Earth’s core is a gigantic ball of liquid metal and is located nearly 2,890 kilometres below us. Scientists have made a fascinating discovery in the outer core where they say a ring-like structure, similar to a doughnut is present. Research published in the journal Science Advances says that this ring is parallel to the equator.
Study co-author and Australian National University geophysicist, Prof Hrvoje Tkalčić says that it is not possible to reach the planet’s core using existing technology. So they relied on seismic waves and looked at the forms generated by large earthquakes as they travelled through the Earth.
They compared the data generated by seismic detectors closer to the poles with results from nearer the Equator. They noticed that the waves slowed down 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.
“Overall, the waves detected closer to the poles were travelling faster than those near the Equator.”
Earth’s core and magnetic field
He stressed that it was important to study the outer core since it is responsible for the magnetic field which protect Earth from the constant bombardment of charged particles from the sun.
The molten iron and nickel in the core has currents moving that act like a “giant dynamo” which generated and sustains the magnetic field. Tkalčić said the presence of this dynamo has confused scientists for years because other planets do not have it.
Earth’s core is slightly larger than Mars. “We can think of it as a planet within our own planet,” Tkalčić said.
While the exact size of this structure is not known, it likely stretches a few hundred kilometres.
“We don’t know the exact thickness of the doughnut, but we inferred that it reaches a few hundred kilometres beneath the core-mantle boundary.”
It consists of lighter chemical elements such as silicon, sulphur, oxygen, hydrogen or carbon.