What keeps the Earth's core so hot?
Chris - It's a combination of things. One, the earth's quite a big planet relative to Mars which is a bit smaller. There was a lot of heat that was in the Earth to start with. When the planets were first forming around the sun in what's called a protoplanetary disc a lot of the swirling and spinning material was crammed together and squeezed together. It had a lot of heat from that, those frictional effects. Also the Earth has what's loosely termed as radioactive compounds in the Earth. As these radioactive compounds break down and decay they produce heat. The heat is obviously concentrated in the core of the Earth and then filters up towards the surface. Because the Earth's a big planet it's got a big core. It's got lots of radioactive decay going on. Some of the heat that we're seeing is because the Earth is sustaining it's own heat by radioactive decay.
Kat - Like having a nuclear reactor in our core.
glenn asked the Naked Scientists: Why doesn't the Earth's core ever cool down? What do you think? glenn, Fri, 3rd Oct 2008
Radiogenic heating, like in a nuclear power station. RD, Fri, 3rd Oct 2008
Also, heat left over from the formation of the planet, but this is small in comparison to the heat produced by the radioactive reactions. rosnathan, Sat, 4th Oct 2008
My understanding is that it has cooled down, and used to be more active over the past 4.6 billion years. frethack, Sat, 4th Oct 2008
Yes, this is known as a "georeactor". The radioactive decay of various elements within the planet's interior produces heat. On the scale of a body as large as the Earth this adds up to a lot of energy, which helps to keep the core of the planet hot.
The abundance of potassium in the Earth's crust and mantle is significantly lower than in stoney meteroites. Researchers suggest that the depleted potassium in the mantle/crust may have formed iron-potassium alloys in the core, postulating that potassium could be the major radioactive heat source in the core. Bass, Sat, 4th Oct 2008
Thanks Bass - I was wondering how the potassium, being quite light in the grand scheme of things, should get into the core.
Hey Bass, does this mean the earth will eventually explode due to becoming an argon balloon?
Explanation of above question: 40K -> 40Ar
Because we don't understand how the energy at the core relates to the mass of the planet.
Not at all; radioactive decay is a stochastic process. Also, the products are themselves radioactive with variable half-lives.
the sun is like a big big Magnetron.like in your microwave oven .a magnetron gives off micro waves.the waves move very fast. radio waves move a lot slower.the micro waver speed up molecules .when molecules move they make friction.witch cause heat.its like rubbing your two hands together very very fast.feel the heat.Lets get back to the sun.the sun gives off radiation . sorry for the spelling.i cant be good at everything.the radiation pass threw the earth and heat the iron core of the earth.like a micro wave oven.I will call it the radiation wave oven affect.LOL.did you ever stick metal in the micro wave oven.it sparks and heats up.thats what the earths core is doing.the radiation hits the earths magnetosphere and enters at the poles .the iron core molecules start rubbing each other.causing heat.So thats how the earth core stays hot.the earth was hit buy the moon.and made the iron core.wright now the sun is getting stronger.like god turned up his natreno wave oven on high.the sun will go back to its low setting . We are not having a global problems .this has been going on for 4 in a half billion years. So the sun goes from low to high.like a micro wave oven.Now the government knows this.and trying to make us pay for it with the global warming act .vote no on the Act.This will be part 1# of my theses. theirs a lot more to talk about .the earth is heating up.the core is getting hotter .when core gets hot. the molten lava starts to expand from the heat.causing earth quakes and erupting volcanoes.last time this happened.is when Yellow stone caldera blow up.Now that took a lot of pressure to do that.So the government should find out how many times the caldera blown up.then they can predict the next one. macgyver2112, Sun, 20th Dec 2009
Wow! That 'part 1' really shows how dangerous a little knowledge can be, being wrong in just about every important respect. LeeE, Mon, 21st Dec 2009
Si, hombre JimBob, Tue, 22nd Dec 2009
Lol - LeeE, Thu, 24th Dec 2009
Everything that moves sure has energy :) americanfridge, Mon, 18th Jan 2010
I have a theory, that in part the heat may be caused on account of the gravitational pull of the moon that causes the molten core to churn, just like the moon is responsible for tides in the oceans. Jai Misra, Sat, 31st Aug 2013