From superman.nu: Supermanica
In the theology of ancient Krypton, the sun-god, who was deemed the chief of all gods. Also, the name given to Krypton's sun.
So great was the respect for the red sun of Krypton that any soldier of Erok-El's time automatically became an officer if he had red hair.
When Jaf-El preached the worship of one god, he gave him the name of Rao, though no longer identifying him specifically with the sun (KC No. 3, Nov 1981: "The Race to Overtake the Past").