A solar term is any of twenty-four periods in traditional Chinese lunisolar calendars that matches a particular astronomical event or signifies some natural phenomenon.[1] The points are spaced 15° apart along the ecliptic[2] and are used by lunisolar calendars to stay synchronized with the seasons, which is crucial for agrarian societies. The solar terms are also used to calculate intercalary months;[3] which month is repeated depends on the position of the sun at the time.

The 24 solar terms
Solar term
Term Longitude Dates
Lichun 315° 4–5 February
Yushui 330° 18–19 February
Jingzhe 345° 5–6 March
Chunfen 20–21 March
Qingming 15° 4–5 April
Guyu 30° 20–21 April
Lixia 45° 5–6 May
Xiaoman 60° 21–22 May
Mangzhong 75° 5–6 June
Xiazhi 90° 21–22 June
Xiaoshu 105° 7–8 July
Dashu 120° 22–23 July
Liqiu 135° 7–8 August
Chushu 150° 23–24 August
Bailu 165° 7–8 September
Qiufen 180° 23–24 September
Hanlu 195° 8–9 October
Shuangjiang 210° 23–24 October
Lidong 225° 7–8 November
Xiaoxue 240° 22–23 November
Daxue 255° 7–8 December
Dongzhi 270° 21–22 December
Xiaohan 285° 5–6 January
Dahan 300° 20–21 January
(Twenty-four) solar terms
Traditional Chinese(二十四)節氣
Simplified Chinese(二十四)节气

According to the Book of Documents, the first determined term was Dongzhi (Winter Solstice) by Dan, the Duke of Zhou, while he was trying to locate the geological center of the Western Zhou dynasty, by measuring the length of the sun's shadow on an ancient timekeeper instrument named Tu Gui (土圭).[4] Then four terms of seasons were set, which were soon evolved as eight terms; until 104 BC in the book Taichu Calendar, the entire twenty-four solar terms were officially included in the Chinese calendar.[5]

Because the Sun's speed along the ecliptic varies depending on the Earth-Sun distance, the number of days that it takes the Sun to travel between each pair of solar terms varies slightly throughout the year. Each solar term is divided into three pentads [zh] (候 hòu), so there are 72 pentads in a year. Each pentad consists of five, rarely six, days, and are mostly named after phenological (biological or botanical) phenomena corresponding to the pentad.

Solar terms originated in China, then spread to Korea, Vietnam, and Japan, countries in the East Asian cultural sphere. Although each term was named based on the seasonal changes of climate in North China Plain, peoples living in the different climates still use it with no changes.[6] This is exhibited by the fact that traditional Chinese characters for most of the solar terms are identical.

On December 1, 2016, the solar terms were listed by UNESCO as an Intangible Cultural Heritage.[7]

NumberingEdit

The even solar terms (marked with "Z", for Chinese: 中氣) are considered the major terms, while the odd solar terms (marked with "J", for Chinese: 節氣) are deemed minor. The year starts with Lichun (J1) and ends with Dahan (Z12).[8]

Multilingual listEdit

Sun's ecliptic
longitude
Chinese
name[9]
Korean name[10] Vietnamese
name
Japanese
name
Ryukyuan
(Okinawan) name
English
name[11]
English
name (Beijing 2022 Winter Olympics official translation)[12]
Gregorian
Date[13]
(± 1 day)
Reference for
Month Intercalating
Chinese zodiac & Earthly Branch of Month Corresponding Astrological Sign
315° 立春
lìchūn
立春 (입춘/립춘)
ipchun/ripchun
Lập xuân (立春) 立春(りっしゅん)
risshun
立春(りっしゅん)
risshun
Spring commences Beginning of Spring Feb 4 1st month initial Tiger (虎)
Yín (寅)
Aquarius
(寶瓶宮)
330° 雨水
yǔshuǐ[14]
雨水 (우수)
usu
Vũ thủy (雨水) 雨水(うすい)
usui
雨水(うしー)
ushii
Rain water Rain Water Feb 19 1st month midpoint Pisces
(雙魚宮)
345° 驚蟄 (惊蛰)
jīngzhé[15]
驚蟄 (경칩)
gyeongchip
Kinh trập (驚蟄) 啓蟄(けいちつ)
keichitsu

驚く(うどぅるく)
uduruku;
驚くー(おどるくー)
udurukuu;
虫驚(むしうどぅるく)
mushi'uduruku

Insects waken Awakening of Insects Mar 6 2nd month initial Rabbit (兔)
Mǎo (卯)
春分
chūnfēn
春分 (춘분)
chunbun
Xuân phân (春分) 春分(しゅんぶん)
shunbun
春分(すんぶん)
sunbun
Vernal equinox Spring Equinox Mar 21 2nd month midpoint Aries
(白羊宮)
15° 清明
qīngmíng[16]
淸明 (청명)
cheongmyeong
Thanh minh (清明) 清明(せいめい)
seimei
清明(しーみー)
shiimii
Bright and clear Pure Brightness Apr 5 3rd month initial Dragon (龍)
Chén (辰)
30° 穀雨 (谷雨)
gǔyǔ[17]
穀雨 (곡우)
gogu
Cốc vũ (穀雨) 穀雨(こくう)
kokuu
穀雨(くくー)
kukuu
Corn rain Grain Rain Apr 20 3rd month midpoint Taurus
(金牛宮)
45° 立夏
lìxià
立夏 (입하/립하)
ipha/ripha
Lập hạ (立夏) 立夏(りっか)
rikka
立夏(りっかー)
rikkaa
Summer commences Beginning of Summer May 6 4th month initial Snake (蛇)
Sì (巳)
60° 小滿 (小满)
xiǎomǎn
小滿 (소만)
soman
Tiểu mãn (小滿) 小満(しょうまん)
shōman
小満(すーまん)
suuman
Corn forms Grain Buds May 21 4th month midpoint Gemini
(雙子宮)
75° 芒種 (芒种)
mángzhòng
芒種 (망종)
mangjong
Mang chủng (芒種) 芒種(ぼうしゅ)
bōshu
芒種(ぼーすー)
boosuu
Corn on ear Grain in Ear Jun 6 5th month initial Horse (馬)
Wǔ (午)
90° 夏至
xiàzhì
夏至 (하지)
haji
Hạ chí (夏至) 夏至(げし)
geshi
夏至(かーちー)
kaachii
Summer solstice Summer Solstice Jun 21 5th month midpoint Cancer
(巨蟹宮)
105° 小暑
xiǎoshǔ
小暑 (소서)
soseo
Tiểu thử (小暑) 小暑(しょうしょ)
shōsho
小暑(くーあちさ)
kuu'achisa
Moderate heat Minor Heat Jul 7 6th month initial Goat (羊)
Wèi (未)
120° 大暑
dàshǔ
大暑 (대서)
daeseo
Đại thử (大暑) 大暑(たいしょ)
taisho
大暑(うーあちさ)
uu'achisa
Great heat Major heat Jul 23 6th month midpoint Leo
(獅子宮)
135° 立秋
lìqiū
立秋 (입추/립추)
ipchu/ripchu
Lập thu (立秋) 立秋(りっしゅう)
risshū
立秋(りっすー)
rissuu
Autumn commences Beginning of Autumn Aug 8 7th month initial Monkey (猴)
Shēn (申)
150° 處暑 (处暑)
chǔshǔ
處暑 (처서)
cheoseo
Xử thử (處暑) 処暑(しょしょ)
shosho
処暑(とぅくるあちさ)
tukuru'achisa
End of heat End of Heat Aug 23 7th month midpoint Virgo
(室女宮)
165° 白露
báilù
白露 (백로)
baekno/baekro
Bạch lộ (白露) 白露(はくろ)
hakuro
白露(ふぁくるー)
fakuruu
White dew White Dew Sep 8 8th month initial Rooster (雞)
Yǒu (酉)
180° 秋分
qiūfēn
秋分 (추분)
chubun
Thu phân (秋分) 秋分(しゅうぶん)
shūbun
秋分(すーぶん)
suubun
Autumnal equinox Autumn Equinox Sep 23 8th month midpoint Libra
(天秤宮)
195° 寒露
hánlù
寒露 (한로)
hanlo
Hàn lộ (寒露) 寒露(かんろ)
kanro
寒露(かんるー)
kanruu
Cold dew Cold Dew Oct 8 9th month initial Dog (狗)
Xū (戌)
210° 霜降
shuāngjiàng
霜降 (상강)
sanggang
Sương giáng (霜降) 霜降(そうこう)
sōkō
霜降(しむくだり)
shimukudari
Frost Frost's Descent Oct 23 9th month midpoint Scorpio
(天蠍宮)
225° 立冬
lìdōng
立冬 (입동/립동)
ipdong/ripdong
Lập đông (立冬) 立冬(りっとう)
rittō
立冬(りっとぅー)
rittuu
Winter commences Beginning of Winter Nov 7 10th month initial Pig (豬)
Hài (亥)
240° 小雪
xiǎoxuě
小雪 (소설)
soseol
Tiểu tuyết (小雪) 小雪(しょうせつ)
shōsetsu
小雪(くーゆち)
kuuyuchi
Light snow Minor Snow Nov 22 10th month midpoint Sagittarius
(人馬宮)
255° 大雪
dàxuě
大雪 (대설)
daeseol
Đại tuyết (大雪) 大雪(たいせつ)
taisetsu
大雪(うーゆち)
uuyuchi
Heavy snow Major Snow Dec 7 11th month initial Rat (鼠)
Zǐ (子)
270° 冬至
dōngzhì
冬至 (동지)
dongji
Đông chí (冬至) 冬至(とうじ)
tōji
冬至 (とぅんじー)
tunjii
Winter solstice Winter Solstice Dec 22 11th month midpoint Capricorn
(山羊宮)
285° 小寒
xiǎohán
小寒 (소한)
sohan
Tiểu hàn (小寒) 小寒(しょうかん)
shōkan
小寒(すーかん)
suukan
Moderate cold Minor Cold Jan 6 12th month initial Ox (牛)
Chǒu (丑)
300° 大寒
dàhán
大寒 (대한)
daehan
Đại hàn (大寒) 大寒(だいかん)
daikan
大寒(でーかん)
deekan
Severe cold Major Cold Jan 20 12th month midpoint Aquarius
(寶瓶宮)

Chinese mnemonic songEdit

The "Song of Solar Terms" (simplified Chinese: 节气歌; traditional Chinese: 節氣歌; pinyin: jiéqìgē) is used to ease the memorization of jiéqì:

The first four lines provides a concise version of the names of the 24 jieqi. The last four lines provide some rules of thumb about the Gregorian dates of jieqi, namely:

  • Two jieqi per month;
  • Gregorian dates are off by one or two days at most;
  • In the first half of the year, jieqi happens around the 6th and 21st day of each (Gregorian) month;
  • In the second half of the year, jieqi happens around the 8th and 23rd day of each (Gregorian) month.

DeterminationEdit

The modern definition using ecliptic longitudes, introduced by the Shixian calendar, is known as 定气法. Under this method, the determination of solar terms is similar to the astronomical determination of the special cases of equinox and solstice dates, with different ecliptic longitudes to solve for. One can start with an approximation and then perform a correction using the anomalies and mean motion of the sun.[18] The JPL Horizons On-Line Ephemeris System may be used to query for exact times of solar terms.

The older method is known as 平气法 and simply divides the tropical year into 24 equal parts.

Regional noteEdit

In Japan, the term Setsubun (節分) originally referred to the eves of Risshun (立春, 315°, the beginning of Spring), Rikka (立夏, 45°, the beginning of Summer), Risshū (立秋, 135°, the beginning of Autumn), and Rittō (立冬, 225°, the beginning of Winter), but currently mostly refers to the day before Risshun. The name of each solar term also refers to the period of time between that day and the next solar term, or 1/24th of a year.

See alsoEdit

ReferencesEdit

  1. ^ "24 Chinese Feasts (Jiéqì, 节气), equivalent to the 24 Chinese Solar Terms". Chinese calendar. asia-home.com.
  2. ^ Until 1644(Chinese Empire and its tributary states) or 1844(Japan) a period of time of the solar year itself had been equally divided instead of the spatial zodiac.
  3. ^ When a lunar month's end does not reach a midpoint of the solar terms, it is regarded as the last month's intercalary one instead of the true "next" month. It is called 歲中閏月法 lit."midpoint intercalating system".
  4. ^ Book of Documents.
  5. ^ Ban, Gu. Book of Han.
  6. ^ なぜずれる? 二十四節気と季節感 (Why off-point? -solar terms and our real feeling of the seasons) An example in Japan. It compares the climate of Taiyuan with that of Tokyo and Kyoto. In maritime Japanese islands difference of the seasonal gap length is the main problem. In subtropical or tropical regions including southern China climate difference is more serious.
  7. ^ "UNESCO - The Twenty-Four Solar Terms, knowledge in China of time and practices developed through observation of the sun's annual motion". ich.unesco.org. Retrieved 9 March 2021.
  8. ^ Aslaksen, Helmer. "When is Chinese New Year?" (PDF). Archived from the original (PDF) on 13 March 2009. Retrieved 27 July 2019.
  9. ^ Simplified Chinese characters are shown in parentheses if they differ from the Traditional Chinese characters.
  10. ^ Hangul are shown in parentheses. For Hangul and romanisation, where the pronunciation differs between South Korea and North Korea, the South Korean pronunciation is given first before the slash, followed by the North Korean pronunciation.
  11. ^ "The 24 Solar Terms".
  12. ^ "二十四节气上了北京冬奥开幕式,牛!".
  13. ^ Date can vary within a ±1 day range.
  14. ^ the Yushi and Jingzhe have been exchanged by Liu Xin in Han dynasty.
  15. ^ the Jingzhe and Yushi have been exchanged by Liu Xin in Han dynasty.
  16. ^ the Qingmin and Guyu have been exchanged by Liu Xin in Han dynasty.
  17. ^ the Guyu and Qingmin have been exchanged by Liu Xin in Han dynasty.
  18. ^ "Determination of Equinox and Solstice Dates". farside.ph.utexas.edu.

External linksEdit