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Thread: Earth's Present Magnetic Field: An Evidence of the Ancient Theia Impact?

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    Earth's Present Magnetic Field: An Evidence of the Ancient Theia Impact?

    Earth's Present Magnetic Field: Is it A present Evidence of the Ancient Theia Impact?

    the other terrestrial planets have neither a strong magnetic field nor a big moon: is it just a coincidence or. the Theia Impact caused them both?

    449px-Simple_model.png

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    Theia could account for some of why we're fairly unique in our system, like our rich mixed surface elemental composition, and our hot core resulting in plate tectonics. And our Goldilocks water: enough for oceans and life, not too much for exposed land area. We have a Goldilocks atmosphere, too, between Mars and Venus in pressure. Any or all of these factors could have a THeia connection:

    Surface comp, the impact may have churned up core material and heavy elements.
    Hot core, obvious, core mass doubled.
    Water, if we'd been a true water world before impact, we were not after, and this allowed meteors and comets to replenish a little bit without drwning out the potential sources of biogenesis like black smokers and tidal pools.
    Likewise, a Venus-like thick atmosphere.

    If supported, it would make the Rare Earth hypothesis somewhat more plausible, IMO.
    Last edited by Noclevername; 2019-May-19 at 04:06 PM.
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    Quote Originally Posted by Barabino View Post
    the other terrestrial planets have neither a strong magnetic field nor a big moon: is it just a coincidence or. the Theia Impact caused them both?

    449px-Simple_model.png
    Venus is very much Earth's twin in terms of mass, etc, yet doesn't have anywhere near our magnetosphere. Universe Today has a good article, saying that the Theia impact could well be responsible for our having one.
    https://www.universetoday.com/138021...d-hard-enough/

    In case you, or other readers, aren't aware, but the Theia impact hypothesis came about in the first place from considerations about the size of the moon, together with the moon rocks brought back by Apollo.

    Pre-Apollo, the fact that we have such a big moon was a real mystery. It's size and mass made it extremely unlikely to have been a remote traveller captured by Earth's gravity, and alternatively no-one could figure out why a protoplanetary disk should give Earth - and Earth alone - such a massive moon. It was even suggested maybe Earth was spinning so fast that a blob escaped by centrifugal force ! (I remember reading an Asimov? story where somebody made a model earth for earthquake prediction, but spun it up so fast it did the same). So no model worked, but those appeared to be the only alternatives in town.

    When Apollo returned with moon rocks, we found that their "chemical fingerprint" (for lack of a better term) matched Earth's, so that totally ruled out the remote-traveller option. Didn't help with the protoplanetary mechanics, however - and of course the moon rocks were bone dry, with no water, It was faced with these issues that someone first hypothesised the giant impact. I can't remember who it was, but I remember reading a while ago their story of when they got the idea, they went to see some friends who did computer modelling of meteorite impacts. So as the friend asked them the salient details (size of body being impacted, mass of body impacting etc), and they were giving these ridiculously HUGE answers (size of earth, mass of mars, etc), they became the centre of attention of all of the friend's coworkers within earshot !

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    Venus has a metal core, but rotates very slowly, largely due to the effects of Solar tides on its dense atmosphere. Maybe that also has something to do with its lack of magnetic field.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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