Vimshottari Dasha
The most popular dasha system is the Vimshottari dasha system. It is based on a 120 year life span, representing the natural, full lifespan of a human being. The order and length of dashas is the same for everyone, only the entry point is different.
The Vimshottari dasha system has 9 dasha rulers, which are the 9 Grahas themselves. The order in which the dashas follow has an astronomical basis, and is the order of increasing distance from the Sun, with some special cases.
Mercury, Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter and Saturn
One special case is the Sun itself, which is placed before the Moon. The other special case is Rahu and Ketu. Rahu is associated with the asteroid belt which is located between Mars and Jupiter, and Ketu is placed opposite of Rahu in this cycle of 9.
The Vimshottari dasha order is the same as the rulerships of the nakshatras. The 27 nakshatras are divided in three cycles of 9, and the nakshatras within each group are ruled by the 9 Grahas. The first Nakshatra is ruled by Ketu, and the other 8 rulers follow in the order of the Vimshottari dashas.
The order in which the dashas follow has an astronomical basis, and is the order of increasing distance from the Sun, with some special cases.
Mercury, Ketu, Venus, Sun, Moon, Mars, Rahu. Jupiter, Saturn
One special case is the Sun itself, which is placed before the Moon. The other special case is Rahu and Ketu. Rahu is associated with the astroid belt which is located between Mars and Jupiter, and Ketu is placed opposite of Rahu in this cycle of 9.
The duration of the dashas is as follows: Ketu 7, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16. Saturn 19, Mercury 17.
The Dasha the person is born in, is determined by the ruler of the Moon’s Nakshatra. For example, Tapash’s Moon is in Poorva Phalg., which is ruled by Venus, therefore you were born in a Venus Dasha. How far this first Dasha has progressed depends on how many degrees the Moon is into that nakshatra. The further the Moon is into the nakshatra, the greater portion of the first Dasha is expired. To calculate the exact Dasha balance at birth, one has to calculate the percentage of degrees the Moon has progressed into its nakshatra, and that percentage of the Dasha’s length is expired at birth.