Earth was born dry until a cosmic collision made it a blue planet

https://www.sciencedaily.com/releases/2025/09/250928095654.htm

by amichail • 10 months ago

269 268 10 months ago

sciencedaily.com

alexey-salmin• 10 months ago

Ah the First Impact

rd07• 10 months ago

I know this reference lol

zkmon2• 10 months ago

All life on Earth is illegal immigrants from another planet.

ReptileMan• 10 months ago

Only if the earth was seeded with life.

pfdietz7• 10 months ago

Which is possible, at least from sites elsewhere in the young solar system. Life might have originated on Mars, for example, or perhaps in one of many small, warm, wet asteroids. These early asteroids were kept from freezing up by the presence of short lived radioisotopes, the decay products of which are detectable today in parts of meteorites.

subscribed• 10 months ago

Which seems to be quite possible. This is what we have from just one mission: https://www.esa.int/Science_Exploration/Space_Science/Rosett...

zkmon2• 10 months ago

Sorry, I was only joking. Someone got busy seriously down voting! Maybe wrong times to utter the phrase "illegal immigrants". I get it.

prerok2• 10 months ago

Well, I for the count of one, didn't think it bad, but thought provoking. We're all immigrants, when you get deep into it (speaking from Europe, where we usurped previously native folk some 1500 years ago), and we all came from Africa anyway.

But, yeah, political implications nowadays are a slippery slope.

shireboy• 10 months ago

This could mean in the Drake equation ne -number of planets capable of life- is very small. A planet has to be hit with a comet big enough to deliver a large amount of water but not so big or fast to destroy it. And be in the Goldilocks zone of the star. Also the mass of the planet would play a part - gravity of more massive ones would be more likely to capture a comet. But again, too massive and I could see that hampering life.

OgsyedIE• 10 months ago

Unless collisions like the article suggests are a statistical inevitability, that is.

dotancohen5• 10 months ago

Hydrogen is the most common element in the universe. So long as you have elemental oxygen, it will react with things and hydrogen is the thing it will react with the most. So having water is almost a given for any Star system. Additionally, protoplanet and cometary collisions are in fact statistically inevitable. The real question is if water can be delivered at a point after enough gravity has amassed to ensure the water stays there.

jug• 10 months ago

Right, that's the sticky point? The likelihood of a planet in the Goldilocks zone to be too hot in the early stage of stabilizing its chemistry that it requires seeding with "post-formation" chemistry? Is that likelihood close to 100%, or maybe not even near and we were just set up for a funny cosmic event.

xbmcuser• 10 months ago

Your assumption we need water for life to exist is in my opinion wrong. We only know Earth so assume that is what is needed for life to exist.

yosefk• 10 months ago

What's the chemistry of life without water? Do you refer to the promising Russian studies of life sustained by alcohol?

joshuahedlund• 10 months ago

There is a hard limit on the number of atomic elements, and an even smaller limit on the number of soluble compounds that facilitate chemical reactions, and water is demonstrably both the best and the most common in the universe.

So while it may be possible for life to exist without water, any alternatives should be reasonably expected to be even more rare than water-based life

caymanjim• 10 months ago

There's a reason life is carbon-based, and it's not random. It's the only element that works, due to abundance; ability to form many bonds; bonds that are just durable enough but not too durable. There's plenty of sci-fi about silicon-based life, but that's infeasible fantasy. And no other elements have any hope. If you have carbon-based life, you need water as solvent and medium.

It's a pretty safe assumption that all life requires water.

warent• 10 months ago

You’re getting a lot of negative feedback for whatever reason, but you’re absolutely right.

I for one remember reading about possible silicon/methane based life, etc. Actually, here’s a whole wikipedia article on what you’re talking about.

https://en.m.wikipedia.org/wiki/Hypothetical_types_of_bioche...

Perhaps HN folks will lose your scent now and direct their snark there

modius2025• 10 months ago

1. xbmcuser’s point: They challenge the anthropocentric (Earth-centric) assumption — “we only know life as we know it.” Philosophically valid, but scientifically weak without proposing a viable alternative chemistry.

2. joshuahedlund’s reply: Grounds the argument in chemistry and probability.

There are only ~90 stable elements → a finite combinatorial chemistry space.

Among possible solvents, water is the most abundant and chemically versatile (dipolar, wide liquid range, high heat capacity, good at dissolving ions and organics). → So even if other solvents can work (like ammonia, methane, formamide), the odds heavily favor water-based life.

3. caymanjim’s addition: Brings in carbon’s unique valence behavior:

4 valence electrons → can form stable, complex chains and rings.

Bonds are strong but not too strong → dynamic yet stable biochemistry.

Silicon (next best candidate) forms brittle, static lattices and poorly soluble oxides → bad for metabolism. → Therefore: if life is carbon-based, water is the only sensible solvent.

adverbly• 10 months ago

No kidding... This would probably resolve the Fermi paradox if proven true...

frankohn• 10 months ago

I agree. In addition to the chemical elements like water, as mentioned in the article, the impact with Theia also enabled strong magmatic activity at the core of the planet, and that was a critical element as well to sustain life.

Probably the strong magnetic activity of the Earth's core was key to maintaining the atmosphere, but also, the magmatic heat contributed to keeping the planet at a good temperature to support life when a young Sun provided significantly less radiation.

All these elements may suggest that the collision is needed to satisfy the very strict requirements about where the planet is located and about the size and composition of the colliding planet. This makes the probability for life-sustaining planets in the Drake equation extremely low.

As an indirect proof of the tightness of the condition is the fact that the Earth in its history had periods of climate extremes hostile to life, like the Snowball Earth when the planet was completely covered by ice and snow, or at the opposite extreme, the very hot periods when the greenhouse effect was dominating the climate.

JamesLeonis• 10 months ago

The Drake Equation is filled with assumptions, like life must appear on a planet in the Goldilocks zone of a star. The whole equation has only one datapoint to extrapolate from. Tweak the equation's parameters and it will predict universes that only have one civilization per galaxy or worse! We have no way of knowing what those parameters are because we haven't seen other examples.

A major reason we are interested in Europa is because it might have underground oceans. Hypothetically, through tidal forces with Jupiter, the moon's core is hot enough to create oceans under the ice crust. Combined with hydrothermal vents you have the possibility for deep sea life similar to our own deep oceans. The Drake Equation does not predict this possibility.

mr_mitm4• 10 months ago

The Goldilocks zone doesn't enter the Drake equation at all.

As a reminder, this is the equation: https://en.wikipedia.org/wiki/Drake_equation#Equation

It makes very few assumptions.

bethekidyouwant• 10 months ago

Not really there’s always gonna be water comets in the frost zone.

corimaith2• 10 months ago

Even if you only had a handful of civilizations, the sheer time that has passed and size of the universe should mean that life should still be alot more apparent.

With sublight velocities achievable today, I recall it would only take around a million years for a Von Newmann probe to cover the entire galaxy. Such a probe is quite conceivable, so why isn't there more evidence of such probes everywhere?

Another point I feel is that proliferation of life should be an self-reinforcing affair, for intelligent life even more so. A spacefaring nation may terraform or just seed planets, and these in time will replicate similar behaviors. At a certain point, a galaxy teeming with life should be very hard to reverse given all the activity. A life itself isn't necessarily evolved from biology, AI machine lifeforms should also well suited to proliferate, yet we don't see them anyways.

adastra22• 10 months ago

FYI just about every outer solar system moon or planetoid has a liquid ocean somewhere underneath. Europa is neither exceptional or even that interesting anymore.

raverbashing2• 10 months ago

Yup

The fundamental problem with the Drake equation is that it's frequentist, not Bayesian

Hence why you get too high sensitivity to parameters you have no way of having an estimate with a small margin of error

We "don't care" about how many civilisations are out there, we care to the point where we can interact with them.

As mentioned, it has several assumptions. "Rate of birth of sun like stars" means nothing. You can "always" have an exception for life that will throw the data off: "star too bright but with a hot Jupiter tidally locked in front of your moon, shielding it" etc

HarHarVeryFunny8• 10 months ago

The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time.

e.g. Say chance of a random planet ever being hit by a water-carrying comet is one in a billion, then with 100B - 1T planets in the milky way it'd happen here 100-1000 times. If chances are only one in a trillion, and we're the one in the milky way, then there are still another 100B - 1T galaxies out there and therefore a similar number of such events.

pavlov2• 10 months ago

Do other galaxies matter here? A civilization would need to be incredibly powerful to be detectable from another galaxy.

tshaddox2• 10 months ago

The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time.

But numbers can go arbitrarily low.

rdtsc• 10 months ago

Just as easily as we can multiply planets times systems times galaxies times cluster groups we can multiply multiple small probabilities of each chemical being present at the right time and right type, temperature ranges, gravity ranges, etc

mattmaroon• 10 months ago

If the numbers you propose turn out to be accurate then the odds of there being other life are near zero because even 1/1000 planets are not habitable likely.

andrewflnr12• 10 months ago

I don't see any reason to believe that giant impact is the only way to get life-supporting amounts of water. We know Mars had liquid water. We know Titan has lots of ice. We're pretty sure Venus at least had noticeable amounts of water. Did all of these come from Theia-type impacts? I don't think we have any evidence of that.

sesm• 10 months ago

Yep, mega-impact is a classic example of an ad-hoc hypothesis. For example, Moon formation is much better explained by multi-impact hypothesis, which also requires less assumptions.

II2II• 10 months ago

Multiple impacts is the standard hypothesis for a source of Earth's water. If I recall correctly, outgassing from volcanos is another source.

Keep in mind, the solar system formed from a relatively homogenous nebula. It was the formation of the sun that forced lighter elements to migrate outwards, and that only happens if the lighter elements aren't already part of a larger object. There isn't much of a difference between a 10 km chunk of ice and a 10 km chunk of iron gravitationally speaking. Bouancy doesn't play a role here, so density doesn't matter. Outgassing does matter, but that is a slow process for large object, like the Earth, or for smaller objects on Earth crossing orbits that don't get too close to the sun.

It's also worth considering that each planet's situation is unique. There is much more water ice on the moons of the outer solar system because there was more water at the time of formation and the lower temperatures mean the water that was there stayed there. As for Mars, even though it is colder than the Earth, it is much less massive. As such, its atmosphere bleeds away lighter molecules (never mind lighter elements).

GWBullshit2• 10 months ago

Speaking of Drake equations, you should (1) see the other comment here with this account name (2) check out the top Pirate Bay rip of Dark City (which predated that other movie) and turn on the English subtitles and count the number of times the characters look at or make gestures pointing to certain alignments of the text in the subtitles and, if you're true "hackers", try to figure out the encrypted messages in the text alignments that the characters are looking at/pointing to at key moments – and then when/if you figure out what the encrypted messages mean, try to figure out how the director worked together backwards so that they could have a script that aligns a certain way using subtitles and then make the scenes so that the actors are looking/pointing to key spots at just the right time.

If you appreciate technical things, you'd be in for a treat.

ctrlp• 10 months ago

The likelihood of those criteria might be vastly different in a younger universe than in this one, no?

quotemstr2• 10 months ago

Planetary collisions happen all the time. All of Mercury, Venus, Earth, and Mars in our solar system had them. We can see their signatures in other solar systems too: see https://en.wikipedia.org/wiki/List_of_extrasolar_planetary_c...

Whatever the great filter is, it's not planetary-scale collisions during the accretion phase of solar system formation.

mr_toad4• 10 months ago

A couple of dozen collisions out of 6000+ known exoplanets. Not exactly common, but not freakishly rare either.

kulahan3• 10 months ago

Don’t forget this can only happen once, really. You need it to be such a rare event that it doesn’t keep sanitizing the planet with repeated impacts, but one really perfect strike will bring what you need and allow life to form.

The number of instances where this (something unreasonably unlikely) happened in our cosmological history is kinda surprisingly high. I’m absolutely convinced there’s no advanced life (and CERTAINLY no technological civilizations) outside of earth.

One other example: we gained most of our adaptability, curiosity, and problem solving skills as very tiny mammals while dinos ruled the earth. The only way we ever took over the planet was thanks to an asteroid wiping out all those huge creatures. Suddenly, high adaptability and intelligence and resilience was what mattered, and being big and strong suddenly was a massive disadvantage.

Our intelligence exploded largely because that extinction event removed almost all major predators, turning earth into a giant survival puzzle sandbox for mammals to grow in.

Edit: our brains only grew big because it was the best means of survival - they’re crazy expensive, so without this “sandbox puzzle” effect, we probably never would’ve grown them.

tastyfreeze• 10 months ago

Earth has been struck by large comets many times killing the majority of life on the planet each time. In an early solar system it would be more frequent. Once a comet impacts there is one less comet out there. The solar system cleans up over time making impacts less likely over time.

mr_toad4• 10 months ago

Suddenly, high adaptability and intelligence and resilience was what mattered, and being big and strong suddenly was a massive disadvantage.

Maybe it was just being small, puny, and having a tendency to cower in burrows was what saved us. Our ancestors may not have been much smarter than squirrels, and squirrels aren’t very bright.

Hominids brains didn’t get big until long, long after the KT extinction. A Tigers brain is not that much smaller than that of an an Australopithecus.

Animats3• 10 months ago

Right. It's discouraging. We now know that many stars have planets, and some of them are even in the Goldilocks zone. But if it takes a planetary collision to get water... And only one planetary collision, because each one wipes out essentially all life.

Look at the rest of the solar system. Mars - almost no water. Luna - almost no water. Venus, maybe water[1], but as steam. Too close to the sun and too hot.

[1] https://phys.org/news/2025-10-venus-clouds-reanalyzed.html

Kerrick• 10 months ago

I find it incredibly encouraging. I fear aliens existing in sufficient enough quantity to find us more than I fear Earth being the only host to intelligent life until we escape it.

nntwozz2• 10 months ago

This also points to panspermia.

"The hypothesis that life, in the form of “seeds” or spores, is distributed throughout the universe, traveling between planets, moons, and other bodies via space dust, asteroids, comets, and possibly even spacecraft."

I want to think that the water contained life and not the barren earth.

jcims• 10 months ago

Bit of a nit but the Drake equation is intended 'to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy' (from the Wikipedia entry for it). Nice thing is that you can drop a few terms to get to origin of life.

29athrowaway• 10 months ago

Mars is technically in the goldilocks zone of the solar system... but water on Mars boils at 0C or 32F due to low atmospheric pressure, which really sucks.

renshijian• 10 months ago

A brilliant summary! You've deepened the question from "Does a habitable planet exist?" to "Does a planet successfully complete the complex dynamics of life's origin?" The habitable zone is merely the ticket, while the conditions you mention are the truly demanding filters. Considering this, the probability of our existence truly seems miraculous

gtowey• 10 months ago

If Mars contained significant amounts of water in its past as we suspect, that would mean we have n=2 just in our own solar system.

shaky-carrousel• 10 months ago

Not so much, because both Venus and Mars also have water. So whatever gave Earth water is common enough to also give it to the other inner planets.

mensetmanusman• 10 months ago

The Drake equation is whatever math leads to Earth being the only planet with intelligent matter out of infinity planets.

nebula8804• 10 months ago

I recently became addicted to the SpaceSimsx and SimulaVerse. My takeaway is that so many just slight deviations can extinguish life on earth. I used to think of possibility of life in other worlds just in the lens of statistics. There are so many combinations and possibilities that it seems inevitable. But seeing just how perfectly aligned our solar system is makes me really reduce the probable number of chances of other habitable scenarios in my mind.

These channels helped me realize just how important all the planets in the solar system are to our continued existence. Its as if we have an entire family thats just perfect to make our existence possible. An entire family each one quietly doing their part without fanfare or credit.

What if we had 2 moons with half the mass?: Destruction [0]: https://www.youtube.com/shorts/v3xxaTkKGTQ

What if we moved Earth 5% further from the Sun?: Destruction [1]: https://www.youtube.com/shorts/g-na5x0Kldk

What if we dimmed the Sun by 1%: Destruction [2]: https://www.youtube.com/shorts/Cc3DRRJxhB8

What If We Delete the Biggest Planet from Our Solar System?: Destruction [3]: https://www.youtube.com/watch?v=kHJpIWoksKw

What If We Delete All Gas Giants Except Jupiter?: You guessed it...Destruction [4]: https://www.youtube.com/watch?v=Eg9fPNg00EE

WalterBright3• 10 months ago

perfectly aligned

No matter what the circumstances, live will evolve to perfectly match the conditions it is under. There are many species so perfectly adapted to their ecological niche, they are in great danger of extinction. Like peacocks, who are stuck in a local optimum with no way out.

snorbleck• 10 months ago

Could a tardigrade withstand these scenarios? If the answer to any of those is yes, could we then say that even with the parameters skewed a bit, there is a chance life exists elsewhere, and under completely different and extreme or (not "normal") conditions? Is the tardigrade here as a "clue" to tell us that life could form potentially anywhere?

javier22• 10 months ago

Well, just keep in mind that its not a "perfect alignment" as this seems to prescribe some kind of intent. It's more a set of requirements that allowed life to not be extinguished so easily. We could never exist in a place where this didn't happen like this, so obviously we have to be here and not some place ealse. So its more that out of the 1 places we have seen that was made like this, we at least know life happened there.

WalterBright3• 10 months ago

Especially in the context of this, I am baffled by people who go to great lengths to prevent life from Earth arriving on other solar system bodies. Such as all the efforts to sterilize the probes.

dleeftink• 10 months ago

Historically to prevent pre-contamination and erroneous biosignature readings. This may ease once we have some solid pointers or confidence there may be none (caution is likely warranted due to the gravity of such a discovery).

akk0• 10 months ago

How does this square with the fact that we have solid evidence of water on Mars as well?

lukan2• 10 months ago

Having some water and having lots of water is a slight difference. The most arid dessert on earth is a jungle compared to Mars.

(Also Mars could have been also hit.)

oceanplexian• 10 months ago

Except Titan likely has more water on it than Earth. Therefore unless we’re a fluke of a solar system planetary bodies with water on them should be extremely common.

hn_throwaway_99• 10 months ago

Mars is further out in the solar system, and I'm assuming it was further out than Theia when the collision occurred.

The article doesn't say no planets can have water, but just that originally Earth was too close to the Sun to have liquid water. Theia, according to this hypothesis, was not.

gitaarik• 10 months ago

And also Saturn's moon Europa

stared2• 10 months ago

Imagine this sci-fi plot twist:

Aliens make live habitable by hitting proto-Earth with a planet, so life can sprout there.

They calibrated it such a way that angular size of Moon is the same as of Sun.

WillAdams• 10 months ago

That is pretty much the premise of Hal Clement's short story "Halo", which I read in _Space Lash_ (originally published as _Small Changes_), but now available in:

https://www.goodreads.com/book/show/939760.Music_of_Many_Sph...

I recommend folks read it in reverse chronological order, starting at the back, then working to the front and bailing when things get too quaint/old-school/golden-age.

aitchnyu• 10 months ago

What if they miscalculated and intelligence evolved when the moon drifted too far to cover the sun?

layer8• 10 months ago

They regularly smashed asteroids onto earth until intelligent life emerged.

shagie• 10 months ago

I would say "spoilers" ... but it's the title of the story. The Fermi Paradox Is Our Business Model

https://en.wikipedia.org/wiki/The_Fermi_Paradox_Is_Our_Busin...

https://www.tor.com/2010/08/11/the-fermi-paradox-is-our-busi...

vardump• 10 months ago

The Moon was much closer to the Earth when it was formed. It's slowly becoming more distant.

So the angular size has matched the Sun only for 450 million years.

In 50 million years it's angular size will be smaller and total solar eclipses will be impossible.

Note: Due to the Moon's orbit, the whole story is more complicated.

stared2• 10 months ago

I know that. But in this scenario, aliens know the timescale of appearance of life intelligent enough it can appreciate solar eclipse.

alganet• 10 months ago

Imagine the real twist being that complex intelligent life on a planet only goes past some critical development point if there's some sort of weird coincidence in the sky that pushes its inhabitants to understand the mystery.

It's the weirdest filter: you need a giant sign that points you where to look for answers. Without it, you're less likely to find what the universe is all about.

pfdietz7• 10 months ago

Original paper: https://www.science.org/doi/10.1126/sciadv.adw1280

praptak• 10 months ago

So we're not only made of elements which formed inside star(s) but also ones merged from two different planets. This is weird.

aeonik• 10 months ago

And the remnants of two neutron stars colliding.

alchemism• 10 months ago

As above, so below. Two humans colliding, too.

neuronic• 10 months ago

In the scale of the universe this is bound to happen, likely infinite times anyway and this is what feels rather weird to me. Not just the perceived "special circumstances" but that independent of the rarity it will still happen many many times and then any conscious lifeform developing technology to realize this be subject to the definition of survivorship bias.

ahazred8ta• 10 months ago

There was a giant incandescent donut involved, too. https://en.wikipedia.org/wiki/Synestia

timbowhite• 10 months ago

Is this the same collision theorized to have created the moon?

wvbdmp• 10 months ago

Yes

rcostin2k2• 10 months ago

That's what is suggested here but according to the Giant Impact Hypothesis the impact happened about 4.5 billion years ago and formed the Moon from debris, and it likely vaporized much of any existing water on proto-Earth rather than delivering it... More investigations needed ...

blindriver3• 10 months ago

Absolute garbage.

The Earth has a nearly perfect circular orbit. Any collision with another planet would have pushed it off its orbit and caused it to at the very least created a more elliptical orbit that likely would have made the swings in temperature more deadly for life on Earth.

This entire article is science fiction.

indigodaddy• 10 months ago

This makes some sense actually. Does anyone have a counterargument to this?

o11c4• 10 months ago

It's backwards. Highly eccentric orbits are the default; near-circular orbits are the inevitable result of averaging out a large number of orbits after they collide.

It's also ignoring the fact that we likely did have additional planets, but after interactions with other planets with nearby orbits, they would have been either ejected out of the solar system entirely, caused to collide, or herded into more circular (non-overlapping) orbits.

This is why Pluto is not a planet.

the_af2• 10 months ago

Isn't the most common scientific theory about the origin of the Moon that a big body collided with Earth?

How can it be science fiction if most scientists currently believe this?

andrewflnr12• 10 months ago

This guy thinks he's smarter than all those scientists. Consider his opinion accordingly.

gus_massa• 10 months ago

The Earth has a nearly perfect circular orbit. Any collision with another planet would have pushed it off its orbit and caused it to at the very least created a more elliptical orbit that likely would have made the swings in temperature more deadly for life on Earth.

There is a lot of evidence of a big collision, but that's a very good question anyway!

I guess the interactions with other planets and asteroids change the orbit to a more circular one. I couldn't find a serious source that confirm, and not even a non-serious, so I'm still curious, very curious.

Anyway, there is a good theory that Jupiter formed at 3 AU and moved later to 5 AU and (very slowly) caused havoc in all the outer solar system https://en.wikipedia.org/wiki/Formation_and_evolution_of_the... So the initial orbits are not fixed in stone.

gustavorg• 10 months ago

Furthermore, robotic exploration of Mars is already yielding sufficient evidence that Mars once had oceans. There is a well-founded suspicion that Europa and Titan have seas hidden beneath their surfaces. Does this article mean that all of this is just our imagination? I don't think so.

sethammons• 10 months ago

Related, a recent study suggests up to 1% of our mantle is water trapped within rock that gets released as subduction increases to higher heat and pressure. This water could account for three times the amount of water on the surface and may represent a whole-Earth water cycle.

https://www.bnl.gov/newsroom/news.php?a=111648

I wonder how this ties in with the submitted link about Theia. And it will be interesting if we ever get similar trapped water discovered in martian rock.

ck45• 10 months ago

This reminds me of Stephen Baxter's novel "Flood"

danudey• 10 months ago

There are structures in Earth's mantle which are believed to be leftover chunks of Theia, which makes the connection feel quite plausible.

https://www.newscientist.com/article/2400567-bits-of-an-anci...

mcswell• 10 months ago

The article says the light elements hydrogen, carbon and sulfur (and oxygen?) were only able to condense on the outer planets (and their moons). And the original article specifically says "the inner Solar System planets Venus and Mercury are largely devoid of volatile elements". If that's the case, why does Venus have so much carbon dioxide?

(I'm not saying the article is wrong, just trying to understand.)

o11c4• 10 months ago

Keep in mind that carbon dioxide is almost 3x heavier than methane. Part of the reason Venus has "so much" CO₂ is because all the lighter gasses have been depleted.

(But yes, Venus is hard to satisfactorily explain, regardless of whether you accept the article's conclusions at face value.)

pfdietz7• 10 months ago

why does Venus have so much carbon dioxide?

Venus doesn't have liquid water, which is needed for the reaction of silicates with CO2 ("weathering"). Without that reaction, CO2 just accumulates in the atmosphere. Most of the carbon on Earth (and there's a lot) is locked up in rocks.

There's also a biological effect. Here on Earth, silica in the ocean is scrubbed out by microorganisms that create silica shells; these tiny shells fall out into sediments, where (in deep ocean) they eventually form a kind of biogenic rock called "chert". Elsewhere, typically in shallow water, carbonate rocks are formed from the remains of other kinds of animals. Without these effects, the dissolved silicon concentration in seawater would be orders of magnitude higher, and the silica would react to form clays. This reaction would acidify the ocean and prevent carbonate formation.

Just such "reverse weathering" has been hypothesized to occur after the Permian-Triassic boundary, where CO2 levels stayed elevated for 5 million years. The extinction event was so severe it disrupted chert formation (a "chert gap").

andrewflnr12• 10 months ago

I've tried reading the paper, which is obviously less hand wavy than this mess of a blog post but pretty tough going for a layman. I still don't see how they conclude that the water arrived all at once instead of in a bunch of comets... https://www.science.org/doi/10.1126/sciadv.adw1280

hammock• 10 months ago

All at once is what explains the isotopic homogeneity (e.g. in oxygen) between the earth and the moon

andrewflnr12• 10 months ago

Meaning not just all the water but all the oxygen came in with Theia?

o11c4• 10 months ago

I also don't see how they disprove the contribution of gravity. Remember that Earth is composed of fifty Titan-sized bodies.

Titan, and probably Uranus and Neptune, probably have their methane etc. as a result of outgassing - initially, the volatiles are embedded in the inner rocks, but as they gravitationally differentiate and heat - and are subject to tide-like interactions with other bodies - the volatiles are released.

(The real questions are "Why does Ganymede not have an atmosphere?" and "What's up with Venus, really?")

andrewflnr12• 10 months ago

I believe the idea is that the water was all cooked out of Earth's protoplanetary disk material before it even formed large chunks. So gravity never got a chance to "contribute" on that front.

tim333• 10 months ago

The

Our Solar System formed around 4,568 million years ago. Considering that it only took up to 3 million years to determine the chemical properties of the Earth

sounds suspiciously precise. You'd imaging the proto Earth would have formed gradually over millions of years from rocks and dust merging rather than suddenly there 4,568 m years ago and then shortly after crashed into?

andrewflnr12• 10 months ago

Well, 3 million is "millions". Anyway, that very quote continues:

"...this is surprisingly fast," says first author Kruttasch.

So they don't entirely disagree that it's weird.

But why are you replying to me with a quote from the article I already called a mess? Try your hand at the paper if you want real answers. :D Like I said, tough going, but they sure seem to think they have the sigfigs to back it up.

8bitsrule• 10 months ago

this mess of a blog post

It's that. Just one more in a long line of wild-eyed 'the Earth collided with' theories.

Scientists have shown that Earth’s basic chemistry solidified within just three million years ...

They haven't 'shown' anything. They may have evidence to support part of one model ... if they can demonstrate that a Theia probably existed in the first place.

Try to read it? Thick going. https://www.science.org/doi/10.1126/sciadv.adw1280. Quoting from that:

"Today’s element abundances of the BSE and isotope constraints strongly suggest that the bulk Earth comprises ~90% PE, ~10% Theia, and ~0.4% late veneer material... Other models suggest that Earth formed from ~60% PE and ~40% Theia ..."

a later collision with Theia likely delivered the water

Etc. If water was so hard to get ... where in the hell did this hypothetical, no evidence 'likely' get the water it 'delivered'?

andrewflnr12• 10 months ago

Water wasn't hard to get in the outer solar system. You know, where all the ice balls are?

They're not here to "demonstrate" the Theia impact theory, because there's already tons of other work doing that.

animitronix• 10 months ago

Not buying it, Mars had water with no major collision.

spenrose• 10 months ago

Claude Sonnet 4.5 summary of the original paper [https://www.science.org/doi/10.1126/sciadv.adw1280] for middle school students:

How Earth Got Its Water: A Cosmic Detective Story

The Big Question: How did Earth become a planet with oceans and life, when it formed so close to the hot Sun?

What Scientists Did:

- They used a "radioactive clock" made from two elements: manganese and chromium - Manganese-53 breaks down into chromium-53 over time (like ice melting at a steady rate) - By measuring these elements in meteorites and Earth rocks, they figured out WHEN Earth's basic chemistry was locked in

Key Finding: Earth's chemical recipe was set within just 3 million years after the Solar System formed (that's super fast in space terms!)

The Problem: At that point, early Earth was missing the ingredients for life—especially water, carbon, and other "volatile elements" (stuff that evaporates easily when hot)

Why Earth Was Dry: Close to the Sun, it was too hot for water and other volatile stuff to stick to the rocks that built Earth—they stayed as gas and floated away

The Solution: About 70 million years later, another planet called Theia (which formed farther from the Sun where it was cooler) crashed into Earth:

This collision created our Moon It also delivered water and other life-essential ingredients to Earth

The Big Takeaway: Earth needed a cosmic accident to become livable. Without that lucky collision bringing water from the outer Solar System, we wouldn't be here!

Why This Matters: If Earth needed such specific, lucky events to support life, habitable planets like ours might be much rarer in the universe than we thought.

flufluflufluffy2• 10 months ago

What I don’t understand is how you define a single point (even if the point spans a million years) of “when the solar system formed.” They say the chemical composition of the Earth solidified “only 3 million years after the solar system formed” — isn’t the formation of the planets itself part of the formation of the solar system? How does one define the moment of formation? Or does this mean that we know with certainty that there was no physically consistent body one could identify as “Earth” 3 million years prior, and then within those 3 million years, it coalesced and solidified?

thangalin• 10 months ago

How does one define the moment of formation?

We don't. It's usually within a range. My illustrated book shows the timeline with more context and detail. Note that the events are provided on a timeline with some uncertainty (e.g., ± 1 million years):

https://impacts.to/downloads/lowres/impacts.pdf

flufluflufluffy2• 10 months ago

That’s what I was thinking but I guess the uncertainty is less than I assumed.

Btw your book is AMAZING!

frutiger• 10 months ago

I was under the vague impression that there is a single moment when the gravitational force in the core of the proto solar system outweighs (ha!) the electromagnetic repulsion of deuterium/tritium nuclei and fusion is achieved.

The resulting radiation pressure clears out the debris from the solar system’s accretion disk, and this process surely is not instantaneous but is relatively fast.

buildsjets• 10 months ago

I wonder how much adenine, guanine, thymine, and cytosine was present in that water.

Panzerschrek2• 10 months ago

I don't understand why all these volatiles (hydrogen, nitrogen) didn't evaporate during such huge collision, which likely melt the whole Earth's crust. Even if a temporary atmosphere was formed, with high post-impact temperatures this atmosphere can't stay long.

ricksunny4• 10 months ago

As far as we know, molecules and atoms escaping into space comes due to the solar wind. Somehow the solar wind activates these atoms and carries them off into the distant vacuum, ad infinitum presumably though (I would imagine) limited by the heliopause.

[edit, benefiting from convo: mechanisms on atmospheric escape, to varying degrees of verification)

• https://en.wikipedia.org/wiki/Atmospheric_escape

• https://en.wikipedia.org/wiki/Hydrodynamic_escape ]

Absent that, our treasured atmospheric molecules would have to autonomousy achieve escape velocity, some 22 km/sec , with no outside assistance. A difficult feat. And so, resident atmosphere.

Panzerschrek2• 10 months ago

With high enough temperature some molecules may achieve velocities enough to escape. The question is - how hot was it really? The initial collision happened at least with escape velocity, so there was roughly enough energy for volatiles an non-volatiles to escape. But non-volatiles condensed presumably pretty quickly (but were still hot) in comparison to volatiles.

ricksunny4• 10 months ago

was rich in volatile elements essential for life, such as hydrogen, carbon and sulphur.

Today years old on learning that 'carbon' is a 'volatile element'. (I come to learn that astrogeology has a unique definition of volatile).

• The summary's own source article points makes no reference to carbon being volatile.

• The wikipedia article for 'volatiles' in the astrogeological sense makes no reference to carbon being volatile https://en.wikipedia.org/wiki/Volatile_(astrogeology) . Similarly, the wikipedia article for 'refractory', posed as the astrogeological opposite of volatile, does not place carbon at all in the spectrum of volatile to refractory.

• Contra: at least two papers do refer to carbon being a volatile element. https://www.nature.com/articles/s41586-022-05276-x and https://arxiv.org/abs/2311.18262

[shrug]

eep_social• 10 months ago

I take this as “volatile” in the sense that it bonds easily with other molecules

brianpan2• 10 months ago

Astrophysicsts would also call these "metals" (anything heavier than helium) so don't read too much into it. :D

https://sentinelmission.org/astrophysics-glossary/metallicit...

ricksunny4• 10 months ago

Thank you, that does make me feel at the same time better as an individual and sadder about my expectations for the astrophysicists’ ability to draw anything resembling reasonable conclusions about the makeup of the celestial bodies.

catigula• 10 months ago

Tough to gain any predictive information here due to the anthropic principle requiring a series of comical happenstance for observation to even occur.

erickf1• 10 months ago

From a purely mathematical, scientific, and logical standpoint, I must regard this article as entirely speculative. The scientific claims it presents are extraordinarily improbable, and sound reasoning compels their complete dismissal.

QuantumGood• 10 months ago

History repeatedly shows that the popular: "extraordinary claims demand extraordinary evidence" is often dependent on the frame of reference.

What is thought to be likely is used to frame conventional wisdom as truth, making the new viewpoint "extraordinary, until, over and over again, the new viewpoint becomes conventional wisdom. So "extraordinarily improbable" is really just an overton window framing (what we accept/don't accept), rather than a statement based in logic. Though your overall framing reminds me so much of historical phrases that I wonder if you are being intentionally ironic.

cyberax• 10 months ago

I thought the consensus was that the water came from comet impacts?

ctingom• 10 months ago

I don’t believe this.

3oil35• 10 months ago

We humans are not from Earth, what more signs need those who can't see? Humans,from all the species, the unique without a natural habitat. Humans, can not live on this planet unless we all get together and start adapting the environment. Otherwise, we can only survive and it's not fun. We have to wear clothing, cut downn trees. We get ill and stuff. Monkey us from? We closer to the pigs and not just the hips.

poly2it• 10 months ago

What?

pinkmuffinere2• 10 months ago

You heard the man! Monkey us from?

3oil35• 10 months ago

Yes.

fnordian_slip• 10 months ago

We get ill and stuff

Just out of curiosity: you do realise that illness is not specific to humans, but also occurs in animals, right?

3oil35• 10 months ago

Of course, yes -hell, even cats have their own AIDS; but what I meant was we get 'easily' ill. I mean, imagine we have to drink the water from a puddle?

marcoalopez• 10 months ago

Interestingly, Earth scientists have long understood that plate tectonics is highly unlikely to exist on a rocky planet without water (to put it simply, water is needed to deform the Earth's upper mantle), given all that this entails. If this hypothesis is true, plate tectonics as such should be post-collision.

nntwozz2• 10 months ago

What about the Mars scientists?

jordanb• 10 months ago

You can see this in Venus. No water and no plate tectonics. Instead you get heat buildup under the crust until there's a cataclysmic overturn event.

osigurdson• 10 months ago

TLDR: Theia

JackAcid• 10 months ago

How did water-rich Theia get its water?

fijiaarone• 10 months ago

Science makes itself look dumb compared to creationism.

watersb• 10 months ago

What are the chances of the Earth forming yet remaining dry?

Exoplanet surveys that I've seen in popular press can see rocky, dry planets. I'm not sure if that's just a selection bias in our current technology or if Earth with ocean and atmosphere is relatively rare.

tiku• 10 months ago

The water also helped with cooling the surface right? And I thought this was already a widely accepted theory, that the water came from a meteor or asteroid.

jijji• 10 months ago

the fact is that there are over 700 quintillion planets in the universe, habitable is over 40 billion... i think our current understanding of physics limits our ability to reach any of them.

Earth was born dry until a cosmic collision made it a blue planet

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