During the Solar System’s first million years, its earliest outer worlds formed from material that was up to 92 percent heat-forged rock, while gas flowing through the young system filtered out much of the surrounding ice-rich dust.

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Two chemical tracers in carbonaceous iron meteorites indicate that the earliest outer Solar System planetesimals contained only 8 to 17 percent fine matrix, extending aerodynamic sorting to the opening era of planet formation. The post During the Solar System…