A plain-language definition for anyone researching solar terms (24 jieqi), what it is, where it comes from, and how practitioners use it.
85 plain-language definitions · Cited sources · Persona-authored
By Master Wei Lin · Updated August 3, 2026
Chinese Metaphysics Scholar
What is solar terms (24 jieqi)?
The 24 Solar Terms (二十四節氣 Èr Shí Sì Jié Qì) are the classical Chinese seasonal divisions, each lasting about 15 days. They divide the solar year into 24 equal segments based on the sun's position and are used in BaZi, agriculture, and traditional Chinese medicine.
The 24 Solar Terms divide the year into 24 segments, each marking a precise sun position on the ecliptic. Names include Spring Equinox (春分 Chūn Fēn), Summer Solstice (夏至 Xià Zhì), Cold Dew (寒露 Hán Lù), and Major Snow (大雪 Dà Xuě). The system predates the lunar calendar in agricultural use and remains foundational to classical Chinese timekeeping.
In BaZi, the Solar Terms determine month boundaries, not the lunar new year, as is often assumed. A BaZi practitioner needs to know which Solar Term you were born within to determine your Month Pillar. Tiger Month (寅月) runs from Beginning of Spring (立春 Lì Chūn) to Awakening of Insects (驚蟄 Jīng Zhé), regardless of where the lunar new year falls.
The 24 Solar Terms emerged from classical Chinese astronomical observation during the Han dynasty (around 200 BCE), with the original 12 terms (節 Jié) and 12 sub-terms (氣 Qì) developed for agricultural timing. The system was inscribed on UNESCO's Representative List of the Intangible Cultural Heritage of Humanity in 2016, recognizing its continued cultural significance.
BaZi practitioners use the Solar Terms to determine the Month Pillar of any chart. The classical sources observe a January-or-February born person needs to know whether they were born before or after Beginning of Spring (立春 Lì Chūn, typically February 3-5) to determine their correct Month Pillar, a critical detail for accurate BaZi reading.
Classical Chinese medicine uses the Solar Terms to recommend seasonal practices, what to eat, when to sleep, which organ systems to support. The classical reading shows this is the most accessible Solar Terms application for non-specialists.
These glossary terms are closely connected to solar terms (24 jieqi):
Twenty-four equal divisions of the solar year, each about 15 days long. Major terms include the equinoxes, solstices, and the four 'beginnings' (Beginning of Spring, Summer, Autumn, Winter). The system divides the year astronomically rather than by lunar phase.
Because the Month Pillar of a BaZi chart is determined by the sun's position, not the moon's. Beginning of Spring (立春 Lì Chūn) marks the start of the BaZi year, typically around February 3-5, which can be before or after the lunar new year.
Yes. They appear in Chinese-language calendars, agricultural almanacs, traditional Chinese medicine seasonal recommendations, and BaZi practice. UNESCO recognized them as Intangible Cultural Heritage in 2016.
Precise calculation matters. The classical sources note cross-checking your birth date against an ephemeris-based BaZi calculator. A few hours can change the Month Pillar at the boundary.
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