The nectar of immortality

Finally, Dhanvantari, the heavenly physician, emerged with a pot containing Amrita, the heavenly nectar of immortality. Fierce fighting ensued between Devas and Asuras for the nectar. To protect the nectar from Asuras, the divine Garuda took the pot, and flew away from the battle-scene. While Garuda was in his flight over planet Earth, it is believed that four drops of nectar fell at four places - Prayag (Allahabad), Haridwar, Ujjain and Nasik. This legend is the basis for the belief that these places acquired a certain mystical power and spirituality. A Kumbh Mela is celebrated at the four places every twelve years for this reason.
However, the Asuras eventually got hold of the nectar and started celebrating. Frightened, devas (demigods) appealed to Vishnu, who then took the form of Mohini. As a beautiful and enchanting damsel, Mohini distracted the asuras, took the amrita, and distributed it among the Devas, who drank it. Two asura, Rahu and Ketu , disguised himself as a deva and drank some nectar. Due to their luminous nature, the sun god Surya and the moon god Chandra noticed the switching of sides. They informed Mohini. But before the nectar could pass his throat, Mohini cut off his head with her divine discus, the Sudarshana Chakra. The head, due to its contact with the amrita, remained immortal. To gain revenge on the sun and moon for exposing this, the immortal head occasionally swallows the sun or the moon, causing eclipses. Then, the sun or moon passes through the opening at the neck, ending the eclipse.
The story ends with the rejuvenated Devas defeating the asuras.