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New evidence suggests giant asteroid impacts created Earth’s continents

80 points by cheinyeanlim 4y ago

andrewflnr 4y ago
They gloss over a lot with the term "crustal differentiation". This page (intro of a book) explains a bit about how magma gets separated into silicate-rich and -poor fractions: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/magmatic-differentiation https://www.sciencedirect.com/topics/earth-and-planetary-sci... .
lampshades 4y ago
100 years from now: “New evidence suggests giant asteroid impacts DIDN’T create Earths continents”
- hinkley 4y ago
  When we actually understand how the moon was created, or when we understand the lumpy core of the earth (some people say they are the same thing) I suspect we’ll know more about the plates. I would also like to invite some aficionados and scientists to spend some time watching olive oil floating on simmering water. Lots of weird stuff happens, and if subduction and aduction zones aren’t cause by plate separation but instead caused it as I suspect, then there’s probably some food for thought to be had in a pot of noodle water.
fallingknife 4y ago
The article mentions that other planets don't have continents, but isn't that an argument against this hypothesis? The same process of asteroid collisions would have happened there too.
- sandworm101 4y ago
  Other planets that we have so-far detected. There are no doubt countless more planets that out current technology cannot detect so easily. It may be that all those with continents are small enough that they slip though the detection net. We should probably hold off on the comparisons until we are able to readily detect earth-sized planets around similarly-sized stars to ours. Then we can talk about whether our arrangement is or is not rare.
- kurupt213 4y ago
  Some theories say water plays a critical role in crust formation. There aren’t a lot of local planets with liquid water on their surface.
hinkley 4y ago
We are on such a Goldilocks planet it isn’t even funny. Or life is so exquisitely tuned to optimize for earth’s conditions it isn’t even funny. Or both. We see magnetic fields this strong on gas giants, but not on inner planets. I wonder too if we will find that some asteroid impacts and the formation of the moon didn’t goose up the magnetic flux of the core while they were at it. Maybe habitable zones only appear on tortured worlds, like earth and some of the moons of a Jupiter, because normal planets are just too boring, don’t have enough building blocks for life.
- colechristensen 4y ago
  Probably true, but as a balance for this there are about 100 billion galaxies in the visible universe each with about a hundred billion stars, each with a chance to build up the right conditions for live. That's 10^22 opportunities to get it right. We can't possibly be alone.
  - pfdietz 4y ago
    Now justify your implicit assumption that the chance life arises on a suitable planet is at least 1 in 10^22.
    - layer8 4y ago
      The point is we don’t know either way. Earth may or may not be a “Goldilocks” planet. Also, the numbers above are based on the observable universe. We have no idea how big the universe is outside that region. It could be infinitely large.
      - pfdietz 4y ago
        Right. So, the argument "10^22 is a lot so we can't be alone" is a non sequitur.
        layer8 4y ago
        I understand it to be a counterargument to the “Goldilocks” non-sequitur.
anonAndOn 4y ago
Wasn't it originally "continent" but thanks to tectonics it has broken up. Could Theia have gifted us a proto-Pangea?
- wrycoder 4y ago
  Yes. The article doesn’t even mention “moon”. Current information indicates that most of the Earth’s lithosphere ended up in the Moon. BTW, George Gamow wrote about the “birth” of the Moon back in the ‘50s.
- Sharlin 4y ago
  I don't think the original configuration of continents is well-understood. The continents have drifted together and apart again several times in the past 3+ billion years. Pangaea was just the most recent supercontinent.
  - gus_massa 4y ago
    Here is a nice video from the last 1000 million years https://bigthink.com/hard-science/plate-tectonics-animation/ https://bigthink.com/hard-science/plate-tectonics-animation/
- xeromal 4y ago
  This bitch don't know 'bout Pangea?
ggm 4y ago
If you like speculative fiction, John Brunner wrote very odd fiction about mobile and ultimately intelligent plants who come into being in a meteor rich planet, from water to land, to space.. https://en.wikipedia.org/wiki/The_Crucible_of_Time https://en.wikipedia.org/wiki/The_Crucible_of_Time
- paleotrope 4y ago
  That was a amazing book. It had so much packed into. So many sf concepts just sort of dumped into it.
Apocryphon 4y ago
So does this make catastrophism real
- andrewflnr 4y ago
  Catastrophism and uniformitarianism are models. All models are wrong, some models are useful. Reality has always been a mix of sudden and long-running processes.
gcanyon 4y ago
"Earth is the only planet we know of with continents..." -- links to a paper comparing Earth with only the inner rocky planets of our own solar system and citing other planet's lack of water, and therefore granite. I think that intro sentence is implying a lot more than the paper it cites is stating. Paper cited: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL010i011p01061 https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL01...
gcanyon 4y ago
Since we already know a pretty decent-sized meteor hit in the Yucatan, shouldn't we expect to see evidence of this process (at least starting to) happening there? I'm not certain what that evidence would look like, and maybe 65 million years is too short a time period?

80 points by cheinyeanlim 4y ago

They gloss over a lot with the term "crustal differentiation". This page (intro of a book) explains a bit about how magma gets separated into silicate-rich and -poor fractions: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/magmatic-differentiation https://www.sciencedirect.com/topics/earth-and-planetary-sci... .

lampshades 4y ago

100 years from now: “New evidence suggests giant asteroid impacts DIDN’T create Earths continents”

hinkley 4y ago
When we actually understand how the moon was created, or when we understand the lumpy core of the earth (some people say they are the same thing) I suspect we’ll know more about the plates. I would also like to invite some aficionados and scientists to spend some time watching olive oil floating on simmering water. Lots of weird stuff happens, and if subduction and aduction zones aren’t cause by plate separation but instead caused it as I suspect, then there’s probably some food for thought to be had in a pot of noodle water.

fallingknife 4y ago

The article mentions that other planets don't have continents, but isn't that an argument against this hypothesis? The same process of asteroid collisions would have happened there too.

sandworm101 4y ago
Other planets that we have so-far detected. There are no doubt countless more planets that out current technology cannot detect so easily. It may be that all those with continents are small enough that they slip though the detection net. We should probably hold off on the comparisons until we are able to readily detect earth-sized planets around similarly-sized stars to ours. Then we can talk about whether our arrangement is or is not rare.
kurupt213 4y ago
Some theories say water plays a critical role in crust formation. There aren’t a lot of local planets with liquid water on their surface.

hinkley 4y ago

We are on such a Goldilocks planet it isn’t even funny. Or life is so exquisitely tuned to optimize for earth’s conditions it isn’t even funny. Or both. We see magnetic fields this strong on gas giants, but not on inner planets. I wonder too if we will find that some asteroid impacts and the formation of the moon didn’t goose up the magnetic flux of the core while they were at it. Maybe habitable zones only appear on tortured worlds, like earth and some of the moons of a Jupiter, because normal planets are just too boring, don’t have enough building blocks for life.

colechristensen 4y ago
Probably true, but as a balance for this there are about 100 billion galaxies in the visible universe each with about a hundred billion stars, each with a chance to build up the right conditions for live. That's 10^22 opportunities to get it right. We can't possibly be alone.
- pfdietz 4y ago
  Now justify your implicit assumption that the chance life arises on a suitable planet is at least 1 in 10^22.
  - layer8 4y ago
    The point is we don’t know either way. Earth may or may not be a “Goldilocks” planet. Also, the numbers above are based on the observable universe. We have no idea how big the universe is outside that region. It could be infinitely large.
    - pfdietz 4y ago
      Right. So, the argument "10^22 is a lot so we can't be alone" is a non sequitur.
      - layer8 4y ago
        I understand it to be a counterargument to the “Goldilocks” non-sequitur.

anonAndOn 4y ago

Wasn't it originally "continent" but thanks to tectonics it has broken up. Could Theia have gifted us a proto-Pangea?

wrycoder 4y ago
Yes. The article doesn’t even mention “moon”. Current information indicates that most of the Earth’s lithosphere ended up in the Moon. BTW, George Gamow wrote about the “birth” of the Moon back in the ‘50s.
Sharlin 4y ago
I don't think the original configuration of continents is well-understood. The continents have drifted together and apart again several times in the past 3+ billion years. Pangaea was just the most recent supercontinent.
- gus_massa 4y ago
  Here is a nice video from the last 1000 million years https://bigthink.com/hard-science/plate-tectonics-animation/ https://bigthink.com/hard-science/plate-tectonics-animation/
xeromal 4y ago
This bitch don't know 'bout Pangea?

ggm 4y ago

If you like speculative fiction, John Brunner wrote very odd fiction about mobile and ultimately intelligent plants who come into being in a meteor rich planet, from water to land, to space.. https://en.wikipedia.org/wiki/The_Crucible_of_Time https://en.wikipedia.org/wiki/The_Crucible_of_Time

paleotrope 4y ago
That was a amazing book. It had so much packed into. So many sf concepts just sort of dumped into it.

Apocryphon 4y ago

So does this make catastrophism real

andrewflnr 4y ago
Catastrophism and uniformitarianism are models. All models are wrong, some models are useful. Reality has always been a mix of sudden and long-running processes.

gcanyon 4y ago

"Earth is the only planet we know of with continents..." -- links to a paper comparing Earth with only the inner rocky planets of our own solar system and citing other planet's lack of water, and therefore granite. I think that intro sentence is implying a lot more than the paper it cites is stating. Paper cited: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL010i011p01061 https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/GL01...

gcanyon 4y ago

Since we already know a pretty decent-sized meteor hit in the Yucatan, shouldn't we expect to see evidence of this process (at least starting to) happening there? I'm not certain what that evidence would look like, and maybe 65 million years is too short a time period?