The dates of the Maha Kumbha are determined in accordance with methods which majorly include the planetary positions. When the planet Brihaspati (Jupiter) enters the astrological sign Vrishabha (Taurus), it coincides with the Surya (Sun) and Chandra (Moon) being in Makara (Capricorn), these changes affect the water and air which results in a totally positive atmosphere. Different planets take different amount of time to complete one revolution around the sun. Jupiter completes this revolution in around eleven years and ten months (approximately twelve years), that indicates the fact that in every twelve years the Jupiter moves into the same position. This decides the occurrence of Purna (Full) Kumbha Mela which is held once in every twelve years. The position of Sun, Moon and the planet Jupiter in different astrological signs determine the site at which Kumbh will be held.
The Kumbh Mela is held in Haridwar when the Sun enters the Aries and the Jupiter enters the Aquarius.
The story of Samudra Manthan, one of the best-known episodes in the Hindu mythology, narrated in the Bhagvad Purana states that the sacred alignments of celestial bodies directly relate to the Kumbh festival. It took 12 divine days to carry the Amrit to the heavens. As one divine day of Gods is equivalent to one year of the humans, the journey to the heavens symbolizes 12 years in human terms. That is why every twelfth year when Jupiter enters the Aries constellation on the day of the new moon in the month of Magh, the Kumbh festival is organized. Mythological studies suggest that the Kumbh festival and the Ganga are related to each other. The Ganga flows in Prayagraj but Godavari of Nasik is also called the Ganga or the Gomti Ganga. Similarly, the Shipra (in Ujjain) is recognized as the north branch, the Ganga of Kashi. From that place onwards, Shipra becomes the east branch where it assimilates with the Ganga.
In continuation to the astrological calculation, the event of Kumbh takes place as per the following astrological positions:
- When Jupiter enters the Aquarius constellation along with the Sun moving in to the Aries constellation, the Kumbh festival is held at Haridwar.
- When Jupiter moves in to Leo, the Kumbh festival is held at Nasik on the banks of Godavari and in the event of Jupiter moving in to Leo and the Sun entering Aries, the Kumbh festival is held at Ujjain.
- When Jupiter enters Libra and the Sun and the Moon remain together on Kartik Amavasya (8th month of Hindu year) then also the Kumbh Festival is held at Ujjain.
- When Jupiter, the Sun, and the Moon enter Cancer on lunar conjunction (Amavasya), then also the Kumbh Festival is held on the banks of river Godavari.
- When Jupiter enters the Aries constellation and the Sun and the Moon are in Capricorn constellation, the Kumbh festival is held at Prayagraj on the new moon day.