How do we know the Earth has an iron core.?

Question

What methods are used to figure this out.

Answer 1

Well, for one, we have a big 'ole magnetic field from the spinning molten core.

Answer 2

So basically, nobody knows.

Firstly, nobody can say as a fact anything about the earth mostly because we can not even con to a fact about what is even at the smack bottom of our very own ocean.

Everything we can conclude has been told to us by someone else and honestly.. a lot of these "theories" are being mistaken as fact.

Firstly, the "Magnetic field" is not magnetic. If it was, than there would be more obvious and conclusive evidence. Such as for instance, if the world itself actually had a "magnetic field" would naturally act magnetic. Electronic devices would be effected, other magnetized things or things that can be magnetized would be pulled or pushed away from the earth inevitably.

Although we can hypothesis on many theories how the center of the earth could have a iron core, it is unlikely that core of the earth is purely iron since all the elements and minerals to produce any other element or mineral has been discovered not at the center of the earth.

Also, to imply that the earth can actually be measured by mass and density is absurd. To imply that the world's mass and density can be calculated while the law of gravity does not apply in space out of the earths gravitational pull within it's atmospheric limits. Also, to measure something by something else we do not fully understand such as the moon to figure out something else we do not fully understand like the earth assume they have any relation with each other to understand something so random would not only be very overestimated as a theory but also would imply the same method to explain what the moons core is retrospect fully, which is useless sense the earth and the moon do not share any similarities. Which would bring about many other questions such as: "Why if all planets gravitate around or to another thing in space, why does something like a human who lands on the moon not fall of it and also get pulled out into orbit since it is much smaller than the earth and the moon?" or "Why if all these things orbit do they orbit in order yet there mass would surely effect the manner and order of those planets and or stars and moons as far as staying where they are designated? Or "Why do things such as the Sun or planets in space move around but not fall or slide out of position if there is in fact a gravitational pull?

All these speculations are merely the deductions of humans that do not apply logic logically in all angles but merely unquestionably not question theories that make only slight sense merely because some one "taught" us this information.

It is very possible that the core could be simply the center or earth being made up of any combination of things, not to also add that we do not fully know how deep the oceans limits actually pierce into earth.

Answer 3

The main evidence is firstly that the density has to be high, to match the calculated total mass, and secondly that all the high-density meteorites we find are nickel-iron. So if the core is something other than iron, why aren't there meteorites of that stuff too? And if the meteorites have so much iron, why would the earth (formed from the same early mixture of stuff) have so little? On balance, then, an iron core answers the obvious questions, and a core of some other metal would just raise more questions.

Correcting a couple of other answers, you do not actually need an iron core to generate a magnetic field. A core of any liquid metal would do it quite nicely. All you need are electric current loops, which create magnetic fields, which induce more electric currents in any moving conducting metal.

Answer 4

From the strength of the magnetic field, we know it has to have a core containing the ferromagnetic materials, iron, nickel or cobalt. By timing earthquake vibrations which travel both around the surface and also through the core, we can calculate the density of the core and the losses of energy as the waves travel through the core. The results we get indicate that the core is mostly iron and some nickel. Curiously, the amounts we have calculated are also in the same range of proportions of those elements found in nickel iron meteorites. Perhaps there used to be another planet orbiting out there, which broke apart, or leftovers from making Earth.

Answer 5

We don't, but it's a pretty good surmise, and getting better all the time as more is discovered.
The Earth's mass can be determined from the period of the Moon's orbit and the distance between the Earth and the Moon. Discounting the atmosphere and oceans as being relatively insignificant in mass, the average density of the Earth is determined by dividing the mass by the volume. This density is about 5.52 g/cc. The density of basalt is about 3.3g/cc., so something more dense than basalt has to be postulated to account for the difference. Since the Earth has a magnetic field, and iron, with a density of 7.87 g/cc, is the most common magnetic material we know, it is the first choice to account for the "discrepancy". Progressively newer and more refined systems of "exploration" have only served to reinforce this notion. The discovery that iron is the most stable of all elements (excepting hydrogen) pretty much guaranteed that the original assumption was right.

Answer 6

Earth's magnetic field is a really strong clue.

So is the great mass and density and hardness of the core, as determined by listening to the acoustic distortion of earthquake waves passing through it.

There is a great deal that can be learned about many things without physical contact. If this were not the case, astrophysics would be a REALLY boring field of study!

Answer 7

refer to the following please:How do scientists know what is in the core of the earth?

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.

Dr. Ken Rubin, Assistant Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu, HI 96822

Answer 8

Magnetism.

Answer 9

If it didn't have an iron core, how could it make its shirts and trousers crease free?