(ORDO NEWS) — Researchers at the Chinese Academy of Sciences have found that the Earth‘s inner core may be stranger than we thought.
The new modeling suggests that this is not just a solid, but a superionic state of matter intermediate between liquid and solid.
Since we can’t drill down to the center of the planet and see it with our own eyes, scientists are studying the Earth’s core mainly with the help of seismic waves from earthquakes.
As these vibrations travel across the planet, they move at different speeds through different materials, and analysis of these changes can reveal the composition of the various layers.
For decades, these studies have consistently shown that the inner core can propagate a type of seismic ripple called shear waves, indicating that it is solid.
However, these waves travel through the core more slowly than would be expected from a ball of hard iron, suggesting that it is slightly softer.
For the new study , the researchers modeled the temperature and pressure conditions at the center of the Earth to find out what other types of matter might be possible down there. They found that some iron alloys can form a superionic state, which explains previous observations.
In a superionic iron alloy, the iron atoms form a solid lattice that holds the material in a unified form, while the lighter elements diffuse through the lattice in an almost liquid state. Simulations have shown that, under the conditions of the Earth’s core, these lighter elements can include hydrogen, oxygen, or carbon.
Importantly, the team calculated how fast shear waves would travel through these superionic alloys and found that this was in good agreement with observations. Other established properties of the inner core can also be explained by the different distribution and convection of these fluid-like elements.
This is an interesting idea, but it’s not the only possible explanation. Previous research has suggested that the slower shear wave propagation may be due to “iron snow” falling on the inner core from the outer core.
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