On the 1st day of the Tamil calendar 1st Month, Chithirai, when a new Tamil Year commences,it has been observed for hundreds of years that the rays of sunlight fall directly on the main deity form of the sivalingam in Thiruvannamalai temple.
This is very considered very auspicious in the traditional Hindu system.
It is indeed a grand spectacle watching the rays of sunlight falling on the main deity form.