What is Chhath Puja?
Chhath is the four-day worship of the Sun and Chhathi Maiya, kept above all in Bihar, Jharkhand and eastern Uttar Pradesh. It is among the most demanding fasts in the Hindu calendar, and one of the very few addressed to the setting Sun as well as the rising one.
How it is observed
The days run Nahay Khay, Kharna, Sandhya Arghya — the evening offering standing in water — and Usha Arghya at dawn, when the fast finally breaks. The fast is kept without water for roughly thirty-six hours.