What a dasha is
A dasha is a stretch of your life assigned to a particular planet. During Jupiter’s dasha, Jupiter is the presiding influence — its condition and house position in your birth chart shape what those years tend to bring — and when that span ends another planet takes over. The word means state or condition, and the idea is that a life moves through a fixed sequence of them rather than being uniformly governed by the whole chart at once. This is a system of internal timing: the clock is set at birth and runs on its own schedule, independent of where the planets happen to be in the sky today. Knowing your current dasha is, for many Vedic astrologers, the first question before any prediction.
How Vimshottari divides 120 years
Several dasha schemes exist, but Vimshottari is the one in general use, and its name means simply one hundred and twenty. That total is parcelled out among the nine grahas in fixed amounts: Ketu gets 7 years, Venus 20, the Sun 6, the Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19 and Mercury 17. The order never varies, and the cycle repeats if a life runs past 120. Each of these major periods is then subdivided into nine sub-periods in the same proportions and the same order, and those subdivide again, so an astrologer can zoom from a nineteen-year Saturn span down to a window of weeks. The arithmetic is entirely deterministic once the starting point is known.
Why your birth nakshatra sets the clock
The sequence has a fixed order, so all that is needed to place a life on it is a starting position — and that comes from the Moon. Each of the twenty-seven nakshatras, the 13°20′ lunar segments the zodiac is divided into, is assigned one of the nine planets, cycling through the list three times. Whichever nakshatra your Moon occupied at birth names the planet whose dasha you were born into, and how far the Moon had already travelled through that segment determines how much of the period had elapsed before you arrived. Someone born at the start of their birth star gets nearly the full span; someone born at the end gets a few months of it. This is why an accurate birth time matters for dasha work.
How Western astrology times things instead
Western practice reads timing mainly from transits — where the planets are in the sky right now relative to your birth chart — supported by progressions and solar returns. Saturn returning to the position it held at your birth around age twenty-nine is the best known example. These are powerful techniques, and Vedic astrology uses transits too, under the name gochar. The structural difference is that transits are driven entirely by current sky positions, so they arrive when the planets arrive and are the same dates for everyone born under a given placement. A dasha sequence is personal from the first day and unfolds regardless of what the sky is doing, which is a genuinely different kind of clock.
Why the difference is worth knowing
If you come to a Vedic reading expecting the vocabulary of transits, the conversation can be hard to follow, because the astrologer is likely working from a period sequence you have never encountered. The reverse is also true: dashas answer the question of what phase of life you are in with a specificity transits are not designed to provide, and their absence is often what a Western-trained reader finds missing when they first look at Vedic technique. Most practitioners use both together — the dasha names the chapter, the transit dates the scene. Neither claim here is about whether the timing proves out, only about how each system is built.