Did moon come from earth?

MeteorWayne · Oct 16, 2007

Yes it is, your 4.4BY date is probably more accurate than my recollection. However, if I remember correctly the timeline on the "whack" was ~ 50,000 years after accretion, and it did consider the dirfferentiation to be done. I admit, off the top of my head, I do not know the timescales of the differentiation. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

adrenalynn · Oct 16, 2007

"The differentiation that occurred to bring about the modern day Earth took billions of years and involved several complex processes. " [Source: ]http://www.umich.edu/~gs265/spheres.htm] [...] "This original continental crust did not become stable until nearly 1 billion years after the separation of the mantle from the core. During its period of instability, Earth was much hotter and saw several times more radioactive decay than today. As a result, some crust would form, melt, and re-form again. As the Earth cooled down, however, this process ceased, and the current crust has been stable for roughly 3.5 billion years. " [Ibid] [...] "the Outgassing Hypothesis argues that the free oxygen came from the photosynthesis of primitive organisms which existed 1.5 - 3.5 billion years ago. The oxygen took approximately 2 billion years to become free, but when it did, it formed the ozone layer, eliminating the dangerous radiation and setting up the foundation for a habitable planet." [Ibid] I'm having a really hard time squeezing this impactor into the geologic record. The more I dig, the harder it gets. I'm just quoting one source here, although bad form, since the other sources I find are primarily (nearly universally) in agreement across the board, and this post could get _really_ long otherwise. Mea Culpa. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

willpittenger · Oct 16, 2007

<blockquote>In reply to:<hr />another intersting point, but certainly not definitive, is the difference between Venus, nearly our size, and Earth. Venus has little tectonic activity, it's basically one or two giant plates, with a thick crust. Earth has a much thinner crust, and a lot more activity.<hr /></blockquote> In fact, Venus's magnetosphere has vanished. The solar wind is now eroding the Venetian atmosphere. So Venus could end up with an atmosphere looking more like that of Mars. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

PistolPete · Oct 16, 2007

It is possible that the whole crust may not have melted with the impact. The impact may have only melted the crust on the side that it impacted with leaving the crust on the opposite side of the Earth to continue cooling and form the first rocks a few hundred million years later. <div class="Discussion_UserSignature"> So, again we are defeated. This victory belongs to the farmers, not us.-Kambei Shimada from the movie Seven Samurai </div>

PistolPete · Oct 16, 2007

A few months ago I either read or saw on TV a hypotheses that liquid water is required as a lubricant in plate tectonics. If there is no liquid water on the surface, there is no plate tectonics. If this is correct, then it might explain why neither Venus or Mars have tectonic plates and may lead to an explanation as to why neither of them have a magnetosphere either. <div class="Discussion_UserSignature"> So, again we are defeated. This victory belongs to the farmers, not us.-Kambei Shimada from the movie Seven Samurai </div>

adrenalynn · Oct 16, 2007

Aha, if only part of the crust liquefied, then a HUGE chunk of the crust of the earth must be thinner than the other half. Voila! Geologic record. You can't take the same mass and spread it over nearly twice the area and not have it thin out. The problem with that is that we don't see it. See the problems I'm having rectifying this? <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

willpittenger · Oct 16, 2007

Actually, Mars has one more culprit for the loss of plate tectonics and magnetosphere: less mass than Earth would lead to more rapid cooling. Also, Mars did have plenty of water at one time -- and is believed to still have quite a bit. Hi-Res got before and after photos of a ravine that changed color. It looked like an outbreak of water happened. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

Saiph · Oct 16, 2007

Actually, if the oldest rock is 4.2 byrs, then any changes to rock in the first, 300 million years will go completely un-noticed, as it's had over 4.2 billion years to be subsumed. I.e. it doesn't give us 300 million years for this all to disappear, it provides 4.2 billion in which we'd notice. Throw in the quoted material stating that the early crust had a much higher turn over rate than our current one, and you're not going to see much left over. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

Boris_Badenov · Oct 16, 2007

I'm stil looking for the article How about this one? The impactors name was Theia, the Titan that gave birth to the moon goddess Selene. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div> </div>

adrenalynn · Oct 17, 2007

Hmmm. I had some problem with groking your post, Saiph, and I'll definitely come back to it. Tonight on The Universe (THC), they covered this very topic. The answer that a couple of "experts" provided to my question is that : A) The moon and the earth both reformed within ONE YEAR. [boggle] B) The earth only had about 90% of its final material content at the time. The additional 10% depositing from further smaller impactors buried any geologic record of this event. Frankly, this feels like it leads to more questions than answers. If additional impactors' materials buried the record AFTER the moon was kicked-off, then the earth's chemical makeup would be different than the moon's - since they're different entities. That's just a first blush thinking about the additional material presented tonight. I don't know if I'm ready to let this one go yet. HOWEVER: To the OP - I feel like I'm doing Original Research in your thread. That's pretty off-topic to your question, really. The accepted theory is as stated before. If all you're looking for the accepted theory, please ignore me - with my sincere apologies. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

alokmohan · Oct 17, 2007

Only moon and cherry2 know where moon came from.But we should have research on it.

MeteorWayne · Oct 17, 2007

Unfortunately this article provides no links to the paper in Science or Nature that I'm thinking of, and it should. I'm still searching the archives.... <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

ashish27 · Oct 17, 2007

what if the moon was formed just like the planets were formed? thereafter it just got caught in the Earth's gravity...

adrenalynn · Oct 17, 2007

The even more conclusive argument against capture is that the earth just simply doesn't have the mass to capture something the size of our moon. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

kyle_baron · Oct 17, 2007

The most likely current theory is that early in the earth's history, it was whacked by a Mars sized object when there were such leftovers floating around the solar system. I have an interesting hypothesis. I think that the Mars sized object is Mercury. It would have had to come from the outer solar system, heading towards the sun. It's got an iron core: http://en.wikipedia.org/wiki/Mercury_%28planet%29 Physically, Mercury is similar in appearance to the Moon as it is heavily cratered. It has no natural satellites and no substantial atmosphere. The planet has a large iron core which generates a magnetic field... The density of the planet is the second highest in the solar system at 5.43 g/cmÂ³, only slightly less than Earthâ€™s density. Mercuryâ€™s density can be used to infer details of its inner structure. While the Earthâ€™s high density results appreciably from gravitational compression, particularly at the core, Mercury is much smaller and its inner regions are not nearly as strongly compressed. Therefore, for it to have such a high density, its core must be large and rich in iron. Mercury has a higher iron content than any other major planet in our solar system, and several theories have been proposed to explain this. The most widely accepted theory is that Mercury originally had a metal-silicate ratio similar to common chondrite meteors (thought to be typical of average solar system rocky matter) and a mass approximately 2.25 times its current mass. However, early in the solar systemâ€™s history, Mercury was struck by a planetesimal of approximately 1/6 that mass. The impact would have stripped away much of the original crust and mantle, leaving the core behind as a relatively major component.[8] A similar process has been proposed to explain the formation of Earthâ€™s Moon (see giant im <div class="Discussion_UserSignature"> </div>

PistolPete · Oct 17, 2007

I highly doubt this. The incoming planet was most likely completely annihilated in the impact. <div class="Discussion_UserSignature"> So, again we are defeated. This victory belongs to the farmers, not us.-Kambei Shimada from the movie Seven Samurai </div>

billslugg · Oct 17, 2007

kyle One of the rules of orbital mechanics, in a two body system, is that when you throw something, it always returns to the exact spot it started from, unless acted upon by a second force. For a body to be captured by another body, in a two body system, there must be a force applied to the captured object in order to slow it down. Capture can occur in three body systems with no external force being applied. If Mercury started at the Earth and swung around the sun, it would return to the spot the Earth was when Mercury was released. In order to allow a circular orbit at its present distance from the Sun, some energy would have to be removed. In other words, you can't just stand on the Earth and throw something at the Sun and have it go into orbit around the Sun at a lesser distance than the Earth. Maybe Mercury smashed into the Earth, creating the Moon, proceeded toward the Sun and ran into another object, lost some orbital energy, and fell into circular orbit around the Sun. I do not think that is what happened, but orbital mechanics does not prohibit it. ed: Tried to make more clear <div class="Discussion_UserSignature"> </div>

willpittenger · Oct 17, 2007

Don't forget the extremely low eccentricity of the Lunar orbit, just 0.0549. Compare that to a moon that probably was captured, Nereid at 0.7512. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

usn_skwerl · Oct 18, 2007

<blockquote>In reply to:<hr />One of the rules of orbital mechanics, in a two body system, is that when you throw something, it always returns to the exact spot it started from, unless acted upon by a second force. For a body to be captured by another body, in a two body system, there must be a force applied to the captured object in order to slow it down. Capture can occur in three body systems with no external force being applied. If Mercury started at the Earth and swung around the sun, it would return to the spot the Earth was when Mercury was released. In order to allow a circular orbit at its present distance from the Sun, some energy would have to be removed. In other words, you can't just stand on the Earth and throw something at the Sun and have it go into orbit around the Sun at a lesser distance than the Earth<hr /></blockquote> What about gravitational resonance? It's already been pointed out that the moon is and was affected by Venus' and Jupiter's gravity. Maybe Mercury was affected similarly, considering something could have been altered with the gravity of Earth, Venus, a little bit of love from Jupiter, and a lot of love from Sol... four gy is a long time for a little bit of change. Kyle, that is an interesting hypothesis. I've never even thought about it. Anyone know if any of the orbit/gravity re-creators (simulators) on the various websites could be used to test the theory? <div class="Discussion_UserSignature"> </div>

adrenalynn · Oct 18, 2007

>> but rather a near miss where tidal debries was lifted from Earth and the near impactor. I've been working on some simulations the past several days - almost obsessively. They're way too primitive to mean all that much at the moment. [That's a disclaimer for what follows] I only have a couple hundred gigahertz to play with here, I definitely need more. [That's another disclaimer] That said - I love your idea, but I question whether or not it could be done in one pass (I can't make that work unless "Theia" was a LOT more massive than stated) and even assuming that it was more massive, this object would perturb the heck out of other inner planetary orbits and the amount of spin that would be imparted to earth can't be accounted for. Relativity and Classical Mechanics don't really "like that". I can make the impactor sort of work, but I get an extra planet(tesimal) out of this that's actually larger than the moon. I also get an earth that's 3/4 the size it should be. That's a lot of deposit on the protoplanet earth in a short period - an additional 25+%??? Surprisingly to me, it really does take almost no time to accrete the moon from the debris field. If it the Splash happens on Jan. 1, the moon starts looking like the moon in mid April, and has fully accreted what isn't going to be permanently stuck out there to be captured by the sun within a year. This is a super interesting topic to me... <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

alokmohan · Oct 18, 2007

What I call this theory?Accretion theory?

adrenalynn · Oct 18, 2007

"The Big Splash", "The Big Splat", or more accurately - "Giant Impact Hypothesis" <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

billslugg · Oct 18, 2007

usn-skwerl What about gravitational resonance? Yes, gravitational resonance could work to circularize an orbit or change its radius. This requires a third body. My comments refer to two body systems only. BTW the three body system is similar to the three link system in classical mechanics. It is not directly determinable by equation, but must be solved iteratively. <div class="Discussion_UserSignature"> </div>

R1 · Oct 18, 2007

here's some links to simulations of the moon origin: <img src="/images/icons/smile.gif" /> http://www.youtube.com/watch?v=Yveo1hRXFME http://www.youtube.com/watch?v=ibV4MdN5wo0 <div class="Discussion_UserSignature"> </div>

adrenalynn · Oct 18, 2007

Thanks John, I first saw that simulation on The History Channel's show "The Universe". It's great, but it's one day. My goals in simulation have been to approximate more and assume less. I don't know how much processing power Dr. Canup and her team had comparatively - I read articles suggesting that they weren't even parallelized. I'm spending my farm time tracking fewer particles but much much longer in time. I certainly won't be as accurate for their 24hr modeled period, but I'm not trying to put a man on the moon. Sometimes rounding can be your friend. <img src="/images/icons/wink.gif" /> Anyway, in a week or two or three - maybe I'll have my own video worth posting. I do have to say - although I still have problems, I'm liking Theia a *lot* more now. <div class="Discussion_UserSignature"> .bipartisan (bī-pär'tĭ-zən, -sən) [Adj.] Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.IMPEACH OBAMA! </div>

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