Science Channel's "The Planets" and a question about Mercury.


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Message boards : Science (non-SETI) : Science Channel's "The Planets" and a question about Mercury.

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Profile Bob DeWoody
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Message 1263989 - Posted: 24 Jul 2012, 7:20:51 UTC
Last modified: 24 Jul 2012, 7:21:26 UTC

Even though I have seen all of the episodes of this series I usually stop what I am doing to watch one when the Science Channel runs one. One of the things I like about them is Paul Gasek's narration.

Now it is widely accepted that a Mars size object collided with the earth about 4 billion years ago from which the moon was formed, but they never mention the fate of the rest of the material.

Now that Mercury has been observed up close and personal they know that it suffered a major calamity a long time ago too. So, is it even remotely possible that Mercury was the object that struck earth and left behind the rubble that became the moon? Or has anyone even thought to look into the possibility?

OK, somebody shoot down my speculation.
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Message 1264008 - Posted: 24 Jul 2012, 8:38:08 UTC - in response to Message 1263989.

The moon is the material from Earth leaving behind the Pacific Ocean basin. We may have been a water planet prior to that event.

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Message 1264034 - Posted: 24 Jul 2012, 11:03:08 UTC - in response to Message 1263989.
Last modified: 24 Jul 2012, 11:04:18 UTC

... Or has anyone even thought to look into the possibility?

OK, somebody shoot down my speculation.

Yes greatly... :-) (By many researches with more details than me.)

The most likely scenario is that the earth and moon were formed from collecting all the combined material. The moon's density suggests that the moon collected a lot of the earth's outer crust. Whatever collided will have been smashed to then be swept up by the earth and moon.

Above a certain mass, I guess you get the type of collisions where nothing big can escape. Everything smashes and the re-coalesces.


Keep searchin',
Martin
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Message 1264224 - Posted: 25 Jul 2012, 21:54:00 UTC

OK, so the mass of the earth and moon is the same, plus or minus, as the mass of the pre collision earth and whatever hit it. I have read that the object that collided with the earth was approximately the same mass as Mars so the earth picked up a lot of additional mass as the result of the collision.
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Message 1264455 - Posted: 26 Jul 2012, 15:33:22 UTC - in response to Message 1264224.

OK, so the mass of the earth and moon is the same, plus or minus, as the mass of the pre collision earth and whatever hit it. I have read that the object that collided with the earth was approximately the same mass as Mars so the earth picked up a lot of additional mass as the result of the collision.


From what I remember of that show was that earth was hit a glancing blow. If it had hit head on earth would no longer exist. So something must have been left of that Mars size object. How does Mercury size up now to mars?
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Message 1264521 - Posted: 26 Jul 2012, 17:32:57 UTC
Last modified: 26 Jul 2012, 17:34:22 UTC

Mercury is one of four terrestrial planets in the Solar System, and is a rocky body like the Earth. It is the smallest planet in the Solar System, with an equatorial radius of 2,439 km.


Mars has an equatorial radius of 3,396 Km. While Mars is larger and more massive than Mercury, Mercury has a higher density. This results in the two planets having a nearly identical gravitational pull at the surface—that of Mars is stronger by less than 1%.

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Message 1265112 - Posted: 28 Jul 2012, 7:09:38 UTC - in response to Message 1264455.

OK, so the mass of the earth and moon is the same, plus or minus, as the mass of the pre collision earth and whatever hit it. I have read that the object that collided with the earth was approximately the same mass as Mars so the earth picked up a lot of additional mass as the result of the collision.


From what I remember of that show was that earth was hit a glancing blow. If it had hit head on earth would no longer exist. So something must have been left of that Mars size object. How does Mercury size up now to mars?

This kind of the direction my thoughts have lead. Nobody has ever claimed that the entire mass of the striking object was absorbed into the earth-moon system which leads to several possible outcomes if it wasn't. Most likely scenario is that whatever escaped the earth's gravity was slung out of the solar system entirely but it does seem possible that the densest part of the object recoalesced and took it's own orbit inside Venus and is now Mercury thus explaning why Mercury is much denser than Mars or the moon.
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Message 1265330 - Posted: 28 Jul 2012, 21:18:16 UTC - in response to Message 1265112.

... but it does seem possible that the densest part of the object recoalesced and took it's own orbit inside Venus and is now Mercury thus explaning why Mercury is much denser than Mars or the moon.

The higher density of Mercury is fully explained by the distance of its orbit from the sun. Just as is the abundance of water for the earth and the lower densities for the gas giants Jupiter, Saturn and Neptune, all for each for their respective orbits.

I don't know of any suggestions that Mercury might be a captured object. Its orbit is far too 'normal'.


Keep searchin',
Martin

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Message boards : Science (non-SETI) : Science Channel's "The Planets" and a question about Mercury.

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