The Magnetic Field Mystery

The magnetic field of the Earth protects the planet from cosmic rays

The magnetic field of the Earth protects the planet from cosmic rays coming from outer space.

Scientists have long searched for an explanation concerning the vast magnetic field acting around the whole globe. As far as the present theories go, the field is generated by the liquid iron covering Earth’s core.

Earth’s magnetic field has protected the planet from cosmic radiations, which are high-energy particles coming from outside the solar system. The origins of the field go back to 3.4 billion years ago, but scientists have no clues on how the field was created and what sustained it for such an extended period.

In 2012, another science gimmick raised the interest in the magnetic field again: The Geodynamo paradox.

The story says that Earth was created from rocky materials, of which iron, being the densest, sank and created the core, the mantle, and the crust.

The inner core of the planet is made of solid iron and other materials and has a temperature of approximately 5,400 degrees Celsius.

The outer core of the planet is made of liquid iron. The motions in the melted metal are supposed to create the magnetic field.

The interactions between the liquid iron and the solid core lead to heat being transferred from the inner core into the outer core with the help of conduction. If such a high quantity of heat had been transferred through conduction, there wouldn’t have been left enough energy to activate the convection.

Thus, Alexander Goncharov and his team tried to replicate the situation by raising the temperature of iron to different levels and testing how liquid iron might react.

In order to do so, they used a diamond anvil cell that squeezed the iron to reach the internal pressure of the Earth and then heated the material to the core temperatures.

“We found very low values of thermal conductivity, about 18 to 44 Watts per meter per Kelvin, which can resolve the paradox and make the geodynamo operable since the early ages of the Earth,” said Goncharov, one of the authors of the study.

The results showed that the previous theoretical assumptions were not correct. The energy needed to sustain the geodynamo was not as high as it was thought. This finding may also explain the fact that the magnetic field was active even before Earth’s cooling; as such a low level of conductivity may have been plausible in extremely different conditions.

The researchers then took matters even further and tried to replicate magnetic fields for planets of various sizes, for example, Mercury, and found similar results.

Image Source: Wikipedia

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