These micrometeorites are roughly half a millimetre in diameter. | Image: J. Feige et al. (2024)

Every day, tonnes of stardust rain down on us in the form of micrometeorites invisible to the naked eye. By measuring radioactive elements created in space by cosmic radiation, researchers have now found out where these tiny meteorites come from. As they expected, some of the tiny particles originated in asteroids in the inner Solar System. “But others have made their way to us from the outer Solar System”, says Ingo Leya, an astrophysicist at the University of Bern.

J. Feige et al.: Transport of dust across the Solar System: Constraints on the spatial origin of individual micrometeorites from cosmic-ray exposure. Philosophical Transactions of the Royal Society A (2024)

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