How did Earth avoid a Mars-like fate? Ancient rocks hold clues - University of Rochester

New paleomagnetic research suggests Earth’s solid inner core formed 550 million years ago and caused our planet’s magnetic field to bounce back.

A depiction of Earth, first without an inner core; second, with an inner core beginning to grow, around 550 million years ago; third, with an outermost and innermost inner core, around 450 million ye… [+5653 chars]

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