Chhath Puja – a hindu vedic festival

Chhath (Devanagari: छठ, छैठ, छठी, छठ पर्व, छठ पुजा, डाला छठ, डाला पुजा, सूर्य षष्ठी) is an ancient Hindu Vedic festival historically native to eastern Uttar Pradesh, North Bihar of India and Mithila State of Nepal.

The Chhath Puja is dedicated to the Sun and his wife Usha in order to thank them for bestowing the bounties of life on earth and to request the granting of certain wishes.
The Goddess who is worshipped during the famous Chhath Puja is known as Chhathi Maiya.

Chhathi Maiya is known as Usha in the Vedas. She is believed to be the beloved younger wife of Surya, the sun god. This is the only parva which signifies rising sun as well as setting sun both 

छठ पूजा एक ऐसा श्रेष्ठतम पर्व हैं जहाँ डूबते हुए सूर्य से करते प्रार्थना हुए व्रत का प्रारंभ होता है एवं सूर्योदय कि पूजा के पश्चात व्रत सम्पूर्ण होता हैं 

“जैसे कि जीवन के संचालन के लिए रात्रि का उतना ही महत्व है जितना दिन का”

(source- wikipedia)