The second of the Tamil month,Vaikasi and the Star Visagam of Libra and Scorpio zodiac, the full moon day is called as Vaikasi Visagam(Sanskrit name Vaisakha)is celebrated with all fanfare. As per Puranas the three asura (demon)brothers, Soorapadman, Singamuhan and Tarakan attained great powers through penance and after attaining the powers they started disturbing the devas who in turn pleaded Lord Siva for help.
Accordingly Lord opened his third eye, the one seen in the forehead and from that formed six sparks of fire and these sparks are carried to River Ganga who in turn turned to the stream called Saravana Poigai. Once floated in the stream the 6 divine male babies born who were cared by six young girls called Karthigai Pengal (Girls).
Meanwhile Goddess Parvathi embraced these kids and they united to one with six faces and twelve hands and thus Lord Shanmuga meaning one with six faces)emerged on the full moon day in the month of Vaikasi and is the embodiment of pure perception and divine knowledge.