How does the sun approach and move away from the earth according to Aristotle?

Aristotle says the sun moves along three spheres: the one of the fixed stars, the one of the ecliptic, and the one of the “inclined circle” (cf. “Metaphysics” Lambda, chapter 8). It seems this last sphere is the one responsible for the sun’s approaching and moving away from the earth, and thus responsible for the four seasons.
What I really need to know is how did Aristotle explain the fact that the sun approaches and moves away from the earth, since it supposedly moves along a circle, and the center of the circle is the center of the earth!