What Are the 24 Solar Terms (Jeolgi)?
"Your Saju year doesn't change on New Year's Day — it changes at Ipchun." "She was born just before Baengno, so her monthly pillar is different." If you've spent any time learning Saju, you've likely heard statements like these. But what exactly are the 24 solar terms, and why do they matter so much?
The 24 Solar Terms (二十四節氣, Ishipsa Jeolgi) are 24 precise moments in the year defined by dividing the sun's ecliptic path into 24 segments of 15° of solar longitude (황경, hwanggyeong). Put simply, they mark 24 astronomically exact points as Earth orbits the sun. Originating in ancient China as an agricultural calendar, they became the backbone of East Asian medicine, philosophy — and today, Saju astrology.
Solar terms have nothing to do with the lunar calendar. They are determined purely by the sun's position — a solar calendar system. This is why they fall on nearly the same Gregorian date every year.
The 24 solar terms alternate between two types: Jeol (節, principal terms) and Jung (中, mid-terms). The odd-numbered terms are Jeol; the even-numbered are Jung. In Saju, the Jeol terms are the critical ones — they mark the exact moment the monthly pillar (月柱, wolju) switches.
Why Solar Terms Matter in Saju — The Monthly Pillar Switch
Here is one of the most common misconceptions in Saju: "I was born in February, so my monthly pillar is the February pillar." This is wrong. In Saju, the monthly pillar does not change on the first of the calendar month. It changes at the precise moment a Jeol solar term begins — called the Jeol-ip (節入) time.
Consider this example: Ipchun (立春, Start of Spring) falls on February 4th at 7:23 AM. Two people are born on that same date:
- Born at 7:22 AM → monthly pillar is Chuk (丑月, January pillar)
- Born at 7:24 AM → monthly pillar is In (寅月, February pillar)
Both were born on "February 4th," yet their monthly pillars are completely different. This is why Saju practitioners always verify the exact time down to the minute for anyone born on or near a solar term day.
Monthly pillar = determined by Jeol-ip time, not the calendar date
Born before Jeol-ip time → previous month's pillar | Born after Jeol-ip time → new month's pillar
Ipchun (立春) is especially significant because it changes both the monthly pillar and the yearly pillar (年柱, yeonju) simultaneously. Ipchun is the true Saju New Year — not the Lunar New Year. Anyone born on Ipchun day must verify the exact Jeol-ip time to know their correct year and month pillars.
All 24 Solar Terms — Complete Reference Table
Below is the full list of all 24 solar terms with their seasonal group, approximate Gregorian date, solar longitude, and corresponding monthly branch (月支).
| Solar Term | Type | Approx. Date | Longitude | Month Branch |
|---|---|---|---|---|
| 🌱 Ipchun 立春 (Start of Spring) | Jeol | Feb 3–5 | 315° | 寅 (Yin) |
| Usu 雨水 (Rain Water) | Jung | Feb 18–20 | 330° | 寅 (Yin) |
| 🌱 Gyeongchip 驚蟄 (Awakening of Insects) | Jeol | Mar 5–7 | 345° | 卯 (Myo) |
| Chunbun 春分 (Spring Equinox) | Jung | Mar 20–22 | 0° | 卯 (Myo) |
| 🌱 Cheongmyeong 清明 (Clear and Bright) | Jeol | Apr 4–6 | 15° | 辰 (Jin) |
| Gogu 穀雨 (Grain Rain) | Jung | Apr 19–21 | 30° | 辰 (Jin) |
| 🔥 Ipha 立夏 (Start of Summer) | Jeol | May 5–7 | 45° | 巳 (Sa) |
| Soman 小滿 (Grain Buds) | Jung | May 20–22 | 60° | 巳 (Sa) |
| 🔥 Mangjong 芒種 (Grain in Ear) | Jeol | Jun 5–7 | 75° | 午 (O) |
| Haji 夏至 (Summer Solstice) | Jung | Jun 21–22 | 90° | 午 (O) |
| 🔥 Soseo 小暑 (Minor Heat) | Jeol | Jul 6–8 | 105° | 未 (Mi) |
| Daeseo 大暑 (Major Heat) | Jung | Jul 22–24 | 120° | 未 (Mi) |
| 🍂 Ipchu 立秋 (Start of Autumn) | Jeol | Aug 7–9 | 135° | 申 (Sin) |
| Cheoseo 處暑 (End of Heat) | Jung | Aug 22–24 | 150° | 申 (Sin) |
| 🍂 Baengno 白露 (White Dew) | Jeol | Sep 7–9 | 165° | 酉 (Yu) |
| Chubun 秋分 (Autumn Equinox) | Jung | Sep 22–24 | 180° | 酉 (Yu) |
| 🍂 Hallo 寒露 (Cold Dew) | Jeol | Oct 7–9 | 195° | 戌 (Sul) |
| Sanggang 霜降 (Frost's Descent) | Jung | Oct 23–24 | 210° | 戌 (Sul) |
| ❄️ Ipdong 立冬 (Start of Winter) | Jeol | Nov 7–8 | 225° | 亥 (Hae) |
| Soseol 小雪 (Minor Snow) | Jung | Nov 22–23 | 240° | 亥 (Hae) |
| ❄️ Daeseol 大雪 (Major Snow) | Jeol | Dec 6–8 | 255° | 子 (Ja) |
| Dongji 冬至 (Winter Solstice) | Jung | Dec 21–23 | 270° | 子 (Ja) |
| ❄️ Sohan 小寒 (Minor Cold) | Jeol | Jan 5–7 | 285° | 丑 (Chuk) |
| Daehan 大寒 (Major Cold) | Jung | Jan 20–21 | 300° | 丑 (Chuk) |
* Jeol = principal term (monthly pillar switch point). Jung = mid-term (midpoint marker). 15° solar longitude intervals.
How to Find Your Birth Solar Term
To identify which solar term you were born under, you need two pieces of information: your birth date and your birth time. The birth date tells you which solar term period you fall in; the birth time is essential if you were born on or near a solar term transition day.
Here is a practical step-by-step:
- Step 1: Find the two Jeol solar terms closest to your birth date (one before, one after).
- Step 2: Check whether your birthday falls between them or exactly on one.
- Step 3: If born on a solar term day, look up the exact Jeol-ip time for that year. Compare it to your birth time.
- Step 4: The solar term period you fall within determines your monthly branch (月支).
If you were born on or very close to Ipchun (Start of Spring), both your monthly pillar and yearly pillar may change. This is the most common source of Saju calculation errors. AI-based Saju tools handle this automatically using precise astronomical Jeol-ip data.
Seasonal Five Element Energy — The Energy You Were Born Into
In Saju, the dominant Five Element energy of the season you were born in is called Wang-gi (旺氣, flourishing energy). That season's element is at full strength, while the opposing season's element is weakest. Understanding your birth season's Wang-gi helps explain the natural strengths and imbalances in your chart.
Solar Terms and Johu Yongsin (調候用神 — Seasonal Balance Energy)
Beyond determining the monthly pillar, the solar term you were born under is the primary basis for identifying your Johu Yongsin (調候用神) — the element your chart most needs for climate-based balance:
- Born in winter (Hae·Ja·Chuk months) — Your chart needs Fire, especially Byeong (丙, sun). Without it, talent lies frozen and untapped.
- Born in summer (Sa·O·Mi months) — Your chart needs Water, especially Im (壬, great river). Without it, burnout and overreach are constant risks.
- Born in spring (Yin·Myo months) — Wood energy is surging; Metal (Gyeong·Sin) helps prune and direct growth productively.
- Born in autumn (Sin·Yu months) — Metal energy is peak; Fire (Jeong·Byeong) refines raw metal into something valuable and bright.
Season & Five Element Quick Reference
| Season | Element | Month Branches | Core Energy | Johu Balance |
|---|---|---|---|---|
| 🌱 Spring | Wood | 寅·卯·辰 | Growth, creativity, start | 庚 Metal / 丙 Fire |
| 🔥 Summer | Fire | 巳·午·未 | Passion, fame, expansion | 壬 Water / 癸 Water |
| 🍂 Autumn | Metal | 申·酉·戌 | Harvest, clarity, refinement | 丁 Fire / 壬 Water |
| ❄️ Winter | Water | 亥·子·丑 | Storage, wisdom, introspection | 丙 Fire / 丁 Fire |
| 🌍 Transition | Earth | 辰·未·戌·丑 | Balance, mediation, stability | Varies by season |
Frequently Asked Questions
In the next article, we explore one of Saju's most powerful concepts — Yongsin (用神, the favored element). Discover which element your chart truly needs and how working with it can shift your fortune in meaningful ways.
※ This content is for educational and entertainment purposes only. It is not scientifically verified prediction. Please consult a professional for important life decisions.
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