The suns energy is from fusion, fine makes sense.
But the core is a hot spinning liquid metal generating tremendous amounts of heat. Why hasn’t it cooled down? How is it replenishing its energy?
In: Planetary Science
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I assume the tremendous pressure, convection and some radioactive material produce quite some heat
Gravity generates immense pressure on the core, and that pressure generates heat. The Earth itself absorbs solar energy which contributes only slightly.
Most of the Earth’s energy to heat it’s core came from gravitational energy of its formation. Some of it probably came from that possible impact that formed the Moon. The interior of the earth will eventually cool, but on our best estimates the sun will be a problem long before that. The core is also warmed some by radioactive decay.
> But the core is a hot spinning liquid metal generating tremendous amounts of heat.
It is *releasing* heat. Billions of years ago when young Earth was forming, many processes were occuring. Asteroids collided with the Earth releasing kinetic energy and adding mass. The sun’s rays added energy through radiation and the atmosphere kept it trapped on Earth. This mass started coming together because of gravity and pressure increased, causing particles to collide with each other releasing more kinetic energy. Radioactive decay of elements deep in the core also released heat. Eventually, Earth solidified and through shifting land movements, this heat became trapped inside it and the outer layer cooled.
> Why hasn’t it cooled down?
It has cooled down and continues to do so, but slowly. The heat is insulated pretty well because of everything surrounding the core, but it isn’t a perfect system so it leaks. We also harvest geothermal energy from places where the crust is thin.
> How is it replenishing its energy?
It doesn’t. All the energy it has came many, many years ago, it doesn’t acquire any more.
it is cooling down. but it’s 1. massive and 2. insulated
think of your hand when it’s cold outside. You can make a fist which will insulate your hand within itself, but it still cools down. now, take a hot rock, and hold it in your fist. Your hand stays warmer longer. The rock will cool down quicker if it isn’t in your hand, and will eventually cool off either way…..
now take that example and increase the size and temperatures into an unimaginably large scale.
It started off very hot and slowly cooled down over time, some additional heat is provided by natural radioactive decay of heavier elements in the Earth.
Earth is not generating energy, during its creation a lot of it was “gathered” from collisions, the thing is that a planet is so huge that it would take billions of years to completely cool down, the sun will engulf earth before it happens
It’s hot for several reasons. It’s kept hot because the surface of the Earth is a very good insulator.
1 – The latent heat from the formation of the earth. It was VERY hot at the formation and is slowly cooling.
2 – Radioactive decay of uranium and other long lived radioactive elements contributes a significant amount of heat.
3 – Gravity. As heavier elements sink into the core, the potential energy they had is converted to heat.
4 – Heat of crystallization. As elements crystallize, heat is released. Under high pressure, some things such as carbon will crystalize.
Side note/question — How much energy input to the earth’s heat comes from gravitational flexing from the moon’s tidal interactions? Some sources I’ve seen claim terrain rise of 2 meters or more as the tidal bulges move with the moon alignment. The friction from this has led to the moon’s tidal lock, and moving further out in orbit. How much of this energy budget goes into the earth as heat?
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