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[kunal]

Whats the Centre of the Earh Made of? Lava? How does one know this? any ideas?

[Chicken]

I hear it is a tiny rubber ball wrapped with rubber bands. (Ever taken apart a golf ball?)

[tfc]

Hi Kunal

What timing: My son and I were just discussing this yesterday (I am not now nor I have ever been a geologist).
The following explanation (by Ken Rubin at the University of Hawaii) appears to be generally accepted:

Well, we have a pretty good idea from a variety of indirect measurements and reasonings:
First, we know the overall density and mass of the Earth based on measurments of how the Earth perturbs the orbits of other planets and the moon.
Second, we know the overall density of the variousd layers of the Earth based upon the way in which seismic pressure waves (compressional waves created by earthquakes) move through the earth to arrive at locations remote from the earthquake source.
Third, by examining a second type of seismic wave (a shear wave, that is equivalnet in motion to a back and forth rubbing of one's hands together) we know that the outer part of the core is liquid, even though it is at immense presure from being underneath so much rock. Shear waves can't travel through liquids.
Forth, we know the overal composition of the Earth by examining the bulk chemical composition of the Sun (by examining its light spectrum) and by analyzing a class of meteorites known as Chondrites (which have similar composition to the Sun and are believed to be similar to the material from which the Earth accreted).
Fifth, we know the composition of the Earth's crust and its mantle, by examining samples of them. For the lower mantle, we use experiments of the effect of pressure on upper (shallow) mantle minerals to predict the mineralogy of the lower reaches of the mantle. We then pass seismic waves through it in the lab to see if our experimental rocks match the observations.
Six, now that we know the size, mass and composition of the whole Earth, its crust, and its mantle, we can contruct a balance sheet of materials and see which chemical elements aren't in the crust (including atmosphere and hydrosphere) or mantle that we know should be on the Earth. These must be in the core.
Seven, to aid us in our assessment, we recall that we need metallic elements in high concentration somewhere in the interior of the Earth to generate our magnetic field. Also, this metal must be able to be in the liquid state even at very high pressures.
Adding all this up, we find the core is predominantly Iron metal (Fe). We find it has a significant amount of the element Nickel (Ni, about 4%) and a light element to make it less dense (about 10% by mass). This light element is either mostly oxygen or sulfur, with the arguments for oxygen (too detailed to go into here) being more believable in general.
We can look at the composition of iron meteorites as well, which are remnants of small planetary bodies from early in our solar-system's history that segregated small cores. The composition of these metal alloys match closely what we predict the composition of our core is using the evidence discussed above.

[Chicken]

I still think it is a tiny rubber ball wrapped with rubber bands.

[tfc]

Chicken:

Yours was the second most popular theory in last month's Core Review.

Never dug into a golf ball, but I did take apart a baseball once. Add string to the rubber ball and bands, and I'll buy your conclusion.

[Edited by tfc on 10-15-2000 at 04:48 AM]

[webfors]

I didn't read the long post, so I'll stick to the rubber band theory too

I always thought it was a hot tub of burning lava, but that's just a guess.

[tfc]

tabernack:

I didn't read it either (cut & paste, you know). Another golfer, eh? Strings, I tell you, Strings (not to be confused with the already confused Superstring Theory Shopping Network). But until a group of tourists heads for the Core, rubber bands'll do. Elasticity. The Universe. The Unhatched Egg. I think Chicken's on to something (no, don't delete that last preposition).

[JTY]

I hear it's made of solidified liquid nickle.

[kunal]

Well, I read the whole thing. And whoooosh, all went over my head. So I think I will stick with chickens rubber band theory too

[tfc]

kunal

You of all people ought to know advertising is allowed only in the...ooops, I read "Swooosh."
Nevermind. Sorry.

[kunal]

Originally posted by tfc
kunal

You of all people ought to know advertising is allowed only in the...ooops, I read "Swooosh."
Nevermind. Sorry.

eh?? whats swoosh?? im confused!

[tfc]

Nike's "swoosh" (not be confused with the NBA exclamation "swish," which I believe is in the public domain).

[kunal]

Ah!

[Duster]

Another theory, though less popular than the molten ferric core, is that the core od the Earth is made of hot chicken fat. That's why animals can sense pending earthquakes. They can smell the traces of chicken fat in the air (and it doesn't smell good).

In fact, when volcanoes erupt and all that really hot chicken fat comes to the surface, more people die from the stench than anything else. P U!

[tfc]

The ol' Shake n Bake Theory moves in geophysical circles, too?

And I thought it was limited to the "Who really wrote Shakespeare's plays?" wannabe controversy.