Solar Terms, Yin Dun, and Yang Dun in Qimen
The current solar term selects the relevant bureau table and divides the year into Yang-Dun and Yin-Dun spans. In the declared table, Yang Dun runs from…
Overview
The current solar term selects the relevant bureau table and divides the year into Yang-Dun and Yin-Dun spans. In the declared table, Yang Dun runs from Winter Solstice through Grain in Ear, and Yin Dun from Summer Solstice through Major Snow. Compare the cast instant with an exact astronomical solar-term boundary, then project that instant into the cast offset for display. A calendar date alone is insufficient near the boundary because the term changes at a specific time.
At a glance
- Page role
- Reproducible calculation rule
- Terms covered
- Yin Dun · Yang Dun · 24 solar terms
- Verification focus
- Compare the cast instant with an exact astronomical solar-term boundary, then project that instant into the cast offset for display. A calendar date alone is insufficient near the boundary because the term changes at a specific time.
- Stop rule
- Do not infer climate, luck, or event timing from the Yin-or-Yang label alone. It is first a placement direction and table-selection fact under the named method.
Direct answer and scope
The current solar term selects the relevant bureau table and divides the year into Yang-Dun and Yin-Dun spans. In the declared table, Yang Dun runs from Winter Solstice through Grain in Ear, and Yin Dun from Summer Solstice through Major Snow.
- Names and related terms: Yin Dun
- Names and related terms: Yang Dun
- Names and related terms: 24 solar terms
How the rule is formed or checked
Compare the cast instant with an exact astronomical solar-term boundary, then project that instant into the cast offset for display. A calendar date alone is insufficient near the boundary because the term changes at a specific time.
Keep the cast moment, UTC offset, method version, palace, and interacting symbols visible before adopting an interpretation.
How to use this in a reading
Expose the previous or current term name and boundary timestamp in the chart audit. If a cast lies within minutes of a boundary, test both sides before diagnosing downstream placement differences.
- Name the visible chart fact before assigning symbolic meaning.
- Compare the asker and matter anchors with every layer in their palaces.
- Record at least one supporting condition and one counter-signal.
- End with a reversible action and an observable review point.
Worked contrast
Two casts on the same local date but opposite sides of the Summer Solstice instant can use opposite Dun direction and different bureau rows. Treating the whole date as one term hides the real boundary.
Common mistake and limit
Do not infer climate, luck, or event timing from the Yin-or-Yang label alone. It is first a placement direction and table-selection fact under the named method.
Sources and editorial basis
- 《煙波釣叟歌》Wikisource lines 112–220: nine palaces, 陰陽遁, 三元, 值符/值使, 三奇六儀, 伏吟/反吟, gates, stars, vigor, 擊刑, 入墓, and selected patterns.A public-domain classical verse used only for the rule passages it actually states, including nine palaces, Yin and Yang Dun, Three Wonders and Six Instruments, Chief Star and Gate, gate and star sequences, vigor, and selected conditions. Legendary origin verses are not presented as verified history.
- OpenFate Qimen hour-chart methodOpenFate docs/QIMEN_SYSTEM.md, “Professional calculation contract,” “Interpretation and evidence contract,” and “Rule-source map,” source-reviewed 2026-09-12.Product-specific reference for OpenFate’s fixed-offset civil-time, hour-Qimen, rotating-plate, Chaibu implementation and its deterministic chart fields. A source review on 2026-09-12 does not prove live deployment, other schools, or predictive validity.