How did Jupiter’s gravity affect the asteroid belt?

Jupiter’s gravity significantly shapes the asteroid belt through gravitational perturbations, primarily by creating Kirkwood gaps—zones of low density where few asteroids orbit.12

These gaps occur at specific distances from the Sun where an asteroid’s orbital period is a simple fraction of Jupiter’s orbital period, a phenomenon known as mean-motion resonance. Because the asteroid and Jupiter return to the same relative positions at regular intervals, the asteroid experiences a repeated gravitational force in a fixed direction. Over time, these perturbations alter the asteroid's orbit, effectively clearing it from that region.12

Conversely, Jupiter’s gravity can also stabilize certain groups of asteroids, such as the Trojan asteroids, which cluster near specific resonances. Additionally, gravitational interactions with Jupiter prevented the formation of a single planet in the region between Mars and Jupiter, leaving behind the smaller bodies that constitute the asteroid belt today.23