Iron forms cubes at the heart of the Earth

And that, says Science, changes everything about Earth — how long ago it formed, and how earthquakes happen today:

For decades, experiments and computer simulations of Earth’s inner core, an alien world of solid iron some 5000 kilometers below the surface, suggested the iron atoms there form close-packed hexagons. But word of the new result has quietly roiled the small community of inner-core researchers. If the structure is instead what is commonly called body-centered cubic (BCC), it could change how heat is conducted, altering when in geological history the inner core began to solidify and how heat and elements were released into the molten outer core. Those processes affect how the outer core churns, powering the dynamo that generates Earth’s magnetic field. “If the structure is different, then the properties will be different,” says Shuai Zhang, a high-pressure researcher at the University of Rochester.

The finding was difficult to publish. It finally appeared in August in the journal Physical Review B, after several high-profile journals turned it down, Merkel says. The delays may reflect resistance to reopening a question many researchers thought was settled. Yet to Jon Eggert, a materials physicist at Lawrence Livermore National Laboratory, “The data is very clear. I’m convinced they see BCC.”

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Yet Maurizio Mattesini, a geophysicist at the Complutense University of Madrid, feels vindicated by the result. “I’ve been suffering for such a long time,” he says. Mattesini argues that only cubic iron can explain some features seen in the seismic waves from earthquakes that pass through the inner core, such as a surprisingly slow speed. BCC, with a more loosely packed, less rigid structure than hexagonal iron, would hamper the waves, like soft sand slowing a runner.