Jupiter or Brihaspati takes approximately 12 years to complete 1 revolution around the Sun. While the world celebrates the new year when Earth completes 1 revolution, in Bharat, we also celebrate the 12-year cycle of Jupiter. We recognise that the gravity of Jupiter protects the Earth from many celestial threats, and life on Earth would have been impossible without Jupiter being in the right place and revolving at the right speed.
We recognize and celebrate the specific position of Brihaspati (Jupiter) along with the position of Surya in the zodiac, and accordingly, the Kumbh Mela is held at four sacred locations-Haridwar, Prayag, Nashik and Ujjain.
The year and location of the Kumbh are decided based on the Kumbha-Yoga, determined by the positions of Brihaspati and Surya. For details of the positions refer to the image above or this table below.
| Celestial Body | Prayag | Nasik | Ujjain | Haridwar |
| Jupiter | Vrshabh (Taurus) / Mesha(Aries) | Simha(Leo) | Simha(Leo) | Kumbh (Aquarius) |
| Sun | Makar (Capricon) | Simha(Leo) | Mesh (Aries) | Mesh (Aries) |
| Moon | Makar (Capricon) | Cancer | Mesh (Aries) | Saggittarius |
Sri Nityananda Misra says in his book - "Kumbha: The Traditionally Modern Mela": "The Moon takes around one month (27.32 days) to orbit the earth during which it transits through the 12 signs. The Sun transits through the 12 signs in around one year (365.2425 days), the time taken by the earth to orbit the Sun. Finally, Jupiter transits through the 12 signs in nearly 12 years (11.8618 years), the time taken by it to orbit the Sun. The transit period of Jupiter being the longest—12 times that of the Sun and around 159 times that of the moon—the kumbha yoga for a location repeats when Jupiter enters the same sign again. This is why the Kumbha Mela is held once every 12 years at a given venue, as a general rule. The seventh Mela after six melas held in 72 years (each held 12 years after the previous one) is held 11 years after the sixth Mela, giving us seven melas in 83 years. The reason is that Jupiter completes seven transits of the zodiac in nearly 83 years (11.8618 × 7 = 83.0326), and moves to the next sign in the 84th year. This is why the Haridwar Kumbha was held in 1938 after 1927 and the Prayaga Kumbha was held in 1977 after 1966. The last Kumbha in Haridwar was in 2010 (1938 + 72), but the next one will be in 2021 (1938 + 83 = 2010 + 11). While 12 years is an overestimate for the time taken by Jupiter to transit through the 12 zodiac signs once, 83 years is an underestimate for seven such transits. Fortunately, 83.0326 is very close to 83, so the thumb rule of seven Kumbha Melas in 83 years works well for a reasonably long period of time." Hence Kumbh is decided based on the position of Jupiter & the Sun.
At each location, when kumbha occurs once in 12 years, it is called Purna Kumbh. However, the term "Purna Kumbh" is commonly used only for Prayag and Haridwar. For Nashik and Ujjain, it is simply called Kumbh. Additionally, Ardha Kumbh (half Kumbh) was introduced some time ago and occurs every 6 years, but only in Prayag and Haridwar. Based on these, the distinctions between Kumbh, Ardha Kumbh, and Purna Kumbh are made. As of now, I haven’t come across any scriptural references about a Mahakumbh being celebrated every 144 years. If anyone has details, please share them with me.
If someone says that Kumbh happens every 3 years in rotation across the 4 locations, it can be confusing because sometimes, in the same year, Kumbh and/or Ardha and/or Purna Kumbh are held at different venues, such as in 2004 and 2016. Multiple Kumbhs in the same year occur because of the Kumbha-Yoga.
The Amrit Snan dates are determined by the tithi, which is based on the lunar phases. As the moon influences both ocean tides and human physiology, the snan dates at Kumbh are calculated using a unique astronomical alignment of Brihaspati (Jupiter), Surya (Sun), and Chandra (Moon).
See the mapping of Kumbh from 1983 to 2033 to understand the above description about Kumbh
