The Moon Earths little sister

[John John]

You may have heard that the origin of the Moon was due to a small planetary body colliding with the Earth.

I believe that this theory is correct and the biggest evidence of this is on the surface of the Moon.

We all can see the large dark areas covering the near side of the Moon called Maria, these are very large lava beds that fill very large craters.

The Maria filled these craters due to the very deep and intense impacts that created them.

The Maria craters are the largest and newest of all the big impacts to occur on the surface of the Moon.

Over 90% of the Marias are on the Earth facing side of the Moon, and it is this fact that brings my attention to the Moon's origin.

As the Moon entered a stable orbit of the Earth it started to collect much of the debris that ejected from the collision as it trailed behind it.

The Earth would have had several smaller Moons forming at the same time as the main body.

As the large ring of billions of dust and rock particles began to clear up collecting on the larger bodies the smaller Moons came home.

A group of small Moons collided while traveling in the same plane as the main body sinking slowly into the Moon's crust.

This very large but slow impact accumulated a very big imbalance in the Moon's side.

The heavier Maria filled side swung in to face the Earth creating the tidally locked situation we have today.

The small embedded Moons that are still embedded within the Moon's near side mantel are attracted to the Earth's gravitation keeping our Moon stable and locked.

Can you see what I see?

Thanks for reading and please tell me what you think.

[Mordred]

5 hours ago, John John said:

You may have heard that the origin of the Moon was due to a small planetary body colliding with the Earth.

Yes research agrees with this 

5 hours ago, John John said:

 

We all can see the large dark areas covering the near side of the Moon called Maria, these are very large lava beds that fill very large craters.

The Maria filled these craters due to the very deep and intense impacts that created them.

The Maria craters are the largest and newest of all the big impacts to occur on the surface of the Moon.

Over 90% of the Marias are on the Earth facing side of the Moon, and it is this fact that brings my attention to the Moon's origin.

As the Moon entered a stable orbit of the Earth it started to collect much of the debris that ejected from the collision as it trailed behind it.

The Earth would have had several smaller Moons forming at the same time as the main body.

As the large ring of billions of dust and rock particles began to clear up collecting on the larger bodies the smaller Moons came home.

 

Maria if I recall is due to asteroid collisions evident of its impact characteristics however those impacts could be the result of debris returning home as you put it.

If I recall the studies also show that the lunar crust is thinner on one side than the other which if I recall it's thicker on the Maria side.

You might want to look into that detail as it's a piece of evidence in regards to which side struck the Earth.

Edit forgot to add tidal locking isn't a result of impacts but a result of gravitational influence between the moon and Earth.  All orbiting bodies gradually become tidal locked unless they are gaining momentum via other influences such as impacts.

5 hours ago, John John said:

 

The small embedded Moons that are still embedded within the Moon's near side mantel are attracted to the Earth's gravitation keeping our Moon stable and locked.

 

This statement is incorrect see above.

Edited August 18 by Mordred

[Halc]

On 8/18/2024 at 5:49 AM, John John said:

 the biggest evidence of this is on the surface of the Moon.

Yes, the biggest evidence is that the surface has similar composition to Earth, which is true of no other planet's moon.

 

On 8/18/2024 at 5:49 AM, John John said:

We all can see the large dark areas covering the near side of the Moon called Maria, these are very large lava beds that fill very large craters.

The Maria filled these craters due to the very deep and intense impacts that created them.

The larger impacts impart enough energy to melt vast volumes of rock, and this liquid spreads out and covers significant area.  The largest impacts might have created a crater perhaps 3 km deep, but the lingering energy from the event also continues to trigger volcanic activity for some time, and this adds to the maria, and also originates from much deeper than just a few km.

On 8/18/2024 at 5:49 AM, John John said:

Over 90% of the Marias are on the Earth facing side of the Moon

I've not seen a consistent explanation for this, but the best explanation seems to be the thickness of the crust.  Where the crust is thin and dense, large impacts can melt rocks instead of just eject lighter thick material sort of like a child jumping into a ball pit.

 

21 hours ago, Mordred said:

If I recall the studies also show that the lunar crust is thinner on one side than the other which if I recall it's thicker on the Maria side.

Other way.  Thicker (and less dense) on the far side, sort of like it's the continent over there, and the near side having thin, more dense crust like our ocean floors.  The near side is the dense side, which is why it faces Earth.

On 8/18/2024 at 5:49 AM, John John said:

The small embedded Moons that are still embedded within the Moon's near side mantel are attracted to the Earth's gravitation keeping our Moon stable and locked.

They're the stuff on the far side actually.  The small merged bits are the low density stuff.

 

On 8/18/2024 at 5:49 AM, John John said:

This very large but slow impact accumulated a very big imbalance in the Moon's side.

Yes, the theory is that there were probably two primary moons for a while, both formed from the same event, which eventually did a slow motion collision/merge, with the smaller less dense moon forming the thick crust on what is now the far side.  It is unclear if the moon becoming tide locked occurred before or after (or because of) this slow merge.

On 8/18/2024 at 5:49 AM, John John said:

As the large ring of billions of dust and rock particles began to clear up collecting on the larger bodies the smaller Moons came home.

Yes, there would have been shrapnel everywhere, which eventually collected into a limited number of moons whose gravity cleaned up all the little pieces. Much of it of course achieved escape velocity and didn't ever come home.  Theia itself?  One would think that it would still be around if it survived, so I think the material merged with the pre-Earth to become one planet-moons system, the material of which was composed of matter from both objects.
The pre-impact planet was not Earth particularly.  It had a different mass, spin, and orbited somewhere other than where Earth is now.  The post-imact Earth orbited similar to where it is now, but more eccentric, with a spin of perhaps 10 hours, similar to Jupiter.

21 hours ago, Mordred said:

You might want to look into that detail as it's a piece of evidence in regards to which side struck the Earth.

I don't think it is meaningful to refer to the 'side which struck Earth', or for that matter, refer to the place on Earth where the Theia impact took place.  Both bodies were reduced to molten balls, a bunch of smaller molten balls, and a lot of ejecta.  A liquid ball does not have a meaningful location of where something occurred on it.  There's not going to be a crater or other scar, or a place where cooling takes place faster. Not if you get it hot enough.

[sethoflagos]

3 hours ago, Halc said:

A liquid ball does not have a meaningful location of where something occurred on it.  There's not going to be a crater or other scar, or a place where cooling takes place faster. Not if you get it hot enough.

Having said that there are a pair of suspicious large low-shear-velocity zones sat close to the core mantle boundary: the African and Pacific LLSVZs.

Some claim these to be Theia remnants.

[Mordred]

3 hours ago, Halc said:

 

I don't think it is meaningful to refer to the 'side which Earth', duced to molten balls, a bunch of smaller molten balls, and a lot of ejecta.  A liquid ball does not have a meaningful location of where something occurred on it.  There's not going to be a crater or other scar, or a place where cooling takes place faster. Not if you get it hot enough.

I was thinking more in lines of bulging occurring during cooling but that would require an early tidal locking prior to completely cooling. 

However I agree with the rest we have to see if the OP returns or not but still a good topic discussion 

Edited August 19 by Mordred

[studiot]

On 8/18/2024 at 4:12 PM, Mordred said:

Yes research agrees with this 

Not all the research.

But yes it is a plausible hypothesis.

 

7 hours ago, Halc said:

but the lingering energy from the event also continues to trigger volcanic activity for some time,

To have volcanic activity, trigerred or not you have to have buried molten rock.

What evidence is the for buried molten rock on the moon ?

 

7 hours ago, Halc said:

Both bodies were reduced to molten balls, a bunch of smaller molten balls, and a lot of ejecta. 

Are you suggesting that the Earth was reduced to a molten ball after it had already cooled suffieiently to solidify on the surface at least ?

 

7 hours ago, Halc said:

There's not going to be a crater or other scar, or a place where cooling takes place faster. Not if you get it hot enough.

Theres not going to be a crater on Earth on account of 4 billion years of tectonic activity and movement.

 

Gravity favours accretion.
It doesn't favour accretion into locally proximal lumps.
The large lumps grow at the expense of the small ones.

 

This favours the alternative hypothesis of the Moon and Earth forming at the the same time, over the chip off the old block hypothesis.

[Halc]

9 hours ago, Mordred said:

I was thinking more in lines of bulging occurring during cooling but that would require an early tidal locking prior to completely cooling.

The moon was not tide locked shortly after the Theia impact, nor was it even 'the moon', something it only became after most of the pieces coalesced.

There was a likely merger of two moons, but what was that like?  Two moons in a similar orbit will set up a horseshoe orbit and never touch. There are several objects that are in the same solar orbit as Earth in such a horseshoe arrangement.

So what else?  Two moons in mutual tide locked orbit might be small/solid enough to do a soft touch, but only if they're in a tight orbit, so lots of angular momentum. There can be no sustained bulge from tides, but you still get the density asymmetry that we see today.

Why is the dense side on the Earth side?  Tide will tend to align a linear mass vertically, but with either end up, not necessarily the low density end.

 

All questions, not so much answers. Yes, interesting discussion.

5 hours ago, studiot said:

What evidence is the for buried molten rock on the moon ?

NASA says "The Moon’s core is proportionally smaller than other terrestrial bodies' cores. The solid, iron-rich inner core is 149 miles (240 kilometers) in radius. It is surrounded by a liquid iron shell 56 miles (90 kilometers) thick. A partially molten layer with a thickness of 93 miles (150 kilometers) surrounds the iron core."

https://science.nasa.gov/moon/facts/

Unsure how they measured this.

5 hours ago, studiot said:

Are you suggesting that the Earth was reduced to a molten ball after it had already cooled suffieiently to solidify on the surface at least ?

Yes I am.  Having something the size of Mars hit us will do that.

There is an alternate (far less consensus) theory that there was no impact, and Earth just turned so fast that it spun off a big gob of material.

5 hours ago, studiot said:

Theres not going to be a crater on Earth on account of 4 billion years of tectonic activity and movement.

Or even one week of simple fluid dynamics.  I cannot leave a scar on the ocean after the waves have dissipated and currents have mixed any dyes and other evidence of disturbance.

 

5 hours ago, studiot said:

The large lumps grow at the expense of the small ones.

That they do.  Many of the pieces either escaped or fell to Earth. Many of the small pieces in orbit were cleaned up by the largest lump, which eventually formed one moon, but perhaps two of them for quite a while.

 

Assuming we wait long enough (far far more than the current age of the universe), and assuming unreasonably that the sun will not consume the Earth/moon system, the moon will eventually fall to low enough orbit to break up into rings like Saturn, and then fall as small bits to Earth. Yes, it's currently receding, but only as long as kinetic energy exists to fuel that.

[studiot]

16 hours ago, Halc said:

There is an alternate (far less consensus) theory that there was no impact, and Earth just turned so fast that it spun off a big gob of material.

Yes there are several alternate hypotheses.

Each one has its own difficulties to overcome and proponents that prefer to ignore these.

 

On 8/19/2024 at 1:48 PM, Halc said:

Yes, the biggest evidence is that the surface has similar composition to Earth, which is true of no other planet's moon.

Whilst this is true for some elements, there is about four times the % of Titanium and 10 times the % Magnesium on the Moon and 5 times the Sodium on Earth.

Core or not, the Moon has no magnetising dipole field like Earth.
Yet some of the rocks brought back by Apollo are found to be magnetised.

 

The large object hypothesis need to explain where the object came from and how it came to collide with the Earth.

It also need to explain how, if it was the precursor of the Moon, the Moon has ended up with its present composition.

 

Forecasting is as uncertain as hindcasting.

16 hours ago, Halc said:

Assuming we wait long enough (far far more than the current age of the universe), and assuming unreasonably that the sun will not consume the Earth/moon system, the moon will eventually fall to low enough orbit to break up into rings like Saturn, and then fall as small bits to Earth. Yes, it's currently receding, but only as long as kinetic energy exists to fuel that.

The Sun is not due to got to the next stage for another 8 billion years, nearly twice the current age of the Earth and Moon.

The alleged impact must have occurred early in  Earth's history, particularly the gob theory.

[John John]

On 8/19/2024 at 10:48 PM, Halc said:

Yes, the biggest evidence is that the surface has similar composition to Earth, which is true of no other planet's moon.

 

The larger impacts impart enough energy to melt vast volumes of rock, and this liquid spreads out and covers significant area.  The largest impacts might have created a crater perhaps 3 km deep, but the lingering energy from the event also continues to trigger volcanic activity for some time, and this adds to the maria, and also originates from much deeper than just a few km.

I've not seen a consistent explanation for this, but the best explanation seems to be the thickness of the crust.  Where the crust is thin and dense, large impacts can melt rocks instead of just eject lighter thick material sort of like a child jumping into a ball pit.

 

Other way.  Thicker (and less dense) on the far side, sort of like it's the continent over there, and the near side having thin, more dense crust like our ocean floors.  The near side is the dense side, which is why it faces Earth.

They're the stuff on the far side actually.  The small merged bits are the low density stuff.

 

Yes, the theory is that there were probably two primary moons for a while, both formed from the same event, which eventually did a slow motion collision/merge, with the smaller less dense moon forming the thick crust on what is now the far side.  It is unclear if the moon becoming tide locked occurred before or after (or because of) this slow merge.

Yes, there would have been shrapnel everywhere, which eventually collected into a limited number of moons whose gravity cleaned up all the little pieces. Much of it of course achieved escape velocity and didn't ever come home.  Theia itself?  One would think that it would still be around if it survived, so I think the material merged with the pre-Earth to become one planet-moons system, the material of which was composed of matter from both objects.
The pre-impact planet was not Earth particularly.  It had a different mass, spin, and orbited somewhere other than where Earth is now.  The post-imact Earth orbited similar to where it is now, but more eccentric, with a spin of perhaps 10 hours, similar to Jupiter.

I don't think it is meaningful to refer to the 'side which struck Earth', or for that matter, refer to the place on Earth where the Theia impact took place.  Both bodies were reduced to molten balls, a bunch of smaller molten balls, and a lot of ejecta.  A liquid ball does not have a meaningful location of where something occurred on it.  There's not going to be a crater or other scar, or a place where cooling takes place faster. Not if you get it hot enough.

Well said, I agree with much of your conclusions but the penetration of 3 kilometers is a bit short. A large impact that makes an 800-kilometer crater will penetrate almost to the center of the Moon even with a slow impact.

On 8/20/2024 at 2:15 AM, Mordred said:

I was thinking more in lines of bulging occurring during cooling but that would require an early tidal locking prior to completely cooling. 

However I agree with the rest we have to see if the OP returns or not but still a good topic discussion 

Yes, I have returned from the past. Thank you for being hopeful of my return. I have been studying the Moon for some 48 years so I am more than happy to elaborate and debate the topic in a civil manner.

On 8/21/2024 at 3:44 AM, studiot said:

Yes there are several alternate hypotheses.

Each one has its own difficulties to overcome and proponents that prefer to ignore these.

 

Whilst this is true for some elements, there is about four times the % of Titanium and 10 times the % Magnesium on the Moon and 5 times the Sodium on Earth.

Core or not, the Moon has no magnetising dipole field like Earth.
Yet some of the rocks brought back by Apollo are found to be magnetised.

 

The large object hypothesis need to explain where the object came from and how it came to collide with the Earth.

It also need to explain how, if it was the precursor of the Moon, the Moon has ended up with its present composition.

 

Forecasting is as uncertain as hindcasting.

The Sun is not due to got to the next stage for another 8 billion years, nearly twice the current age of the Earth and Moon.

The alleged impact must have occurred early in  Earth's history, particularly the gob theory.

Over time many celestial bodies would have come close to the Earth, The Moon is just the one that came too close and hit.

I believe the Earth never had the vast number of craters like the Moon, it was too big and hot so all the impacts were leveled by the heat.

The craters on the Moon are from its own debris field that orbited the Earth most of which returned to the Moon very little to the Earth.

[Mordred]

1 hour ago, John John said:

 

I believe the Earth never had the vast number of craters like the Moon, it was too big and hot so all the impacts were leveled by the heat.

 

One significant difference the moon has no erosion while the Earth does. It's more likely the Earth was hit more frequently due to higher gravity but due to erosion the evidence has long been wiped out.

+1 for the considerable improvement in thread quality.

Edited August 21 by Mordred

[John John]

Just now, Mordred said:

One significant difference the moon has no erosion while the Earth does. It's more likely the Earth was hit more frequently due to higher gravity but due to erosion the evidence has long been wiped out.

Yes, the Earth was impacted far more than the Moon ever was but the Earth was molten for much longer than the Moon so all of the craters on the Earth melted flat the Moon received rapid impacts after it cooled the Earth received very little after it cooled. It is true the Earth can hide most of its little craters due to erosion and plate movement but it was the heat that did most of the work making the Earth smooth. If large 1000-kilometer craters slipped under the crust we would see the depressions from that on the new plate.

[studiot]

1 hour ago, Mordred said:

One significant difference the moon has no erosion while the Earth does.

No erosion.  +1

 

3 hours ago, John John said:

Over time many celestial bodies would have come close to the Earth,

Such as ?

3 hours ago, John John said:

The Moon is just the one that came too close and hit.

Did you really mean to say that or something else ?

3 hours ago, John John said:

The craters on the Moon are from its own debris field that orbited the Earth most of which returned to the Moon very little to the Earth.

What process of logic leads to that conclusion ?

 

3 hours ago, John John said:

I believe the Earth never had the vast number of craters like the Moon, it was too big and hot so all the impacts were leveled by the heat.

How does this square with the gravitational theory of accretion ?

Even today impactors bypass the Moon and head for Earth.
We have just been treated to the regular meteor showers by the perseids

https://science.nasa.gov/solar-system/meteors-meteorites/perseids/

[John John]

3 minutes ago, studiot said:

No erosion.  +1

 

Such as ?

Did you really mean to say that or something else ?

What process of logic leads to that conclusion ?

 

How does this square with the gravitational theory of accretion ?

Even today impactors bypass the Moon and head for Earth.
We have just been treated to the regular meteor showers by the perseids

https://science.nasa.gov/solar-system/meteors-meteorites/perseids/

1. If there weren't many near collisions then that would make the appearance of our Moon even more unlikely to have occurred.

2. I do mean to say that, after all, it did hit the Earth if the theory is correct.

3. Well if the Moon entered a permanent orbit with the Earth then most of the debris would follow along as well, and much of that debris would return to the Moon leaving all the craters that we see today.

4. The debris orbited the Earth with the newly forming Moon so it would be more likely to hit the Moon over time than return to the Earth. Most of the debris would have a similar velocity as the Moon so it would orbit the Earth at a corresponding distance.

[Mordred]

Well in terms of debris one might be surprised at what is shown under simulations.

This is one example. Paper here

 https://arxiv.org/abs/2210.01814

NASA website pop media coverage with the simulation 

https://www.nasa.gov/solar-system/collision-may-have-formed-the-moon-in-mere-hours-simulations-reveal/

I've seen different simulations and searches the results can vary greatly on how debris gets applied.

[John John]

2 minutes ago, Mordred said:

Well in terms of debris one might be surprised at what is shown under simulations.

This is one example. Paper here

 https://arxiv.org/abs/2210.01814

NASA website pop media coverage with the simulation 

https://www.nasa.gov/solar-system/collision-may-have-formed-the-moon-in-mere-hours-simulations-reveal/

I've seen different simulations and searches the results can vary greatly on how debris gets applied.

The simulation is a calculation based on many factors but it can't deal with the velocity and angle that occurred on impact. We could make many simulations but without knowledge of what really took place any simulation is just guesswork at best.

[Mordred]

Well guesswork with known physics being applied. The simulations are very useful as one can further use them to look for other evidence.

For example one simulation suggests we can find a significant portion  of Theia below our crust though if I recall something on the order of 80 km. Which is one other issue "where are the remnants of Theia ?"

 

[John John]

1 minute ago, Mordred said:

Well guesswork with known physics being applied. The simulations are very useful as one can further use them to look for other evidence.

For example one simulation suggests we can find a significant portion  of Theia below our crust though if I recall something on the order of 80 km. Which is one other issue "where are the remnants of Theia ?"

 

I think the problem is Theia could have entered Earth's orbit in many configurations, the velocity, the mass, and the angle of impact are the keys to knowing.

Faster and smaller, or bigger and slower a steep impact versus a shallow glance, all this is unknown and anything is possible.

One thing is for sure if Theia is real then it is outside our window every day with the scars to prove it.

[Mordred]

Well I believe everyone agrees we need tighter constraints on the impact possibilities nothing is particularly conclusive at our stage of research. 

[John John]

5 minutes ago, Mordred said:

Well I believe everyone agrees we need tighter constraints on the impact possibilities nothing is particularly conclusive at our stage of research. 

It drives me crazy not knowing for certain but science does all it can to work it out. The Earth and the Moon are very unique and we need to know more about our closest neighbour.

[Halc]

On 8/20/2024 at 1:44 PM, studiot said:

The large object hypothesis need to explain where the object came from and how it came to collide with the Earth.

It also need to explain how, if it was the precursor of the Moon, the Moon has ended up with its present composition.

I don't know if I'm a proponent of any particular explanation.  A large glancing collision might result in a big molten planet which spins too fast for stability, giving time for all the material to mix and become somewhat one composition.  I don't know the dynamics of spinning too fast, nor the possible dynamics of a slow collision, especially if two non-mutually orbiting moons are to collide.  It's a little easier to envision if they're orbiting each other, but Roche limits would tear apart both bodies before they coalesced I'd think.  Not unreasonable to say that happened.

On 8/20/2024 at 1:44 PM, studiot said:

The Sun is not due to got to the next stage for another 8 billion years, nearly twice the current age of the Earth and Moon.

8 BY is less than the time before the moon turns around and starts approaching Earth again, and peanuts to the amount of time (trillions of years) before it hits Earth.

It seems the sun will swallow the pair before then, unless the sun loses sufficient mass to let Earth's orbit get sufficiently far away, and I don't think it will lose enough.

4 hours ago, John John said:

Well said, I agree with much of your conclusions but the penetration of 3 kilometers is a bit short.

Damage deeper than that, yes, but the crater is 3 km, filled with maria (lava).  The cooled lava field (the dark stuff we see) is measured at 3 km at worst. Yay for them knowing this.  What, do they set up seismic sensors all over the place?  I don't know what all Apollo brought with them.

4 hours ago, John John said:

Over time many celestial bodies would have come close to the Earth, The Moon is just the one that came too close and hit.

I believe the Earth never had the vast number of craters like the Moon, it was too big and hot so all the impacts were leveled by the heat.

The craters on the Moon are from its own debris field that orbited the Earth most of which returned to the Moon very little to the Earth.

I don't think the moon 'hit' us. If there was a collision, the moon was formed by the ejecta of that collision, but the collision was with something not-moon.  If this is the case, yes, where did it come from and where did it go?  Was the matter entirely absorbed by Earth such that no significant chunk retained escape velocity?  What was Earth's orbit before that hit, and why is its orbit so 'undisturbed' now??  That question seems to be one ignored by proponents of the Theia idea.

Yes, of course Earth had as many craters as any other object, but like Jupiter, Earth doesn't retain them long, the smaller ones leveled by weather more than heat. You can see a lot of the really large ones (Hudson bay being one), but none as big as the one creating the moon. No crater from that, and it erased all prior craters.

Plenty of the current moon craters (the ones on top) are from hits from material that is not 'returning', but rather new unrelated objects.  4 billion years is plenty time to clean up the original bits that flew off that collision, but slow enough to 'come back'.  Every single object that retains its craters is pretty much covered with them everywhere. It is just a show of lack of erosion, as studiot points out.

1 hour ago, John John said:

Most of the debris would have a similar velocity as the Moon so it would orbit the Earth at a corresponding distance.

If that were true, the debris wouldn't have left 'the moon' in the first place.  Earth is a bigger target and larger gravity source, but so is the sun, and I imagine not much of the ejecta found its way there, so I admit that it being bigger isn't a valid argument.  But returning material would move too slow to make much of a crater. Most of the big damage seems to be done by things not in Earth orbit.

36 minutes ago, Mordred said:

NASA website pop media coverage with the simulation 

Moon forming within hours.  It would almost have to, no?  I mean, if it isn't ejected in hours, it's not going to eject.  Coalescing in hours?  Maybe...  Depends on what percentage coalescs into one or a limited number of small objects before somebody decides "yes, that's 'the moon' now".

30 minutes ago, John John said:

The simulation is a calculation based on many factors but it can't deal with the velocity and angle that occurred on impact. We could make many simulations but without knowledge of what really took place any simulation is just guesswork at best.

The simulation needs to produce an Earth-moon pair of current mass and spin. They don't just pick random values (except as guesses).  So to counter their proposal, you need to run a different simulation with different masses, speeds, and offset, one that produces an outcome more similar to what we see today. So it's not all unknown, since most guesses result in wrong results.

23 minutes ago, John John said:

One thing is for sure if Theia is real then it is outside our window every day with the scars to prove it.

If Theia was not totally absorbed (something continued on, not in Earth orbit), then yes, it should be out there.  Scars on it?  Heck no. Those would be gone for the reason you yourself gave. Melted away.  But we don't see any object that fits the bill.

 

26 minutes ago, Mordred said:

For example one simulation suggests we can find a significant portion  of Theia below our crust

I was involved in another topic about this sort of solid anomaly we have at our core.  The center of Earth has asymmetrical lumps of different material.  Related?

 

[Mordred]

14 minutes ago, Halc said:

 

I was involved in another topic about this sort of solid anomaly we have at our core.  The center of Earth has asymmetrical lumps of different material.  Related?

 

Plausible if I recall the paper suggested its still sinking to our core. 

[John John]

42 minutes ago, Halc said:

I don't know if I'm a proponent of any particular explanation.  A large glancing collision might result in a big molten planet which spins too fast for stability, giving time for all the material to mix and become somewhat one composition.  I don't know the dynamics of spinning too fast, nor the possible dynamics of a slow collision, especially if two non-mutually orbiting moons are to collide.  It's a little easier to envision if they're orbiting each other, but Roche limits would tear apart both bodies before they coalesced I'd think.  Not unreasonable to say that happened.

8 BY is less than the time before the moon turns around and starts approaching Earth again, and peanuts to the amount of time (trillions of years) before it hits Earth.

It seems the sun will swallow the pair before then, unless the sun loses sufficient mass to let Earth's orbit get sufficiently far away, and I don't think it will lose enough.

Damage deeper than that, yes, but the crater is 3 km, filled with maria (lava).  The cooled lava field (the dark stuff we see) is measured at 3 km at worst. Yay for them knowing this.  What, do they set up seismic sensors all over the place?  I don't know what all Apollo brought with them.

I don't think the moon 'hit' us. If there was a collision, the moon was formed by the ejecta of that collision, but the collision was with something not-moon.  If this is the case, yes, where did it come from and where did it go?  Was the matter entirely absorbed by Earth such that no significant chunk retained escape velocity?  What was Earth's orbit before that hit, and why is its orbit so 'undisturbed' now??  That question seems to be one ignored by proponents of the Theia idea.

Yes, of course Earth had as many craters as any other object, but like Jupiter, Earth doesn't retain them long, the smaller ones leveled by weather more than heat. You can see a lot of the really large ones (Hudson bay being one), but none as big as the one creating the moon. No crater from that, and it erased all prior craters.

Plenty of the current moon craters (the ones on top) are from hits from material that is not 'returning', but rather new unrelated objects.  4 billion years is plenty time to clean up the original bits that flew off that collision, but slow enough to 'come back'.  Every single object that retains its craters is pretty much covered with them everywhere. It is just a show of lack of erosion, as studiot points out.

If that were true, the debris wouldn't have left 'the moon' in the first place.  Earth is a bigger target and larger gravity source, but so is the sun, and I imagine not much of the ejecta found its way there, so I admit that it being bigger isn't a valid argument.  But returning material would move too slow to make much of a crater. Most of the big damage seems to be done by things not in Earth orbit.

Moon forming within hours.  It would almost have to, no?  I mean, if it isn't ejected in hours, it's not going to eject.  Coalescing in hours?  Maybe...  Depends on what percentage coalescs into one or a limited number of small objects before somebody decides "yes, that's 'the moon' now".

The simulation needs to produce an Earth-moon pair of current mass and spin. They don't just pick random values (except as guesses).  So to counter their proposal, you need to run a different simulation with different masses, speeds, and offset, one that produces an outcome more similar to what we see today. So it's not all unknown, since most guesses result in wrong results.

If Theia was not totally absorbed (something continued on, not in Earth orbit), then yes, it should be out there.  Scars on it?  Heck no. Those would be gone for the reason you yourself gave. Melted away.  But we don't see any object that fits the bill.

 

I was involved in another topic about this sort of solid anomaly we have at our core.  The center of Earth has asymmetrical lumps of different material.  Related?

 

Let's say the Moon is 200 billion tonnes, If Theia was 300 billion tonnes with a velocity of 10,000 km/h it would have the same force as Theia being 600 billion tonnes with a velocity of 7,500 km/h. The difference would be the amount of splash and the depth of penetration. The fact is that whatever the size and weight was it was a glancing blow, not a direct impact. A direct impact would not form the Moon as all of the momentum of Theia would be canceled and the debris would be going in all directions. If Theia is what happened then it was just chance it ended as it has.

There is no suggestion of Theia orbiting the Sun after impacting the Earth only orbiting the Earth.

Theia may have been orbiting the Sun in a radical elliptical orbit before hitting the Earth, or it may have been a visitor from outside our solar system.

[studiot]

8 hours ago, John John said:

Let's say the Moon is 200 billion tonnes,

No.  Let's not 'say'  ie guess.

Let's use the actual value, whcih is so easy to obtain these days.

 

So the Moon is 7.4 x 10¹⁹ Tonnes. 

Your guess is 2 x 10¹³ T   or a factor of 3.5 x 10⁶ out  ie it is more than 3 million times too small!

There are many good sources of data these days, here is an extract from

The Cambridge Handbook of Earth Science Data.

Another good source is The Cambridge Guide to the Solar System, which is much bigger and includes lots of discussion and colour plates.

And if you really want to go for broke then you need chapter 9  - Lunar Theory of

Orbital Motion By A E Roy

Adam Hilger pub.

 

 

Or you could just ask the internet.

 

[John John]

3 hours ago, studiot said:

No.  Let's not 'say'  ie guess.

Let's use the actual value, whcih is so easy to obtain these days.

 

So the Moon is 7.4 x 10¹⁹ Tonnes. 

Your guess is 2 x 10¹³ T   or a factor of 3.5 x 10⁶ out  ie it is more than 3 million times too small!

There are many good sources of data these days, here is an extract from

The Cambridge Handbook of Earth Science Data.

Another good source is The Cambridge Guide to the Solar System, which is much bigger and includes lots of discussion and colour plates.

And if you really want to go for broke then you need chapter 9  - Lunar Theory of

Orbital Motion By A E Roy

Adam Hilger pub.

 

 

Or you could just ask the internet.

 

It was just an example of energy, velocity over mass. I was making a point regarding the way Theia would behave in different situations.

Having all of the Moon data isn't going to help.

[studiot]

3 hours ago, John John said:

It was just an example of energy, velocity over mass. I was making a point regarding the way Theia would behave in different situations.

Having all of the Moon data isn't going to help.

 

What you have said is pointless.

If you want help say so and cooperate with others.

Otherwise please stop wasting their time.