Lunisolar Calendars track the rhythm of nature better

Lunisolar Calendars track the rhythm of nature better.

by tonytran2015 (Melbourne, Australia).

Click here for a full, up to date ORIGINAL ARTICLE and to help fighting the stealing of readers’ traffic.

(Blog No.123).

#lunisolar calendar, #lunar calendar, #solar term, #tiết, #leap month, #solstice, #moon phase,

When traveling to Asia, Westerners are often surprised that many locals still use Lunar Calendars. The mystery will dissolve when they know more about Lunar Calendars.

In terms of survival, East Asian Lunar Calendars offer many advantages which keep them in use in East Asia and maybe in some other countries as well.

1. The East Asian Lunisolar Calendars.

The East Asian Lunisolar Calendars are based on Lunar Months and on Seasons.

They have the following characteristics:

1. A new month begins with the appearance of a New Moon any time during the WHOLE night of of the first day of the new month.

Note that a Lunar “day and night” period in East Asian Lunar Calendar just mean exactly that. It does not means from midnight to the following midnight. A Lunar “day and night” starts on a Sunrise and end at the next Sunrise.

MoonShapesNAngles5C

Figure 1: Phase of the Moon. A new Moon is the Moon with a thin white crescent on its leading edge (top right corner of the picture) which is first visible right after sunset on the Western horizon

2. The New Year of East Asian Lunar Calendar has been traditionally celebrated only from the First day (after Sunrise) of the New Year. The Midnight Firecracker Celebration on the last night of the expiring year is a hybrid concept of the beginning of a New Year.

The Firecracker custom by Chinese was traditionally used to keep some “Evil dragon” away from people’s houses during the change of guards in Heaven and at family Altars.

3. The post-solstice Month following a Winter Solstice (December 21st) is called the Final Month (“tháng Chạp” in Vietnamese meaning Preservation (?) Month).

4. The Month following the post-Solstice Month is ALWAYS a First Month of the next year (“tháng Chánh” in Chinese Vietnamese meaning Principal Month, “tháng Giêng” in Vietnamese).

5. Months are given names like Month 1 (First or Principal Month), Month 2, …, Month 11, Final Month (post-Solstice and last month).

6. As the beginnings of days and Lunar months depend on the longitude of an observer, the beginning of days, months may differ between countries seperated by few degrees in longitude. The Lunisolar Calendars of China, Korea, Taiwan and Vietnam may have their New Years differing by more than 28 days.

7. As Lunar months are only about 29.5 days long, every few (nearly 3) years there will be one Lunar year with 13 Lunar months. The additional month is called a Leap Month for that year.

8. As East Asian lives have been traditionally based on agriculture, the Lunar Calendars must help people track seasons. The Lunar months are named so that each denotes a particular time of the seasons.

For examples:

There is a folk phrase in Vietnamese “Tháng Năm (5) chưa nằm đã sáng, Tháng Mười (10) chưa cười đã tối.” It means 5th Months have shortest nights while 10th Months have shortest days.

One of planters’ songs about planting times for various crops in Vietnam is “Tháng chạp là tháng trồng khoai, Tháng giêng trồng đậu, tháng hai trồng cà. Tháng ba cày vỡ ruộng ra, Tháng tư làm mạ mưa sa đầy đồng. Ai ai cùng vợ cùng chồng, Chồng cày vợ cấy, trong lòng vui thay. Tháng năm gặt hái đã xong, Nhờ trời một mẫu năm nong thóc đầy…”. It means “final month is for planting root crops, principal month planting bean crops, second month tomato crops. Third month is for tilting and ploughing soil, fourth month for planting rice seedlings under the rain, …, fifth month comes with all harvesting well finished,…”

9. To preserve the characters of months, the leap month in any year with 13 Lunar months is inserted between month 1 and month 11 such that seasonal characters of other months are preserved.

10. There are 24 nearly equally spaced, designated (by East Asian Astronomers) marker points on the Ecliptic called “Solar terms” in “Chinese English”. The position of the Sun relative to these markers tell its progress along the Ecliptic and the season in the year. Any leap month is inserted such that the Sun does not go far from its expected positions for the month [6].

star map mercatorx1p6

Figure: The wavy line in this Mercator map of the sky is the Ecliptic. The Sun travels on it. There are 24 marker points on this line used by East Asian Astronomers to quantify the position of the Sun on this line.

The time the Sun goes past any marker is called a “tiết” in Old Chinese-Vietnamese; “tiết” means a beginning of any one of 24 sub-seasons in the exact solar year (Each traditional astronomically based season is further subdivided into six sub-seasons by East Asian Astronomers.). There are 24 sub-seasons of roughly equal lengths and their 24 “tiết”s with 24 individual names:

Solar R.A. = 270°冬至 dōngzhì Đông chí Dec 22 11th winter maximum (solstice). DATE for ANCHORING 11th month. This anchoring may make months 11 in neighbouring countries differ by nearly 28 days.

Solar R.A. = 285°小寒 xiǎohán Tiểu hàn Jan 6, bit frigid

Solar R.A. = 300°大寒 dàhán Đại hàn Jan 20 most frigid, roughly the middle of 12th month,

Solar R.A. = 315°立春 lìchūn Lập xuân Feb 4 spring begins, close to the beginning of CONVENTIONAL 1st month, There is NO LEAP month from 11th to 1st month.

Solar R.A. = 330°雨水 yǔshuǐ Vũ thủy Feb 19, more rain than snow, LEAP month may be inserted after 1st monrh and before 11th month.

Solar R.A. = 345°驚蟄 (惊蛰)jīngzhé Kinh trập啓蟄 Mar 6, hibernating insects awaken,

Solar R.A. = 0°春分 chūnfēn Xuân phân Mar 21 2nd month midpoint, spring center (equinox) , Target date for middle of 2nd month,

Solar R.A. = 15°清明 qīngmíng Thanh minh Apr 5, clear and bright

Solar R.A. = 30°穀雨 (谷雨) gǔyǔ Cốc vũ Apr 20 3rd month midpoint wheat rain , Target date for middle of 3rd month,

Solar R.A. = 45°立夏 lìxià Lập hạ May 6, summer begins

Solar R.A. = 60°小滿 xiǎomǎnTiểu mãn小満 May 21 creatures plentiful , Target date for middle of 4th month,

Solar R.A. = 75°芒種 (芒种) mángzhòng Mang chủng Jun 6, seeding millet

Solar R.A. = 90°夏至 xiàzhì Hạ chí Jun 21 summer maximum (solstice) , Target date for middle of 5th month,

Solar R.A. = 105°小暑 xiǎoshǔ Tiểu thử Jul 7, bit sweltering

Solar R.A. = 120°大暑 dàshǔ Đại thử Jul 23 most sweltering , Target date for middle of 6th month,

Solar R.A. = 135°立秋 lìqiū Lập thu Aug 8 autumn begins

Solar R.A. = 150°處暑 (处暑)chǔshǔ Xử thử Aug 23 heat withdraws , Target date for middle of 7th month,

Solar R.A. = 165°白露 báilù白露 Bạch lộ Sep 8 dew

Solar R.A. = 180°秋分 qiūfēn Thu phân Sep 23 autumn center (equinox) , Target date for middle of 8th month,

Solar R.A. = 195°寒露 hánlù Hàn lộ Oct 8 cold dew

Solar R.A. = 210°霜降 shuāngjiàng Sương giáng, Oct 23 frost , Target date for middle of 9th month,

Solar R.A. = 225°立冬 lìdōng Lập đông Nov 7 winter begins

Solar R.A. = 240°小雪 xiǎoxuě Tiểu tuyết Nov 22 snows a bit , Target date for middle of 10th month,

Solar R.A. = 255°大雪 dàxuě Đại tuyết Dec 7 snows a lot

The leap month is inserted so that months with the same names mostly contain the same solar-determined sub-seasons over years.

2. Disadvantages of Lunisolar Calendars.

1. The lengths of months do not follow any simple pattern.

2. Calendar users have to rely on central astronomers to know when is a leap year and which month will be the leap month for that leap year.

3. As the beginnings of days and Lunar months depend on the longitude of an observer, the beginning of days, months may differ between countries separated by few degrees in longitude. The Lunisolar Calendars of China, Korea, Taiwan and Vietnam may have their New Years differing by more than 28 days.

4. The number of days between any two given dates are hard to calculate.

5. Consequently it is difficult for house builders or any contractors to work out the number of working days in any project. However, East Asians are often concerned with weekly matters (how long is the harvest period, etc..,) or with decade long matters (when and where will their children live, migrate to!).

3. Advantages of Lunisolar Calendars.

1. The day in the calendar month is displayed by the Moon. Some Vietnamese can tell the day without any delay just by looking at the Moon.

2. Market days and Buddhist fasting and festival days are always on the 15th day of the Lunar months. There is plenty of Moonlight on those days.

3. The tides are strongest on full Moon and No-Moon days. This makes easy planning with water transportation on rivers and canals. (Wedding celebrations in remote areas in Southern Vietnam are still carried out with great timing precision so that guests can arrive and return by boats).

4. Any two distant parties may agree to conveniently meet each other halfway at each full-Moon.

5. Before full Moon, the lit side of a Non-full Moon always points Westwards. After full Moon, it points Eastwards. So the Calendars help with nighttime navigating.

6. Rodents and insects are exposed to their predators (such as night-owls, cats, snakes…) at night in full Moon. So their nighttime forage depends on Moon phase and days in the Lunar months.

7. Seeds and succulent seedlings are exposed to rodents and insects in Moon lit nights. Planters (including Asian and European) have known it is best to count days from full Moon to plant various seeds.

8. Water creatures like crabs do get fattened or skinny depending on Moon phase (probably due to their feeding and mating habits). Vietnamese wisdom advises against buying crabs for meals after full Moon.

4. Conclusion.

Lunisolar calendars track the rhythm of nature better. People in East Asia may retain the calendars as their lives are more dependent on this rhythm.

References.

[1]. https://survivaltricks.wordpress.com/2017/01/19/simple-determination-of-east-asia-lunisolar-new-year/

[2]. https://en.m.wikipedia.org/wiki/Lunisolar_calendar

[3]. Sima Qian, Records of History by the grand historian (translated by Burton Watson), Qin Dynasty, Han Dynasty I (Rev. Ed.) and Han Dynasty II (Rev. Ed.), the Res. Cent. for Transl. The Chinese Univ. of Hon Kong and Colubia Univ. Press, Hong Kong and New York, 1961. Han Dynasty II p.38 showed that in 113BC, month 11 has the solstice.

[4]. Helmer Aslaksen, The Mathematics of the Chinese Calendar, http://www.math.nus.edu.sg/aslaksen/calendar/chinese.shtml, accessed 19 Jan 2017.

[5]. Ho Ngoc Duc, Thuat toan am lich (in Vietnamese), https://www.informatik.uni-leipzig.de/~duc/amlich/calrules.html, accessed 19 Jan 2017.
[6]. https://en.m.wikipedia.org/wiki/Solar_term

[7]. https://vi.m.wikipedia.org/wiki/%C4%90%E1%BA%A1i_h%C3%A0n

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Simple determination of East Asia lunisolar New Year

Simple determination of East Asia lunisolar New Year

by tonytran2015 (Melbourne, Australia).

Click here for a full, up to date ORIGINAL ARTICLE and to help fighting the stealing of readers’ traffic.

(Blog No.49).

#East Asia New Year, #lunar New Year, #lunar leap year, #lunar leap month, #lunisolar calendar, #Vietnamese New Year, #lunar calendar.

When traveling to or working with East Asia countries Westerners are sometimes puzzled by their Calendar and long New Year festivals which vary from year to year on the Western Calendar.

This blog gives simple explanation to Westerners the rules of East Asia Lunisolar calendar which is based on Celestial observations and has been designed to give season information to users.

To easily understand this article, readers are advised to first read the simple summary on stars in the sky [1] to know the declination, right ascension and the date of a star.

Simple calculations [2] shows that each lunar month is 29.530 days. Two lunar months has a length of 59.06 days. The lunisolar calendar used in China since ancient time has had Winter solstice falling on the 11th month of the year since more than 2000 years ago, since 113BC (Han Dynasty II p.38 [3]) .

The solstice point (the point from ecliptic most South of the celestial equator) is moving slowly in the sky and is currently opposite to 90 degree Right Ascension.

1. New Year time is just a convention.

A lunisolar year can be made to start at any of its seasonal point, the point can be in the Winter or in the Summer. It all comes to a matter of convention. For example, the Burmese lunisolar calendar has its New Years starting when the Sun enters the constellation Aries.

For East Asia lunisolar calendar making, there are two major alternatives for determining its New Years as in the following.

2. Simple rules.

MoonShapesNAngles5C

Figure 1: Phase of the Moon. A new Moon is the Moon with a thin white crescent on its leading edge (top right corner of the picture) which is first visible right after sunset on the Western horizon.

If the calendar makers want their people to have simple and clear rule on the start of a New Year, they can define the New Year starting on the Second New Moon after Winter Solstice day.

This would be easy for ordinary people and people in remote areas to work out their two last (11th and 12th) lunar months of the year, and have enough time to prepare for the New Year festival.

3. Precision rules with uniform determination of months.

polrnorthq2c30.jpg

Figure: Inversion map of the Northern Celestial 3/4-sphere. The non-concentric circle is the ecliptic and winter solstice is its most distant point from the North pole (on the left of the North pole).

The Eastern Asia lunisolar Calendar requires each of its lunar month has a characteristic star in the sky to match with the seasons. There are 12 chosen characteristic stars. A lunar year has either 12 lunar months (normal year) or 13 lunar months (leap year). Any lunar month not containing any of those 12 chosen characteristic stars is called a leap month and is named after its preceding month.

Each Lunar month begins with a New Moon and ends before the next New Moon.

If the Calendar Makers insist on astronomical precision with uniform determination of months then they can define each month having to contain a star at regular spacing of Right Ascension, that is 11th month having some star of 90 degree R.A. on the meridian line at midnight on one night of the month and so on [4], [5].

Therefore they would require that

11th month has a star of 90 degree R.A.,
12th month has a star of 120 degree R.A.,
1st month has a star of 150 degree R.A., (Regulus of Leo has 152.05° R.A., 12° decl.)
2nd month has a star of 180 degree R.A.,
3rd month has a star of 210 degree R.A.,
4th month has a star of 240 degree R.A., (Delta Scorpii has 240.22° R.A., –22.60° decl.)
5th month has a star of 270 degree R.A.,
6th month has a star of 300 degree R.A., (Altair of Aql has 297.7° R.A., 8.85° decl.)
7th month has a star of 330 degree R.A.,
8th month has a star of 0 degree R.A.,
9th month has a star of 30 degree R.A.,
10th month has a star of 60 degree R.A.,

any month that has no star in the above list is called a leap month bearing the same name as its preceding non-leap month. Therefore it is hard for ordinary people to know the beginning of the Year.

4. Most probable choice.

I would think that the ancient Calendar makers chose the first alternative rather than the more difficult second alternative.

The second alternative also has an additional complication that there is a precession of Equinox at a rate of 360 degree per(approximately) 25,920 years. In 2000 years the Winter Solstice has moved by 27.7 degrees (about one month). Chines Calendar Makers would have noticed it and saw the need for adjustment had they chosen the second alternative but I could not find any literature about that kind of adjustment.

It is most likely that Chinese Calendar Makers had chosen the first alternative. Their choice may have had influence on Calendar Makers of neighboring countries.

If East Asian Calendar Makers chose the easy rules of for determining New Year day then the 1st month of any East Asian New Year would contain a star that has a date of 18 February(= 21 December + 59.06 days), 59.06 days after Winter Solstice. That would come to a simple rule for star watchers (for the current configuration of Earth orbit):
The New Year starts on the second new moon after Winter Solstice day and the first lunar month of the lunisolar calendar should have a star of 18 February (= 21 December + 59.06 days) of Right Ascension of nearly 152 degrees (near to that of Regulus of Leo) on its meridian at midnight.

The second through to the tenth months of the lunisolar calendar have been anchored to seasons by requiring each to have a star chosen as specified in section 3. If bright stars of approximate Right Ascensions are chosen instead, there would only be more or less leap months repeating the name of the preceding months. The choice of bright stars of approximate Right Ascensions may also have been influenced by superstition and politics.

It is common to find references to Festivals of First Full Moons of the years (Tết Nguyên Tiêu) in ancient Chinese historical texts but it is not easy to find references to Festivals of First New Moons ( Tết Nguyên Đán) in those ancient texts.

References

[1]. tonytran2015, Finding North and time by stars ,survivaltricks.wordpress.com, https://survivaltricks.wordpress.com/2015/08/28/finding-north-and-time-by-stars/

[2]. tonytran2015, Finding North direction and time accurately from the horn line of the Moon, survivaltricks.wordpress.com, https://survivaltricks.wordpress.com/2015/08/12/finding-north-direction-and-time-accurately-from-the-horn-line-of-the-moon/

[3]. Sima Qian, Records of History by the grand historian (translated by Burton Watson), Qin Dynasty, Han Dynasty I (Rev. Ed.) and Han Dynasty II (Rev. Ed.), the Res. Cent. for Transl. The Chinese Univ. of Hon Kong and Colubia Univ. Press, Hong Kong and New York, 1961. Han Dynasty II p.38 showed that in 113BC, month 11 has the solstice.

[4]. Helmer Aslaksen, The Mathematics of the Chinese Calendar, http://www.math.nus.edu.sg/aslaksen/calendar/chinese.shtml, accessed 19 Jan 2017.
[5]. Ho Ngoc Duc, Thuat toan am lich (in Vietnamese), https://www.informatik.uni-leipzig.de/~duc/amlich/calrules.html, accessed 19 Jan 2017.

Added after 2018 April 06:

There are 24 nearly equally spaced, designated (by East Asian Astronomers) marker points on the Ecliptic called “Solar terms” in “Chinese English”. The position of the Sun relative to these markers tell its progress along the Ecliptic and the season in the year. Any leap month is inserted such that the Sun does not go far from its expected positions for the month [6].

star map mercatorx1p6

Figure: The wavy line in this Mercator map of the sky is the Ecliptic. The Sun travels on it. There are 24 marker points on this line used by East Asian Astronomers to quantify the position of the Sun on this line.

References (cont.)

[6]. https://en.wikipedia.org/wiki/Solar_term

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