Sri Krishna Jayanti marks the celebration of the birth of Bhagavan Sri Krishna. Sri Krishna was born on the 'Rohini' nakshatram (star) on Ashtami day. The festival Sri Krishna Jayanti is also known as Gokulashtami and Janmashtami.
The actual day of celebration can be on two different days as the star 'Rohini' and Ashtami may not be on the same day.
This occurs between August and September. Sri Krishna is the eight avatar(incarnation) of Lord Vishnu. He is considered to be the Lord's most glorious incarnation. Chanting His holy name and having HIM in mind always brings joy in the hearts of His devotees.
Sri Krishna himself was a manifestation of joy at all levels and in all walks of life. The life and message of Sri Krishna is the most stirring saga of one of the greatest saviours and propounders of Dharma. Born in the dungeons of Kamsa who was out to kill him at the very moment of his birth, Sri Krishna's life is replete with many such mortal dangers which he successfully triumphs over.
He was the unchallenged hero of his times both in terms of his bodily prowess and his intellectual brilliance. Sri Krishna Jayanti, therefore, signifies not merely the birth of a Great and Divine Teacher of mankind in some distant past but the lighting of the spark of the Divine Power in every one of us, which spurs us on to play our dynamic part in this world of practical and hard realities with a sense of high spiritual purpose.
The philosophical aspects deal with the knowledge of the personality behind the festival Sri Krishna Jayanthi. Sri Krishna is Sanatana Dharma itself. In the Bhagavad Gita, Lord Krishna explains to Arjuna the meaning and purpose of life.
The great Bhishma in Vishnu Sahasranama (the 1000 names of Vishnu) relates the attributes of Vishnu in the pressence of Sri Krishna, as both Vishnu and Krishna are essentially one and the same. Since Lord Krishna was born at midnight, symbolizing light dispelling darkness, worshipping during Janmashtami is done in the late evening hours.