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What does the core of the earth mean, as hot as the sun, and how does it maintain its temperature for billions of years?


Shichun Huang, an associate professor of earth and planetary sciences at the University of Tennessee, described the Earth as an onion, layer by layer, from top to bottom. There’s the crust, which includes the surface you walk on; then at the bottom, the mantle, mostly solid rock; then the innermost, outer core, made of liquid iron; And finally, the inner core, made of solid iron, and the deeper you go, the hotter it gets, so parts of the core are as hot as the surface of the sun.

A trip to the center of the earth

According to the “Space” website, just as a doctor can use a technique called ultrasound imaging to take pictures of structures inside your body using ultrasound, scientists use a similar technique to image the internal structures of the Earth, but instead of ultrasound, geoscientists use seismic waves, They are sound waves produced by earthquakes.

On Earth’s surface, you can see dirt, sand, grass, and pavement, of course, and seismic vibrations reveal below boulders, large and small, that’s all part of the crust that can go down as far as 20 miles (30 kilometers); It floats above a layer called the mantle.

The upper part of the mantle usually moves with the crust, and together they’re called the lithosphere, which is about 60 miles (100 kilometers) thick on average, although it can be much thicker in some locations.

The lithosphere is divided into many large blocks called plates. For example, the Pacific Plate lies beneath the entire Pacific Ocean. The North American Plate covers most of North America. The plates are like puzzle pieces that roughly fit together and cover the Earth’s surface.

But the plates are not stationary. They move. Sometimes it’s the smallest fraction of an inch over a period of years. Other times, there’s more movement, and it’s more sudden. And it’s this kind of movement that causes earthquakes and volcanic eruptions.

Temperatures

The temperature at the bottom of the plates, at a depth of about 60 miles (100 kilometers), is about 2,400 degrees Fahrenheit (1,300 degrees Celsius), and by the time you reach the boundary between the mantle and the outer core, which is 1,800 miles lower ( 2,900 km), the temperature is approximately 5,000 F (2,700 C).

Also, at the boundary between the outer and inner cores, the temperature doubles to nearly 10,800 F (more than 6,000 C). But because the core is under high pressure deep within the planet, the iron that makes it up remains liquid or solid.

collision in outer space

Where does all this heat come from? It is not from the sun, the sun’s rays cannot penetrate miles of the interior of the planet, but instead, there are two types of sources, one of which is the heat that the earth inherited during its formation 4.5 billion years ago.

Earth was made from the solar nebula, a giant cloud of gas, amid endless collisions and mergers of bits of rock and debris called planetesimals, a process that took tens of millions of years.

An enormous amount of heat was produced during those collisions, enough to melt the entire Earth, and although some of that heat was lost to space, what was left of it was trapped inside the Earth, where much of it remains today.

As for the other source of heat, they are radioactive isotopes that are scattered everywhere on Earth, and they are not stable, and they release a steady stream of energy that is converted into heat. Potassium-40, Thorium-232, Uranium-235, and Uranium-238 are four of the radioactive isotopes that Preserves the heat of the earth’s interior.

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