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Old 03-26-2012, 09:52 PM
 
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FYI.......

"A new analysis of isotopes found in lunar minerals challenges the prevailing view of how Earth's nearest neighbor formed. Geochemists looked at titanium isotopes in 24 separate samples of lunar rock and soil, and found that the moon's proportion was effectively the same as Earth's and different from elsewhere in the solar system.

Findings Cast Doubt on Moon Origins - ScienceNOW
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Old 04-02-2012, 07:19 AM
 
Location: PRC
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so what are we saying here... that the Moon broke off from Earth because the titaium isotopes are the same?
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Old 04-03-2012, 05:17 AM
 
Location: North Beach, MD on the Chesapeake
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Years ago I saw someone's theory that the Moon was a chunk of the Earth knocked off by a meteor strike. I can't find it now.
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Old 04-03-2012, 05:30 AM
 
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Quote:
Originally Posted by North Beach Person View Post
Years ago I saw someone's theory that the Moon was a chunk of the Earth knocked off by a meteor strike. I can't find it now.
That's pretty much accepted as canon in the scientific community.
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Old 04-09-2012, 02:14 AM
 
Location: PRC
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I understood that planets and bodies were round because when they were loose particles of matter, and before they had formed properly, all the pieces clumped together around a central point, so making it round.

Now, if the Moon was a piece of the earth, wouldn't the Earth and Moon be kind-of NOT roundish?

Actually, what do scientists know about the Moon? They have no idea about the inside, they have no idea about how all the different kinds of rilles form (apart from the theory of being lava tubes(?) ).
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Old 04-09-2012, 08:39 AM
 
Location: Brooklyn, New York
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Quote:
Originally Posted by ocpaul20 View Post
Now, if the Moon was a piece of the earth, wouldn't the Earth and Moon be kind-of NOT roundish?
That's because the moon and the Earth have sufficiently strong gravitational pull to make them round. The mass of the planet always wants to get closer to its center of gravity, and the closest way to do that is to form a sphere. If you have a cube floating in space, if its big enough, overtime it will form a sphere by itself.
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Old 04-09-2012, 09:10 AM
 
Location: Somewhere in northern Alabama
18,530 posts, read 55,444,914 times
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Quote:
Originally Posted by Gantz View Post
That's because the moon and the Earth have sufficiently strong gravitational pull to make them round. The mass of the planet always wants to get closer to its center of gravity, and the closest way to do that is to form a sphere. If you have a cube floating in space, if its big enough, overtime it will form a sphere by itself.
Resistance is futile? Picard only needed to wait.
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Old 04-09-2012, 09:37 AM
 
Location: Texas
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Quote:
Originally Posted by Gantz View Post
That's because the moon and the Earth have sufficiently strong gravitational pull to make them round. The mass of the planet always wants to get closer to its center of gravity, and the closest way to do that is to form a sphere. If you have a cube floating in space, if its big enough, overtime it will form a sphere by itself.
Yep. It helps that the core is mostly molten.
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Old 04-10-2012, 01:00 AM
 
Location: Pluto's Home Town
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Seems like if both were molten at the time of impact, and the impactor was not so different in composition, we would see some magma sloshing and some magma staying. Perhaps it is like a cue ball and the momentum lodged a bit right out the other side of the earth. Regardless, it was pretty toasty.

Anyone checked this out? Give you an idea of the kinetic energy and consequences of meteor strikes.

Earth Impact Effects Program

Shoot a 1000 km diameter meteor into the earth at about 17 km/sec. or a big snowball if you like.

Rather grim entertainment.

Last edited by Fiddlehead; 04-10-2012 at 01:12 AM..
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Old 04-10-2012, 02:48 PM
 
Location: Wasilla, Alaska
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Quote:
Originally Posted by plwhit View Post
FYI.......

"A new analysis of isotopes found in lunar minerals challenges the prevailing view of how Earth's nearest neighbor formed. Geochemists looked at titanium isotopes in 24 separate samples of lunar rock and soil, and found that the moon's proportion was effectively the same as Earth's and different from elsewhere in the solar system.

Findings Cast Doubt on Moon Origins - ScienceNOW
George Darwin (son of Charles Darwin) first proposed the giant impact hypothesis in 1898. Where an object roughly the size of Mars, called Theia, impacted with earth and formed our moon.

The impact would have combined the molten cores of both Earth and Theia, while flinging lighter material into space to form an accretion disk and eventually our moon. They estimate this impact occurred approximate 4.53 billion years ago.

Giant impact hypothesis - Wikipedia, the free encyclopedia
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