According to sidereal astrology popularly specified in the oldest manuscript of Vedic studies the birth chart specifies certain predictions of a human life’s timeline but it is imperative to understand that these forecasting may change in the course of an individual’s time span. Studies justify that every zodiac is interlinked to a planet according to the element that dominates that body, for example Aries links with the planet Mars and it justifies for its fiery , aggressive , extremely passionate nature. Cancer which comes under the influence of Jupiter is a water element and that moulds and forms the flexible nature of the person but as mentioned earlier the variation and adjustment of continuity from the time of the birth chart till the present day or coming future proceeds because of the principle planet prevailing to influence the certain factors at that time. This period is popularly known as dasha, this duration indicates or decides on the good or bad approaching one’s life in accordance with the planet who’s Dasha is established in the recent chart. This can change the further prophecies and also alter the consequences faced in different houses of the sun-sign. Certain examples of Dasha are Mangal Dasha [Mars], Rahu Dasha and this particular scenario many precautions and remedies have to be considered as Rahu is always determined as an inauspicious sign. A dasha continues for a span of 18 to 19 years.
Now once the conception of dasha or planetary period is explained the other speculations that highlight the most because astrology enthusiast are always discussing about it are mahadasha, antardasha and pratyantar dasha. Now before concentrating on the fact on how they are predicted in the readings and what it does to a human life and its diurnal activity it is crucial to know the definition of the three perceptions. Mahadasha is that period of time among the time span of dasha which is the most the positive and high point of a person’s life and if premeditated properly an individual can strive a lot in their both personal and professional endeavor. There is also a subjected time span allocated for every planet and celestial being for example sun takes a lot of 6 years while Saturn takes up to 16 years on the other hand, moon time span stays up to 10 years and Venus stays for 20 years. It is imperative to mention that a mahadasha comes every 120 years in a person’s life so it's impossible for a same person being affected by the mahadashas of two planets in one lifetime.
While mahadasha talks about just one planet or graha antardasha is segmented into 9 parts within the mahadasha, antardasha comprises of the influence that the other planets have along with the dominant planet. The Antar Dasha of different planets come in a chronological manner, like Ketu comes first and then second is Ketu/venus then comes along Venus and then Sun and so on so forth. Though people believe astrology is a complex matter and it takes worldly knowledge to understand the concept, the calculation of antardasha I actually very simple. As stated earlier every mahadasha as a specific allotment of time is considered in every planet, so the calculation goes that for example, if the moon has a mahadasha for 10 years it is 10*10/120=0.8, so the antardasha will stay for a time span of eight months. There are certain predictions that an astrologer can predict when does dasha enters a person’s life and when is the optimistic time span of mahadasha , so if the time could be sighted it will be beneficial for the person as pending works or goals could be accomplished very easily during this time.