|315°||Lichun||4 – 5 February|
|345°||Jingzhe||5 – 6 March|
|15°||Qingming||4 – 5 April|
|45°||Lixia||5 – 6 May|
|75°||Mangzhong||5 – 6 June|
|105°||Xiaoshu||7 – 8 July|
|135°||Liqiu||7 – 8 August|
|165°||Bailu||7 – 8 September|
|195°||Hanlu||8 – 9 October|
|225°||Lidong||7 – 8 November|
|255°||Daxue||7 – 8 December|
|285°||Xiaohan||5 – 6 January|
|(Twenty-four) solar terms|
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. The points are spaced 15° apart along the ecliptic 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; which month is repeated depends on the position of the sun at the time.
According to the Book of Documents, the first determined term was the Winter Solstice, also named Dongzhi by Zhou Gong, while he was trying to locate the geological center of his kingdom, by measuring the length of the sun's shadow on an ancient timekeeper instrument named Tu Gui (土圭). 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.
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 (候 hòu) (ja), 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. This is exhibited by the fact that traditional Chinese characters for most of the solar terms are identical.
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).
(± 1 day)
|Remark||Chinese zodiac & Earthly Branch of Month||Corresponding Astrological Sign|
|Lập xuân (立春)||立春（りっしゅん）
|Feb 4||1st month initial||Spring Begins
|Vũ thủy (雨水)||雨水（うすい）
|Feb 19||1st month midpoint||More Rain Than Snow
|Kinh trập (驚蟄)||啓蟄（けいちつ）
|Mar 6||2nd month initial||Hibernating Animals Awaken
|Xuân phân (春分)||春分（しゅんぶん）
|Mar 21||2nd month midpoint||Spring Center
|Thanh minh (清明)||清明（せいめい）
|Apr 5||3rd month initial||Clear and Bright
(Bright and Clear, Qingming Festival)
|Cốc vũ (穀雨)||穀雨（こくう）
|Apr 20||3rd month midpoint||Wheat Rain
|Lập hạ (立夏)||立夏（りっか）
|May 6||4th month initial||Summer Begins
|Tiểu mãn (小滿)||小満（しょうまん）
|May 21||4th month midpoint||Creatures Plenish
|Mang chủng (芒種)||芒種（ぼうしゅ）
|Jun 6||5th month initial||Seeding Millet
(Corn On Ear)
|Hạ chí (夏至)||夏至（げし）
|Jun 21||5th month midpoint||Summer Maximum (Summer Solstice)||Cancer|
|Tiểu thử (小暑)||小暑（しょうしょ）
|Jul 7||6th month initial||A bit Sweltering
|Đại thử (大暑)||大暑（たいしょ）
|Jul 23||6th month midpoint||Most Sweltering
|Lập thu (立秋)||立秋（りっしゅう）
|Aug 8||7th month initial||Autumn Begins
|Xử thử (處暑)||処暑（しょしょ）
|Aug 23||7th month midpoint||Heat Withdraws
(End of Heat)
|Bạch lộ (白露)||白露（はくろ）
|Sep 8||8th month initial||Dews
|Thu phân (秋分)||秋分（しゅうぶん）
|Sep 23||8th month midpoint||Autumn Center
|Hàn lộ (寒露)||寒露（かんろ）
|Oct 8||9th month initial||Cold Dews
|Sương giáng (霜降)||霜降（そうこう）
|Oct 23||9th month midpoint||Frost||Scorpio|
|Lập đông (立冬)||立冬（りっとう）
|Nov 7||10th month initial||Winter Begins
|Tiểu tuyết (小雪)||小雪（しょうせつ）
|Nov 22||10th month midpoint||Snows a bit
|Đại tuyết (大雪)||大雪（たいせつ）
|Dec 7||11th month initial||Snows a lot
|Đông chí (冬至)||冬至（とうじ）
|Dec 22||11th month midpoint||Winter Maximum
(Winter Solstice, Dongzhi Festival)
|Tiểu hàn (小寒)||小寒（しょうかん）
|Jan 6||12th month initial||A bit Frigid
|Đại hàn (大寒)||大寒（だいかん）
|Jan 20||12th month midpoint||Most Frigid
Chinese mnemonic song
chūn yǔ jīng chūn qīng gǔ tiān,
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.
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. 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.
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.
- "24 Chinese Feasts (Jiéqì, 节气), equivalent to the 24 Chinese Solar Terms". Chinese calendar. asia-home.com.
- 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.
- 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".
- Book of Documents.
- Ban, Gu. Book of Han.
- 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.
- "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.
- Aslaksen, Helmer. "When is Chinese New Year?" (PDF). Archived from the original (PDF) on 13 March 2009. Retrieved 27 July 2019.
- Simplified Chinese characters are shown in parentheses if they differ from the Traditional Chinese characters.
- 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.
- Date can vary within a ±1 day range.
- literal meaning based on the climate of North China
- "24 solar terms中國24節氣中英文對照 Flashcards | Quizlet". quizlet.com. Retrieved 2016-12-20.
- "The 24 Solar Terms".
- the Yushi and Jingzhe have been exchanged by Liu Xin in Han dynasty.
- the Jingzhe and Yushi have been exchanged by Liu Xin in Han dynasty.
- the Qingmin and Guyu have been exchanged by Liu Xin in Han dynasty.
- the Guyu and Qingmin have been exchanged by Liu Xin in Han dynasty.
- "Determination of Equinox and Solstice Dates". farside.ph.utexas.edu.