Question Earth Moon Origin

How did our moon form?
Smooth on near side
Rough mountains on the dark side.
Harry Costas, interesting question. The present-day science model answer is the giant impact with Theia and a proto-earth. After the giant impact between Theia and the proto-earth, the Moon continues to evolve from the debris disc postulated to form close to the proto-earth and the smaller, proto-earth continues to accrete and grow into its present-day size and mass.

Showing specifics for this scenario is difficult like what was the original length of day for the proto-earth, how much mass did it have, how close was the proto-Moon or Moon to the proto-earth after the giant impact, etc.
 
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The reason the Moon is so rough on the far side is because the far side is exposed to incoming impactors. Anything aimed at ther near side of the Moon has to get past the Earth first.
Good observation. Harry Costas did ask, 'How did our moon form?'

It will be interesting to see what is presented, if something very different than the giant impact model. Otherwise, the giant impact model got started back in 1975 after Apollo lunar missions, growing and evolving after that :)
 
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The Moon has some unusual features that has led to the idea that the Moon was originally formed, after the impact event, from two blobs. The book, "The Earth had Two Moons", is an interesting read.
Helio, I have many reports in my home database using MS ACCESS that show various reports on the giant impact scenario for the origin of the Moon - too many now :)

How the moon formed: New research sheds light on what happened, https://phys.org/news/2020-03-moon.html, "How the Earth got its moon is a long debated question. The giant impact theory – which states that the moon formed from the a collision between the early Earth and a rocky body called Theia—has become the front runner among the explanations. But the details around how this happened are blurry and there are many observations that scientists are still struggling to explain. Now a new study, published in Nature Geoscience, has shed light on what actually happened by solving one of the biggest mysteries surrounding the crash—why the moon ended up being nearly identical to Earth, rather than Theia, assuming she existed..."

It seems we need a good central repository now for all the lunar origin models presented in science, especially now for the giant impact scenarios :) We did have the capture, accretion from a nebula or disc around earth and George Darwin the fission view blowing out of a rapidly spinning earth and the Moon gets blasted out to form.
 
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FYI, it is interesting to review reports on the "How did our moon form?"

I have a 1963 book, The How and Why Wonder Book of the Moon. Pages 4-6 discuss the origin of the Moon, capture, accretion, and fission spitting out of a rapidly spinning early earth, including perhaps the Pacific Ocean area for ejection. On page 14 the book says, "These changes due to tidal friction have been going on for billions of years, just as they are still going on. The earth-day, which was originally less than five hours, has lengthened to 24 hours. And the moon-month, which was originally the same length as the earth-day, has increased to about four weeks."
 
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Although George Darwin was wrong with his spin-off hypothesis, what made him famous was correctly applying tidal friction to the orbital migration of the Moon due to tides.

I doubt there is anything that could tell us what the rotation rate of the Earth was prior to impact since all evidence, I assume, would have been destroyed by that cataclysmic event. Thus, we have to do retrodictive science where time is run backwards in the various models. BBT, of course, is another big example of running backwards in time to see what we might discover.

Only the models, however, that demonstrate a Moon forming are the ones that make any sense, so this seems to limit the sizes and impact angles Theia would have had.

I think there is a recent thread, and paper, that addresses how little the Moon has migrated in the past 2 billion years, which surprised me. But I didn't dive into it, yet it might be worth reviewing.
 
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Although George Darwin was wrong with his spin-off hypothesis, what made him famous was correctly applying tidal friction to the orbital migration of the Moon due to tides.

I doubt there is anything that could tell us what the rotation rate of the Earth was prior to impact since all evidence, I assume, would have been destroyed by that cataclysmic event. Thus, we have to do retrodictive science where time is run backwards in the various models. BBT, of course, is another big example of running backwards in time to see what we might discover.

Only the models, however, that demonstrate a Moon forming are the ones that make any sense, so this seems to limit the sizes and impact angles Theia would have had.

I think there is a recent thread, and paper, that addresses how little the Moon has migrated in the past 2 billion years, which surprised me. But I didn't dive into it, yet it might be worth reviewing.
Helio, the recent thread is here, Why is Earth's day 24 hours long (and how did the sun keep it from being longer)?, https://forums.space.com/threads/wh...-keep-it-from-being-longer.62225/#post-584950

Concerning Earth's original LOD, the problem is finding the rocks and strata to document that :)
 
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Concerning Earth's original LOD, the problem is finding the rocks and strata to document that :)
Yep. Theia messed things up in that regard. :)

Perhaps the Moon, however, holds some of that evidence in tact. Maybe even a few NEO's from long ago have some of that evidence that gently fell to their surface without damage.
 
If everybody walks the same path, they will trip over the same path.
No theory has solid foundations.

Thinking outside the circle, or off the beaten track.

Imagine a few billion years ago.
The possibility, that our Sun gained enough matter travelling through a Nebulae.
Had enough Dipolar Electromagnetic Vector fields expelling matter in the form of an hourglass, the Iron and heavy metals formed planets and moons and millions of rocks.
Water expelled to the outer solar regions.
In Chaos for millions if not billions of years.

If the Earth and the Moon were formed at the same time from such origin.
This can explain their unison motion.
We can explain the properties of the Moon near face and the dark side by gravitational impact by Earth and the Sun.
If they were both molten at the time.
The properties can be explained by physics.

Yes, the moon and Earth have had many impacts, some deep.

The mountains on the dark side are amazing.
The Russian were the first to observe the Dark side back in 1959.
 
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If everybody walks the same path, they will trip over the same path.
No theory has solid foundations.

Thinking outside the circle, or off the beaten track.

Imagine a few billion years ago.
The possibility, that our Sun gained enough matter travelling through a Nebulae.
Had enough Dipolar Electromagnetic Vector fields expelling matter in the form of an hourglass, the Iron and heavy metals formed planets and moons and millions of rocks.
Water expelled to the outer solar regions.
In Chaos for millions if not billions of years.

If the Earth and the Moon were formed at the same time from such origin.
This can explain their unison motion.
We can explain the properties of the Moon near face and the dark side by gravitational impact by Earth and the Sun.
If they were both molten at the time.
The properties can be explained by physics.

Yes, the moon and Earth have had many impacts, some deep.

The mountains on the dark side are amazing.
The Russian were the first to observe the Dark side back in 1959.
Harry Costas, what makes your post here different than what I presented about the origin of the Moon in my post #8? "I have a 1963 book, The How and Why Wonder Book of the Moon. Pages 4-6 discuss the origin of the Moon,"

The accretion model for the origin of Earth and Moon has been around for many decades now including early ideas about the Sun passing through a Nebulae. Some ideas included all the planets forming like this too where nebula matter was strung out and condensed into the solar system planets we see today. At present, astronomy has apparently abandoned all those previous origin models in favor of the giant impact with Theia now to explain the origin of the Moon. I do see that this model has holes in it too. Geology cannot show the early Earth had a 5 hour or shorter day originally, and that the early Moon moved around the Earth with a lunar month less than 10 hours. Strata must be preserved tracing out certain lamination patterns and then mapped to lunar tides and the rotation period of the Earth. Very tough job here IMO.
 
FYI, past reports on the changing length of day for the Earth based upon the Moon show much variation too on answers.

Ancient shell shows days were half-hour shorter 70 million years ago, https://www.sciencedaily.com/releases/2020/03/200309135410.htm

"Summary: Earth turned faster at the end of the time of the dinosaurs than it does today, rotating 372 times a year, compared to the current 365, according to a new study of fossil mollusk shells from the late Cretaceous. The new measurement informs models of how the Moon formed and how close to Earth it has been over the 4.5-billion-year history of the Earth-Moon gravitational dance." "Earth turned faster at the end of the time of the dinosaurs than it does today, rotating 372 times a year, compared to the current 365, according to a new study of fossil mollusk shells from the late Cretaceous. This means a day lasted only 23 and a half hours, according to the new study in AGU's journal Paleoceanography and Paleoclimatology..."
 
I'm just curious. Has there been any estimates of the earth's and the moon's increase in size and volume during these bombardment events? Can we assume that when this finished, both surfaces would look very similar?

Could they have grown up together?
 
The problem with the Condensation Model is that the Moon would be expected to have more volatiles* than it has today. At one point it must have been completely molten and exposed to the vacuum of space. Slow accretion models don't have the energy to do that. (Paniello 2012)

*In this context a volatile is one of the lighter isotopes of an element, more easily lost during evaporation of the melt in a large scale heating event in a vacuum. Zinc is used as it is common and moderately volatile as elements go, thus will give the best indicator of isotopic ratio.
 
Presumably, and may be part of the current theory, both Earth and Moon were pretty much molten right after the collision and Moon formation. There were likely convection currents, then any water would vaporize into whatever the atmosphere was. The Earth would have had enough gravity to retain most of the water vapor but the Moon did not. But, much, or at least some of the water that the Moon had is still there frozen below the surface.
 
Yes, the Earth had plenty of water. The Moon could have condensed from the same nebula that formed Earth and the Moon would have had water too. Being as the Moon is so small, it cannot hold onto such light weight compounds. The Moon would have lost its water billions of years ago no matter what the formation mechanism was. Water is too volatile to be a good indicator of formation model.
Zinc, on the other hand, is moderately volatile. Enough of it volatilizes such that the mechanism that separates isotopes can function, but is non volatile enough that some of it is going to be left to analyze.
The Moon is depleted in light weight zinc isotopes. This is from lava that came out of volcanoes on the Moon. They can tell that lava was molten, divided into samll droplets and exposed to the vacuum in space at some point during its life. Not as a flood basalt but as fine molten droplets.
 
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Brass melts at a higher temperature than zinc boils. When you melt a bunch of brass in a furnace the zinc is driven out in a whitish color vapor that will make you violently ill if you breathe it. I know this because some guy told me.
 
Interesting reading, some of you may be quite correct.

Sorry I'm quite busy running a project. So, my time is limited.

Science allows us to look at all options.
All the theories as to the origin of the moon are still theories with faults.

Yes, deep collisions occurred on both the Earth and the moon.

It may take me several years and may lead me to a dead end.

I will look at the origin of the Earth and the Moon as part of Chaos Theory after our Sun expelled its solar envelope. Along the journey I will learn other serendipity issues.

There is more to it than meets the eye.

And very challenging.

I'm also looking at one of the Moons of Jupiter IO
 
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Sorry could not resist posting this paper.

[Submitted on 5 Jul 2023]

Distribution of s-, r-, and p-process nuclides in the early Solar System inferred from Sr isotope anomalies in meteorites​

Jonas M. Schneider, Christoph Burkhardt, Thorsten Kleine
Nucleosynthetic isotope anomalies in meteorites allow distinguishing between the non-carbonaceous (NC) and carbonaceous (CC) meteorite reservoirs and show that correlated isotope anomalies exist in both reservoirs. It is debated, however, whether these anomalies reflect thermal processing of presolar dust in the disk or are primordial heterogeneities inherited from the Solar System's parental molecular cloud. Here, using new high-precision 84Sr isotope data, we show that NC meteorites, Mars, and the Earth and Moon are characterized by the same 84Sr isotopic composition. This 84Sr homogeneity of the inner Solar System contrasts with the well-resolved and correlated isotope anomalies among NC meteorites observed for other elements, and most likely reflects correlated s- and (r-, p-)-process heterogeneities leading to 84Sr excess and deficits of similar magnitude which cancel each other. For the same reason there is no clearly resolved 84Sr difference between NC and CC meteorites, because in some carbonaceous chondrites the characteristic 84Sr excess of the CC reservoir is counterbalanced by an 84Sr deficit resulting from s-process variations. Nevertheless, most carbonaceous chondrites exhibit 84Sr excesses, which reflect admixture of refractory inclusions and more pronounced s-process heterogeneities in these samples. Together, the correlated variations of s-, (r-, p-)-process nuclides revealed by the 84Sr data of this study refute an origin of these isotope anomalies solely by processing of presolar dust grains, but points to primordial mixing of isotopically distinct dust reservoirs as the dominant process producing the isotopic heterogeneity of the Solar System.
 
Harry Costas et al. Keep digging. The Earth-Moon system is very difficult to determine original angular momentum and original mass compared to present day values. The best data in astronomy uses solar eclipse records that can be traced back at least 2700 years ago.

Earth's days getting longer: study (Update), http://phys.org/news/2016-12-earth-...e=menu&utm_medium=link&utm_campaign=item-menu

"Earth's days are getting longer but you're not likely to notice any time soon—it would take about 3.3 million years to gain just one minute, according to a study published on Wednesday. Over the past 27 centuries, the average day has lengthened at a rate of about +1.8 milliseconds (ms) per century, a British research team concluded in the journal Proceedings of the Royal Society A. This was "significantly less", they said, than the rate of 2.3 ms per century previously estimated—requiring a mere 2.6 million years to add one minute."

Measurement of the Earth's rotation: 720 BC to AD 2015, https://ui.adsabs.harvard.edu/abs/2016RSPSA.47260404S/abstract

"Abstract New compilations of records of ancient and medieval eclipses in the period 720 BC to AD 1600, and of lunar occultations of stars in AD 1600-2015, are analysed to investigate variations in the Earth's rate of rotation."

Extrapolating beyond the solar eclipse records preserved from ancient history, is where everything gets very interesting :)
 

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