We often think we need a vacation because the days never end. However, it may not be just a sign that you need rest: in fact, scientists have revealed that the days on Land they might increase in length, thanks to changes in the rotation of our planet’s inner core. The speed and direction in which it rotates is dictated by the magnetic field generated by the liquid outer core that surrounds it. Earth’s interior is layered like an onion, where the solid iron-nickel inner core has a radius of 745 miles — about three-quarters the size of the moon — and is as hot as the sun.
It is surrounded by a fluid outer core of molten iron and nickel and is about 1,500 miles thick. This outer core is surrounded by a mantle of hot rock 1,800 miles thick and covered in a thin, cool, rocky crust at the surface.
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The fact that the inner core is inside the liquid core means that it is able to rotate independently of the Earth’s rotation; spin is thought to be largely determined by the Earth’s magnetic field, generated by the outer core.
As heat escapes from the inner core, the iron in the outer core moves by convection and the motion generates powerful electric currents.
The rotation of the Earth on its axis causes these electric currents to form a magnetic field that extends around the planet and into space. But the effect this has on the rotation of the inner core is counterbalanced by the gravitational effects of the mantle, slowing it down or turning it into a wobble.
However, exactly how the inner core rotates is often debated, largely because it’s impossible to observe it directly, so researchers have to rely on indirect measurements to explain the pattern, speed, and cause of its motion and changes.
After 2009, however, seismic wave characteristics suggested that the inner core was moving more slowly than the rest of the planet. The data also showed the scientists that the inner core reverses its rotation once every 70 years, with the latest turning point occurring in the 1970s. This was related to regular changes in the Earth’s magnetic field and day length. The research authors wrote: “These observations provide evidence of dynamic interactions between the Earth’s layers, from the deepest interior to the surface, potentially due to gravitational coupling and angular momentum exchange from the core and mantle to the surface.” .