Chandra bala and chandrashtama

Twelve positions from one sign

Where tara bala counts nakshatras, chandra bala counts whole zodiac signs: the transiting Moon's sign, counted inclusively from the birth Moon's sign, gives a number from one to twelve. That position — not the sign's name, just its distance from the birth Moon — is what the classical reading sorts into three bands.

Because the Moon changes sign roughly every two and a quarter days, chandra bala shifts on the same rhythm: a birth chart has one fixed reference point, but the reading itself moves through all twelve positions over the course of a lunar month.

The favourable, middling and unfavourable positions

Positions one, three, six, seven, ten and eleven from the birth Moon are read as favourable. Positions two, five and nine are middling — the classical sources are less unanimous about these three than about the clearly good or clearly bad positions, which is part of why they sit in the middle. Positions four and twelve are read as unfavourable.

That leaves position eight, which is not folded into chandra bala's own scale at all — it is handled separately, as chandrashtama, because the classical reading of the Moon's eighth-house transit is severe enough to warrant its own treatment rather than being one more point among twelve.

Chandrashtama — the Moon in the eighth from itself

Chandrashtama is the specific case of the transiting Moon occupying the sign eighth from the birth Moon's sign. The eighth house is classically associated with disruption and the unforeseen, and the Moon's monthly passage through it from its own birth position is one of the most consistently avoided windows in muhurta practice — stronger, in the classical reading, than an ordinary unfavourable chandra bala position.

Because the Moon spends roughly two and a quarter days in each sign, a chandrashtama window recurs for a similar stretch every lunar month, its exact start and end fixed by when the Moon crosses into and back out of the eighth sign.

A birth Moon in Mesha places chandrashtama in Vrischika, the eighth sign counting from Mesha; each time the transiting Moon enters Vrischika, a chandrashtama window opens and holds for as long as the Moon remains there.

The transiting Moon's own strength

Separately from its position relative to the birth Moon, the transiting Moon's dignity in its current sign is read on its own terms. The Moon is exalted in Vrishabha and considers Karka its own sign, and a transit through either is read as adding to the Moon's classical strength regardless of which chandra bala position that sign happens to occupy for a given birth chart.

Waxing versus waning

Whether the Moon is waxing (shukla paksha, growing from new to full) or waning (krishna paksha, shrinking back toward new) is read as a separate, simple strength factor: a waxing Moon is classically considered to be gaining light and is read as mildly favourable, distinct from both chandra bala's sign-count and the Moon's own dignity.