17 नवंबर : सूर्यषष्ठी व्रतारंभ (मिथिलांचल), 3 दिन की छठपूजा शुरू- नहाय खाय.
18 नवंबर : सौभाग्य-लाभ पंचमी, पाण्डव पंचमी, ज्ञानपंचमी (जैन), स्कन्दषष्ठी व्रत, छठपूजा का दूसरा दिन-खरना (बिहार-झारखण्ड).
19 नवंबर : छठपूजा का मुख्य दिन-सायंकाल सूर्यास्त के समय सूर्यदेवको प्रथम अघ्र्य.
The Sun has been worshipped in almost all civilizations since the beginning of human existence. Even the tribal communities across the world have celebrated and worshipped the essential forces of nature and the source of energy like the Sun. Probably, one the most pious and difficult worships among all of the Hindu festivals in India is the Chhat Puja of Bihar where the devotees worship the Sun in a four days ritual.
Chhat is a festival dedicated to the Sun God, considered to be a means to thank the sun for bestowing the bounties of life in earth and fulfilling particular wishes. Worship of sun has been described in the Rigveda, the oldest Hindu scriptures, and mantras praying to the sun in the Vedas are found. The Rigveda Says the sun is the soul of the universe and it controls the animate as well as the inanimate. In Chhandogya Upnishad the Sun has been called Omkar. In “Aditya Hrudayam” which is mentioned in Ramayan, is another ancient practice which involves surya namaskar. It is a procedure of saluting The Sun, taught to Bhagwan Sri Ram by Sage Agastya, before his fight with Ravan.
It is described in the "Yuddh Khand" Canto 107 of Ramayan.
In Bhagavadgita (Ch. 10. 35), Lord Krishna states:
Brihat saama latha saamnaam |
Gayatri chandasaam aham ||
Maasaanam maarga sirshoham |
Ritunaam kusumaakarah ||
Among the hymns, I am the Brihat saama sung to Lord Indra, of the poetry, I am the Gayatri verse sung daily by the initiated, Of all the maasas (months), I am the margasira (November- December). Among all the ritus (seasons), I am the flower bearing spring.
More information about Surya can be found in Brahmaanda puraana, Markandeya puraana, Regveda, Uttara Ramayana, Kashi Khanda and Mahabharata. Surya was born to Kashyapa Prajaapati, one among Navabrahmas and Aditi, a celestial maiden, thus lord SUN is considered as he is belonging to Kashyapa gotra. According to Markandeya puraana, Surya is considered as the creator, the Brahma. From this ancient supreme god the whole world evolved. He is looked upon as the creator, the sustainer and the destroyer of the whole universe. Surya is the chief among the Navagrahaas.