What propels the sun through the air on a ball earth?
Do you believe the earth is spinning or the sun revolves around the ball? In either case, what propels it?
Is there an explanation for what makes it go in a circle rather than another direction?
.
The movement of the heavenly bodies is a mystery in every system of astronomy, but since they clearly move, something is obviously moving them.
It is definitely possible for one heavenly body to orbit another. Even if you don't believe in the moon orbiting the earth, anyone with even a cheap telescope can see the moons of Jupiter orbiting that planet, so that type of motion is definitely possible. It is completely reasonable to say that the sun and moon move around the earth in the same type of movement as we see the moons of Jupiter orbiting that planet.
But there is no otherwise observable example of the type of movement that flat earthers posit is how the sun and moon move around the earth. This is another major problem with flat earth theory.