Why is the Earth's core hot even after 4billion years?

Answer 1

Gravity is the first reason. The core has a lot of mass on top of it pushing down. This force is converted into heat.

The mantle also acts like an insulator, keeping the heat inside and allowing very little to escape into the outer regions.

Answer 2

There are three main sources for the heat energy of the Earth's core: 1) Remnant heat energy; 2) decay of radioactive elements; 3) latent heat of crystallisation.

The first source, remnant heat energy, refers to heat energy left over from the formation of the Earth. In the past, scientists believed that this was the main source of the Earth's heat energy. A famous physicist, Lord Kelvin, used measurements of the Earth's heat flow, together with assumptions about the initial temperature of the Earth (essentially guessing how hot the Earth was when it formed), to work out how old the Earth was. Essentially, he assumed that the Earth had started out at a certain temperature, and had been cooling ever since. His calculations gave an age of 100 million years, a figure that was accepted for many decades.

Eventually, however, geologic age dating revealed that the Earth was a lot older than that. So if the Earth was as old as 4.67 billion years, by now it would've cooled down to the point where it would be a "dead planet". So it was clear that there was something inside the Earth that was actually GENERATING heat. The first candidate was radioactive elements. When they decay, they release energy (think about atom bombs). So, it was supposed that the energy released by radioactive elements in the Earth was "keeping the planet warm". However, there's a problem there: most radioactive elements are "lithophiles", or elements that prefer to be in the Earth's crust. So most of the radioactive elements (the "big three" are Uranium, Thorium and radioactive Potassium-39) are in the crust, not in the core. There are some radioactive elements in the core, but not enough to account for how hot the core is.

So the answer is the third source: latent heat of crystallisation. Simply put, when things crystallise (change from liquid to solid), heat energy is released. This energy is termed latent heat of crystallisation. Due to the slow cooling of the Earth through time, the liquid outer core is slowly crystallising. This slow crystallisation releases energy that slows the cooling of the Earth's core, keeping the core "hot".

The explanation given by #1 accounts for how the Earth "got hot in the first place", during the formation of the solar system. In other words, it explains the origin of the "remnant heat". However, it doesn't explain why the core is still hot.

Answer 3

The temperature is ungodly. I'm guessing that even if the outer edges started to cool off and turn to crystal that the earths rotation would eventually change that location of core back into it's melting stage. Though scientists have proven that the earths core is slowly, VERY slowly becomming less Hot. Think about it. A lot of the planets in our solar system do not have a core. They cannot sustain life. Unfortunately without our core I believe we will become too cold of a planet. The sun would help keep us warm, but i'm assuming that the earths core plays a large part.

Answer 4

The earth is like one very hot water bottle. On the inside, the water is very hot. on the outside, the earth is semi-cold.
This is because the earth as many miles of insulation.

But here's the best part:
Did you know that a thermos is like a vacuum?
By this i mean that somebody sucked out almost all the air between the inside layer and the outside layer.
Since, there is no air inside the walls of the thermos, it is very hard for the heat to escape. WHY?
Heat is transmitted through a medium.
Air is a medium. Space is elmost void of matter, so it is a vacuum as well.
SO- the heat can't escape from the Earth! It's stuck here FOREVER! Well....almost. Thermos' aren't perfect, and neither is the Earth.

Side note: If Earth did not have a rotating core, the earth would not have a magnetic field (what moves the compass needle) then the sun's electromagnetic waves would be able to get through and kill us all-but very slowly.

Mars is said to have been a planet like Earth is now- but it couldn't protect itself from the sun's electromagnetic waves, and now it is all red and dusty.

Answer 5

The earth's core is made of iron and other heavy metals; therefore, the gravitational pull at the center of the earth is the most powerful. The force of gravity increases the density of the metals in the earth's core producing intense friction and temperatures. The intense friction and temperatures produces expansion and the expansion and gravity balance each other out. Basically, the gravity causes heating and expansion of the earth's core but the gravity holds it in place. As long as this condition exists, the earth's core will remain hot. There are also other forces at work.

Answer 6

the enormous mass of the Earth holds this planet together with a tremendous amount of gravity. this very powerful force creates enormous pressure within the planet. this pressure forces the elements of the Earth's core into very close proximity, which causes friction and agitation, generating enormous heat. so while the core of our planet is very hot and very molten, it is also very dense, which is quite different, really, from being liquid.
we know that the moon does not have a molten core, but in general scientists aren't sure about whether or not other planets have a molten core or are uniformly solid all the way through. perhaps we will find out one day, and that should help us understand even better why our wolrd is the way that it is.

Answer 7

I read somewhere that about half the heat is left over from the formation, when the moon was knocked out of the earth and the earth was totally melted, and about half is from the decay of radioactive elements in the core.

Answer 8

You might know that ,

Energy is never made and is never destroyed. It only changes its form. Energy remains constant.

The Earth's core is still hot because the energy(heat) stored inside the Earth's core does not have anywhere to go. So, it's still hot.

Answer 9

If I told you the Earth wasnt 4 billion years old that would explain it right ? Well the earth is only about 6 thousand years old, and that is why the inner core remains smoking hot. I laugh when I see people throw these billions and millions of years around

Answer 10

Radioactivity plays an important part too.Ernest Rutherford discovered that.

Answer 11

Cause it was REALLY hot 4 billion years ago. Seriously it is in the very slow process of cooling down.