The quality of the year is defined by the transit of Jupiter through the Rāśi or signs. Each Rāśi occupied by Jupiter is said to symbolise one of the twelve rivers which gets blessed by the presence of Jupiter in it. Jupiter stationed in this Rāśi makes the river auspicious for visits and during the first twelve days of Jupiter’s entry into these Rāśi the auspicious event of Puṣkara Tirtha is held where the river is bathed in and worship performed to attain salvation.
Notably twelve days corresponds to the average motion of Jupiter through one degree of a Rāśi. Similarly one Navāṁśa or 3º20’ takes fourty days for Jupiter to cover, giving us deeper insight into the importance of spiritual rites performed for the length of forty days.