NEW DELHI, Oct. 25 -- At the ghats in Delhi this morning, women lined up after taking a sacred dip in the Yamuna.

They carefully drew long, narrow streaks of orange vermillion using thin sticks, peeking into hand-held mirrors or the screens of their phones. It was the first day of the Chhath festival, known as Nahay Khay, and the air was filled with the quiet bustle of prayer and preparation.

The four-day festival began with this ritual bath, which is followed by a simple satvik meal eaten once after sunrise - the last meal before women begin their arduous fast in reverence to Lord Sun and Chhathi Maiya for the well-being of their families.

On Kharna, day two, a strict waterless fast is observed from sunrise to sunset. Traditionally, thi...