Simhastha is a very holy occasion in Hinduism. It occurs when
Navagraha Guru or Brihaspati (planet Jupiter) enters Simha Rashi (zodiac sign
Leo) in Hindu astrology. As Guru takes about twelve years to complete one full
rotation around Surya (sun), it passes through all twelve rashis in twelve
years. Its transit through Simha Rashi takes place periodically after every
twelve years.
Puranas state that when Brihaspati graham is in Simha Rashi,
the holy gana is deemed to flow into Godavari River in a hidden form.
When Simhastha takes place, it is presumed that all the gods and
goddesses in Hindu pantheon take holy dip in the Godavari River.
It is also believed that the holiness of all the sacred
places and teerths in the world join in Godavari during the period. Therefore
it is believed that taking a holy dip Godavari River during the period will
help in achieving sin redemption, moksha and fulfillment of desires.
An important mela is held during this period at Nashik in
Maharashtra.
Legend has it that Lord Shiva who was pleased with devotion
of Gautama Rishi handed over a strand of his sacred hair to the Rishi. The sage
installed the strand of hair on Brahmagiri mountain and Godavari River
originated from that place. The incident occurred on Magh Shukla Paksha Dasami
or the tenth day during the waxing phase of moon. On that day, the Brihaspati graham
was in Simha Rashi, which is the Simhastha period. It is for this reason that
Simhastha is also considered to be the birthday of Godavari River.