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https://www.theguardian.com/environment/article/2024/aug/31/vast-doughnut-discovered-in-molten-metal-of-earth-core>
"By travelling to the centre of the Earth via seismic waves scientists have
discovered a ring-like structure within the swirling pool of molten metal known
as the outer core.
Research published in the journal
Science Advances has identified a
doughnut-shaped region within the outer core, parallel to the equator.
A study co-author and Australian National University geophysicist, Prof Hrvoje
Tkalčić, said because scientists could not reach the core with current
technology, the team had analysed the forms of seismic waves generated by large
earthquakes as they travelled through it.
They found the waves slowed down as they passed through a section near the
ceiling, before the mantle. “By understanding the geometry of the paths of the
waves and how they traverse the outer core’s volume, we reconstructed their
travel times through the Earth,” Tkalčić said.
“We realised that seismic waves slow down in the zone that mathematically is
called a torus.”
To most people this looked like a doughnut, he said.
Understanding the outer core was important, he said, as it was critical to the
survival of life at the surface. It was responsible for the magnetic field,
which protected Earth from the constant bombardment of charged particles from
the sun.
Currents moving within the molten iron and nickel acted like a “giant dynamo”
that generated and sustained the Earth’s magnetic field.
Tkalčić said scientists did not yet know why the Earth had this active dynamo
when many other planets did not: “It’s fair to say that we understand the
surfaces of other planets in more detail than our own planet’s interior.”
Earth’s interior – a solid centre containing the inner core, encapsulated by a
liquid outer core and then the mantle – was just as immense, he said.
Overall the core was slightly larger than Mars. “We can think of it as a planet
within our own planet,” Tkalčić said."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
