Origins
Year Pillar · Jupiter-Cycle Years
Jupiter circles the sky in about 11.86 years. Ancient Chinese astronomers divided the heavens into twelve stations; "one station per year" earned Jupiter the name Sui Star (Year Star). Because its apparent motion runs opposite to the twelve branches, a mirror-image counter-star — Tai Sui — was imagined to pace the branches, and this is the origin of the year branch. Jupiter actually runs slightly fast, gaining a station roughly every 85 years, so from the Han dynasty onward the calendar decoupled from the real planet and adopted the purely mathematical sexagenary cycle. The golden "太岁" marker shows the idealized year position; compare it with real Jupiter to see the drift.
Month Pillar · Solar Longitude
The month pillar has nothing to do with lunar months: it is determined entirely by the Sun's position on the ecliptic. Starting from Lichun (longitude 315°), every 30° of solar travel marks one "node", mapping to the twelve month branches. The teal beam in the scene is Earth's line of sight to the Sun — whichever sector it lands in on the outer ring is the month branch. The year also changes at Lichun, not at Lunar New Year.
Day Pillar · The Sixty-Day Count
The day pillar depends on no celestial event at all: it is an unbroken base-60 count, pairing ten stems with twelve branches in a sixty-day cycle. Shang-dynasty oracle bones already record days this way — an unbroken run of over three thousand years, the longest continuous day-count in human history. This model anchors on January 1, 2000 (a 戊午 day). The inner golden Jiazi wheel is that counter: the vermilion needle advances one notch per day, one full turn per sixty days.
Hour Pillar · Twelve Double-Hours
One rotation of the Earth divides into twelve double-hours, with 子 beginning at 23:00. The hour stem is not independent — it derives from the day stem by the "Five Rats" formula, so within a day the hour pillar is locked to the day pillar. The small teal hour dial beside Earth keeps its noon mark facing the Sun; the vermilion bead is the observer, riding one lap per day — whichever cell it sits in is the hour branch (zoom in for a closer look).
Clashes & Combinations · Disc Geometry
Once the twelve branches are spaced evenly around a circle, their relations become pure geometry: the six clashes are six diameters (180° apart); the three harmonies are four equilateral triangles (120° apart) — Water 申子辰, Wood 亥卯未, Fire 寅午戌, Metal 巳酉丑; the directional assemblies are three consecutive branches filling one quadrant; and the six harmonies form six mutually parallel chords. The ten stems add five combinations (甲己, 乙庚, 丙辛, 丁壬, 戊癸). Tick "All" to see every rule shape at once.
Luck Pillars · The Month Sequence, Slowed
The luck-pillar rule is "three days equal one year": the days from birth to the adjacent solar node, divided by three, give the starting age; the sequence then walks forward or backward from the month pillar (forward for males born in yang years and females in yin years, otherwise backward), ten years per pillar. In other words, luck pillars stretch the solar-term year about 120-fold across a lifetime — each decade replays one month of the year. The purple "Luck" marker shows the branch your current pillar borrows. It is pure numerology, corresponding to no sky event.
Five Elements · The Five Visible Planets
The five elements take their names directly from the five naked-eye planets: 辰星 (Mercury — swift, hugging the Sun), 太白 (Venus — brilliant white), 荧惑 (Mars — red and wayward), 岁星 (Jupiter — one circuit in twelve years), and 镇星 (Saturn — about twenty-eight years per circuit, "guarding" one lunar lodge per year). The planets in this model are tinted by their elements.
