A tiny fraction of carbon helps account for the oddly light density of Earth's iron core, a new computer simulation finds.
Though the core is only 0.1 percent to 0.8 percent carbon, the iron ball is the largest reservoir of carbon on the planet, the study authors said.
An impenetrable 1,790 miles (2,890 kilometers) below the planet's surface, the core is a compelling mystery. The density of pure iron is heavier than the core's observed density, which is calculated from seismic and laboratory studies.
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