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Re: North America 77 Million B.C.

By: Zimbler0 in GRITZ | Recommend this post (0)
Mon, 19 May 25 1:36 AM | 7 view(s)
Boardmark this board | Grits Breakfast of Champeens! 		Msg. 08512 of 08526
(This msg. is a reply to 08510 by Fiz)
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Fiz > FWIW, the theory I heard said THAT collision is what gave the earth its spin!


I doubt that one Fiz. Seems most (if not all) of the planets do spin. And, most of them spin in the same direction.

Uranus is off kilter. By over 90 degrees.
Mercury appears to spin once each orbit - keeping the same face to the sun. (Tidal lock, anybody?)

On the other screen I've got a graphic which suggests Venus might be similarly 'tidal locked'.

http://laughingsquid.com/rotation-speed-of-planets-in-solar-system/

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Venus is not fully tidally locked, but it is very close to that state. Its slow rotation and thick atmosphere prevent it from synchronizing its rotation with its orbit around the Sun, which means that one side does not permanently face the Sun like the Moon does with Earth.
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Mercury is not tidally locked in the same way as the Moon is to Earth, but it does have a 3:2 spin-orbit resonance, meaning it rotates three times on its axis for every two orbits around the Sun. This results in a unique rotational pattern rather than synchronous rotation.
>>>

Funny the things one can learn when one starts looking for them.

Interesting stuff . . How the planets spin. Kind of like how the water in a sink spins around on its way down the drain.

Zim.




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The above is a reply to the following message:
Re: North America 77 Million B.C.
By: Fiz in GRITZ
Mon, 19 May 25 1:19 AM 		Msg. 08510 of 08526

I still haven't found a good article dating the ejection of the moon from the earth, after a collision which would have liquified any rock on the surface and sterilized any life.

But I did find this, dated just this January!

http://phys.org/news/2025-01-moon-chunk-ejected-earth-formation.html

"New measurements indicate that the moon formed from material ejected from the Earth's mantle with little contribution from Theia.

In addition, the findings support the idea that water could have reached Earth early in its development and may not have been added by late impacts. The results are published in the Proceedings of the National Academy of Sciences."

Apparently there is a long way yet to go in coming up with a reasonable story. They still apparently aren't sure if the earth had most of its water before, or only formed that after?

FWIW, the theory I heard said THAT collision is what gave the earth its spin! So, if there had been no collision, there likely wouldn't have been the day night cycle which keeps the earth's oceans from super-heating?

The whole thing seems a lot more improbably fortunate than the "mere" continental drift, which supposedly enabled all the mountain formation relatively recently! And without the mantle turning like that, the evolution of life would have gone way differently -- if at all.

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Ok. Well I guess all the theories say it would have been (relatively) shortly after the formation of the solar system itself "around 4.5 BILLION years ago". http://science.nasa.gov/moon/formation/

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