Chhath is an ancient Hindu Vedic festival historically native to the Indian subcontinent, more specifically, the Indian states of Bihar,and, Jharkhand and the southern parts of Nepal. Prayers during Chhath puja are dedicated to the solar deity, Surya, to show gratitude and thankfulness for bestowing the bounties of life on earth and to request the granting of certain wishes. Chhathi Maiya, the mother goddess and Sun's sister, is worshipped as the Goddess of the festival. It is celebrated six days after Diwali, on the sixth day of the lunar month of Karthika (October–November) in the Hindu calendar Vikram Samvat. The rituals are observed over four days. They include holy bathing, fasting and abstaining from drinking water (vrata), standing in water, and offering prasad (prayer offerings) and arghya to the setting and rising sun. Some devotees also perform a prostration march as they head for the river banks. Environmentalists have claimed that the festival of Chhath is one of the most eco-friendly religious festivals. All devotees prepare similar prasada (religious food) and offerings. Although the festival is observed most elaborately in the Madhesh (southern) region of Nepal and the Indian states of Bihar, Uttar Pradesh and Jharkhand, it is also prevalent in areas where the diaspora and migrants from those areas have a presence. It is celebrated in all northern regions and major north Indian urban centers like Delhi. Hundreds of thousands of people celebrate it in Mumbai.
Chhath puja is dedicated to the sun god Surya. The sun is the god visible to every being, is the basis of life of all creatures on earth.[20] Along with the Sun God, Chhathi Maiya is also worshipped on this day. According to Vedic astrology, Chhathi Maiya or Chhathi Mata protects the offspring and provides longevity to them.
In the Hindu religion, the Shashthi Devi has also been known as Manas, the daughter of Brahma. In the Puranas, she is also said to be the mother Katyayani, who is worshipped on Navratri on the Shashti date. Shashthi Devi is said to be Chhath Maiya in the local language of Bihar.
As per legends, Chhath Puja is being performed from the early Vedic period by sages who would fast for days and perform the puja with mantras from Rigveda. It is believed that Chhath Puja was also performed by Karna, the son of Lord Surya and the king of Anga Desh, which is the modern-day Bhagalpur in Bihar. According to another legend, Pandavas and Draupadi also performed the Puja to overcome obstacles in their lives and gain their lost kingdom. For the people from Bihar and other close by areas, Chhath Puja is considered as Mahaparva.