r/interestingasfuck • u/howimetyourcakeshop • 9h ago

Our moon being formed.

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u/Rxckless92 6h ago

I'm rather uneducated about this stuff, but how do the scientist know for sure this is how it happened?

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u/JimTobin89 6h ago

This is actually quite easy to answer, Im surprised no one mentioned this.

When we went to the moon, the samples we brought back revealed that a lot of the material analyzed is made of the same stuff from the earth.

This theory formed as a result of that data.

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u/Qzy 6h ago

Did we eat Theia's core?

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u/Solid-Childhood-4876 6h ago

There are articles floating around that talk about evidence from seismic observations that the Earth's core layers aren't as clean as we see drawn in the science books. According to what I read, there appears to be density anomalies (the core is lumpy) that lend credence to this theory.

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u/FortressCaulfield 3h ago

Makes me wonder if we have theia to thank for our magnetic field being as strong as it is

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u/amitym 3h ago

Probably more because the early Moon's close influence kept the Earth's interior liquid for longer, at a point where other planets' interiors were cooling off and solidifying. It's the liquid interior sloshing around that sustains our magnetic field.

But yeah, the Moon increasingly seems tied up pretty closely in what makes Earth special.

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u/elciteeve 1h ago

Can you elaborate? Heating ferous material removes the magnetism, so how does the core being molten or moving contribute to the magnetic field?

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u/War_Hymn 51m ago edited 46m ago

From what I gather, the molten metals and other conductors in the mantle act like fluid wires in a electric generator (hence, a "geodynamo"). As they flow via convection through the mantle, they get electrified as they move through existing weak magnetic fields (idk from where originally). The electrified magma then generates electromagnetic fields of its own (like the primary winding in a transformer) that excite more magma to do the same, and a strong self-sustaining planetary magnetic field is generated.

But yeah, I don't think humans have figured out exactly how it works, at least not enough to create an accurate model. Just a rough theory.

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u/Ednw 4h ago

the core is lumpy

Earth should have a doctor check that, it may be somethin malign...

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u/Meldanorama 3h ago edited 1h ago

Its just well defined abs. Gaia works out.

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u/BobFellatio 52m ago edited 48m ago

Not to worry, the earth will die long before the malign lumps have time to spread and become fatal. You see, the earth has this nasty parasite infection called "The Humans", its nasty and has a tendency to spread exponentially after reachin a treshold. Anyway, they are pretty much guaranteed to end up killing everything and themselves in the process.

Right now, they've got this great trifecta going, where they fuck up the climate while racing towards creating a super intelligence they wont be able to control. Just to be sure, they decided that one of the, factually, dumbest humans on the planet would be their best candidate to have control over a arsenal with nuclear missiles, powerful enough to blow the earth to pieces 250 times over.

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u/DoggedDoggystyle 53m ago

Does gravity not apply to articles??

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u/Solid-Childhood-4876 50m ago

Not on the internet. You have to lock them down or risk loosing them.

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u/Kalamazoohoo 6h ago

This also lends credence to my theory that the core is made of tootsie rolls.

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u/Stuman93 3h ago

More like a tootsie pop. The Earth will end when the great owl tests how many licks it takes to get to the center.

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u/LordDagwood 6h ago

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u/Haunting-Vanilla1624 3h ago

What the hell is this gif from?? I see it everywhere

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u/LordDagwood 2h ago

Monster House

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u/DissociatedAuthor 6h ago

Yo, i literally just rewatched this last night for the first time as an adult. It fucking rocked

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u/loptthetreacherous 4h ago

Yes, but only because it was her birthday and she specifically requested it.

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u/OdiousAltRightBalrog 4h ago

We also drank her milkshake.

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u/Min-Oe 4h ago

I've heard that the extra core in our core is why we've got such a decent magnetosphere, which has been an amazing shield against whatever electromagnetic bullshit the sun throws our way. Thanks Theia!

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u/ch7mbucket 3h ago

We let in come in

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u/bishopsechofarm 6h ago

That makes sense. But how did they get this video footage of it from way back then?

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u/yourmamaistheproblem 6h ago

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u/Fredness101 6h ago

So the real question is how did that shirt get over this dudes head?

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u/finefornow_ 6h ago

It didn’t. Just needed to fit over his torso

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u/yourmamaistheproblem 5h ago

Buttons in the back

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u/sinsculpt 5h ago

He puts it on from the bottom

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u/SteveMartin32 4h ago

Zipper on the back

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u/BobIoblaw 6h ago

It was released under the freedom of information act.

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u/ElectricJunglePig 6h ago

Makes sense, it took them 6 billion years to release it.

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u/Durum4x 4h ago

Ayy lmao

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u/bidooffactory 6h ago

It's public record, it was a personal account of the event. Video footage used to be extremely high quality until humans started doing things.

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u/nothingtohidemic 6h ago

I assume it's royalty free or is galactic copyright law a bit different?

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u/Flimsy-Poetry1170 5h ago

Depends on if the person who filmed it has been dead for 70 years or not.

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u/fridgemadness 6h ago

And slow motion, too. Now the only thing natively in slow motion is Pamela Anderson running on a beach to save a life....

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u/Funny-Try-6151 2h ago

Besides, it's in the public domain by now.

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u/GuiokiNZ 1h ago

If you fly fast enough away from earth (faster than the speed of light) for long enough, then look back towards earth with enough magnification, you can see what happened in the past.

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u/ObjetVapeur 6h ago

by reversing newtonian dynamics

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u/Rough_Airline6780 6h ago

Someone filmed it obv

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u/Couple-seeking6684 6h ago

They asked God for it.

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u/Prudent_Rice7840 6h ago

Blork from Kepler-452b posted it to TikTok

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u/jingiski 5h ago

Just send a polite mail to God. He has a bunch of old videos predating cameras or humanity.

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u/PTSD1983 5h ago

It was me. I was the cameraman

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u/CrunchingTackle3000 4h ago

Shared one drive I guess

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u/MerryMarauder 4h ago

The way back machine duh

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u/ShowerGrapes 4h ago

the original copyright finally expired on the video

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u/Beetso 4h ago

They didn't, LOL. What are you daft or something? It was originally filmed on Super 8. It's been fully restored and digitized.

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u/Rune_Council 3h ago

Tachyon cameras.

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u/Funny-Try-6151 2h ago

It's easy actually. You take a ship about 4.5 billion light years out and then use gravitational lensing or any other really powerful telescope to point back at the earth. Boom, you're getting images from 4.5 billion years ago.

Easy peasy.

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u/mysqlpimp 2h ago

Thankfully it was archived by the same beings that made the pyramids, and like butt stuff.

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u/Grand-Helicopter-709 2h ago

Same way they got the music. Prehistoric bootleggers.

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u/Commercial_Fox5549 2h ago

Freedom of Information Act

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u/ChemicalRain5513 6h ago

that a lot of the material analyzed is made of the same stuff from the earth.

They were formed in the same solar system, I bet Mercury is made of a lot of the same stuff as Earth too, no? Not to disagree with the hypothesis, but I am guessing there must be more evidence?

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u/NaturalTechnician737 6h ago

It's not just that it's the same stuff, but it's the same stuff in the same (or very close) proportions as here. There's also the other planet's core, which is presently observed as an overdense blob in the mantle (so we can see it with seismography).

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u/SoaringElf 6h ago

That comment had me in the first half, ngl... take my upvote...

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u/ChemicalRain5513 5h ago

She is actually one of the Gallilean moons of Jupiter. With fuel prices these days it is getting harder to visit.

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u/myktylgaan 4h ago

My boss often calls me an Overdense blob. 😭

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u/Feowen_ 6h ago

Yes and no, generally heavier elements around closer to the Sun and the lighter stuff around the outer solar system (hence why we got gas giants out there and Rocky planets near the Sun.. generally).

As a result, each planet as a unique "element figure print" which lets us ID rocks as from say Earth, the Moon or even Mars (yes, we've ID'd rocks from Mars that we've found on Earth).

https://en.wikipedia.org/wiki/Martian_meteorite?wprov=sfla1

Given we've been to the moon and brought rocks back it's even easier to figure out that the elemental makeup is.. soon similar and seemingly dated to a similar time to be a coincidence. Something caused both the Earth and Moon to "reset" around the same time.. hence the impact theory.

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u/sebaska 6h ago

Other planets have slightly different isotopic composition. The exact ratios of various isotopes differ. Go to Mars - local minerals have martian isotopic signature. Check out meteorites - they have even different signatures. Go to the Moon - and the damn thing has the same signature as the Earth.

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u/LordBlackadder92 3h ago

According to the clip the moon is 76% Theia. So the moon samples were collected at the other 24%?

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u/HanseaticHamburglar 1h ago

yes but the 25% of Theia is mixed up pretty well in earth, so scientists would see that as being the "earth signature" and thus matching it to the moon. Both the earth and the moon are a mix of earth and theia, the proportions might differ but there was enough mixing going on

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u/Mdgt_Pope 2h ago

The other 24% is earth, you watched the clip but missed that chunk come from the impact?

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u/Longjumping_Wolf_912 2h ago

Yes, but I think what they are saying/asking is if 76% of the material of the moon is not of Earth and that of Theia, it should still have a different signature. Which I think is a valid question, but I’m sure there is a scientific explanation. I don’t know what a signature is or how it is measured/determined.

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u/JalapenoConquistador 2h ago

I think we’re missing that most of Theia is in Earth. So we have EarthTheia here. And the moon has TheiaEarth with all the same signatures.

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u/Longjumping_Wolf_912 2h ago

It would be helpful if they put the mass of Earth and Theia in the video. But that is a good point. I’m also curious if this is based on a collection of samples from both Earth and the moon. As in some samples have matching signatures, but others don’t. To get a homogenous distribution of matter of both bodies on both surfaces seems unlikely (I’m not sure if they had drills on the moon and if so, how deep the samples were).

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u/Mdgt_Pope 2h ago

The other part of Theia is on earth. They’re both earth and theia. Just a different concentration of each

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u/BedBubbly317 1h ago

That’s not what the video is claiming though. They are just discussing size, not the isotopic composition. When the two planets collided they became one massive blob of super heated magma, which took the earth an estimated 300 million years to cool off and regain its solid surface. Their isotopic composition blended together over those 300 million years. Helping to create what we now consider to be the earths chemical signature, which is identical to every moon sample we’ve ever tested. But vastly different from every other planetary body within our solar system.

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u/LordBlackadder92 2h ago

Of course I didn't. Did you miss that the moon consist of 76% Theia?

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u/Mdgt_Pope 2h ago

And the other 24% is earth.

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u/sebaska 2h ago edited 2h ago

Maybe it is, or maybe it is not close to that ratio. What's pretty certain is that there was significant mixing of Theia and proto-Earth. Moon may be or may be not 3/4 Theia, but it's certainly not 3/4 of Theia. It's likely dozen or so percent of Theia. And vast majority of Theia went back into the Earth.

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u/BedBubbly317 1h ago

After the collision the isotopic makeup of each planet essentially blended together. When the collision happened, Earth and Theia became a molten ball of superheated magma with no solid surface whatsoever. It took the Earth an estimated 300 million years just to cool off and regain its solid surface again.

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u/Lost_Paladin89 5h ago

You got a lot of great answers. So in just gonna add that we got so good at knowing which rocks are not from earth, that we even figured out that mars also got hit, and we got some of the debris here on earth. https://en.wikipedia.org/wiki/Martian_meteorite

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u/ProbablySlacking 6h ago

Yeah. Typically you have different distributions of elements on each planet. The moon being closer to ours than say, Mars, indicates that they either formed closely, or that there was a mixing event.

This theory presents answers to second and third questions:

  1. Why is the moon so large compared to us? Typically objects that orbit are results of captures. Typically those captured moons are significantly smaller than their hosts (see Phobos/Deimos, Ganymede, etc) because if they’re similarly sized, you risk destabilizing the orbit.

  2. Why do we have an iron core that is far larger than one would expect due to the abundance of iron in the early solar system?

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u/ReputationSalt6027 5h ago

What are the contents of Uranus?

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u/ChemicalRain5513 3h ago

An atmosphere of CH4 and H2S

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u/ReputationSalt6027 3h ago

Well played

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u/notpostingmyrealname 4h ago

Earth and the Moon are Angelfood cake, Mercury is banana bread. Most of the same stuff, but in different proportions, pan type, bake times and temps, and different methods. I don't know if we know the full make-up of Mercury, but we can tell it's different from what is now Earth.

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u/docnig 3h ago

So the moon is cheese?

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u/Mattscrusader 4h ago

No all the planets have their own elemental makeup.

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u/CTTMiquiztli 4h ago

An over simplificación, But that still works: Gravity plays a Big factor in this. Imagine the sun pulling stuff over due it's Gravity. Different weighted stuff gets pulled at different speeds. So, materials are separated due the closeness to the sun, and then they form planets (and other stuff). That's why, Even if we havent Taken samples from Mercury, we know it's composition is different from those of earth, and Even mars, a "close" neighbor, Is diferent too, But our moon Is very similar.

This Is just a figurative example. Is not 100% scientifically accurate, But works well enough to illustrate and explain the concept.

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u/Tymew 3h ago

It is the most likely cause of our axial tilt (seasons). Without something to knock it off, the equator would match the plane of the ecliptic. As far as I've read it takes an impact to change the tilt. if Theia had been a near miss it would have just perturbed our orbit but not affected the tilt or been captured by our gravity.

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u/Ambitious-Pirate-505 3h ago

The Moon formed approximately 4.5 billion years ago when a young Earth collided with a Mars-sized proto-planet named Theia. The giant impact blasted molten rock and debris into orbit, which slowly coalesced via gravity to create our natural satellite. This process is detailed in science books like Our Moon by Rebecca Boyle.

This stuff has been documented for years. They put it in a video because people dont read anymore.

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u/MWave123 3h ago

No bro. It’s exactly the same, isotopes.

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u/37853688544788 2h ago

Perhaps it’s part of a larger truth that we are all the same stuff.

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u/BedBubbly317 1h ago

No. For example Mars has a vastly different makeup than earth does. We also have multiple gas giant planets in our solar system as well, which are very clearly not made up of exactly the same amounts and type of material our planet is. Where exactly in the solar system each planet originally formed played a huge role in its material. No two planets have the same makeup. The moon and the earth are identical however.

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u/Homoiberikus75 6h ago

I think same

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u/sebaska 6h ago

Actually not.

We put our hands on stuff from space - in the form of meteorites. We also measured stuff on Mars (actually, we also put our human hands on stuff from Mars - some meteorites came originally from Mars - we know that because we compared it to what our probes measured in place up there).

And we found out that the stuff from other places differs slightly - it has measurably and repeatably different ratios od certain isotopes.

Mars rocks have their isotopic fingerprint, meteorites have their fingerprints specific to particular stream, our Earthly rocks have their Earth specific fingerprint. The trouble is Moon rocks have the same fingerprint as Earth ones.

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u/Pees-Upwind 6h ago

Others have commented correctly. The ratios of heavy to light elements are the same which is very, very compelling. The only other real option was a captured celestial body which would require the moon to be more icy or dense.

Another thing to look at are the concentration of specific isotopes of common elements. I believe they are the same as well which would tend to point toward the material being from the same origin.

Logically, it passes muster as well. Our moon is much larger, relative to our mass, than any other planet. Which, to me, lends credibility to the idea.

There is not RIGHT answer here though. Just good science and a solid hypothesis that is backed up by data. If there were better explanations you would be able to see and measure their results. I dont believe that is currently the case.

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u/PracticalMushroom693 6h ago

Sorry to be pedantic but it’s a hypothesis not a theory

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u/snarl2 6h ago

Soooo rock?

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u/interesseret 6h ago

Rock is a very large category of material.

On Pluto, water ice is rock.

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u/platypodus 6h ago

What level of "stuff" are we talking about here? Same minerals? Isotopes?

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u/No_Landscape4557 6h ago

Basically yes. For a simpler version for thought experiment, let’s say I somehow magically have 8 cups in front of me and inside of each cup was a sample of each planet(that we somehow magically got). How would you know which cup belongs to which planet?

Well four planets are just made of gas and four are made of rock. If you analyzes the materials down to its atoms you can form a likely idea. If you cup it full of hydrogen then it’s not gunna be from earth.

Each body in the solar system has its own fingerprints. Most asteroids are just pure iron and nickle.

For the moon I believe oddly enough has the same carbon ratio as we see here

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u/WookiePhart 6h ago

Would that be the case for every celestial body in this solar system? Given all the elements in the solar system come from the same source?

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u/mrbananas 2h ago

No. The gas giants are made of different composition of materials from each other. Jupiter and Saturn are mostly hydrogen and helium, while Neptune and Uranus are more water and methane based

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u/Long-Lettuce3146 5h ago

That's a shit answer I was expecting more

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u/JimTobin89 5h ago

I may not have the details of what exactly, but you get the point. Its more than just a guess.

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u/phlogistonical 5h ago

Not only is it the same stuff, the rocks of the moon are the same age as the oldest rocks on earth (that is: the moon and the earth's rocks solidified at the same time).

Then scientists ran many, many simulations of different colissions (different masses, different speeds, different angle) until they figured out what the one that actually formed the moon must have been like. As shown in the video, it would have been a glancing blow by a protoplanet about the size of mars.

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u/BuvantduPotatoSpirit 5h ago

It's important to note compositionally it's mostly crust, too. Matching isotopes + matching elements would mean formed together

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u/benjitheboy 5h ago

it's also because the moon is way too big to be a naturally captured satellite like every other moon in the solar system is

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u/henkdemegatank 4h ago

Which is also one of the major issues with this theory. Theia would have its one isotopic ratios mixed in, and models show that at least part of the moon has to be from Theia, but it matches nearly exactly earths isotope ratios. So there are three options

  1. Complete luck, Theia and Earth were insanely similar by pure chance

  2. The models are wrong, maybe a different orbit and speed explains it? (although we have been very thorough so this is unlikely)

  3. This theory is not what actually happened.

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u/TwoRoninTTRPG 4h ago

"In 2009, researchers in the Netherlands analyzed a museum display piece given to former Dutch Prime Minister Willem Drees in 1969. They found it was not a moon rock at all, but a piece of petrified wood from Earth." This kind of analysis?

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u/Wet_Side_Down 4h ago

There is other evidence..

Our moon is exceptionally large relative to the size of Earth. It is unlikely the young earth could have captured the moon with gravity.

Apollo 11 left behind as special mirror on the surface of the moon that allows scientists to precisely the measure the distance to the moon using a laser.

The moon is slowly drifting away from the Earth. Projecting back in time the moon was much much closer to the Earth long ago.

Both of these facts are best explained by the collision hypothesis.

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u/EmbarrassedDust9284 4h ago

Does this collision responsible for the current earth rotation around itself ?

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u/gatobacon 3h ago

But only 24% of the material is from earth. How do they know the rest came from a single planet called Theia?

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u/sic-transit23 3h ago

If they knew this for sure they wouldn’t call it a theory… duh

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u/LordBlackadder92 3h ago

The clip says the moon is 76% Theia, which I never heard of before, but that doesn't say much.

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u/Witty-Lawfulness2983 1h ago

And they’re finding some interesting evidence of Theia’s remains in the mantle as well. Giant structures anyway.

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u/IWannaGoFast00 48m ago

But the moon was formed by a separate planet so why would it have a lot of the same material?

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u/Local_Dragonfruit930 21m ago

I also heard our iron core is also much larger than one would expect given a planet our size

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u/icefr4ud 6h ago

https://youtu.be/wnqPqV6DdFQ?is=y85mGDrOY5t9c65A

Same simulation is discussed in this video and why we think this is the best explanation we’ve found

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u/neorapsta 6h ago

It's impossible to know for sure but we can make fairly good guesses by looking at the composition of the Earth and the Moon and the  running simulations of what we think might have happened. Then we can see if the results are similar or if there's something we're missing 

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u/Own_Sheepherder_6244 6h ago

It's our best guess, not known for sure. Lots of evidence from moon soil samples and such but now way to know 100% like the Big Bang until we invent time travel

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u/Lucid-Design1225 4h ago

Futurama already did that

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u/THEddt005 6h ago

It’s best guess using samples from the moon that match the earth and other stuff

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u/yungScooter30 6h ago

how do the scientist know for sure this is how it happened

They don't know, it's a hypothesis. It's possible to be 99% sure that this is what happened, but since we ultimately cannot go back in time and see for ourselves, this will forever be a hypothesis that we simply assume is the correct one.

But yeah the other guy answered it better. Moon stuff is Earth stuff

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u/tino_tortellini 6h ago

Computer

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u/BlkSubmarine 6h ago

We don’t. It’s a theory that is supported by the data. Another piece of proof: why do we only see one side of the moon from Earth’s surface?

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u/_patator_ 6h ago

Gravitational (or tidal) locking. That tells nothing about the moon creation.

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u/VeryVideoGame 6h ago

They have years of current data about the moon's movements and distance from us. Then, just play the tape in reverse as far as it goes, and Earth and Moon are eventually colliding.

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u/jmims98 6h ago

Howtown made a very cool YouTube video on this, it's a fun and informative watch.

https://youtu.be/ghW7BEC0byg

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u/Exyodeff 6h ago

We don’t, but this is one of the most probant theories. I kinda like the synestia one too

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u/Outside-Bid-1670 6h ago

It's the only hypothesis left that can explain the moons existence and still agrees with all of the math. Every other theory has holes.

The only part of this that may be suspect is the core of Theia. I agree the 2 large unexplainable deposits in the Earth are probably part of the core but, Theia's core being the foundation of the moon would explain a lot of the moon's oddities like the crater depths and the ringing when struck.

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u/minimim-wage-enjoyer 6h ago

We don’t. This is just the theory that makes the most sense.

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u/Poupulino 6h ago

There's a huge chunk of Earth's mantle whose composition and configuration can only be explained if another celestial body merged with Earth.

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u/DJ_Baxter_Blaise 6h ago

They actually don’t. There isn’t one generally accepted theory about how the moon formed yet. There’s a few good ones like this one.

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u/mr_dumpsterfire 6h ago

Also to add from what others have said, the moon is moving slowly away from earth. Run the clock back billions of years and you see the time where the moon and earth had to be in the same place.

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u/MrPelham 5h ago

they were there

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u/AuntJibbie 5h ago

They don't ' know '. It's just a guess, or a theory.

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u/sebaska 5h ago

We know each larger rocky body in our Solar System has its own isotopic fingerprint. That means the rocks from particular body have certain ratios of various isotopes different than all rocks from another body. The likely reason for that is that during Solar System formation (which took millions of years) various processes like heating by the young Sun, heating by infalling into forming bodies, etc... causes some degree of distillation (for example, lighter stuff being preferentially removed) and that distillation process differed between different forming bodies (different distance from the Sun, different degree of heating when infalling (larger bodies caused more heating, and they also formed faster). Each major body was its own distillation jar.

We know the fingerprints of a lot of stuff, because, conveniently, a lot of it came to us in the form of meteorites. We also did measurements in-situ on Mars, and we brought stuff from the Moon. And there was a surprise: Moon fingerprint is pretty much the same as the fingerprint from the Earth. The stuff is as similar as meteorites originating from the same bodies (large collisions yeet stuff all around, but this stuff keeps its isotopic fingerprint). If both bodies formed gradually as a smaller dust and gas whirlpool (Moon) orbiting a larger one (Earth) they should have been different (for example bigger whirlpool would have produced higher temperatures). But it's pretty clear material from both bodies went through essentially the same distillation jar (or jars).

Additionally, Moon has way less density than the Earth (Earth is roughly 50% more dense) which makes having the same fingerprint even more astonishing.

But it all fits together if they both come from the same original body, or rather pair of bodies: proto-Earth sized as Venus and Theia the rough size of Mars. After an oblique collision some mixed mantle was ejected to form the Moon, while most of it and Theia's core has fallen back onto the bigger body - the Earth.

Also, we know such big disasters were common in the newborn Solar System. Venus is somehow rotating in reverse (only similar collision could explain it). Uranus is rotating on its side - again way bigger collision must have happened there (Uranus is almost 15× heavier than the Earth - to topple such big body required the toppling object to be big - as big as the Earth or bigger). Then we have Neptune which yoinked a large Kuiper belt body and made it its biggest Moon (Triton). We even suspect that originally there were not 4 but 5 giant planets, but one got ejected from our System (Jupiter and Saturn are likely culprits).

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u/TK-528491 5h ago

They don't. It's a theory. Nobody knows and can prove the creation of the Earth or it's moon. We can only speculate.

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u/Embarrassed_Camp_291 5h ago

speculate with extreme degrees of statistical certainty and huge amounts of evidence

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u/TK-528491 5h ago

Perhaps, but perhaps not. I don't think we have quite as much evidence for this as you may think. Quite frankly, it is very common for scientists to think we have it all figured out and then just get proven wrong with a new advancement in technology or just an experiment from a different perspective. Science is great, but it is smart to take things with a grain of salt. Most scientists are fairly biased as well which makes these kinds of studies harder to dissect.

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u/Embarrassed_Camp_291 5h ago

This isnt very common. This might be what youre told by the media, but the media dilutes away all the statistical analysis because the general public doesnt want to read pages of maths or understand how an MCMC mathematically works before reading the result.

Scientists are extremely conservative in there conclusions. Any good paper will have a discussion section discussing their limitations and uncertainties in the model. If you read the SWIFT paper it talks about all the issues (e.g. verlet list method, numerical artifacts, subgrid modelling, HPC nuance issues, etc) and approximations in the code as well as everything it gets right.

It is not common for scientists to be proven wrong by results from new technology. We were just unsure about what was going on in the paramter space the new technology let's us probe. We had ideas and constraints, the new technology let's us constrain it further. The media will have you believe "scientists thought they were clever and knew everything but look, theyre wrong! They know nothing" because it gets more clicks.

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u/TK-528491 4h ago

I have a Master's degree in Mechanical and Energy Engineering. I have studied both math and science extensively. I am not trying to downplay that science is incredible and not to trust it or anything like that. I just am a skeptical person and have noticed that scientists can be overconfident in their solutions (especially in fields of studies that cannot be directly observed). Most media is ridiculous in their portrayal of science, I agree. Most of my takes come from directly studying it. I have learned a lot by being skeptical and questioning things is all I was trying to promote. I admit I am not an expert in this field particularly though.

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u/Jsolidlo 5h ago

They don't know for sure is the answer. It's a theory.

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u/karoxxxxx 5h ago

I think until fairly recently the collision-hypothesis was just one of several discussed iedas (along capture and co-evolving).

Simulation like this show that the right kind of collision results in the right kind of objects (density, orbits) so thats no proof but a hint.

Samples show that the naterial of moon and earth are similar in Isotope ratios (meteorites for example have different ratios), and that some of the lighter elements are almost completly missing on the moon.

The moon has aldo a compararively small core and a magma surface.

The collision hypothesis explains all of these things with one event.

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u/Epic_Elite 5h ago

When it comes to space and things that are difficult to observe due to timelines and a lack of physical access it isnt as much a matter of "know for sure" as much as it is a "best working theory".

This is the most applicable theory with all information that we have available to us at this time. When a better theory comes around, that one will be the new working theory.

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u/Weakonomics 5h ago

Ur mom so old she was there bruh. NASA just asked her lmao

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u/kongtomorrow 5h ago

They don't know for sure; I guess science is almost never "for sure", but this one isn't really accepted consensus, it's something being explored that seems like it might be plausible.

https://phys.org/news/2026-09-giant-impact-intact-moon-hours.html

[edit] I think the five hours is new, but I guess the "giant impact" model is currently the favored theory, if not exactly settled consensus. https://en.wikipedia.org/wiki/Giant-impact_hypothesis

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u/questionname 5h ago

It’s a theory, based on evidence collected from the moon, and how much commonality with what we have on earth.

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u/literally_tho_tbh 5h ago

Here's a fun tip! If you are referring to multiple things, you usually add an S on the end! This indicates the plural form of the word! If you have one, they are a scientist. If you have many, they are scientists. This applies to many words in English. And typically, in English, if something is plural that ends in a Y, you change the Y to an "I" and add "ES". If you have more than one furry, for instance, you have multiple "furries"

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u/twodaloo007 5h ago

They don't. They just make crap up and then every 20 or 30 years make a correction

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u/jimgoose1977 5h ago

They just watched the ring cam footage

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u/Tabnstab 4h ago

There's literally a video of it happening. Didn't you watch it?

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u/TroGinMan 4h ago

There is also a density distribution pattern we see with the Earth's crust and mantle. This is what clues is in on the angle of impact and size of Thea. In other words, we know a massive object struct the Earth when it was forming, then the samples from the moon showed similar competition as the earth.

From that we know an object hit earth and a celestial body was formed with similar competition.

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u/watt-ever 4h ago

I always answer such questions for myself by perusing a Wikipedia page, satisfying myself that I understand everything perfectly, then promptly forgetting all of it.

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u/philthy_barstool 4h ago

To follow on from what the other responses have mentioned about moon rock samples, etc.

The specific simulations for the formation of the moon were developed using supercomputers at Durham University and their Institute for Computational Cosmology. They used a lot of what people already said, combined with a bunch of stuff I don't understand to make fancy videos of moons being formed.

There's a paper about it here: https://iopscience.iop.org/article/10.3847/2041-8213/ac8d96

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u/NegativeAccount 4h ago

With all scientific discovery, it's our best guess until more information presents itself

But until it is disproven, the theory stands. We aren't even sure if gravity works the way we think it does

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u/lemonyishbish 4h ago

We don't know for sure, but some of the contributing evidence is really fun. People have talked about soil already, but you can guess at this theory of moon formation without ever going there - if you know the Earth's mass, you can make estimates of the moon's mass using the period and size of its orbit due to the Earth's gravity. If you divide by the volume of the moon, which can also be calculated with observations from Earth, you'll find that the density of the moon is pretty much the same as the density of the upper mantle of the Earth, which is a fairly big coincidence.

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u/PomegranateHot9916 4h ago

they're not absolutely 100% certain.

this is just one theory based on available evidence.
we will never know the truth anyway, and I doubt it has any bearing on our lives how we got the moon.

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u/phoenixemberzs 4h ago

They don't it's good fiction though

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u/Money4Nothing2000 3h ago

We don't really need to know *for sure* that this is how it happened. What we do need, is a theory that explains all the data and observations that we have, and is physically and mathematically plausible. The theory of Theia fits our data better than any other theory that we have right now. If or when more data is discovered, the theory could be modified.

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u/astralseat 3h ago

Simulations, kinda like the one you're in. Wake up!

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u/ChangKai-Shrek 3h ago

The moon is very weird and we don't know really anything about its origin for certain. That's true for just about everything in the universe (including the universe itself), but it's a plausible explanation based on the available evidence.

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u/PlayerBlocked 2h ago

They don't know for sure. This is a theory. Most of what science presents to you is opinions and guesses with little evidence and usually zero hard proof. Especially when it comes to space. Humans do not even know what gravity is or exactly how it works, it is a theory.

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u/AdeptusAtaris 2h ago

We don't know "for sure" but we're pretty confident.

The moons orbit doesn't align with features present in other naturally captured moons in the solar system. That indicates that it may be unique. The moon is definitely receding, which means in the past it was much closer.

When the Apollo missions brought back moon rocks, the signatures are much closer to earth geological chemistry than samples of meteorites we've studied.

This indicates that the moon is in large part made of material originating on earth. The fact that it used to be much closer, and the bizarre orbit, all point to the moon being made of ejecta from an enormous collision early in earths history.

The objit that hit us, had to have been around the size of mars. We call it Theia by convention. Some anomalous findings in seismic surveys suggest that parts of Theia settled in the Earth's core.

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u/someoftheanswers 2h ago

And how did they know it was already Named Earth??

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u/Fabulous_Run_3383 2h ago

Science doesn't know it happened for sure. It is just the best fitting hypothesis based on the evidence at hand. 

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u/Edwin81 2h ago

They recently found a tape with this recording on it.

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u/Greata2006 1h ago

Physics is perfectly predictable, so any theory we have can be simulated and should induce some results on earth's and moon's tilt, spin, atomic composition, etc.

So basically we make an hypothesis, make simulations that match current data, figure what the simulation says should happen that we didnt observe yet, and try to observe it.

In the end we dont know what happened, but have one or multiple models that matches what we observe better than other models. This is how scientists figure what likely happened.,

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u/BedBubbly317 1h ago

No. But we do know without a shadow of a doubt that the moon is made up of the exact same material that the earth is, meaning the moon did originally come directly from the Earth. That part isn’t up for debate. Being hit by Theia and forming that way is merely the most logical and scientifically supported hypothesis at this time.

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u/snuffaluffagus74 48m ago

They don't as scientists have came out and said that the moon is older than the Earth. Also a lot of cultures have stories of times before the Earth had a moon. I'm talking about cultures on the opposite side of the planet

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u/Wulph422 37m ago

Piggy backing off of that, what's with that time counter? Is that happening in 12 hours accurate?

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