Mahadasha Meaning in Vedic Astrology
A mahadasha is a major planetary period in the Vimshottari dasha, the system of timing that Jyotisha uses above all others. Life is divided into a sequence of nine periods, one for each graha, of fixed lengths that sum to 120 years; within any mahadasha the planet that rules it presides over the affairs of life, and the events its natal position promises fall due. The dasha running at any moment is the first thing a Vedic astrologer asks after the chart itself.
The nine periods
| Graha | Years |
|---|---|
| Ketu | 7 |
| Venus | 20 |
| Sun | 6 |
| Moon | 10 |
| Mars | 7 |
| Rahu | 18 |
| Jupiter | 16 |
| Saturn | 19 |
| Mercury | 17 |
The order is fixed and cyclic; after Mercury comes Ketu again. It is the order of the nakshatra lords, and the two are one system: the dasha is the unfolding of the birth star.
Where the sequence starts
The first mahadasha is that of the lord of the Moon's nakshatra at birth. The portion of the nakshatra the Moon had already traversed is subtracted proportionally from the period: a Moon at the very beginning of Rohini begins a full ten-year Moon dasha, while a Moon three quarters of the way through Rohini begins with two and a half years of it remaining, after which Mars follows. This remainder is the dasha balance at birth, and everything after it is arithmetic.
Because the Moon moves about one nakshatra a day, the balance is sensitive to the birth time. An error of an hour shifts the boundaries of every later period by days to weeks, and an error that carries the Moon across a nakshatra boundary changes the whole sequence. A chart with an unknown birth time gives an approximate dasha at best, and the tradition says so rather than dating events from it.
Sub-periods
Each mahadasha divides into nine antardashas, also called bhuktis, in the same order, beginning with the mahadasha lord itself, each with a length proportional to its own share of the 120 years. In the twenty-year Venus mahadasha, the Venus antardasha lasts three years and four months, the Sun antardasha one year, the Moon antardasha one year and eight months, and so on through Mercury. Antardashas divide again into pratyantardashas, and the tradition reads three levels routinely; the finer levels exist in the texts and are used when the birth time is exact. The reading of any moment is the mahadasha lord, the antardasha lord, and the relation between them.
Reading a mahadasha
A mahadasha delivers what its lord is placed to deliver. The tradition weighs five things. The houses the lord rules from the lagna: a planet gives, above all, the results of its lordships, so that the lord of the ninth brings fortune and the lord of the eighth brings obstruction, whatever the planet's own nature. Its house of placement: the affairs of that house come to the fore. Its dignity: exalted, in its own sign, in a friend's or an enemy's sign, or debilitated, and its strength in the Navamsa. Its relation to the lagna lord and to the antardasha lord: a benefic's dasha with a hostile bhukti lord has hard stretches within it. And the yogas it takes part in: a Raja yoga or Dhana yoga formed by the lord is delivered in its dasha, and in particular in the antardasha of the other planet forming it.
A functional benefic's dasha, and a yogakaraka's above all, is the period the chart was waiting for. A functional malefic's dasha, the lord of the sixth, eighth, or twelfth, or a maraka, the lord of the second or seventh, in its time, is a period of illness, loss, or danger, and the tradition names it as such, with its length, rather than calling it a lesson. The transits, the gochar, of Saturn and Jupiter running through a dasha give the finer timing, and a Sade Sati inside a hard dasha is the tradition's hardest case. The reverse also holds: a strong Jupiter transit inside a benefic dasha is the tradition's best.
Other dashas
Parashara gives many dasha systems, of which Vimshottari is the one he makes general. Ashtottari, of 108 years, is prescribed by some texts for particular positions of Rahu; Yogini and Kalachakra dashas are in regional use; and the Jaimini Chara dasha runs by signs rather than by planets. Modern practice following B. V. Raman takes Vimshottari as the default and brings in another system to confirm a date, never to replace the Vimshottari reading. The Western tradition's nearest equivalents are the time lords of annual profections and the planetary periods of the Persian and Arabic astrologers, which likewise hand the years of life to one planet at a time.