US media: The core of the earth discovers a "new hidden world"

According to the American Fun Science website reported on October 27, researchers have now found that the earth's "solid" core may actually have some mushy areas.

For more than half a century, the scientific community has believed that the Earth's core is a compressed solid iron alloy ball wrapped in a liquid outer core. But the new findings, published Sept. 20 in the journal Earth and Interior Physics, show that the sphere's hardness is not set in stone, with multiple states ranging from hard to semi-soft to liquid metal.

Jessica Owen, a seismologist at the University of Bristol in the United Kingdom who was not involved in the study, told the Fun Science website: "The more we studied deeply, the more we found that it was not a boring block of iron. We are discovering a whole new hidden world. ”

In a sense, the core of the earth is still as mysterious as Jules Verne's 1864 science fiction novel Journey to the Center of the Earth. While scientists have known since the 1950s that the planet we inhabit is not hollow as Verne predicted, the Earth's core remains an unexplored field; ultra-high temperatures and pressures make it impossible for humans or any man-made probe to reach it. Owen said: "Unless something terrible happens to our planet, we will never directly observe the core of the earth." ”

However, geophysicists can rely on seismic waves generated by earthquakes to explore. By measuring such large-scale vibrations, Owen said, scientists were able to reconstruct images of the Earth's interior in a way that "resembles a human CT scan." There are two main styles of this wave: linear compression waves and undulating shear waves. Each wave may accelerate, decelerate, or experience a rebound from a different medium as it advances.

According to Lett Butler, a geophysicist at the Hawaii Institute of Geophysics and Planetology, the new study began with the problem of data mismatch. Butler was watching how seismic waves from strong earthquakes at 5 different locations traveled through the earth's core and reached the other side of the planet. But some of the data is not normal — the shear wave, which was supposed to pass through the solid metal ball of the Earth's core, was shifted in some areas.

The numbers came as a surprise to Butler. He knew that the method of calculating seismic waves was correct, so that such a result could only mean a situation in which scientists had mistaken the structure of the Earth's core. "When doing this work, the data has to match," he said. So Butler and the study's co-authors re-evaluated their underlying assumption that the Earth's core is a complete solid sphere mechanism. They found that if the Earth's core was not a solid sphere, but rather small patches of liquid and "mushy" semi-solid iron near the surface, then the seismic waves they observed made sense.

Butler said the density interval of iron in earth's core is particularly striking. "We're seeing evidence that not all areas of the Earth's core are soft, but some places are extremely hard," he said. On the outside of the molten or paste-like iron, there is a hard shell. So we see a lot of details in the core of the earth that we didn't know in the past. ”

This research has the potential to revolutionize our perception of Earth's magnetic field. According to a 2019 study published in the journal Science Advances, Earth's liquid outer core drives the planet's magnetic field, but the core plays a role in correcting the magnetic field. According to NASA, the interiors of other planets, including Mars, are liquid, but have neither a core nor a magnetic field. Therefore, Butler and Owen believe that a deeper understanding of the planet's core will help scientists understand the relationship between the planet's internal structure and its magnetic field activity.

Source: Reference News Network