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33 votes
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How can we determine the size and composition of Earth's inner core?

We know the the size of the inner core through seismology. From my answer to this question: How are subsurface wave speeds determined without subsurface sensors?, we can determine the speeds of the ...
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32 votes
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Why is Earth's inner core solid?

Earth's inner core is solid even though the temperature is so high because the pressure is also very high. According to the Wikipedia article on the Earth's inner core, the temperature at the center ...
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32 votes
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Could the Earth's core lose its heat?

Part 1, see Neos answer. Earth will lose its heat no matter what we do, and our extraction of geothermal energy is insignificant (Wikipedia quotes a BP figure of 11.4 GW electrical, 28 GW heating). ...
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31 votes
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Can we really travel through earth's core?

As Chris Mueller said, in short: it isn't, or at least highly infeasible. Projects to drill into the mantle, such as the Kola Superdeep Borehole, have all failed because drilling equipment can't ...
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27 votes
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What percent of the Earth's core is uranium?

Good question! Geochemists and geophysicists agree to disagree, sometimes quite strongly. There are also disagreements within each group as well as between the two groups. It's not just uranium. There ...
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21 votes
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Why is Earth's inner core made of an iron-nickel alloy?

The first thing you should think about is how the accretionary disk cooled and the cosmochemical constraints this put on Earth (But I am not going into details here). From studying meteorites it is ...
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21 votes

Why is Earth's inner core solid?

In addition to the answers below and my comment above, I believe the following phase diagram, from DavePhd's answer here, sourced from here, is more appropriate for the pressure levels near the Earth'...
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21 votes
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How long until Earth's core solidifies?

Global warming has to do with the surface only, and at best involves changes of 20 degrees at the outside extreme, in comparison to the earth's core, which is as hot as the surface of the sun. For ...
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20 votes

Could the Earth's core lose its heat?

This question is relevant, Why is the inside of the Earth so hot? The short answer is the core is losing heat no matter what we do. You see, heat is transported from the core to the surface, but its ...
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  • 6,356
20 votes

Can we really travel through earth's core?

Short answer: No. Long answer: Our deepest drills failed around 12km down when the drill bits were having to cope with temperatures hot enough to melt the drills. 12km down is only a tiny distance ...
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19 votes
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Why is Earth's outer-core liquid?

First, you need a phase diagram that goes to higher pressure. The pressure at the inner/outer core boundary is over 300 GPa. The one in the question would only get us into the mantle: (link to source)...
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19 votes
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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 ...
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18 votes

Could the Earth's core lose its heat?

Put a frying pan on a stove burner and make the pan hot. Measure its temperature every minute over half an hour or so to get an idea of how rapidly it naturally cools. Then start the experiment over ...
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18 votes
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Which theory is stronger, that iron came from outside or was formed within earth?

The only elements that were formed on Earth are those produced by radioactive decay. There are four natural decay chains that start with transuranic elements and none terminate in iron; neither do the ...
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16 votes

Why is Earth's outer-core liquid?

The pressure gradient is given by hydrostatic equilibrium. In a solid, this may not be exactly true, but creep will make it so. Let $p$ be the local pressure, $g$ be the local acceleration of ...
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14 votes
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At what point does plate tectonics stop?

One permanent threat to plate tectonics is the oceans vanishing. The scientific jury may still be out on this matter, but most geologists and geophysicists consider water to be the lubricant that ...
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13 votes

Could the Earth's core lose its heat?

Could all the drilling and digging to use the earth's natural heat as geothermal energy be affecting Earth's core, causing it to cool down? Yes. But by how much? Let's do some rough math. We'll just ...
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13 votes

Why is Earth's inner core solid?

You are only considering the melting point at atmospheric pressure. Melting point depends upon pressure. The pressure in Earth's core is about 350 GigaPascals. It is important to study the phase ...
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13 votes
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Is the Earth's hot inner core necessary for life?

Whether the high temperatures of the core is strictly necessary to maintain a habitable temperature at the surface I'm not sure, as the global temperatures are largely controlled by insolation and the ...
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  • 2,602
13 votes

Could the Earth's core lose its heat?

... causing it to cool down? This answer to the question 'Why has Earth's core not become solid?' over on Physics seems to claim the answer is no. The core is heated by radioactive decays of ...
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13 votes
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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 ...
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  • 2,201
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 (+ ...
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12 votes

Can we really travel through earth's core?

There is one vaguely plausible method that has been proposed: blow open a crack in the Earth's crust using a hydrogen bomb and then fill the crack with molten iron. The iron then sinks to the core, ...
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11 votes
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Why does Earth's outer-core rotate in the opposite direction to the inner-core?

Is it true that Earth's outercore rotates in the opposite direction to Earth's inner-core? No. You misread a badly written for-the-masses science article. The article summary is at best rather ...
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11 votes

Which theory is stronger, that iron came from outside or was formed within earth?

All the material that eventually formed our solar system is essentially recycled star dust. All iron on Earth was produced by large stars that existed before our Sun formed: the iron was created ...
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11 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. ...
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11 votes
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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 ...
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10 votes

Why is Earth's inner core made of an iron-nickel alloy?

Your guess A is correct. Iron, nickel, and other heavy metals like gold, are what makes up the core of the earth because they are the heaviest of the metals and so sank toward the center of the earth. ...
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