Against the backdrop of the lack of modern science, the ancient Roman people associated the sun with a god named "Phoebus" (a.k.a. "Apollo" in Greek mythology).

Well, science is a newly found layer of human beings' cognition of the universe, from the human society development perspective.

In addition, it's said that Phoebus drives around in his chariot. Well, why doesn't he fly about instead, like other gods? Because the sun is too heavy for a god to carry around?