Dasha — the Vimshottari time system

A birth chart is a snapshot. A dasha system is what makes it a sequence: a scheme of planetary periods that says when the chart's promises are likely to mature.

This is the single most distinctive feature of Jyotish. Lesson 2 noted that the twelve signs and houses came from the Hellenistic world; the dasha systems did not. There are many — Ashtottari, Yogini, Chara and others — but Vimshottari is the default, and it is the only one this course teaches.

The cycle

Vimshottari means "one hundred and twenty". The full cycle runs 120 years, divided between the nine grahas in fixed proportions:

Add them: 7 + 20 + 6 + 10 + 7 + 18 + 16 + 19 + 17 = 120. If your arithmetic gives anything else, you have the table wrong.

The order is fixed and is the same nine-step cycle as the nakshatra lords in Lesson 7: Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury — then back to Ketu.

Where the sequence starts

At the Moon's nakshatra at birth.

If the Moon is in Rohini, whose lord is the Moon, the sequence begins with a Moon mahadasha. If the Moon is in Ashlesha, ruled by Mercury, it begins with Mercury. This is why the janma nakshatra matters so much, and why an accurate birth time is not optional.

The balance at birth

You are almost never born at the exact start of a nakshatra, so the first period is partial. The remaining portion is proportional to how much of the nakshatra the Moon has left to travel.

A worked example. Suppose the Moon is at 6°40' into Rohini. A nakshatra spans 13°20', so the Moon has travelled exactly half of it and has half remaining. Rohini's lord is the Moon, whose full period is 10 years. The balance at birth is therefore 5 years of Moon mahadasha.

After that runs out, the sequence proceeds in order: Mars 7 years, Rahu 18, Jupiter 16, and so on.

Sub-periods

Each mahadasha subdivides into antardashas (also called bhuktis), in the same nine-graha order, each proportional to its own share of 120.

Two rules worth knowing:

• An antardasha's length is (mahadasha years × antardasha graha's years) ÷ 120.
• The first antardasha within any mahadasha belongs to the mahadasha lord itself. A Saturn mahadasha opens with Saturn–Saturn.

So a Saturn mahadasha of 19 years opens with a Saturn–Saturn antardasha of (19 × 19) ÷ 120 = about 3 years. Subdivision continues below this into pratyantardasha and further, though the returns diminish quickly.

How dasha is actually used

The standard formulation: the chart shows what is promised; the dasha shows when it is delivered.

A graha's period activates what that graha signifies naturally, what it rules by house, where it sits, and what it aspects. A strong 10th lord's mahadasha is where a career is expected to move. A yoga formed by two grahas tends to deliver during their periods and stay quiet outside them.

The practical consequence is that dasha and transit must agree. Lesson 20 takes that up.