Karthigai Deepam is one of the brightest Hindu celebrations, taking place during the full moon evening in the month of Karthigai, according to the Tamil calendar. The festival usually falls on November or December, and the ancient celebrations are dedicated to Lord Shiva and Muruga, his son. It is believed that Muruga has six faces that symbolize six stars of the Pleiades. The festival is usually marked with fireworks and the lighting of lamps (called Agal Vilakkus) to ward off evil spirits and to invite prosperity and success. The holiday also has a philosophical meaning.
Karthika Deepam is especially famous in Tamil Nadu and Kerala. The holiday is known as 'Lakshabba' in the Nilgiris area of Tamil Nadu. In some regions, Agal Vilakkus lamps are lit every day for the whole month of Karthigai. Lamps with 365 wicks are lit in Lord Shiva temples. Thiruvannamalai, with its large Arulmigu Arunachaleswarar Temple dedicated to Shiva, holds the biggest celebrations in the country.
A giant fire called Thiruvannamalai Maha Deepam is lit every year at the top of Arunachala Hill, 813-m (2667-ft) holy mountain. This fire is a culmination of the holiday, marked by mass pilgrimage. Sri Arthanareeshwara is blessing tens of thousands of devotees in the Temple. The Maha Deepam is visible for 35 km around that area while people pray and make offerings. Karthika Deepam is celebrated in Thiruvannamalai for 10 days.
The lighting of lamps is a profoundly symbolic ritual since the wick means human selfishness that is fueled by oil. However, the flame that means wisdom can burn human ego, representing the victory of light over darkness, good over evil.