Questions tagged [planetary-formation]

Questions about the processes, theories and evidence for the formation of planetary bodies, mostly the Earth.

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1 answer
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Do scientists ever make rock vapor in a laboratory? If so, is it ever used to study planetary or lunar formation?

This answer to What is the nature of "rock vapor" in this description of the formation of the Moon? explains what "rock vapor" is and how scientists use the concept to understand ...
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4 votes
1 answer
180 views

How did hydrogen make its way into proto-Earth?

Background I read (what I could understand of) this article in which authors Yuan and Steinle-Neumann "...use advanced quantum mechanical simulations on silicate and metallic melts showing that ...
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2 votes
0 answers
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Is continental drift a chaotic phenomenon?

Suppose that we reran Earth from two billion years ago changing the position of one atom. Would the continents drift to positions completely different from those today?
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2 votes
2 answers
51 views

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?

As stated above.... I really cannot think of a good reason, on my own, why this should be so.... Is it a mystery to geologists?
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7 votes
1 answer
102 views

Was Earth completely covered in Oceans prior to the onset of plate tectonics?

Following recent develoments in geophysics (Schmidt et al. (2014), and a popular summary), we now know there to be a significant reservoir of water in the mantle-transition of planet Earth, now often ...
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7 votes
0 answers
175 views

Wasn't Earth a magma ocean before core-mantle differentiation?

I've always thought that the process of planetary accretion was energetic enough to keep the proto-Earth entirely molten, and the subsequent evolution of the planet (the formation of the crust, etc...)...
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1 vote
1 answer
233 views

Why does the Earth's crust have more aluminum than magnesium while the Sun has more magnesium than aluminum?

Magnesium represents 0.07 % of the composition of the Sun's photosphere while aluminum represents 0.006 %. Therefore, there is much more magnesium than aluminum in the Sun's photosphere. But the same ...
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2 votes
1 answer
126 views

Why is Venus so cracked?

Wired.com's Space Photos of the Week: Perfectly Safe Celestial Coronas includes radar images of the surface of Venus taken from spacecraft in orbit around it. One of them shown below. What causes ...
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1 vote
1 answer
487 views

How can radiometric dating of meteorites determine the age of the earth? Wouldn't this only determine the age of the decaying nuclide in each rock? [duplicate]

How can the radiometric dating of different meteorites determine the age of the earth? Wouldn't radioactive decay have already been occurring in all of those meteorites long before they hit earth? ...
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3 votes
1 answer
402 views

Why is there so much more silicon than carbon in the Earth's crust?

Some arguments I've seen about the viability of silicon-based life involve the relative abundance of silicon vs carbon. In the universe as a whole, there's a lot more carbon than silicon around. Yet, ...
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1 vote
1 answer
213 views

Geological Differentiation: variables and size requirement

Geological/Planetary differentiation is one of those topics that gets glossed over in intro Geo courses. We know that differentiation occurs over deep time (and will never end) and is a result of the ...
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1 vote
0 answers
19 views

Does outgassing change the isotopic D/H ratio?

It is known that the D/H-ratio of Earth's water inventory is very similar to that of asteroids. This is usually interpreted in a way that Earth's water must have come from similar, asteroid-like ...
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6 votes
1 answer
687 views

How is Karst topography formed on land?

I read that the source of Karst topography is coral reefs, when coral reefs are found in water bodies, how is karst topography formed on land?
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4 votes
0 answers
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Endogenous Theories For the Origin of Earth's Water (Dry/Wet Accretion?)

I have really two questions: (1) what evidence is there in favour that the majority of Earth's water formed with the planet. (2) what evidence is there that the majority of water did not form with ...
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  • 181
5 votes
2 answers
506 views

Plate Tectonics vs Gravity for Creating Highs and Lows

I have a question that I thought of when discussing a Worldbuilding scenario here. In that question, a super earth with gravity 1.35 times that of earth's is discussed, and is assumed to have shallow ...
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1 vote
1 answer
59 views

Mountains and solids on other planets

Are there planets that lack mountains or have constrained availablilty of solids. For example a planet that has clay but not more solid stones like normal stones. The direct reason why I wonder is ...
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5 votes
0 answers
155 views

Did Theia collide directly with proto-Earth?

I was learning about the formation of Earth on Kahn Academy where it was mentioned that a protoplanet named Theia had a glancing impact with the earth and formed the moon. It seems like there is also ...
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2 votes
2 answers
108 views

Why is "at least a small tilt" between rotation and magnetic axis required by models of magnetic field formation?

I saw something I don't understand in the Gizmodo article Cassini's First Grand Finale Images Are Stunning—But What Are We Really Looking At?. In a quote of Caltech Professor of Planetary Science ...
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8 votes
0 answers
250 views

1950's - 60's Earth Science

I'm writing some lore for a fictional world, which is set in the 50's early 60's roughly. One thing I'd like to bring is a fairly grounded explanation for the creation of the planet and the universe, ...
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5 votes
2 answers
690 views

Were all of Earth's minerals created before Earth's formation, during, or after?

I've heard that during the accretion of proto-planets that formed the earth, 60 minerals were created through the reactions of atoms and molecules in the nebula. Do these first minerals still make up ...
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6 votes
3 answers
2k views

Pangaea - Why did all the land mass form in one area?

The thing I find most interesting about Pangaea is that, if all the landmasses were connected, it leaves a massive amount of uninterrupted ocean everywhere else. It seems to suggest that there is a ...
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6 votes
1 answer
74 views

Is the giant impact hypothesis still alive?

It used to be thought that the unusual amount of water on our planet was the result of a giant collision between proto-Earth and a dwarf planet or planetoid called Theia. I recently heard of some ...
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12 votes
3 answers
6k views

Why is Earth's Core Iron?

The two major constituents of the Earth's core are iron and nickel. In documentaries and scientific conversations, iron gets more attention than nickel, probably because it makes up a bigger ...
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13 votes
1 answer
419 views

Did Jupiter really make Earth (in)habitable?

A new study by Batygyin and Laughlin suggest that a Jupiter migration toward the inner region of the Solar System during the early stages of system formation cleared the habitable region (Goldilocks ...
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10 votes
0 answers
113 views

Where did the energy released due to gravitational binding energy of the Earth go? [closed]

The gravitational binding energy of the Earth is $2×10^{32} J $, so the same amount of energy must have been released during the Earth's history. According to this and this, the current internal ...
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36 votes
5 answers
3k views

How do we know the asteroids formed at the same time as earth?

In continuation of the question Why is Earth's age given by dating meteorites rather than its own rocks?, what evidence do we have that the asteroids indeed formed at the same time as earth? Is there ...
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10 votes
1 answer
270 views

'Late Veneer' on other planets

Is there any evidence of external material source events, like the 'Late Veneer' on other planets? Or is this theory specific just for Earth? Note, that this question may be related to How and why ...
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11 votes
1 answer
364 views

Regarding the theory of the origin of water on Earth through meteorites, why wouldn't the water evaporate on impact?

Water on earth has been theorized to have come through comets trapped inside crystals. But why wouldn't that water evaporate on impact, and wouldn't the atmosphere at that time allow the vapours to ...
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