There are many methods to time the events indicated in the chart.Most Indian astrologers follow Dasa systems. Most popular system is Vimshottari Dasa detailed below. Other Dasa systems are kala chakra dasa, Ashtottari Dasa, yogini dasa and many more. Most of the dasa systems are based on the sidereal longitude of Moon at the time of birth.
In western astrology, Astrologers time events on the basis of profections , progressions etc.
Many older systems are based on the age of native.More details about these systems are given here.
Other timing systems
Many sages have in the past provided many systems to overcome the problem of timing of events. However vedic astrologers appear to agree that of the many systems available, the vimshottari Dasha seems to offer the most accurate results.
Vimshottari literally means "120" in Sanskrit. The vimshottari dasha system follows a cycle of 120 years.
The twenty seven nakshatras are divided into three groups of nine nakshatras each.Each nakshatra is 13 degree 20 minutes wide. Lordship planet for first nakshatra is ketu, for second nakshatra venus, then sun moon , mars rahu , jup sat mer. Lord for 10th nakshatra is again ketu and cycle repeats. similarly lord of 19th nakshatra is again ketu and cycle follows the above sequence.
The table below gives the number of years for each planet in Vimshottari Dasha.
| Ketu( S Node) | 7 Years |
| Venus | 20 |
| Sun | 6 |
| Moon | 10 |
| Mars | 7 |
| Rahu( N node) | 18 |
| Jup | 16 |
| Sat | 19 |
| Mer | 17 |
| Total | 120 |
The first step in calculating the vimshottari dasha for a native's chart is to work out the position of the moon and the corresponding nakshatra in which the moon is located. Then the balance in minutes for that nakshatra to complete from the position of the moon is evaluated. The ratio of this balance and the total range of a nakshatra (13degrees and 20 minutes or 800 minutes) is then multiplied by the number of years corresponding to the planet that rules the nakshatra in which the moon is located. This represents the balance of that planet (or dasha) at the time of birth. Subsequent dashas will depend on this starting dasha at the time of birth. The cyclical order starting with Venus would be Sukra (Venus), Ravi (Sun), Chandra (Moon), Kuja (Mars), Rahu (imaginary), Guru (Jupiter), Sani (Saturn), Budha (Mercury) and Ketu (imaginary).
Dasha calculation example…
As an example, let us say a native's moon is located at 11S 22d 50m 34s (which reads 11 complete signs and 22 degrees, 50 mins and 34secs into the 12 sign). This is the equivalent of (11 * 30 + 22*60+50) = 21170 minutes from the first point of Aries. If we divide this by 800 minutes (range per nakshatra) we will know which nakshatra this belongs in. => 21170 / 800 = 26.4625. (or in other words the moon is in the 27th nakshatra). The 27th nakshatra starts at 26 * 800 = 20800 minutes and ends at (20800 + 800) 21600 minutes.
For this native the moon is .4625 into the 27th nakshatra. or in other words, 21170 - 20800 = 370 minutes into Ravati (27th nakshatra). The Lord of Revati is Budha (Mercury) which has a life of 17 years. => (370 * 17)/800 = 7.8625 years of Mercury is completed at the time of birth. => balance of mercury at birth is (17 - 7.8625) = 9.1375 or 9 years, 1 month and 15.165 days.
So for the native chosen in this example, the individual starts with Budha (Mercury) dasha at birth and then moves on to Ketu dasha at the age of 9. Ketu will last for 7 years and then the native will move to Sukra at the age of 16. Sukra will last for 20 years and then the native will move to Ravi at the age of 36 and so on.
Life consists of cycles within cycles within cycles. This is reflected in the dasha scheme through the sub-dashas or sub periods known as Bhukthi or Antardasha. Just as there are 9 major dasha periods, called mahadashas (maha means great, so mahadasha means great period), there are also sub-periods. There is no limit to the number of sub-periods that can be considered, but in most cases 2-4 are considered.
Each sub-period consists of the 9 graha periods, in the same order as shown above, starting with the mahadasha period. For example, the Mercury dasha starts with the Mercury sub-dasha, followed by Venus, Ketu, Sun, Moon, Mars, Rahu, Jupiter, and ending with Saturn. After this the Ketu mahadasa begins, with the sub-periods being Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, and Mercury.
The length of each sub-period maintains the same ratio as the length of the mahadasha period. For example, the Mercury mahadasha lasts 17 years, which is 17/120 of the entire Vimshottari dasha cycle. The Mercury sub-period of the Mercury mahadasha is therefore 17 x 17/120 = 12 months. The Venus sub-period of Mercury lasts 17 (length of Mercury mahadasa) x 20 (length of Venus mahadasa)/120 = 2.83 years. In a similar way, the lengths of all the sub-periods, sub-sub-periods, and so on can be calculated.
