Day 1- Atham
The first day of Onam celebration starts with people visiting the temples in the morning. It is believed that King Mahabali starts his preparations to descend from Pathala (netherworld) to Kerala on this day.
The Onam celebrations across the state called Atthachamayam, starts off with a grand procession at Thrippunithura near Kochi, the place where Mahabali is believed to have been banished from earth.
The traditional ritual of laying Pookalam (floral carpet) starts on Atham day.
The size of Pookalam on this day is called as Athapoo and is small in size and the size increases with each passing day of the festival. Only yellow flowers will be used on this day and the design will be simple.
[“Source-economictimes”]