New Research has Found ：The Earth’s Core is Only a Billion Years Old

New research has found that the solid inner core at the centre of the Earth is only a billion years old.

The modern Earth is like a layer cake, with a solid crust at its outermost layer, and a hot, slimy mantle, a liquid outer core, and finally a solid inner core. As the molten iron in the core cools down and crystallizes, the solid inner core grows slowly. This process helps to increase the agitation of the liquid outer core, creating a magnetic field that envelops the earth and protects plants from harmful cosmic rays.

In other words, the inner core is particularly important.

But we do not know much about the history of the diameter of a 2442-kilometer iron ball. We estimate its age range from 500 million to more than 4 billion years old, about the same age as the earth at 4.5 billion years old. Now, researchers have used two diamonds to squeeze an exceedingly small piece of iron and then run a laser at it. The result is a new estimate, between 1 billion and 1.3 billion years-a time range that matches a measurable increase in the earth’s magnetic field that occurred around the same time.

Jung-fu Lin, an earth scientist from Texas University said, “Earth is unique in the solar system because it has a magnetic field and is habitable, and ultimately our results can be used to study why other planets in the solar system don’t have magnetic fields.”

Geodynamo

The earth’s magnetic field is maintained by what scientists call the “geodynamo”. The movement of the iron-rich outer core turns the entire planet into a giant magnet. Thanks to the geodynamo, the earth has its poles and an invisible magnetic shield that deflects, and traps charged particles from the sun. Without a magnetic field, these charged particles would slowly strip the Earth’s atmosphere.

Part of the inner core’s motion is powered by heat, its thermal energy. As the earth’s core cools, it crystallizes from the inside. The energy released by this crystallization can be used to further power the outer core, which is still liquid. Lin said, the energy released by crystallization is called the component energy source of the geodynamo.

Lin and his team wanted to use experimental evidence to find out the energy in each of these sources. Knowing the energy data, they were able to estimate the age of the inner core.

To do this, the researchers created conditions in the core on a small scale. They heated a sheet of iron which is just six microns thick (about the length of a red blood cell) to 2727 degrees Celsius, then squeezed the sheet with two diamonds to mimic the extreme pressure inside the earth’s core. Then they measured the electrical conductivity of the sheet iron under these conditions.