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Early Mercury shrank as magma escaped its core through heat pipes

NASA/Johns Hopkins University Applied Physics Lab/Carnegie Institution of Washington

Mercury is a mysterious little world. Many features on its surface show evidence that since its formation, cooling of its core has caused the entire planet to shrink by between about 5 and 10 kilometres in radius, but for that shrinking to occur, heat must have somehow escaped. A series of simulations now show that it may have travelled from Mercury’s core through its mantle via heat pipes.

Many of our current models for the early history of …