Chhath Puja, a thanksgiving festival to the Hindu Sun god, has begun on Sunday and it will continue till November 14. Known as the most eco-friendly Hindu festival, the day is marked to offer gratitude to the Hindu Sun god - Lord Surya and Chhati Maiyya for the bountiful life on earth. The rituals of the festival are rigorous, which include holy bathing, fasting and offer prayers to the rising Sun for four days.