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Posted by David Williams on June 18, 2006, 11:43 pm
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-> Comparing the cummulative mass of satellites to the mass of their
-> central gas giants produces a constant ratio of 0.0001 which is a
That works pretty well for Jupiter, Satuen, and Uranus, but it's
nowhere near right for Neptune. Triton, alone, has a mass about 0.0014
of that of Neptune. Add in the other satellites, and the ratio becomes
even higher.
Of course, Triton is exceptional. It's almost certainly a captured
Kuyper Belt Object. But Earth's moon is exceptional too, having been
formed by an interplanetary collision, unlike the satellites of
Jupiter, Saturn and Uranus, which probably condensed from disks of dust
and gas which surrounded these planets soon after their formations.
Your notion that Earth is a remnant of a gas giant is a fun idea, but
there's no evidence to support it. In fact, there is solid evidence
against it. Rocks exist that date back to the early history of the
Earth, which show no evidence of having been formed in the interior of
a gas giant.
dow
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Posted by Jonathan Silverlight on June 19, 2006, 1:05 pm
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Posted by George on June 20, 2006, 12:16 am
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>>-> Comparing the cummulative mass of satellites to the mass of their
>>-> central gas giants produces a constant ratio of 0.0001 which is a
>>
>>That works pretty well for Jupiter, Satuen, and Uranus, but it's
>>nowhere near right for Neptune. Triton, alone, has a mass about 0.0014
>>of that of Neptune. Add in the other satellites, and the ratio becomes
>>even higher.
>>
>>Of course, Triton is exceptional. It's almost certainly a captured
>>Kuyper Belt Object. But Earth's moon is exceptional too, having been
>>formed by an interplanetary collision,
>
> Isn't Charon thought to have been formed by a similar process? Not so
> exceptional, perhaps.
One example doesn't disprove the hypothesis. Since there are dozens to
hundreds of objects orbiting the gas giants, you definitely need more than
one oddball to dispel the notion that the Earth's moon is exceptional in
its origin.
George
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Posted by John Curtis on June 19, 2006, 3:24 pm
Please log in for more thread options > Rocks exist that date back to the early history of the
> Earth, which show no evidence of having been formed in the interior of
> a gas giant.
>
Formation of diamonds requires pressures in excess of 30 kilobars:
http://www.ucolick.org/news/1999/99-09-29.html
Although such pressures are achievable at mantle depth of 150 km,
the conduits for such diamonds, the kimberlite pipes, are only a
few kilometers deep.
A massive atmospheric pressure, 3 x Neptiune's, would allow
diamonds to be formed in the shallow waters of emerging cratons
as suggested by the elevated solar Neon-20 and elevated solar
helium-3 in diamonds:
http://wwwrcamnl.wr.usgs.gov/isoig/period/ne_iig.html
John Curtis
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Posted by George on June 19, 2006, 3:51 pm
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>> Rocks exist that date back to the early history of the
>> Earth, which show no evidence of having been formed in the interior of
>> a gas giant.
>>
> Formation of diamonds requires pressures in excess of 30 kilobars:
> http://www.ucolick.org/news/1999/99-09-29.html
> Although such pressures are achievable at mantle depth of 150 km,
> the conduits for such diamonds, the kimberlite pipes, are only a
> few kilometers deep.
> A massive atmospheric pressure, 3 x Neptiune's, would allow
> diamonds to be formed in the shallow waters of emerging cratons
> as suggested by the elevated solar Neon-20 and elevated solar
> helium-3 in diamonds:
> http://wwwrcamnl.wr.usgs.gov/isoig/period/ne_iig.html
> John Curtis
The only problem with that scenario as it relates to the Earth is that
inclusion studies indicate that most diamonds have Re-Os isotopic ages that
range in age from ~2.9 Ga to the Proterozoic, a time period for which the
composition of the Earth's atmosphere is well known, and easily shown NOT
to be equivalent to that of any of the gas giant planets. The ~2.9 Ga age
population of diamonds links late Archean subduction-accretion events
involving an oceanic lithosphere component to craton stabilization. These
events resulted in a widely-distributed, late Archean generation of
eclogitic diamonds in an amalgamated craton. Subsequent Proterozoic
tectonic and magmatic events altered the composition of the continental
lithosphere and added new lherzolitic and eclogitic diamonds to the already
extensive Archean diamond suite. That diamonds form in mantle-derived host
rocks is not disputed.
http://sajg.geoscienceworld.org/cgi/content/abstract/107/1-2/91
George
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