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Why do most meteorites found on Earth come from asteroids?
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Asteroid
This rock would take out more than just a T. rex.
Most meteorites found on Earth originate from the asteroid belt, a region located between the orbits of Mars and Jupiter. This occurs primarily because gravitational perturbations from planets, especially Jupiter, effectively move asteroidal fragments into Earth-crossing orbits.12
The process is driven by several key factors:
- Collisional Fragmentation: Asteroids frequently collide at high velocities, creating debris that ranges from large fragments down to fine dust.2
- Gravitational Resonances: Regions known as Kirkwood gaps contain orbital resonances with Jupiter. These resonances exert regular gravitational "nudges" on fragments, causing their orbits to become chaotic and eventually shift their perihelion inside Earth’s orbit.2
- Constant Supply: Various processes within the asteroid belt cause asteroids to migrate, ensuring a continuous supply of material is fed into these resonance zones.2
While a very small fraction of meteorites originate from the Moon or Mars, the vast majority are remnants of the early solar system preserved within the asteroid belt.12