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CosmosUp | July 16, 2019

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Earth's Inner Core has an Inner Core of its Own?

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Earth’s Inner Core has an Inner Core of its Own?

While there’s no prehistoric land hidden at the centre of our planet, as author Jules Verne imagined, the Earth’s core may not at all be like what scientists have led us to believe. Geologists have discovered that the Earth’s inner core – previously thought to be a solid lump of iron – may in fact have its own even smaller core within it.

Researchers from China and the US suggested that innermost layer of our planet has another distinct core within itself – a fact that has baffled scientists who hitherto had very little information on the subject and thought that it was filled with Iron.

The research team at the University of Illinois and its colleagues at Nanjing University in China said that the discovery of the “Inner core within the core” sheds light to a mysterious and surprising property of our Earth and could reveal important information about the unknown history of the planet.

A research team from the University of Illinois and colleagues in China found earth's inner core has an inner core of its own, with crystals aligned in a different direction. Image courtesy Lachina Publishing Services.

A research team from the University of Illinois and colleagues in China found earth’s inner core has an inner core of its own, with crystals aligned in a different direction. Image courtesy Lachina Publishing Services.

“Even though the inner core is small – smaller than the moon – it has some really interesting features. It may tell us about how our planet formed, its history, and other dynamic processes of the Earth. It shapes our understanding of what’s going on deep inside the Earth,” said Prof Song, who is a co-author of the paper published in the journal Nature Geoscience.

Scientists use seismic waves from earthquakes to scan below the planet’s surface, much like doctors use ultrasound to see inside patients. Prof Song and his colleagues used a technology that gathers data not from the initial shock of an earthquake, but from the waves that resonate in the earthquake’s aftermath.

“It turns out the coherent signal enhanced by the technology is clearer than the ring itself. The basic idea of the method has been around for a while, and people have used it for other kinds of studies near the surface. But we are looking all the way through the center of the Earth,” Prof Song said.

The inner core of the Earth is located roughly 3,100 miles beneath the surface of the planet. In 2003, a proposal to send a probe, the size of grapefruit, deep into the Earth, in order to explore the core. That mission was never carried out.

The inner core of the earth was once believed to be made of complex structural properties. These studies will also shed light as to how planet has evolved and right from the center of the Earth. The iron crystals lying in the inner-inner core behave differently from their counterparts. The core continues to grow about 0.5mm each year.

“For the moment, however, the model proposed in this paper needs testing against other ways of analysing the seismic properties of Earth’s innermost core, since no other researchers have previously considered evidence for the same conclusions in their studies.”

How the earth’s core protects the planet from harm

The Earth is made up of three major layers – the crust, the hot layer of magma known as the mantle and the core. Geologists have known for some time that the core is made of a liquid outer core of iron and nickel and a solid inner core. It is thought that the liquid outer core, which reaches 4,000 to 5,000 degrees C, is responsible for controlling the Earth’s magnetic field and helps protect the planet from charged particles from the sun.

Temperatures in the inner core, which is around 750 miles thick, reach between 5,000 and 7,000 degrees C, although the extreme pressures there means that the iron it is made from is solid. In 2004, scientists discovered that the inner core rotates in the liquid of the outer core surrounding it far faster than the Earth itself spins.

They calculated that every 400 years or so it overtakes the spin of the rest of the planet and may help to explain why the north and south poles have ‘wandered’ over time. However, more recent research in 2011 has suggested that the inner core may spin slower than this – gaining just one degree on the rest of the Earth every million years or so. This easterly spin also helps to drive the rotation of the outer inner core in the opposite direction. It is this strange dynamic that generates the geomagnetic field that deflects potentially harmful particles from our planet.

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Sciece Journal: http://goo.gl/thpaFJ.

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