Strange behaviour of Earth's core reveals a mystery inside our planet

Strange behaviour of Earth's core reveals a mystery inside our planet

There's something weird going on with Earth's core and scientists aren't sure why.

Science & Tech

Scientists have discovered a mystery at the centre of the Earth. The solid iron core of our planet is cooling faster on one side than the other, and nobody knows why.

The interior of Earth is arranged in layers. Moving downward from the surface, there's the rocky crust and mantle, the liquid nickel-iron outer core, and the solid nickel-iron inner core. Crushed under all the weight of the rest of the planet around it, the inner core experiences pressures over 3.5 million times stronger than the air pressure we experience here on the surface. With this intense pressure comes intense heating. The temperature of the inner core is around 5,200°C — nearly as hot as the Sun's surface.

As the solid core's heat radiates outward, it is absorbed by the liquid outer core, which keeps the metal churning around and generating Earth's protective geomagnetic field. At the same time, the heat lost from the core results in more iron solidifying around it, causing it to grow by about 1 millimetre every year.

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There's something unusual going on with this process, though.

A team of researchers, led by Dr. Daniel Frost, a seismologist at the University of California Berkeley, found that seismic waves behave very strangely as they pass through the inner core.

These seismic waves are generated by the numerous earthquakes that occur near the planet's surface. As the waves are picked up by various seismic monitors positioned around the world, the differences in how long it takes the waves from an earthquake to reach different monitors can tell us two things. First, since these waves travel quickly through the crust, it allows seismologists to triangulate exactly where the earthquake took place. Second, these waves also travel through the planet's interior and move at different speeds depending on what kind of material they pass through. Thus, they can provide us with a reasonably accurate picture of the interior structure of Earth.