Dasha — which planet is timing your life right now.

A dasha is a planetary period — a span of time in a Vedic chart during which a specific graha (planet) is the primary timer of events. The Vimshottari system, the most widely used, gives each of the nine Vedic grahas (Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury, Ketu, Venus) a fixed number of years; together they sum to 120, and the complete cycle of nine mahadashas runs a full human lifespan. Which mahadasha you are born into depends on the precise nakshatra of your Moon at birth.

A mahadasha is the major period (e.g., Venus mahadasha = 20 years). Within each mahadasha, the same nine lords cycle again as antardashas (sub-periods), but weighted — so Venus-in-Venus antardasha is longest within Venus mahadasha, and Sun-in-Venus is shortest. Each antardasha contains pratyantardashas (sub-sub-periods), and so on. Most practitioners work with three levels, but the system extends down to five. The current pratyantardasha tells you this month's flavor; the mahadasha tells you this decade's.

No. Unlike a birth chart (where latitude and longitude determine the Ascendant and house cusps), dasha depends only on the Moon's sidereal position at birth — which is calculable from birth datetime alone, because the Moon's geocentric position at a given moment is the same regardless of where on Earth the observer is. So: birth date, time, and timezone are all you need.

The Moon moves about 13° per day, which is roughly one nakshatra per 24 hours — but it can change nakshatra at any hour, not just at midnight. If your birth time is off by even an hour or two, your natal nakshatra may shift, and along with it the starting mahadasha and the dates of every period that follows. If you don't have an exact birth time, try a range and see whether the current-period interpretation matches your lived experience — that's the rectification technique practitioners use.

Vimshottari is the default in modern Vedic practice and accounts for the large majority of consultations. Yogini (36-year cycle across 8 lords) is often used for cross-verification. Ashtottari (108-year cycle) is used when certain chart conditions favor it. Kalachakra is a specialized system. If you're new to dasha, Vimshottari is where to start — the other options are useful second opinions.