The Study of Jyotisha · Chapter 22 of 54 · Part Five · Timing

#Vimshottari dasha

#Timing

A chart describes a life, but not when things happen in it. For timing, Jyotisha has two great tools: dashas, periods of life ruled by the planets in turn, and transits, the planets' actual movements after birth (Chapter 24). This chapter explains the most widely used dasha system, Vimshottari, "the hundred-and-twenty".

The idea of dashas is old: Varahamihira gives a whole chapter to a dasha system of his own, based on his method of computing the length of life (Brihat Jataka VIII; Chapter 23). The Brihat Parashara Hora Shastra describes many systems (chapter 46 and after), Vimshottari among them (46.12–16). Today Vimshottari is used by almost every Jyotishi.

#The periods

In Vimshottari each of the nine grahas rules a period of a fixed length, and the nine periods add up to 120 years:

The order is always the same, round and round: Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury, then Ketu again.

This is exactly the order of the nakshatra lords (Chapter 4): Ashvini is ruled by Ketu, Bharani by Venus, Krittika by the Sun, Rohini by the Moon, and so on, three times round the twenty-seven nakshatras. That is the key to the system.

(Parashara's own statement counts from Krittika with the Sun first: "count from Krittika to the birth star, divide by nine". This gives the same result as the list above, starting from Ketu at Ashvini.)

#Where the cycle starts

The dasha running at birth is the one ruled by the lord of the Moon's nakshatra. And since the Moon at birth is part of the way through its nakshatra, part of that first period has already "passed" before birth. Only the remaining fraction — the balance — is lived.

The rule:

balance of the first dasha = (part of the nakshatra still to be crossed ÷ the whole nakshatra) × the years of its lord

#The example chart

The Moon is at 18°55′ Taurus, which is 48°55′ from the start of Aries.

1. Which nakshatra? Each nakshatra is 13°20′. Rohini, the fourth, runs from 40°00′ to 53°20′. The Moon is in Rohini, whose lord is the Moon.
2. How far through? The Moon is 48°55′ − 40°00′ = 8°55′ into Rohini, out of 13°20′. In minutes of arc: 535′ out of 800′, that is 0.669 of the way.
3. What is left? 1 − 0.669 = 0.331 of Rohini.
4. The balance. The Moon's period is 10 years, so the balance is 0.331 × 10 = 3.31 years — about 3 years, 3 months and 20 days.

The person was born on 15 August 1990, so the Moon's period ran until about 4 December 1993. Then the cycle continues in order:

(These are the dates this website's engine gives, using a year of 365¼ days.)

#Sub-periods

Each dasha (also called the mahadasha, "great period") is divided into nine sub-periods (antardasha or bhukti), one for each graha, in the same order, starting with the dasha's own lord. The length of each is in proportion to the graha's own years:

sub-period = (years of the dasha lord × years of the sub-period lord) ÷ 120

For example, in Jupiter's 16-year dasha, the sub-period of Saturn lasts 16 × 19 ÷ 120 = 2.53 years. Jupiter's own sub-period, which comes first, lasts 16 × 16 ÷ 120 = 2.13 years.

In the example chart, Jupiter's dasha (2018–2034) divides like this:

The nine sub-periods add up to 16 years. Each sub-period can be divided again in the same way into sub-sub-periods (pratyantardasha), and so on, though the finer divisions are only as reliable as the birth time (see below).

#How precise is it?

The dasha dates depend on the Moon's exact position, and so on two things the reader must get right.

The birth time. The Moon moves about half a minute of arc per minute of time. In Rohini, each minute of arc of the Moon's position is worth 10 years ÷ 800 = about 4½ days of dasha. So a birth time wrong by 10 minutes moves every dasha date by about 3 weeks. A birth time rounded to the nearest hour can move them by four months. For the main periods this hardly matters; for sub-sub-periods it is decisive.

The ayanamsa. The Moon's sidereal longitude depends on the ayanamsa (Chapter 2). Different ayanamsas in use differ from Lahiri's by up to about a degree. One degree of the Moon in Rohini is worth 10 years ÷ 13⅓ = 9 months of dasha. So the choice of ayanamsa can shift every dasha date by months.

The year. The texts do not say clearly whether a dasha "year" is a calendar year (365¼ days) or a 360-day year. The two drift apart by about 5¼ days a year, which adds up to more than a year over a long life. This website uses 365¼ days and says so.

A good reader states these assumptions, and does not claim to time events to the day.

#Judging a dasha

A planet's dasha brings out everything that planet means in this chart. To judge it, gather what you already know about the planet:

1. Its natural meanings (Chapter 8). Jupiter's dasha brings Jupiter's things: teachers, learning, children, wisdom, wealth, religion.
2. Its houses, both the house it is in and the houses it rules (Chapter 9). These are the areas of life the period activates.
3. Its strength and dignity (Chapters 10, 14, 15). A strong, well-placed planet gives a good period; a weak or afflicted one, a difficult one.
4. Its yogas (Chapters 17–21). A yoga gives its results in the periods of the planets that form it (Brihat Jataka XI.19).
5. The sub-period lord's relation to the dasha lord. If the two are friends and well placed from each other, the sub-period goes smoothly; if they are enemies, or in the 6th, 8th or 12th from each other, it is more difficult. (This is a common rule in the later books.)
6. Transits during the period (Chapter 24).

For Rahu and Ketu, which own no signs, the later books say they give the results of the lord of the sign they are in, and of the planets they are joined with.

#Varahamihira's grades of a period

Varahamihira classifies a planet's period by the planet's condition at birth (Brihat Jataka VIII.5–7). The scheme is worth knowing because it applies to any dasha system:

Varahamihira also says that a period is good if the dasha lord is in an upachaya house (3rd, 6th, 10th or 11th) from the ascendant, or if a friend of it or a benefic is in the ascendant (Brihat Jataka VIII.10).

#The example chart

Jupiter's dasha (2018–2034, ages 28 to 44). Jupiter is in Cancer at 5°36′, only 36′ past its deepest exaltation at 5° (Chapter 10). So it is just "descending" — but it is in the navamsa of Leo, ruled by its friend the Sun, which makes its period Madhyama, a good one, by Varahamihira's scheme; and it is so close to its exaltation degree that it is very nearly Sampurna. It is in the 10th house, an upachaya (Brihat Jataka VIII.10: a good period). It forms Hamsa (Chapter 18) and is the "special helper" of Mars (Chapter 17). By lordship it rules the 3rd and 6th houses (Chapter 19). The overall picture: a period of growth in career and standing (10th house), through Jupiter's qualities — knowledge, teaching, advice, ethics — and through effort, competition and service (3rd and 6th). For most people, ages 28 to 44 are when a career is built; this chart says it will be built well.

The sub-periods. As this chapter was written (October 2026), the example person was finishing Jupiter–Ketu and starting Jupiter–Venus (17 October 2026 to 17 June 2029). Venus is the ascendant lord, placed in the 10th house with Jupiter, and in exchange with the Moon (Chapter 19). It is in the same sign as Jupiter, so the two are well placed from each other. By the rules above, a good sub-period for personal standing and career, with something of Venus's 8th-house lordship in it.

Rahu's dasha (2000–2018, ages 10 to 28). Rahu is in Capricorn, the 4th house (home, education, inner security), and gives the results of its sign lord, Saturn, the yogakaraka, placed in the 3rd. A long period of education and of building foundations, through Saturn's patience and effort.

Saturn's dasha (2034–2053, ages 44 to 63). Saturn is the yogakaraka for a Libra ascendant (Chapter 19), retrograde and strong in shadbala but weak in Vimshopaka (Chapters 14–15), in the 3rd house. A period in which the 4th and 5th houses — property, home, children, intelligence — are activated, and in which the earlier promise of the chart is consolidated through persistence.

These are descriptions of tendencies. What they become depends on the person and their circumstances.

#Summary

• Vimshottari gives each graha a period: Ketu 7, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19, Mercury 17 years — 120 in all, in the order of the nakshatra lords (Brihat Parashara Hora Shastra 46.12–16).
• The first dasha is that of the lord of the Moon's nakshatra; only the remaining fraction (the balance) is lived.
• Sub-periods start with the dasha lord and last (dasha years × sub-period years) ÷ 120.
• The dates are sensitive to the birth time (about 4½ days per minute of arc of the Moon), the ayanamsa (months per degree) and the length of the year.
• Judge a period by the planet's meanings, houses, strength, yogas and its relation to the sub-period lord; Varahamihira grades periods by the planet's condition at birth (Brihat Jataka VIII.5–7, 10).

#Exercises

1. The Moon is at 2°00′ Leo. Which nakshatra is it in, whose dasha is running at birth, and what is the balance?
2. How long is the sub-period of Rahu in Saturn's dasha? Of the Sun in Venus's dasha?
3. In the example chart, which dasha begins when the person is 44, and why might it be important?
4. A birth time is known only "around 6 in the morning", within half an hour. Roughly how uncertain are the dasha dates?
5. A planet is in its own sign, but in its debilitation navamsa. Which of Varahamihira's grades does its period have?

Answers: 1. 2°00′ Leo is 122°00′ from Aries. Magha (the tenth nakshatra) runs from 120°00′ to 133°20′; its lord is Ketu. The Moon is 2°00′ into it, leaving 11°20′ of 13°20′ = 0.85. Balance: 0.85 × 7 = 5.95 years of Ketu. 2. Rahu in Saturn: 19 × 18 ÷ 120 = 2.85 years. Sun in Venus: 20 × 6 ÷ 120 = 1 year. 3. Saturn's, which is the yogakaraka (lord of both a kendra and a trikona) for a Libra ascendant. 4. Half an hour moves the Moon about 15′, which (in a nakshatra of a 10-year lord) is about 2 months; for a 20-year lord, about 4 months. 5. Mishraphala, mixed.