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Moon was produced by head-on collision?



 
 
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  #1  
Old January 31st 16, 01:55 AM posted to sci.astro,sci.physics
Yousuf Khan[_2_]
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Posts: 1,692
Default Moon was produced by head-on collision?

Moon was produced by head-on collision | Astronomy.com
http://www.astronomy.com/news/2016/0...d-on-collision

The Theia Theory used to talk about a glancing blow between the early
Earth and a Mars-sized Theia, perhaps at 45 degrees. New data suggests
that Theia might have actually hit head-on with the Earth. That's
because the percentage of Oxygen 16/17/18 isotopes between the Earth and
Moon are nearly identical, indicating that they came from the same source.

My question is, if the isotopic evidence which was used to create the
Theia Hypothesis in the first place, due to a previously perceived
difference in isotopic abundances, so now that that isotopic evidence
has disappeared, why keep the Theia Hypothesis? There were other
theories prior to that, which were discarded due to the isotopic evidence.

Yousuf Khan
  #2  
Old January 31st 16, 05:17 AM posted to sci.astro,sci.physics
Sam Wormley[_2_]
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Posts: 3,966
Default Moon was produced by head-on collision?

On 1/30/16 6:55 PM, Yousuf Khan wrote:
Moon was produced by head-on collision | Astronomy.com
http://www.astronomy.com/news/2016/0...d-on-collision


The Theia Theory used to talk about a glancing blow between the early
Earth and a Mars-sized Theia, perhaps at 45 degrees. New data suggests
that Theia might have actually hit head-on with the Earth. That's
because the percentage of Oxygen 16/17/18 isotopes between the Earth and
Moon are nearly identical, indicating that they came from the same source.

My question is, if the isotopic evidence which was used to create the
Theia Hypothesis in the first place, due to a previously perceived
difference in isotopic abundances, so now that that isotopic evidence
has disappeared, why keep the Theia Hypothesis? There were other
theories prior to that, which were discarded due to the isotopic evidence.

Yousuf Khan



Thanks for Posting this.


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to the discussion of physics, news from the physics
community, and physics-related social issues.

  #3  
Old January 31st 16, 04:25 PM posted to sci.astro
dlzc
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Posts: 1,426
Default Moon was produced by head-on collision?

Dear Yousuf Khan:

On Saturday, January 30, 2016 at 5:55:31 PM UTC-7, Yousuf Khan wrote:
....
My question is, if the isotopic evidence which
was used to create the Theia Hypothesis in the
first place, due to a previously perceived
difference in isotopic abundances, so now that
that isotopic evidence has disappeared, why keep
the Theia Hypothesis? There were other theories
prior to that, which were discarded due to the
isotopic evidence.


How many of them involved collision-and-mergence of two bodies? The only variant I am aware of that is significantly different, is gravitational capture, and that took a third body.

Still have an initial Theia...

David A. Smith
  #4  
Old January 31st 16, 06:44 PM posted to sci.astro,sci.physics
The Starmaker
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Posts: 67
Default Moon was produced by head-on collision?

Yousuf Khan wrote:

Moon was produced by head-on collision | Astronomy.com
http://www.astronomy.com/news/2016/0...d-on-collision

The Theia Theory used to talk about a glancing blow between the early
Earth and a Mars-sized Theia, perhaps at 45 degrees. New data suggests
that Theia might have actually hit head-on with the Earth. That's
because the percentage of Oxygen 16/17/18 isotopes between the Earth and
Moon are nearly identical, indicating that they came from the same source.

My question is, if the isotopic evidence which was used to create the
Theia Hypothesis in the first place, due to a previously perceived
difference in isotopic abundances, so now that that isotopic evidence
has disappeared, why keep the Theia Hypothesis? There were other
theories prior to that, which were discarded due to the isotopic evidence.

Yousuf Khan



The truth is...the origin of our solar system is...unknown.



So, how everthing got put together is unknown...including the moon.

--- news://freenews.netfront.net/ - complaints: ---
  #5  
Old February 1st 16, 02:02 AM posted to sci.astro
dlzc
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Posts: 1,426
Default Moon was produced by head-on collision?

Dear Starmaker:

On Sunday, January 31, 2016 at 10:44:33 AM UTC-7, The Starmaker wrote:
....
The truth is...the origin of our solar system
is...unknown.

So, how everthing got put together is unknown...
including the moon.


Does "unknown" mean "unknowable"? Is all quest for knowledge ultimately doomed to failure? Or are you a post-only nay-sayer?

We have brains, and we have data. Do you mind if we use one, and try and understand Nature, while you fiddle away, Nero?

David A. Smith
  #6  
Old February 1st 16, 08:10 AM posted to sci.astro,sci.physics
The Starmaker
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Posts: 67
Default Moon was produced by head-on collision?

The Starmaker wrote:

Yousuf Khan wrote:

Moon was produced by head-on collision | Astronomy.com
http://www.astronomy.com/news/2016/0...d-on-collision

The Theia Theory used to talk about a glancing blow between the early
Earth and a Mars-sized Theia, perhaps at 45 degrees. New data suggests
that Theia might have actually hit head-on with the Earth. That's
because the percentage of Oxygen 16/17/18 isotopes between the Earth and
Moon are nearly identical, indicating that they came from the same source.

My question is, if the isotopic evidence which was used to create the
Theia Hypothesis in the first place, due to a previously perceived
difference in isotopic abundances, so now that that isotopic evidence
has disappeared, why keep the Theia Hypothesis? There were other
theories prior to that, which were discarded due to the isotopic evidence.

Yousuf Khan


The truth is...the origin of our solar system is...unknown.

So, how everthing got put together is unknown...including the moon.



For those seeking to know the origin of our solar system...all one has
to do is start and end he

'In the beginning God created the heavens and the earth.'


The above sentence contains all the information one needs to understand
the origin of our
solar system and the universe.


Within this sentence contains the entire knowledge of the origin of the
universe.
'In the beginning God created the heavens and the earth.'

You just need to know how to decode it.


For example, ..."created the heavens and the earth", .. "heavens"
doesn't necessarly mean stars. It could mean
how stars looked before they became stars...without the light.

In other words, the earth and the stars were created at the same time,
they just both weren't formed completely then.
  #7  
Old February 1st 16, 09:13 AM posted to sci.astro,sci.physics
Yousuf Khan[_2_]
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Posts: 1,692
Default Moon was produced by head-on collision?

On 01/02/2016 2:10 AM, The Starmaker wrote:
The Starmaker wrote:
The truth is...the origin of our solar system is...unknown.

So, how everthing got put together is unknown...including the moon.



For those seeking to know the origin of our solar system...all one has
to do is start and end he

'In the beginning God created the heavens and the earth.'


The above sentence contains all the information one needs to understand
the origin of our
solar system and the universe.



Yeah, that's the hypothesis we usually start off with initially, and
then we invent new instruments and obtain new observations which lead to
better hypotheses, and then eventually to some proper theories.

Yousuf Khan
  #8  
Old February 1st 16, 07:36 PM posted to sci.astro,sci.physics
The Starmaker
external usenet poster
 
Posts: 67
Default Moon was produced by head-on collision?

Yousuf Khan wrote:

On 01/02/2016 2:10 AM, The Starmaker wrote:
The Starmaker wrote:
The truth is...the origin of our solar system is...unknown.

So, how everthing got put together is unknown...including the moon.



For those seeking to know the origin of our solar system...all one has
to do is start and end he

'In the beginning God created the heavens and the earth.'


The above sentence contains all the information one needs to understand
the origin of our
solar system and the universe.


Yeah, that's the hypothesis we usually start off with initially, and
then we invent new instruments and obtain new observations which lead to
better hypotheses, and then eventually to some proper theories.

Yousuf Khan



Well, it reads "the heavens and the earth", not 'the heavens and then the earth'.


So, somewhere along the line...your new instruments, your better hypotheses, and proper theories
is off by 5 billion years.

--- news://freenews.netfront.net/ - complaints: ---
  #9  
Old February 1st 16, 11:27 PM posted to sci.astro,sci.physics
Steve Willner
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Posts: 1,172
Default Moon was produced by head-on collision?

In article ,
Yousuf Khan writes:
Moon was produced by head-on collision | Astronomy.com
http://www.astronomy.com/news/2016/0...d-on-collision


The UCLA press release is at
http://newsroom.ucla.edu/releases/mo...forming-planet
and the article in _Science_ is at
http://science.sciencemag.org/content/351/6272/493.full

I couldn't find a preprint, but there might be one somewhere.

The Theia Theory used to talk about a glancing blow between the early
Earth and a Mars-sized Theia, perhaps at 45 degrees. New data suggests
that Theia might have actually hit head-on with the Earth. That's
because the percentage of Oxygen 16/17/18 isotopes between the Earth and
Moon are nearly identical,


Specifically, the new data show the isotope ratios (actually a ratio
of differences) is the same within 2 ppm. A paper last year
http://science.sciencemag.org/content/344/6188/1146

found apparent differences at the 18 ppm level. The new paper
suggests that was sample selection, i.e., the rocks analyzed earlier
were not characteristic of the whole Moon.

indicating that they came from the same source.


If the isotope ratios are identical, _either_ Earth and Theia had
identical ratios to begin with (possible but not very likely) _or_
the present Earth and Moon have identical fractions of Theia
material. That last would require a head-on collision with everything
getting mixed; a glancing collision would put a larger fraction of
Theia material into the Moon.

I'm very much an outsider here, but this looks to me like a highly
technical insider dispute that most of us shouldn't worry about.

My question is, if the isotopic evidence which was used to create the
Theia Hypothesis in the first place, due to a previously perceived
difference in isotopic abundances,


The isotope ratios are _at least_ very similar, now seemingly
identical within measurement accuracy. This tends to support the
Theia hypothesis. If the Moon formed on its own and was somehow
captured by the Earth, it would be expected to have very different
isotope ratios.

so now that that isotopic evidence has disappeared, why keep the
Theia Hypothesis? There were other theories prior to that, which
were discarded due to the isotopic evidence.


That evidence being the _similarity_ of ratios, which is now stronger
than before. The argument now seems to be about the details of the
collision, but as I say, I'm an outsider.

For a different hypothesis to be viable, it will have to be
consistent with not only the isotope ratios but also the element
ratios and other evidence. As with all scientific hypotheses, it
will have to be testable (falsifiable) to receive scientific
consideration.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
  #10  
Old February 2nd 16, 01:44 AM posted to sci.astro,sci.physics
Yousuf Khan[_2_]
external usenet poster
 
Posts: 1,692
Default Moon was produced by head-on collision?

On 01/02/2016 5:27 PM, Steve Willner wrote:
In article ,
Yousuf Khan writes:
My question is, if the isotopic evidence which was used to create the
Theia Hypothesis in the first place, due to a previously perceived
difference in isotopic abundances,


The isotope ratios are _at least_ very similar, now seemingly
identical within measurement accuracy. This tends to support the
Theia hypothesis. If the Moon formed on its own and was somehow
captured by the Earth, it would be expected to have very different
isotope ratios.


The Moon capture hypothesis was only one such hypothesis. That one would
still be excluded by this recent finding.

Other ones that would still be viable are the Fission hypothesis, where
the Moon was once a part of the Earth, but due to an imbalance it
pinched itself off of the Earth. This would certainly maintain identical
isotope levels between the Earth and Moon.

Another one is the Condensation Hypothesis, which suggested that the
Earth and Moon formed from the same section of the original solar system
nebula. So basically the two worlds evolved together as a twin planet
system. This would also pretty much maintain identical isotope levels.

This site even says that if the isotope levels are different, then the
above theories would be unlikely, but now that the isotope levels are
similar, those theories come back into play.

Theories of Formation for the Moon
http://csep10.phys.utk.edu/astr161/l...formation.html

Yousuf Khan
 




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