Guru Purnima Katha : According to mythology, Ved Vyas, the son of Maharishi Parashar and Nishad daughter Satyavati, had gone to the island of Dwaipayana for penance as soon as he was born. It is believed that he was born on Ashadhi Purnima. He had become black due to intense penance and was called Krishna Dvaipayana because of going to the island of Dwaipayana for penance. There is also a legend that he was born on an island in the middle of the river Yamuna, due to his dark complexion, he was named Krishna Dvaipayana. Veda Vyasa is a title, Krishna Dvaipayana was the 28th Veda Vyasa.
created the first geographical map of the earth