Britannica
Sources used in this answer
How can asteroid collisions send fragments from the asteroid belt into Earth-crossing orbits?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
Earth impact hazard
An artist's rendering of the impact of a near-Earth object 66 million years ago in what is today the Caribbean region. Many scientists think that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction of dinosaurs and many other species near the end of the Cretaceous Period.
Asteroid collisions are a primary mechanism for creating the debris that eventually reaches Earth. When asteroids in the main belt collide, they fragment into smaller pieces. These fragments are then transported into Earth-crossing orbits through two main processes:12
- Yarkovsky Effect: For smaller asteroids, the anisotropic emission of thermal radiation creates a small force that causes them to drift over time. This drift can move fragments into Kirkwood gaps—zones of low density caused by gravitational resonances with Jupiter.32
- Gravitational Resonance: Once a fragment enters a resonance zone (such as the 3:1 resonance), it experiences regular gravitational "nudges" from Jupiter. These perturbations make the object's orbit chaotic, eventually shifting its perihelion inside Earth’s orbit.31
While direct collisional ejection can technically place material into Earth-crossing orbits, it is generally considered inefficient compared to the resonance mechanisms, which are the primary drivers for injecting asteroidal material toward Earth.1