Karthigai Deepam 2006

Karthigai Deepam - Festival of Lights is celebrated in TamilNadu on the occurrence of Karthigai Nakshatram/Star in the tamil month of Kiruthigai.Hindus decorate their homes and alters with little oil lamps to celebrate this day, which marks the death of a historic Rakshasan (Demon).The Karthigai Nakshatram is of great importance to Sri Murugan, as it is considered as his birth star. When it falls on a Monday, and occurs during the month of Karthigai, it is considered especially sacred, and devotees undertake fasts and special prayers to seek the Lord’s blessings.
courtesy : http://www.sttemple.com/STT/english/karthigai.asp

More about Karthigai Deepam Festival ...

In tamilnadu,Thiruvannamai- Sri Arunachaleswarar temple is famous for Karthigai deepam.
It is believed that every year during the Tamil month of Karthigai in Kiruthigai Star, exactly at 6.00 p.m. Arthanareeswaramurthi presents himself as Jyothi Swaroopa to his devotees at the time of Karthigai Festival 10th day.
Courtesy : googling

Thiruvannamalai Deepam

So at 6 o' clock people lit their home with lamps to worship the lord himself in the Jyothi form.

Pic : Deepam in my home