In the prehistoric ages of Krypton, Rao was the name of an ancient sun-deity, part of a larger Kryptonian pantheon.
But when the people of Krypton later came to worship just one God, the name Rao was applied.
In that earlier, unrecorded mythology of old, Rao as the sun-deity was deemed to be the leader of all gods.
At that time, so great was the respect for the red sun of Krypton that any soldier of Erok's time who had red hair
was automatically promoted to being an officer.
When Jaf-El later preached the worship of the "One God,"
he used the name of Rao, though no longer identifying Rao specifically with the sun:
Note that in later wedding ceremonies, the phrase used was "Rao, who kindled the sun," not "Rao, the sun" —
showing Rao to now be the sun's creator; no longer the sun itself —