A new study in Nature Geoscience, from two Stanford researchers, indicates that our planet’s super-dense, super strong core may not be as strong as we’d thought.
It’s very difficult to replicate the kind of ultra-high-pressure environment of Earth’s iron core; we can’t dig down there and monitor it, so researchers have relied on reading and tracking seismic waves and extrapolating other information from there. The outer core, which is more liquid, produces the geomagnetic field that stretches all the way out past the ionosphere and into space, where it meets the solar wind. That geomagnetic field protects our atmosphere from solar radiation, which could strip away the ozone layer and make life on Earth impossible.
The study is the first to use a tool called a DAC, or diamond anvil cell, to measure the core. A DAC smooshes a very tiny amount of material between two diamonds with incredible force: it’s able to exert up to a 300 gigapascals. That’s about three million times the pressure on Earth’s surface.
In this particular experiment, the researchers stuck a piece of pure iron in there to emulate what goes on in the Earth’s core. They found, according to the lead author of the paper, that “The strength of iron under these extreme pressures is startlingly weak.” In fact, it’s only 40% as strong as previous estimates had indicated, and prone to shearing.
The researchers don’t really know what this means. It’ll probably impact our understanding of the geomagnetic shield and its effects, however.
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