Why is it that Apollo, the Sun God, is used for the space shuttles to the moon?

My guess? For the sake of irony.
My researched answer: It was named after a NASA manager named Abe Silverstein, who said, "I was naming the spacecraft like I'd name my baby." To be more accurate about the whole sun god thing, he's actually the god of light and music. He is known as the sun god because the sun is the source of light.