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 B. C. 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.
On December 1, 2016, the Solar Terms were listed by UNESCO as an Intangible Cultural Heritage.
List of solar terms
| Sun’s ecliptic longitude |
Chinese name |
Korean name | Vietnamese name |
Japanese name |
Ryukyuan (Okinawan) name |
Gregorian Date (± 1 day) |
Reference for Month Intercalating |
Remark | 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 |
Feb 4 | 1st month initial | Spring Begins (Spring Commences) |
Tiger (虎) Yín (寅) |
Aquarius (寶瓶宮) |
| 330° | 雨水 yǔshuǐ |
雨水 (우수) usu |
Vũ thủy (雨水) | 雨水（うすい） usui |
雨水（うしー） ushii |
Feb 19 | 1st month midpoint | More Rain Than Snow (Spring Showers) |
Pisces (雙魚宮) |
|
| 345° | 驚蟄 (惊蛰) jīngzhé |
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 |
Mar 6 | 2nd month initial | Hibernating Animals Awaken (Animals Waken) |
Rabbit (兔) Mǎo (卯) |
|
| 0° | 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 |
Mar 21 | 2nd month midpoint | Spring Center (Vernal equinox) |
Aries (白羊宮) |
|
| 15° | 清明 qīngmíng |
淸明 (청명) cheongmyeong |
Thanh minh (清明) | 清明（せいめい） seimei |
清明（しーみー） shiimii |
Apr 5 | 3rd month initial | Clear and Bright (Bright and Clear, Qingming Festival) |
Dragon (龍) Chén (辰) |
|
| 30° | 穀雨 (谷雨) gǔyǔ |
穀雨 (곡우) gogu |
Cốc vũ (穀雨) | 穀雨（こくう） kokuu |
穀雨（くくー） kukuu |
Apr 20 | 3rd month midpoint | Wheat Rain (Corn Rain) |
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 |
May 6 | 4th month initial | Summer Begins (Summer Commences) |
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 |
May 21 | 4th month midpoint | Creatures Plenish (Corn Forms) |
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 |
Jun 6 | 5th month initial | Seeding Millet (Corn On Ear) |
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 |
Jun 21 | 5th month midpoint | Summer Maximum (Summer Solstice) | 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 |
Jul 7 | 6th month initial | A bit Sweltering (Moderate Heat) |
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 |
Jul 23 | 6th month midpoint | Most Sweltering (Great Heat) |
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 |
Aug 8 | 7th month initial | Autumn Begins (Autumn Commences) |
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 |
Aug 23 | 7th month midpoint | Heat Withdraws (End of Heat) |
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 |
Sep 8 | 8th month initial | Dews (White Dew) |
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 |
Sep 23 | 8th month midpoint | Autumn Center (Autumn Equinox) |
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 |
Oct 8 | 9th month initial | Cold Dews (Cold Dew) |
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 |
Oct 23 | 9th month midpoint | Frost | 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 |
Nov 7 | 10th month initial | Winter Begins (Winter Commences) |
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 |
Nov 22 | 10th month midpoint | Snows a bit (Light Snow) |
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 |
Dec 7 | 11th month initial | Snows a lot (Heavy Snow) |
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 |
Dec 22 | 11th month midpoint | Winter Maximum (Winter Solstice, Dongzhi Festival) |
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 |
Jan 6 | 12th month initial | A bit Frigid (Moderate Cold) |
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 |
Jan 20 | 12th month midpoint | Most Frigid (Severe Cold) |
Aquarius (寶瓶宮) |
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:
春雨驚春清穀天 |
春雨惊春清谷天 |
chūn yǔ jīng chūn qīng gǔ tiān, |
Regional note
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.