Da Yun

Da Yun (Chinese 大運, dàyùn — "great fortune", "great cycle") is the ten-year period of destiny in the Chinese Ba Zi astrology (八字, "the Four Pillars of Destiny", #10).

What Da Yun sets. Each Da Yun is defined by a pair of Heavenly Stem + Earthly Branch (Ganzhi, 干支) and sets the background of the decade — which elements are strengthened and which are weakened.

Calculation of Da Yun

The calculation depends on the Yin/Yang of the birth year and the gender:

• Yang year + male or Yin year + female → count forward
• Yang year + female or Yin year + male → count backward

Age of entry. The starting age of entering Da Yun is computed from the moment of birth to the nearest seasonal node (節氣, jiéqì). For this reason, each person has a unique "starting age".

Comparison with Dasha

The structural analog in Jyotish is Dasha (दशा, #18), but the mechanism is fundamentally different:

• Duration. Da Yun is always exactly 10 years; Vimshottari Dasha periods have individual lengths (from 6 to 20 years)
• Ontology. Da Yun is a "pillar of time" (stem + branch); Dasha is a "planetary force" (Graha)

The key difference. In Ba Zi, destiny unfolds through the transformation of elements over time; in Jyotish, through the activation of planetary archetypes. The same segment of life will be interpreted fundamentally differently in the two systems.