Dasha (Vimshottari)

Dasha means period. The most used system is Vimshottari, which divides a 120-year cycle among nine grahas in a fixed order: Ketu 7 years, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19 and Mercury 17.

Where a person's own cycle begins depends on the nakshatra the Moon occupied at birth. The ruler of that nakshatra gives the first period, and how far the Moon had travelled through the nakshatra decides how much of that period is left at birth. After that the periods follow in order.

Each major period (mahadasha) is divided into sub-periods (antardasha) in the same order, so at any date a person is said to be running one planet's period and another's sub-period. The texts read the nature and house position of those two planets to describe the themes of the time. A birth chart report lists these periods with exact dates.