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I've always been in awe of what plate tectonics, or the lack thereof means for other planets in the solar system - Venus' lack of magnetic field could be due to

I've always been in awe of what plate tectonics, or the lack thereof means for other planets in the solar system - Venus' lack of magnetic field could be due to a lack of plate tectonics trapping heat in the mantle, thus preventing the convection currents found in Earth's core that lead to magnetism. And likewise, what would Mars' atmosphere be like if all the oxygen in its rocks was periodically liberated by cycling through the mantle? And above all, I wonder why Venus and Mars don't have tectonics, but we do.

mncharity 6y ago
> And above all, I wonder why Venus and Mars don't have tectonics, but we do. Quibble: They both have tectonics (large-scale crustal processes). And may have had plate tectonics in the past. Fwiw, here's a recent survey article on Venus[1] - "Why not now?" appears an open question. I didn't quickly find one for Mars. [1] https://link.springer.com/article/10.1007/s11214-018-0518-1 https://link.springer.com/article/10.1007/s11214-018-0518-1
- EdwardDiego 6y ago
  You're right, I meant plate tectonics. :)
cwbrandsma 6y ago
Don't quote me on this, it has been a long time since I read the article on Mars, so I'm probably out of date on my information. There is a theory that Mars used to have plate tectonics, but was hit by a MASSIVE asteroid (around the size of our moon) a long time ago, probably in the southern hemisphere. This is also why Mars has such a huge volcano in the north, almost directly opposite where the asteroid hit. This turned Mars into an egg shaped planet for a while, which caused the core to stop spinning, and stopped its plate tectonics. This is the closest article I could find on this: https://www.scientificamerican.com/article/giant-asteroid-collision-may-have-radically-transformed-mars/ https://www.scientificamerican.com/article/giant-asteroid-co...

mncharity 6y ago

> And above all, I wonder why Venus and Mars don't have tectonics, but we do. Quibble: They both have tectonics (large-scale crustal processes). And may have had plate tectonics in the past. Fwiw, here's a recent survey article on Venus[1] - "Why not now?" appears an open question. I didn't quickly find one for Mars. [1] https://link.springer.com/article/10.1007/s11214-018-0518-1 https://link.springer.com/article/10.1007/s11214-018-0518-1

EdwardDiego 6y ago
You're right, I meant plate tectonics. :)

cwbrandsma 6y ago

Don't quote me on this, it has been a long time since I read the article on Mars, so I'm probably out of date on my information. There is a theory that Mars used to have plate tectonics, but was hit by a MASSIVE asteroid (around the size of our moon) a long time ago, probably in the southern hemisphere. This is also why Mars has such a huge volcano in the north, almost directly opposite where the asteroid hit. This turned Mars into an egg shaped planet for a while, which caused the core to stop spinning, and stopped its plate tectonics. This is the closest article I could find on this: https://www.scientificamerican.com/article/giant-asteroid-collision-may-have-radically-transformed-mars/ https://www.scientificamerican.com/article/giant-asteroid-co...