writing a book.  I’m only writing a post.  So I will stop here.  🙂

(to be continued)


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