Kirkwood gaps
The Kirkwood gaps are regions in the asteroid belt where few asteroids are found. These gaps occur at specific distances from the Sun, corresponding to the orbital resonances with the largest planet, Jupiter. When asteroids enter these resonant zones, their orbits can become unstable, leading to their ejection from the belt.
The gaps were first identified by the American astronomer Daniel Kirkwood in the 19th century. He noted that the absence of asteroids in these areas was linked to gravitational interactions with Jupiter, which can disrupt the orbits of smaller bodies, preventing them from accumulating in those regions.