How do scientists know what the center of the earth is made of?

Question

We haven't been able to drill that far (I guess a second question is how deep HAVE we been able to drill for samples). I know that some of this is based on how the earth behaves in space, but I am still skeptical. So -- what does the earth (deep down) consist of and how do we know that's true?

Answer 1

We don't know exactly what the center of the earth is made of, because we don't have direct access to it yet. Nevertheless, we do have very important clues, that allow us to have confidence in our interpretations about earth's core.

We do know that the earth is denser going to the center. this is based on the known the size of the earth 1,024,000,000,000 km^3 (sphere of 6400 km radius) and the known mass of the earth 6*10^24kg. So we know that the density of the earth is about 5.5 gr/cc. Nevertheless, the density of the crust is roughly 2.7 gr/cc, and the density of the mantle is also known because
we have a few samples from the mantle.

1) We know that the center of the earth is dense, and should have the density close to the metal iron.

We also know that the denser the rock the faster the seismic waves propagates and seismologists know that the earth is not homogeneous but formed by layers of increasing density. They are: the crust, the mantle, the outer core, and the inner core. there is a shadow of the S-type wave (they don't travel in liquids) that strongly suggest that the outer core is a dense liquid while the inner core is a dense solid.

2) We now that the earth have a liquid outer core and a solid inner core and their thicknesses.

With this bits of information and also based on the composition of meteorites. We know that the earth core is formed by an
iron and nickel alloy with another minor components (like U, K and probably some P and S).

We are doing experiments to simulate the conditions of the core and in the lower mantle. We are learning a lot in the process, this is too long to detail in here.

We also have to explain the earth magnetic field, and the iron-nickel alloy model, also explains it.

We also have computer models based on what we know about iron and nickel alloys.
We don't know the exact composition of the core, but we have a pretty good idea based on what I described previously.

Answer 2

Scientists know the total mass and the total volume of the Earth, and can figure out the density of the Earth. By knowing the average density of the surface rocks and the density of some mantle rocks (from xenoliths and from seismic studies), the density of the core can be extrapolated. When meteorites (assumed to be similar to the Earth) are compared to facts of the density of core rocks, a pretty good idea of these rocks can be determined.

Answer 3

Initially scientists thought that the center of the world was filled with carmel and nouget, but when they tried digging to China it quickly dispelled that rumor. I think they performed some kind of sonar detecting to see the density of different parts of the earth. Then they compared that density to various other elements and their properties. Science is never gonna be an exact science. All we're ever given are all these stupid theories. Then they go around thinking they're better than religious fanatics. Both sides are totally reliant on the faith in their ideas without proof. Scientists nowadays just watch movies, like "The Core" to tell them what the Earth is made of.

Answer 4

Earth scientists know the composition of inner layers due to sismological data essentially. They use also data of magnetic fields generated by the liquid metal core movement. It is obvious that is not possible to get into the planet's core but those data are enough to stablish the current model of Earth's structure.

Remember that models that allow to predict some behaviours and observed phenomena are accepted as valid in science.

Forget "The Core" movie. That is really just fantasy!

Answer 5

Scientists be attentive to the great mass and the great quantity of the Earth, and could be certain the density of the Earth. by skill of understanding the standard density of the exterior rocks and the density of a few mantle rocks (from xenoliths and from seismic analyze), the density of the middle could be extrapolated. whilst meteorites (assumed to be such as the Earth) are whilst in comparison with info of the density of middle rocks, a enormously stable concept of those rocks could be desperate.

Answer 6

How do we know gravity exists, or smoking is bad for you, or we are all alive right now, we dont, we collect data and make guesses - sometimes these are wrong (global warming, evolution, heart disease due to cholesteral).