In this quote, Thomas Pynchon uses the imagery of a yo-yo to explain the motion of a planet in its orbit around the sun. He depicts the planet's journey as a swinging motion, similar to how a yo-yo moves when it’s thrown and pulled back. This suggests a playful yet intricate relationship between celestial bodies and their orbits.

Pynchon's mention of aphelion refers to the point in a planet's orbit when it is farthest from the sun, drawing a parallel with the term apocheir, which describes the farthest point from the hand holding the yo-yo. This analogy highlights the complexity and symmetry in the movements of planets, emphasizing both their distance from the sun and the central force that governs their paths.