Where Did Earth's Water Come From?

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Speaker 1: Hey, it's Thanksgiving week and we just wanted to say thank you for listening to our podcast. Thanks everyone, this podcast has been amazing experience and it's only possible because you actually downloaded and listen to what we say. And hey, if you want to thank us for doing the podcast, please rate us on iTunes or the I Heart radio app, or leave us a comment at feedback at Daniel and Jorge dot com. Or show up at Jorge's house and Thanksgiving Day with a stack of bananas. He'll be very grateful. Or a big cosmic turkey, big cosmic turkey. Alright, Happy Thanksgiving everyone. Hey Daniel, you know that water that you're drinking right now? It's delicious and crisp and clear. Yes, yeah. Or that water that you took a shower with this morning, I mean, assuming you took a shower this morning. Yeah, that water is less crisp and clear right now, but yes. Or the water in the oceans and lakes and ponds and rivers all around the earth. Do you know the water you're making me have to go to the bathroom? Or hey, well I heard that all that water came from space. Are you telling me that I'm drinking and showering in space. Water space water water from space. But here's a big mystery. Nobody knows wearing space all this water came from. I mean like it's a huge ice water tanker out there somewhere. Yeah, or me a giant alien to the squirt gun, and they probably are going to come and get their water back eventually. We'd better drink it up or flush it down. And now that's nially won't want it back, you know what, You just keep your water Earth, We'll go find some more. Hi. I'm Jorge, and I'm Daniel, and this is Daniel. And Jorge explained the universe, the entire universe explained for you, all the parts of it, even the wet ones, the damp ones, the dry ones, the one you left out to drive it didn't actually drive very much well and gave you chafing the next day. All of that's going to be explained. Yeah, even the chafing part, even the chafing, even the uncomfortable bits. We are not shying away from that. To be on the episode, we're going to ask the question where did all the water on Earth come from? That's right. Earth is the only planet we know of that has liquid water on the surface. Is it the only planet the universe with liquid water? And where did all this water come from? Yeah? Did somebody just opened a tap and fill filled up the oceans there? Or did it rain from outer space? Some interstellar RV just flushed their toilet onto the Earth billions of years ago. That's right. May we're just the where the gray water ump for the for interstellar space. Yeah, we're we're the latrine forces. Yeah. Well, it's a fascinating question because you know, the Earth has been around for four and a half billion years, and we're pretty sure there's been water on it for almost all of that time. For most of that time, because life has been around for more than four billion years and life needs water. Yeah, it's super important, but scientists don't really know where it came from. A Bradley, that's right, because when the Earth was forming, it was really hot and nasty and there was no atmosphere. So in the very early days of the Earth it must have been dry. It was being blasted by solar radiation and boiled off from the surface, So there's no water on the surface of the Earth in the beginning, but then there's water later, So it's a big mystery. Where did all the water on Earth come from? That's right. As usual, we went out and asked people in the street. Here's what you had to say. That's a good question. I never thought of that. Ice maybe, But then again, how did dice come about? I don't know. Oh, that's all right, I don't I don't know that. I already don't know. Comments that's my guess. Oh, I don't know. I think it was here, but I mean, because there's like glaciers and I don't know what that's I don't know if that's a good question. I don't know. All right, So nobody said where the latrine of the universe? That's good. It's not a popular opinion. Yeah, which means you own that idea, all right. That is your idea. In the future, when that one has proven true, you will be given soul credit for it. Yeah. Yeah. Or what I'm thinking of, like, um, septic tag. That's the word I was looking for, septic tag. I'm glad you just put that image into everybody's mind in um. The thing I really liked about these interviews, going around asking these people is that most of the people had never thought of this question at all. I mean, people have thought about the water cycle, evaporation and rain and toilet flushing, but nobody ever wondered where did the water come from in the first place. Well, yeah, it's such a natural thing, you know, like you we can't even imagine life without water, so why would we wonder where it came from? It's just there, right, Well, you look at other planets, though you don't see water like you see Look at Mars, it's not covered in liquid oceans, right, I guess I hadn't thought about that before, you know, like why is the Earth the only blue planet on the Solar System? Like why why are we so special? Yeah? Well, Earth has some advantages, right, It's in the right zone. So in order to have liquid water, you need first of all to have water, but then you also need to have enough temperature to keep it liquid and enough pressure enough atmosphere to keep it from boiling off. You need to be in the zone to have water. That's right. The Earth was in the zone, the sloppy, wet happy zone of the Solar sytem the slipping slide zone. They should have called it the slipping slide zone, not the golden blocks. I mean, like when you go to at least water parks or like a sea world, and if you sit to close you might get splashed. Exactly, you're in the water zone, right, We're not actually the only planet, right, Like um, Mars had water at some point, right, because they found evidence of rivers and um they think maybe there's still water, maybe frozen at the ice caps of Mars. There's definitely water on Mars in the form of ice. The question is whether there's still liquid water. And they recently found some things that suggests there might be subterranean oceans on Mars. And there are other places in the Solar System to have oceans under like frozen ice or under the ground. But the Earth is the only place in the Solar System we know that has liquid water on the surface. Mars definitely has ice on its surface. You can see the polar ice caps which are partially SEO two and partially water. But there's definitely water on Mars, just not liquid oceans. Let's break it down what you said before. So you say we need to have to write temperature and the right pressure. That's interesting, Like I can imagine if Earth was hotter, everything would boil off, but wouldn't if it even if it boils off, wouldn't it just hang around as clouds or water vapor? That's a great question. Yeah, so if the Earth is hot enough, then it will boil off all the water. It couldn't be liquid. But then you need something to keep it, to keep it around the Earth. Right, water vapor floats, right, there's not a whole lot of gravitational pull on water vapor, and so it's just going to drift out into space unless there's something keeping it here, some blanket wrapping the Earth and keeping stuff on it. And that's the atmosphere. You mean, gravity wouldn't be enough to hold the water vapor in. Yeah, I think if you if your Earth suddenly lost all of its atmosphere, then the water the oceans would boil into space. It would yeah, well I think it would take a while. It wouldn't be instantaneous, And you're right, probably we'd be first surrounded by a haze of water um as the oceans boiled off into nearby space. But we wouldn't be able to hold the hold the oceans to the Earth's surface without the atmosphere doing its job. So you're saying, because we're wrapped in a blanket of gas, other gases like air and nitrogen and oxygen that helps keep the water inside. That's right, Yeah, And that's why we're pretty sure Earth was dry in its early days, because there wasn't an atmosphere when Earth first formed. Okay, so step is bad. So how do we know that Earth wasn't just born with water? Why does water need to come from somewhere? Why couldn't we just have water? So the Earth probably was born initially with water, right, And the Earth is formed out of dust and gas on all this just rubble from earlier supernova, right, stuff from the inside of stars strewn out into space, collected together into a solar system to form the Sun and all the other planets, and included in that was definitely some ice, right, because these stars burned and they make oxygen and oxygen and reacts with hydrogen and you get water and out in space water becomes ice. So in the early days some of the ingredients that maybe Earth were definitely water. But you can press it down you form the Earth that gets really really hot, and the water bubbles up to the surface and there's no atmosphere and just boils away. In fact, all of the inner planets probably also got blasted by the sun so much solar radiation just fried all that ice and turned it into vapor, which floated away. So then the Earth was born with water, but it probably probably dried it out right away exactly. Then we needed a source for water, and it must have come from somewhere outside of the earth. That's right. It's like you leave your you know, shirt out to dry in the sun. Right, it gets all dry, and you come back a few hours later and it's wet again. You imagine somebody must have hosted down use source of water came and refreshed it. So that's the most that's where we are. That's where we are now. Sure it is wet. Why is it wet if I left it out in the sun dazing exactly? Who emptied their latrine on my shirt? Slash planet? This is getting pretty uh dirty, it's getting pretty septic in here. Yeah, so water must have come from outside of the earth. But then, I guess do you have to we have to wait until we formed an atmosphere before water could stick around. Yeah. Absolutely, you need an atmosphere to keep water on the service, so you need the service. Are cool down a little bit, right, A few engine million years or a hundred million years, and you also need atmosphere, okay, and where did the atmosphere come from? That's a good question. Um. A lot of it that people think came from volcanic eruptions. So it's just like CEO two vented from volcanoes. Some of it may have come from, you know, um asteroids being vaporized when they landed, and but mostly the early atmosphere was CEO two. We didn't have oxygen the atmosphere until later. So people are wondering about whether we could have made water on Earth from combining hydrogen oxygen In the very early days before life, there was no oxygen. You mean, like the rocks that formed the Earth maybe had gases inside of it, inside the rock, and then eventually that all kind of popped out to the surface and then we formed our atmosphere and possibly also water. Yeah, so the initial rocks definitely had some gas in there, and then you know, it bubbles up like a like a big belt and comes out of volcanoes and forms an early atmosphere. UM. And so so we didn't have what we needed to keep the water early on. So we know that we didn't that we couldn't have kept the water early on, we must have lost it. And so now we've been then and then we formed the capacity to keep the water around to build a canteen. So the earth burped formed the coat around it, which said, hey, now we can hold water. That's right open for business, burp Okay. So there's different possibilities then, Um, if the water didn't come from the Earth and we didn't make it with our own gases, Um, what are some of the ways that Earth could have received this water that we shower in? Now? Well, we're pretty sure it has to come from inside our solar system because everything else is just too far away, and that would be too incredible and probably the subject of an awesome science fiction novel. Somebody should write about extra solar water. Star water, star water, star waters, Return of the East too, Oh, return the water strikes back. Um, But there's plenty of water in the Solar system, right. The outer planets also have huge contributions of ice, Like two thirds of Uranus and Neptune are probably made of ice. Wait, two thirds of Uranus is made out of water. That's right, Uranus, And you know the comets and the asteroids and everything sort of outside of the asteroid belt, a little further away, out of the inner planets, has huge amounts of ice in it, and they're far enough away from the Sun that they weren't blasted by the solar radiation and so it's stayed as ice. So if you're looking for like the raw material, there's plenty of ice out there in the Solar System. The question is how does it get from out there a comet, an asteroid, a chunk of a planet and land on Earth. Right, That's that's the mystery. It's not like water is rare in the Solar System. There's a lot of water in the Solar City. The question is just like, how did it get to our planet, which is sitting pretty close to the Sun, that's right. Yeah, since our planet got boiled dry, how did it get refilled? And how do you get that water from the outer parts of the Solar System into the inner part of the Solar System. Okay, so you said some possibilities there, like some comets could have brought it, asteroids could have brought it. Yeah, so comets was a really favorite hypothesis for a while. Um. I also think it's pretty awesome, right to imagine like imagine a dry earth, and then and then how could you get enough water to make oceans? I mean, oceans are just it's mind bogglingly vast. I mean I live by the Pacific. Every time I see it, I just can't imagine how much water that is. I mean miles deepen like the size of the ice cube that must have crashed into Earth for there to be so much water, Yes, But then you think about it other ways, and it's actually not that much water. I mean it covers like the Earth's surface, right, but it's really thin layer compared to the size of the Earth. The depth of the oceans is almost nothing. Wow, It's like, um, it's vast and immense, but at the same time, with the right perspective, it's like a little wet coating on a big rock. That's right, if you held the Earth in your hands, right, all the things that we think are big features of the Earth, right, the mountains in Asia, the deep deserts and all that stuff, the oceans, these are tiny little details on the scale of the Earth. Right. Remember, the Earth is eight thousand miles in diameter. Mount Everest, for example, is what six miles high? The Marianas trenches like eight miles deep. These things are tiny features. The Earth would feel like a smooth like an eight ball in your hand, maybe with a little bit of dampness where where the oceans are, so you don't actually need that much water, because if the ocean is only eight miles deep at its deepest, and the Earth is eight thousand miles in radius, then we're really just talking about like a little tiny coating on the surface of the Earth. Right, Yeah, it's a thin film of water on the surface of the Earth. Of course, it's but jillion of gallons of water, right, but it's not that much compared to the size of stuff that's out there, So you really just need a few big blobs of ice and boom you have an ocean. Right, So how big space glaciers have you seen that anywhere? Like, has anyone calculated how big of an ice cube was it crash into Earth for us who have as much water as we have. Yeah, it's not that much volume, I mean compared to like the size of those ice planets, right, Neptune and uh and Urinus. It's a tiny little bit. You just need to break off a little piece. And there are asteroids out there in the asteroid belt that are big enough for sure, and anyway, so it's it's fun to look out at the ocean and imagine, like, wow, this whole ocean could just be like melted comets. Right, imagine how many comments that would take. But melted comments, yeah, exactly, Let's go for a swim in the melted comets. Let's stop calling them oceans or seas, Let's just call them melted comments. Right, except that nowadays we're pretty sure it's not comets. I mean, it's it's an open question. The short answer is nobody knows. But the first idea was comments, because people know the comments are mostly made of ice, so they thought, well, if enough comments hit the Earth, maybe that would explain it. As a crazy idea, is that sounds right, It actually would explain it because the comment is just a giant flying ice ball. It's a huge snowball, exactly, and that's orbiting the Sun. And that's how they get their tail, is that they the snow is melting and spraying, and you can see when they come into the inner part of the Solar system. The Sun does to a comment what it did to the Earth billions of years ago. It fries it and dries it. Oh, I like that. Fries it and dries it. That's the motto from my um fast food Chaine, which I'm opening soon and new product now on sale in the home shopping network fried and dry it and dry it com um It's called Yeah, it's called the suns. I don't even have to ship you anything and say lead outside, we'll be fried and dry. It's just hope. Nobody even drump UMSI latrina. So people thought comments was the explanation for a while. But then they went out and they measured some commets, and they looked at the ice on the comets, and they discovered that the ice on Earth is different. The water on Earth is different from the kind of water that you find on those commets. Wait, so you we can tell what kind of water is in a commet. First of all, there's different kinds of water. That's like, yeah, regular water, light water, dark water. There's mineral water, there's bubbly water. There's vitamin water. Is that what you mean? Smart water? Life water water? So we we know that water is made out of H two. Oh right, that's hydrogen and oxygen. But there are actually a few different kinds of hydrogen. It depends on how many protons and neutrons. So you can make it out of normal hydrogen, or you can make it out of deuterium, which has an extra neutron in it. And the ratio of like normal hydrogen to deterium um you find in your water tells you something about where the water was made. Specifically, it tells you how cold it was when the ice was formed. What do you mean, how cool? How would the coldness effect which kind of type of hydrogen you would use to make water? Well, the water and ice is a really strange thing. It's like huge fields of study of people studying how ice is formed and the ice crystals and and it's a really complicated subject that we still don't understand. But that's a topic for a whole other day. But the temperature at which the ice forms determines how much of different kinds of hydrogen like to get into the ice, and and what and what fraction and like to mix together. And so the colder it is, the more you you get deterium as a part of the ice. And so you can see where ice was made, because the further away from the sun it was made, the more of this deterium it has in it, right, it will be a different flavor depending on where in the Solar System it became water. Yeah, I don't know if it actually tastes different. I've never licked a commet before. Have Have you licked a common hore? Feels like something I should know about you already? Maybe, yeah, Well that's why you need to fry it and drive it space commets, fried giant and then lick it. I don't know if it tastes different. I don't know if it's healthy or not. But the water on Earth has a very particular ratio of this deterium, and the stuff out in space is a different ratio. And so people landed on commets and got samples from comets, and they measured the water on these comets, and they found out whoa this These comets were formed out in the deep reaches of space. That ice is different from the ice we found here on Earth. So it couldn't have come from a comment. The thing is, we haven't measured that many comets. It's not like easy to go up and sample commets. So the first few measurements people got they thought, oh wait, this is totally different. And then they measured another commet and it had water, which was pretty consistent with Earth. So you don't have a whole lot of samples of comets, but it makes sense if the water from comets is colder, was formed when it was colder, and so it has a different ratio, and so it's a sort of a different flavor, as you say, than the water we found on Earth. That makes comments less likely to be the source of water on Earth. Well, this is a perfect point to take a break. So they checked off comets could not be the source of water on Earth, right. Well, another really good possibility are asteroids, because asteroids are much closer right there's the whole asteroid belt out there in the Solar System. Comets come from much further out right, the Arch cloud, these frozen objects deep beyond Pluto. M Asteroids are hanging out here in the Solar System with us, and so they have a ratio of deteriorm normal hydrogen that's much closer to what we find on Earth, and so they are much better candidate. I mean, there's like big chunks of ice in the asteroid belt. Is that what you mean? Or is the ice kind of mixed in with the asteroids both. I mean, every asteroid is different, but they think on average asteroids are like water no hitting. Yeah, yeah, and they've even found um asteroids that have liquid water inside them inside of the rock. Yeah, the water can survive inside the rock. But also the just the asteroids are there's snowballs. Also, they have you know, chunks of ice in them as well, less so than comets, but they're more rock, but there are big chunks of ice out there. I guess they're out in space, which is like a big freezer, so they would maybe naturally pick up any water that's floating around exactly exactly. Now, somebody out there listening might be thinking, well, still, asteroids are further out there than Earth, right. If the water came from the asteroid belt or from stuff out there like Neptune, then shouldn't it still have a different ratio? And how would that explain the water we see here on Earth. Um. So, to that listener, yeah, good question. That's basically the heart of the question right now. People don't understand that that's what we're all thinking. Yeah, wait, so you're saying the water on Earth still doesn't match the water in the closer asteroid belt. It's still a different kind of water. That's right. Some asteroids seem to match it, but other asteroids don't. And so some people think, oh, we've understood it. It's definitely from these asteroids. Other people think, no, it's not. It's not well explained because, um, some of those many of those asteroids have a different balance of deterior and hydrogen. So it's not a perfect match. It's not a perfect match. Yeah. So it's still like the DNA evidence in a c s I episode. That's it's like, yes, your honor, the water came from this asteroid. This asteroid is guilty of dumping itself on Earth and providing for all life. Yeah, no, we should be congratulated. What about calling it guilty? Right? I mean without this, these asteroids or whoever providing the water, that none of us would be here talking about it. So it's not possible for the water to have come to Earth and then change somehow in terms of the ratio of of the different kinds of water. It's not possible, not that I'm aware of. That's a good question. Wow, Okay, so it's still a mystery. Then it's still a mystery, And um, there's one fun idea, which is that maybe the Solar system was arranged differently when this ice was made. It could have been that that Saturn and Jupiter used to be much closer to the Sun, and the asteroid belt was also much closer, and that's when that ice formed. And then m Saturn and Jupiter had a near miss which caused them to both like jump out further and settle in further out orbits and pull the asteroids with them. And so it could be that the asteroids were formed when they were closer to the Sun, so it was a little warmer, and that's when that water was formed, and then it got moved out into the asteroid belt. Um, but people don't really know. There's a lot of crazy ideas about to explain the configuration of the solar system. Oh you mean water we have on Earth could come from a different solar system, basically like back when the Solar system was different, and that would explain why it's different than the water that we see out in the asteroid belt. Yeah, not a different solar systems than another one, but a solar system that's arranged in a different order, and so that a younger, hotter sem literally younger hotter, tighter, wetter solar system. It's just got an s f W. People are measuring this stuff and trying to figure it out, and it's a hard problem to solve because the information is out there, but it's literally out there, right. It's not easy to go and say, what is the water like on Neptune, what is the water like on Urinus? What is the water like around Jupiter? Right, It's not like we have that data. But it's so frustrating sometimes from the science point of view, because we know that data is out there, and if you could just go out there and measure this and a quick measure of this and a quick measure of that, then you could know so much about the history of the solar system and and how it formed. And to me, this is really important stuff because it helps us think about the question is there likely to be another planet with water on it? I mean, it's sort of an elaborate thing, like imagine how that whole scenario is true that in order to get ice on the in order to get liquid oceans on the Earth, you have to have a solar system range this way one at one point and then later be arranged another way, and the water to get transported via these asteroids. It's really complicated, right, It's like a Rube Goldberg machine. To me, it's like having a snowball's chance, you know, and the bolls chance in space. And yeah, and it makes it seem less likely that another planet out there is going to be found with liquid oceans, if that, in fact is all necessary, right, There could be a thousand other ways though, for water to end up on a planet. You mean, like, the only reason we are here, you and I are here, and that any life is here is this random collision of two objects in the vastness of space. Yeah. Well, probably more than two objects. Probably a lot of asteroids rained down on Earth and deposited their water. But yeah, okay, yeah, exactly. But it could also just be due to the randomness of Jupiter and Saturn's orbits, you know right now the orbit further out from us, and they serve to shield us actually for a lot of stuff like um, also, a lot of comets don't hit the Earth because they're pulled away by Jupiter. Jupiter acts like a big linebacker out there, knocking out big objects that might otherwise hit the Earth, and so um, it makes it harder for us to be hit by commets, so the particular arrangement of our solar system might be absolutely necessary to get water onto the Earth. Um wow, it really makes you think how precious life is. Like life came about an Earth because of this really tiny, almost invisible, thin film of water on this giant rock that could easily evaporate if the right condisions are not mad, and that needed to have come from some other part of the solar system. Like that just seems incredible that we're here at all. Absolutely. You know, when I'm cooking, for example, I'm always skeptical of a recipe that doesn't just let you dump all the stuff in together at once and mix it up. Right. That's how I like to cook, Like, just put it. You're skeptical. Yeah, When when a recipe is like now wait, don't add the egg whites until this step, I'm like, that's not necessary anyway. Maybe that's why my souflet doesn't. But that's basically the recipe for the Earth, right, It's like mix a bunch of rock, compressed it together, wait a few million years, then shower it with asteroids. Otherwise you're not going to get this perfect thin film of water. That allows life to grow. Oh my goodness, that's the Earth Souflat recipe. People are out there looking to see if there are other planets that have water on them, and there's a particular signature of liquid water on a planet, you can tell from the kind of light that passes through the atmosphere of a distant planet. But so far we've never identified another planet that has liquid water on it, even outside the Solar System. So even if we look for extra planets and other Solar systems outside of ours, do we still haven't seen any with water, No conclusive evidence of liquid water on any planet anywhere other than the Earth on the surface. There are a few places that have liquid water are under the surface, like Europa, one of those moons I'm pretty sure has a huge ocean under a surface of ice. You mean it's one of the wounds of Jupiter, right, Yeah, so it's not that far away, not that far away, yeah, And it's this huge liquid water ocean, but it's under a thin coating of ice that protects it, and the under the ice is the water, which is kept warm by various activities inside the planet, you know, gravitational stress from Jupiter, etcetera. Various sources of energy internally to keep the water um from freezing, so it's not just covered with ice, and then you have this layer of ice that protects it from cosmic radiation. All sorts of stuff sort of acts like an atmosphere. So I imagine an ice atmosphere, an ice smith fear, and so people think there could be, for example, life in that ocean, right, that's a huge pile of liquid water. They would be called Europeens. It would be called Europens, and they would probably want to be part of the European Community European Union, which would be a branding disaster. That would be that PR committee would need to get to work. Stat But so far, no water on the surface anywhere other than Earth, but we'll keep looking. It's a cool mystery makes my mouth water exactly, So next time you really let my appetite for knowledge. So next time you go out there and flush your toilet, think about the cosmic journey that those water molecules took. Yeah, writing an asteroid from deep into space, traveling trillions of miles, hitting the Earth, joining the ocean, nestling life, evaporating into a cloud, raining down in a reservoir, all just to flush down your toilet. Sometimes in science we ask questions about the simple things around us and don't have good answers, like where does all the water come from? So there are great mysteries all around us. Well, signing enough, see you next time. Yeah, if you still have a question after listening to all these explanations, please drop us a line. We'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge That's one word, or email us at Feedback at Daniel and Jorge dot com.