In Jules Verne’s classic 1864 novel Journey to the Center of the Earth, adventurers eager to explore the interior of the planet descend through an Icelandic volcano into a vast underground world inhabited by prehistoric creatures. The real center of the Earth does not compare to this fanciful representation, and to some extent the reality is even more dramatic, writes Reuters on Tuesday, citing Agerpres.

On Tuesday, scientists announced that an intensive study of the Earth’s interior, based on the behavior of seismic waves during strong earthquakes, confirmed the existence of a distinct structure within the core of our planet – an extremely hot, hard ball of iron and nickel with a diameter of about 1,350 kilometers.

The diameter of the Earth is about 12,750 kilometers. The internal structure of our planet consists of four layers: a rocky outer crust, then a rocky mantle, an outer magmatic core and a solid inner core. This metallic inner core, about 2,440 kilometers in diameter, was discovered in the 1930s also based on seismic waves passing through the Earth.

In 2002, scientists proposed the idea that inside this core there would be an inner part separated from the rest, a structure similar to a nesting doll. Increasingly advanced seismic monitoring equipment has confirmed this fact.

Earthquakes cause seismic waves that sweep through the planet and can reveal the contours of its internal structure by changing the shape of the waves. So far, scientists have managed to detect waves that propagated a maximum of two times from one side of the Earth to the other and back. The new study analyzed waves from 200 magnitude-6 earthquakes that bounced like ping-pong balls up to five times inside the planet.

A solid ball about the size of Pluto

“We may know more about the surface of other distant celestial bodies than we do about the depths of our planet,” said seismologist Thanh-Song Pham of the Australian National University in Canberra, lead author of the study published in the scientific journal Nature. Communications.

“We analyzed digital ground motion data, known as seismograms, from strong earthquakes over the past decade. Our research was made possible by the unprecedented expansion of global seismic networks,” Pham added.

The outer shell of the inner core and its newly confirmed inner sphere are hot enough to melt, but they retain their solid state of a solid iron-nickel alloy under the immense pressure from the center of the Earth.

“I like to think of the inner core as a planet within a planet. Indeed, it is a solid sphere, roughly the size of Pluto and slightly smaller than the Moon,” said Hrvoje Tkalčić, a geophysicist at the Australian National University and co-author of the study.

What protects life on Earth

“If we could somehow take apart the Earth by removing its mantle and liquid outer core, the inner core would emerge as bright as a star. Its temperature is estimated at about 5500-6000 degrees Celsius, similar to the temperature on the surface of the Sun,” said Tkalchich.

The transition from the outer core to the inner sphere appears to be gradual rather than abrupt, Pham noted. The researchers were able to distinguish between the two regions because the seismic waves acted differently between them. “This could be caused by different arrangements of iron atoms at high temperatures and pressures, or by better alignment of the growing crystals,” Pham said.

The inner core slowly increases in size at the expense of the outer core by solidification of molten materials as the Earth gradually cools, as it has done since its formation about 4.5 billion years ago.

“Latent heat released as Earth’s inner core solidifies causes convection in the liquid outer core, creating Earth’s geomagnetic field,” Pham said. “Life on Earth is protected from harmful cosmic rays and would be impossible without such a magnetic field,” the researcher added.