Origin story
Surya is the son of Kashyapa and Aditi and the father of Yama, Manu and the Ashvins. The Aditya Hridayam, a hymn to the sun, was taught to Rama before his battle with Ravana, and the daily Surya Namaskara keeps the same reverence alive in practice.
The seven-horse chariot is the seven colours and the seven days, the charioteer Aruna is the dawn, and the lotus is the unfolding of life. Surya is honoured at sunrise in Kerala's temples, where the first light is offered before any other ritual begins.
Source: Wikipedia: Surya — https://en.wikipedia.org/wiki/Surya