The Goddess that 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 consort of Surya, the sun god. Some scholars are of the view that she is only the beloved of Surya and some suggest that She is Surya’s wife.
Usha is the term used to refer to dawn – The first light of day. But in the Rig Veda she has more symbolic meaning. Symbolically Usha is the dawn of divine consciousness in the individual aspirant.
During the Chhath Puja, Chhathi Maiya is invoked to bless us with this divine consciousness which will help us to overcome all the troubles in the world – this bless will help us to Moksha or liberation.
Here are few Shlokas that are dedicated to Usha in the Rig Veda
Lover of praises, O Usha, deathless one, which mortal is fit to enjoy thee? O luminous one, whom does thou attain? (1.30.20).
Satyamantra ajanayan ushasam – By the truth in their thoughts, they brought to birth the Dawn. (7.76.4)
Brilliant guide to happy truths is Usha of many hues. She has opened our doors. Lighting up the entire world, she has illuminated wealth for us. She issues forth all the worlds. (1.113.4)
Her radiant lustre beheld again, spreads everywhere and dispels darkness. (RV 1.92.5)
We have crossed over to the other share of darkness, Leaving darkness, she prepares discoveries of knowledge. (RV 1.92.6)