Why is the Earth's core molten and is it true that it is made of some sort of metal?

Question

what is causing all that heat?

Answer 1

When earthquakes are detected on seismographs and those graphs are compared from elsewhere, there are pictures of the shockwaves traveling through the earth and sometimes even bouncing back. Comparing the measurements and their exact times from various parts of the world, they get some indications. One is that below our crust is a zone, we call it the mantle, which covers like a coat the core, which itself is essentially two zones. The very center core appears to be dense metal, like nickel and iron. The area around it also has such indications but sometimes looks like it isn't fully solid, like it might also be liquid. When we have volcanoes, we find the molten rock of the mantle that has bubbled up in cracks or fissures in the earth's crust. Some of what bubbles up is not fully mantle material, such as the reheated rocks of one of the earth's crust plates sliding under another, something we call a subduction zone. The cascade mountains on the American Pacific coast are made from stuff like that, as are the Aleutian islands of Alaska, and the Islands of Japan, etc. Then there are places where an upwelling of currents in the mantle below make what we call hot spots. The Hawaiian islands, the Ozark mountains of northwestern Arkansas and very southern Missouri, Yellowstone park, these are (but not limited to) such hot spots, past or present.

Some of the heat for all that rock melting is extreme pressures of miles of rock pressed down by gravity, or miles of massive crustal plates pressing against other plates (the mid-atlantic ridge seems to be the biggest driver, spreading out plates and the Pacific plates meanwhile are the biggest losers with lips sliding under the contenental land mass plates). or the friction of rock masses sliding past each other.

Some of the heat is apparently from radio active decay as ancient uranium and its daughter products slowly fission themselves into lesser elements on its way to stable isotopes like lead. This makes part of the earth's deep heat like a great big nuclear reactor.

Part of the heat is the original heat forming from the coalescing and condensing into a planet. The solid surface of the earth is like an egg shell (only thinner), a cooled crust, like the skin that forms over cooked milk, or the hard part over bread baking.

The pull of gravity, the pressure of matter pulled by that gravity, it all draws down into a ball. We happen to be sitting on the top of that ball and the denser stuff has settled to the bottom, the middle of that ball in this case.

Answer 2

First, let me make a correction: the outer core is molten and the inner core is solid. The reason that the outer core is molten is due to radioactive decay of elements such as uranium, thorium and potassium. The reason the inner core is not molten, despite having a higher temperature is due to the immense pressure at the center of the Earth. The inner core is thought to be a single crystal of nickel-iron sulfide. Nickel and iron are metals, sulfur is a non-metal.

Answer 3

The inner core is indeed mostly iron and nickel and is solid. It is growing as the liquid iron nickel outer core solidifies though it will take billions of years for it to cool sufficiently. When it does we will pretty much lose our our magnetosphere (our magnetic north and south pole). The main heat in the earth's interior results from decay of radioactive isotopes losing neutrons in a manner similar to a nuclear bomb, only much slower. We are sure that there is a liquid outer core because S-waves (if memory serves) (type of earthquake wave) will not penetrate liquids so there is a shadow in the sonar reflections/ refractions revealing the size and shape.

Answer 4

There is tremendous temperature and pressure at the center of the Earth, causing the rock to be molten. And yes it is thought to be Iron at the core, causing the Earth's magnetic poles.

Answer 5

There is a theory that the Earth's core has enough radioactive material to be a natural nuclear reactor. That is what is making all of the heat.

And the Earth's core is mostly nickle and iron. Only the outer core is liquid. The center is compressed enough to be a solid.

Answer 6

Core is molten iron at about 12,000 F
It turning at a speed different than the mantle causes the magnetic field that protects us from cosmic rays.