Please explain this with cause-and-effect, without disrespecting the passage:
Give me your best scientific explanation, please.
With these words, he (Achilles) hefted his long-shadowed spear,
then hurled it. However, anticipating the throw,
splendid Hector saw it coming and evaded it
by crouching down, so the bronze spear flew over him,
then struck the ground. But Pallas Athena grabbed it
and returned it to Achilles, without Hector,
that shepherd of his people, seeing what she'd done.
Give me your best scientific explanation, please.

Highly unlikely, but not impossible