cbkeller

44 ms·

391.
by cbkeller 8y ago
It seems increasingly likely that there was originally quite a bit of liquid water on Mars during the Noachian ( https://en.wikipedia.org/wiki/Noachian ) and Hesperian ( https://en.wikipedia.org/wiki&#x2F
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by cbkeller 8y ago
Yep! Plus the lack of a magnetic field, which is largely also due to Mars being too small, and losing heat too fast to have any liquid metal convecting in the core anymore
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by cbkeller 8y ago
Geologist here. I would tend to agree, considering that present-day oxidizing conditions on mars are generally thought to be due to photolysis and hydrogen loss, not life/photosynthesis, e.g.: https://www.liebertpub.com&#x2F
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by cbkeller 8y ago
Geologist here. Yeah, there are a few places you can find microbial survivors of the GOE: https://en.wikipedia.org/wiki/Green_sulfur_bacteria https://en.wikipedia.org/wiki/Purple_sulfur_bacteria O
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by cbkeller 8y ago
That's spot on. The folks who argue for a "blue marble" Earth early on, even in the Hadean (>4 billion years ago) are fond of pointing out that while the name was chosen to evoke a hellscape, Hades in Greek mythology ruled
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by cbkeller 8y ago
There's also an active debate about whether the LHB actually happened, which adds to the stakes a bit: http://www.pnas.org/content/113/39/10802
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by cbkeller 8y ago
Tidal dissipation is also a very interesting subject, but the energies involved are lower (about 2.8 TW) and concentrated near the surface of the earth where the heat is lost really fast. It might be resolved now, but for a while there was
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by cbkeller 8y ago
Big enough that that's a totally reasonable question! I don't think I can even put a number on it very confidently, but maybe something like 1.0 -0.7/+2.0 Ga? One counterpoint that comes to mind is that the Ediacaran fauna i
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by cbkeller 8y ago
Two reasons: (1) the earth has really huge thermal inertia (2) radiogenic heat production. (2) often gets a lot of the credit (who doesn't like radioactivity), but (1) is probably doing more of the heavy lifting At present day, Earth
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by cbkeller 8y ago
There's a whole interesting dynamic that leads to this sort of press release: whenever someone publishes a high-profile Nature or Science paper, they usually have a chance to work with the university communications department to make a
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by cbkeller 8y ago
Ya, it's a perennial at "bad geoscience movie night"
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by cbkeller 8y ago
The new study by Tkalčić and Phạm is cool work, but it's not even the first observation of PKJKP, so this press coverage is irresponsible. The "perspective" by Irving accompanying the Tkalčić and Phạm paper is pretty readable
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by cbkeller 8y ago
I'm a geologist. This press release is pure BS. We've known beyond reasonable doubt that the inner core is solid for more than a decade - for instance: http://science.sciencemag.org/content/early/2005&#x2