19
votes
Accepted
Are we experiencing lower level of gravity now compared to past?
Earth's radius is about 6400 kilometres. That's 6400000 metres. Let's say that you have a mound 20 metres high, burying an older settlement. Your new "radius" is now 6400020 metres.
Let's say that $g ...
- 23.1k
13
votes
Accepted
How is known that the Earth core is solid?
This is a good observation. The reason we can measure S-wave (transverse) propagation in the inner core is because P-waves can set up S-waves and vice versa. When an S-wave hits the mantle-outer core ...
- 2,221
13
votes
Does Earth's magnetic field arise from a fission reactor in its core?
The conventional explanation for the Earth's magnetic field is that some combination of differential rotation and/or convection occurs in the Earth's outer core, primarily in molten iron-nickel (+ ...
- 14.2k
12
votes
Why is Earth's Core Iron?
I can only answer the question of why is it mostly iron. Not too sure of the magnetic properties of iron versus nickel.
As said in another answer, there is simply much more iron around than nickel. ...
- 23.1k
11
votes
Accepted
How fast does the Earth's inner-core spin?
Roughly once per day, but a tiny bit faster. As the website for Columbia University's Lamont-Doherty Earth Observatory says:
The inner core rotates in the same direction as the Earth and slightly ...
- 3,548
8
votes
Accepted
Is the iron on Earth's crust a leftover of the Iron catastrophe, or it was brought back by volcanoes?
Not all the iron sank to the core. Have a look at my answer to a previous question:
https://earthscience.stackexchange.com/a/7076/725
Your question is similar, but coming the other way. You're ...
- 23.1k
8
votes
Accepted
What if we detonated the entire worlds nuclear supply in the center of the earth?
I'll ignore the complete impossibility of getting the world's nuclear arsenal to the center of the Earth and the impossibility of exploding them all at once. The total number of nuclear weapons, ...
- 23.1k
8
votes
Accepted
How do scientists confirm iron core at the centre of the earth?
This is more a geophysics than an astronomy question—and thus the available methods of investigation are greatly increased. An Earth model also is not a one-person-show based on one measurement, but ...
- 204
8
votes
How much does earth's core temperature affect earth's global surface temperature
It's not the earth's core temperature per se that matters, but rather the amount of heat that flows from the core to the surface. Just like holding a cup of hot coffee - if the mug is insulated, it's ...
- 176
7
votes
Accepted
Does the Earth 'Flare' like the Sun does?
The medium for a solar flare is plasma, so nothing like that occurs in the Earth's core. The outer core fluid is highly conductive and has a low viscosity, so changes may occur in the core's field, ...
- 288
7
votes
Why is Earth's Core Iron?
The main reason that there is more iron than nickel in the Earth's core, and in the universe generally, is that Nickel-56 beta-decays to Iron-56 (via cobalt-56).
Much nickel-56 forms in Asymptotic ...
- 5,962
7
votes
Accepted
Does iron in core have chance to come out to crust?
No, we occasionally get fragments of upper mantle overthrust onto the Earth's crust, but then the specific gravity (density) contrast is not so great, roughly 2.7 to 3.0 for crust, about 3.2 for ...
- 14.2k
7
votes
Accepted
Can there be ice in the core because of pressure?
what happens if you manage to add some water in the inner core or near it.
It will probably react with the solid iron to form iron (oxy)hydride:
Our observations indicate that H2O is likely ...
- 23.1k
6
votes
Which theory is stronger, that iron came from outside or was formed within earth?
Somewhat more from volcanic activity than meteor impacts, but both are important.
The Earth has an iron-nickel ($\ce{Fe}$-$\ce{Ni}$) core that originates from Earth's formation out of the collision ...
- 1,207
6
votes
Why is Earth's outer-core liquid?
Just to add to Dave's answer, the above phase diagrams give the illusion of high precision. In fact, in addition to the temperature distribution, we are not even entirely sure how many sub-solidus ...
- 14.2k
6
votes
Accepted
Why is uranium only in the crust, really?
(tl;dr below)
First, a correction. Siderophile elements are "iron-loving" elements, those that go in the core with the Fe-Ni liquid. Uranium is lithophile, or "rock-loving". It partitions to silicate ...
- 23.1k
6
votes
How Can We Establish Precisely What Earth's Core is Made Of?
We know the density of the core from seismology.
We also know the density of pure iron at given pressure (P) and temperature (T).
From these two, people have long noticed that there is a discrepancy: ...
- 7,729
6
votes
Why is the inner core about 85% iron and the rest (mostly) nickel, while the outer is roughly 80%/20%, if nickel is denser than iron?
Once you're in the metallic part of the Earth, the compositions of the different constituents (solid and liquid) are not determined by density.
The whole metallic part (core) is denser the the ...
- 23.1k
6
votes
Accepted
How does the rotation of Earth's inner core influence climate?
I have four things to say regarding this:
The paper is far too new. I'm not saying the first paper is wrong (it is in fact rather interesting), but having been published yesterday, it is far too new ...
- 23.1k
5
votes
Why doesn't the Earth's outer core dissolve into the mantle?
From the comments:
And indeed, after browsing trough a few sections they seem to assume that "Liquid metal separates rapidly from liquid silicate", like oil and water, and they don't mix ...
- 23.1k
5
votes
Are we experiencing lower level of gravity now compared to past?
To address your original concern, no, the fact that there are buildings underground does NOT mean that the surface of the earth is higher than in the past. What is actually happening is that these ...
- 51
5
votes
Can there be ice in the core because of pressure?
The answer is maybe -- if you are looking deep in the mantle rather than in the core, and if you are prepared to accept "superionic" ice in which the molecular structure of water has broken ...
- 3,666
4
votes
Why is the core of the earth thought to be iron rather than metallic oxygen?
1) The density of the core approximately matches that of high pressure Ni-Fe, but is way denser than solid oxygen (roughly 1.4).
2) If the core was oxygen then the overall elemental abundance of the ...
- 14.2k
4
votes
How can we determine the size and composition of Earth's inner core?
In 1906, Richard D. Oldham found that the increasing speed of seismic waves with depth within the Earth holds only down to 2890 km below the surface. Deeper than that, the mechanical waves (sound) ...
- 1,723
4
votes
How much would a nine inch slice of the Earth's inner core weigh?
An oddly specific question, but quite straightforward to calculate. Let's start by calculating the volume of your slice. I'm taking values for the inner core's physical characteristics from this ...
- 5,431
4
votes
How much of the Earth's heat is caused by the hot centre?
Given the insulating effect of 6370 km of rock (the average radius of the Earth) & its low thermal conductivity, if the temperature at the center of the earth was 18 °C it contribution to warming ...
- 24.6k
4
votes
Why is the core of Earth in a reduced state? ($\text{Fe}$ and $\text{Ni}$)
Because there wasn't enough oxygen to oxidise all of it. There is only so much oxygen on Earth. Most of it went to oxidise the elements that have higher affinities to oxygen: silicon, magnesium, ...
- 23.1k
4
votes
Do there exist reasonable numbers on the density/radius/mass of the various geological layers of the Earth?
One model that will help you is the admittedly dated (1981) Preliminary Reference Earth Model. It provides density models for the inner and outer core as functions of distance from the center of the ...
- 23.1k
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