A solar term is any of 24 points in traditional East Asian 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. Solar terms originated in China, and then spread to Korea, Vietnam, Taiwan, and Japan. This is exhibited by the fact that traditional Chinese, Hanja, and Kanji characters for most of the solar terms are identical.

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 (hou). Each pentad consists of five days (rarely six), so there are 72 pentads in a year.

* List of solar terms

Longitude

Usual translation

Korean name

Date

Remark

315°

start of spring

입춘 (立春)
ipchun

Feb 4

330°

rain water

우수 (雨水)
usu

Feb 19

more rain than snow

345°

awakening of insects

경칩 (驚蟄)
gyeongchip

Mar 6

Lit. Awakening of hibernating insects. See the note at Chinese calendar Solar term.

vernal equinox

춘분 (春分)
chunbun

Mar 21

Lit. spring division (or center)

15°

clear and bright

청명 ()
cheongmyeong

Apr 5

time for tending graves

30°

grain rain

곡우 (穀雨)
gogu

Apr 20

Lit. grain rain: rain helps grain grow

45°

start of summer

입하 (立夏)
ipha

May 6

60°

grain full

소만 (小滿)
soman

May 21

grains are plump

75°

grain in ear

망종 (芒種)
mangjong

Jun 6

Lit. awns (beard of grain) grow

90°

summer solstice

하지 (夏至)
haji

Jun 21

Lit. summer extreme (of sun's height)

105°

minor heat

소서 (小暑)
soseo

Jul 7

120°

major heat

대서 (大暑)
daeseo

Jul 23

135°

start of autumn

입추 (立秋)
ipchu

Aug 8

150°

limit of heat

처서 (處暑)
cheoseo

Aug 23

Lit. dwell in heat

165°

white dew

백로 (白露)
baekro

Sep 8

condensed moisture makes dew white

180°

autumnal equinox

추분 (秋分)
chubun

Sep 23

Lit. autumn division (or center)

195°

cold dew

한로 (寒露)
hallo

Oct 8

210°

frost descent

상강 (霜降)
sanggang

Oct 23

appearance of frost and descent of temperature

225°

start of winter

입동 (立冬)
ipdong

Nov 7

240°

minor snow

소설 (小雪)
soseol

Nov 22

255°

major snow

대설 (大雪)
daeseol

Dec 7

270°

winter solstice

동지 (冬至)
dongji

Dec 22

Lit. winter extreme (of sun's height)

285°

minor cold

소한 (小寒)
sohan

Jan 6

300°

major cold

대한 (大寒)
daehan

Jan 20

* Date can vary within a ±1 day range.