Why has the inside of the Earth remained as hot as the Sun for billions of years?

The Earth's interior is filled with layers of extremely hot rock and metal, with a core that reaches temperatures of more than 6,000°C, comparable to the surface of the Sun. What has kept our planet 'boiling' for billions of years?

The deeper you go into the Earth, the higher the temperature - Photo: AI

The Earth is structured like an onion with many layers. From the outside in, we have the crust (where humans live), then the mantle which is mostly solid rock, then the outer core made of molten iron, and deepest is the inner core made of solid iron, with a radius 70% the size of the Moon.

The deeper you go, the hotter the temperature gets. In some parts of the core, temperatures can reach more than 6,000°C, which is about the same as the surface temperature of the Sun.

The Earth's crust is "drifting"

Just as doctors use ultrasound to look inside the human body, scientists use seismic waves from earthquakes to “look” inside the planet. This allows them to discover structures beneath the layers of rock we see every day.

The crust and the upper part of the mantle are bound together to form the lithosphere, a rigid layer about 100km thick. This layer is not continuous, but is divided into giant tectonic plates like pieces of a jigsaw puzzle, for example: the Pacific plate, the North American plate...

These plates are constantly moving, sometimes very slowly, sometimes suddenly, causing earthquakes, volcanoes and the formation of new mountain ranges. It is this movement that has contributed significantly to the evolution of life on Earth, forcing organisms to constantly adapt to changing environmental conditions.

The source of heat from the earth

At a depth of about 100km, the temperature has reached 1,300°C. Deeper down to the boundary between the mantle and the outer core, the temperature is close to 2,700°C. And at the boundary between the outer core and the inner core, the temperature reaches an extreme of more than 6,000°C.

So where does this immense heat come from? It doesn’t come from the Sun. Although the Sun warms us and all the plants and animals on the surface, its light doesn’t penetrate miles into the planet’s interior.

According to scientists, there are two main sources of heat: heat from the time the Earth was formed and radiation from elements deep within the earth.

4.5 billion years ago, the Earth was formed from a giant cloud of gas and dust called the solar nebula. During the collision and fusion of small planetesimals, a huge amount of heat was generated, enough to melt the entire planet.

Although some of that heat was released into space, most of it was trapped inside the Earth and remains there today.

A large portion of the remaining heat comes from the radioactive decay of radioactive isotopes such as potassium-40, thorium-232, uranium-235, and uranium-238. These elements continuously release energy as heat as they decay.

They act as “natural nuclear reactors,” silently warming the Earth from within. Although some isotopes like uranium-235 and potassium-40 are nearly depleted, there are still plenty of thorium-232 and uranium-238 left to keep the Earth warm for billions of years.

Without heat, could life exist?

It is the heat from the earth's core that causes tectonic plates to move, forming continents, oceans, and creating diverse living environments for billions of years.

If the Earth cooled, these movements would stop. The planet's surface would become "motionless", dry, and possibly uninhabitable. Humans and all life would cease to exist.

So every time you walk on the ground, remember that beneath your feet is a seething world that not only keeps the planet moving, but also keeps life alive and thriving.

MINH HAI

Source: https://tuoitre.vn/vi-sao-ben-trong-trai-dat-van-nong-ngang-mat-troi-suot-hang-ti-nam-20250806120216474.htm