Why is the center of the Earth still hot?

The Earth is already 4.6 billion years into its existence, yet the lava at its core is still not freezing, as it continues to remain at a stable temperature. The internal heat of the Earth is caused mainly by four sources. The first source is the approximately 10,000 degrees Celsius of heat generated during the period of the Earth’s formation that is still not discharged in the space. The second source is when a few million years after the Earth’s formation, an object from space that has the same size as Mars collided with Earth, and the impact between the two heavenly bodies generated immense heat. It is interesting to note that our moon is formed from debris that came out as a result of this massive collision. The third source is the internal flow of hot liquids in the Earth that is generating heat out of friction with certain substances they come in contact with. The fourth source is the core of the Earth itself, which is rich with radioactive substances, such as uranium, thorium, and potassium-40 that generate heat while decaying.

On the one hand, the 6 to 40 kilometers thick external crust that have already cooled down blocks internal heat from coming out, and on the other hand, the flow of liquids and the decay of radioactive substances below the crust constantly generate heat up to this day. As a result of the continuous buildup of heat that cannot escape at the center, the core heats up more and more, and the decaying substances would both normalize the heat and regain it. This situation is generally favorable to the life on Earth because if it would turn as cold as the planet Mars, then it would lose the electrical flows at the core and, in turn, the magnetic fields. Once the protective shield vanishes in the atmosphere, the Sun’s intense radiation would kill all life on Earth.

How was the Earth’s core created?

The core of our planet is created through a process called accretion, where one object in space controlled by the Sun’s gravitational force is joined by millions of other space objects to form a bigger object. It is believed that meteorites were the objects that formed the Earth, and these meteorites attracted each other through gravity. When the core of the Earth that is comprised of thousands of meteorites became bigger and bigger, it was able to draw larger space objects, thus forming the shape of the planet. The process of gravitationally attracting nearby space objects accumulated heat the center of the planet, and the heat is further intensified if two or more objects collide in a violent manner, which is what happened when the Earth collided with the massive meteor millions of years ago.

The core’s heat that is accumulated by attracting meteorites is still in its system today, although it is only at 10%. The 90% of the core’s heat is generated by the decay of radioactive isotopes, which was mentioned previously. These isotopes would often radiate heat whenever they have to shed energy and normalize their temperature for stabilization. However, most of the isotopes are not found on the core, as it is contained within the Earth’s mantle, and the heat they radiate would usually seep through several parts of the crust. As such, the crust would generate heat too.

Would the heat on Earth cool down?

According to researchers, the heat that the core and the mantle generate would eventually cool down after a few billion years. If the generation of heat stops, the mantle would first join with the crust, and they both would have the same composition and structure. Afterward, the core would also experience the same phenomenon, and heat would totally be gone on the planet. When there is no heat, the Earth will turn into a bigger moon, which is a barren and dead heavenly body where life cannot and will not exist. However, several scientists believe that the probability of the Earth being a cold planet is low since the Sun would be a red giant star first. When the Sun becomes a red star, it will swallow our planet and the others nearer to its location before the Earth’s core could even turn cold.