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Speaker 1: Daniel. It's great to be talking to you today. So

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Speaker 1: now I would love for you to go ahead and

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Speaker 1: reassure me that today we're not going to be talking

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Speaker 1: about how scary and dangerous the universe is.

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Speaker 2: Oh no, no, not at all. Well, I mean maybe

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Speaker 2: a little bit.

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Speaker 1: Uh, Daniel, that is clearly hedging. I'm gonna need more clarity.

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Speaker 2: I mean, we're only going to talk about scary and

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Speaker 2: dangerous family destroying things that already happened in.

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Speaker 1: The past because we have some way to prevent these

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Speaker 1: scary and dangerous things from happening in the future, like

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Speaker 1: to my children. Right, no comment, dude, not okay, totally, totally,

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Speaker 1: not okay.

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Speaker 2: You got to embrace the danger, Kelly. That's where the

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Speaker 2: thrill is.

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Speaker 1: I I guess I'm pushing through one way or another.

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Speaker 1: So let's do this just another show my kids won't

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Speaker 1: listen to.

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Speaker 3: Hi.

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Speaker 2: I'm Daniel, I'm a particle physicist and a professor at

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Speaker 2: UC Irvine, and I'm looking forward to the destruction of

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Speaker 2: the Earth.

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Speaker 1: I'm Kelly Waitersmith, adjunct faculty at Rice University, and I'm

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Speaker 1: looking forward to yet another episode filled with existential dread.

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Speaker 2: You know in those moments as the Earth is being

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Speaker 2: obliterated by some huge impactor, We're going to learn a

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Speaker 2: lot about how the Earth is put together and what's

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Speaker 2: inside of it. And as all those insides come to

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Speaker 2: the outsides.

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Speaker 1: You know, I'm going to hope that in that moment

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Speaker 1: we all stop worrying about the details and we just

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Speaker 1: hug our kids and our dogs and stuff. But I'm

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Speaker 1: sure the physicists we'll still be collecting data, and the

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Speaker 1: economists will be quantifying something, and anyway, well.

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Speaker 2: We are all still live and wondering about the universe.

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Speaker 2: And so welcome to the podcast Daniel and Jorge Explain

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Speaker 2: the Universe, a production of iHeartRadio in which we do

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Speaker 2: our best to understand the nature of the universe before

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Speaker 2: it comes crashing down on us. We try to cast

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Speaker 2: our minds out into the deepest, darkest reaches of space

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Speaker 2: and understand what's out there, how does it all work.

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Speaker 2: We look back into the history of the universe to

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Speaker 2: understand where it all came from, how it all works,

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Speaker 2: and how we got to be where we are. Jorge

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Speaker 2: can't be with us today, but I'm very glad to

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Speaker 2: have with us. Kelly. Kelly, thanks for joining us on

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Speaker 2: another adventure of dangerous history of the universe.

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Speaker 1: Thanks for having me. Despite what it might sound like,

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Speaker 1: I really do enjoy these episodes.

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Speaker 2: And there is a lot of danger out there in

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Speaker 2: the universe. If you cast your telescopes up to the Moon,

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Speaker 2: for example, you see that the surface is riddled with craters.

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Speaker 2: It looks like it's survived a drive by asteroiding. And

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Speaker 2: if you look even further out into the Solar System,

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Speaker 2: you can see crazy things like comets smashing into Jupiter,

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Speaker 2: creating fireballs the size of Earth. All this kind of

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Speaker 2: stuff seems to be happening all over the Solar System.

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Speaker 2: It's a dangerous place, epic and that might make you wonder,

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Speaker 2: of course, how safe is our home here? Is the

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Speaker 2: plan be strategy for a planet Earth super important? Do

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Speaker 2: we need to scramble to get off of Earth before

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Speaker 2: something comes and obliterates us. One way to answer that

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Speaker 2: question is to think about our cosmic history. Of course,

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Speaker 2: we'd like to know what might be hitting us in

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Speaker 2: the future, but the best way to learn about that

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Speaker 2: might be to think about things that have already hit

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Speaker 2: us in the past.

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Speaker 1: Are you going to be making me a question? The

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Speaker 1: conclusions from my book that maybe we do need that

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Speaker 1: Plan B and we need to start today because our

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Speaker 1: demise is imminence.

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Speaker 2: Maybe, or you could also look at this history and say, hey,

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Speaker 2: we survived all this stuff, so maybe it's not such

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Speaker 2: a big deal.

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Speaker 1: Right, all right, Well, let's see where this goes.

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Speaker 2: And so today on the podcast, we're going to be

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Speaker 2: diving deep into the history of Earth to answer the

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Speaker 2: question what is the largest asteroid impact in Earth's history?

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Speaker 1: You know who has a big impact. Your listeners, Let's

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Speaker 1: hear what they have to say.

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Speaker 2: Thanks very much to everybody who volunteers for this audience

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Speaker 2: participation segment of the podcast. We really love hearing your voices.

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Speaker 2: It helps us calibrate the level of the podcast. Plus,

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Speaker 2: we love you guys. We want to hear your voices

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Speaker 2: and we hope you enjoy hearing your own voice on

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Speaker 2: the podcast. If you'd like to play for a future episode,

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Speaker 2: don't be shy. Write to me two questions at Danielandjorge

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Speaker 2: dot com. Here's what listeners had to say. Wasn't just

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Speaker 2: the asteroid that made the dinosaurs extinct? Almost meaning?

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Speaker 4: Was it thea the planetoid that theoretically smashed into the

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Speaker 4: Earth and kind of blew them both apart and became

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Speaker 4: the Moon. I saw a model recently that looked so

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Speaker 4: beautiful of kind of this orange fluid, two spheres banging

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Speaker 4: into each other, and then the Moon forming, So maybe

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Speaker 4: it was that one.

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Speaker 3: I think that there's remnants of an ancient impact crater

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Speaker 3: in Europe somewhere, or maybe South America.

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Speaker 2: I can't really remember.

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Speaker 3: From memory. There was a very large asteroid impact in

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Speaker 3: South America somewhere that closed one of the dinosaur extinctions,

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Speaker 3: but I can't remember what its name is. Well, alternatively,

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Speaker 3: could the moon the collision that created the Moon be

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Speaker 3: the largest impact that the Earth has they've experienced. I

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Speaker 3: don't know whether that counts as an asteroid, but maybe

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Speaker 3: the first one.

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Speaker 5: That comes to mind disaster that killed the dinosaurs, though

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Speaker 5: I guess that was only like sixty five million years ago.

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Speaker 5: Since the Earth has been around for I think billions

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Speaker 5: of years are probably many more, much larger than that

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Speaker 5: earlier on. I guess another idea might be whatever it

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Speaker 5: was that hit the early proto Earth and split off

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Speaker 5: into the Moon.

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Speaker 6: Well, the extinction event of the dinosaurs comes to mind

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Speaker 6: up top, but probably there was a larger collision when

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Speaker 6: the planet was still pretty squishy. Probably there was a

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Speaker 6: larger one there, my best guess.

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Speaker 1: So one thing that I thought was interesting about the

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Speaker 1: responses is that I think there was a bit of

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Speaker 1: reticence to answer because folks weren't certain that they had

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Speaker 1: the difference between asteroids, meteors, comets meteorites clear. Should we

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Speaker 1: quickly go over like which ones and clarify that we're

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Speaker 1: specifically talking about asteroids today or do you think we

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Speaker 1: don't need to go over that.

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Speaker 2: No, I'm always down for exploring the ridiculous naming systems

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Speaker 2: in physics.

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Speaker 1: Or is today's episode just like giant hunks of stuff

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Speaker 1: and we're being general?

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Speaker 2: I mean, from a physics point of view, it doesn't

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Speaker 2: really matter. It's giant hunks of stuff hurtling themselves towards

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Speaker 2: the Earth that created huge explosions and left marks on

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Speaker 2: the Earth's surface. But it does kind of matter where

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Speaker 2: those things came from if you want to think about

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Speaker 2: our future prospects and whether, for example, your children will survive.

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Speaker 1: And I do care about that because I'm not a physicist,

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Speaker 1: And so what's the difference between an asteroid, a comet.

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Speaker 2: And a meteor yeah, great question. So an asteroid is

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Speaker 2: basically a small rock that orbits the Sun. These things

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Speaker 2: are smaller than a planet if they're like bigger than

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Speaker 2: the pebble sized objects that are called medioroids. So asteroids

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Speaker 2: are bigger than meteoroids, but smaller than planets. And it's

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Speaker 2: also the distinction that planets have to like clear the

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Speaker 2: path they're in. So you can have like a bunch

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Speaker 2: of asteroids in like a ring around the Sun and

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Speaker 2: that's not an issue. But nothing in there can basically

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Speaker 2: be a planet, even if it's as big as a planet.

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Speaker 2: So there's a complicated distinction there between like planets, dwarf planets,

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Speaker 2: asteroids and meteoroids. And then of course there's comets.

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Speaker 1: Okay, but it's mostly all just a matter of size.

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Speaker 2: It's mostly a matter of size. Comets actually come from

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Speaker 2: a different place that come from deeper in their Solar system.

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Speaker 2: There's either the Kuiper Belt or the Ort Cloud for

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Speaker 2: really distant stuff, and we'll talk about that a little bit.

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Speaker 2: So that's asteroids and meteoroids and comets. Those are all

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Speaker 2: things out in the Solar System. A meteor is something

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Speaker 2: that's burning up in our night sky, something that hits us,

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Speaker 2: and so that can be an asteroid or a comet

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Speaker 2: or a little bit of alien space junk or whatever.

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Speaker 2: So meteor is basically when it hits the Earth, asteroid,

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Speaker 2: meteoroid in comet is when it's still out there in space.

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Speaker 1: Got it, Okay? And so the listeners were very interested

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Speaker 1: or very aware of the extinction events where an asteroid

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Speaker 1: wiped out the dinosaurs. And then there was another person

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Speaker 1: who wanted to know if when the early Earth got

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Speaker 1: hit and the Moon split off, does maybe that count? Yeah,

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Speaker 1: the listeners are pretty darn well informed.

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Speaker 2: I'd say it's almost like they're listening to an awesome

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Speaker 2: podcast regularly that teaches them all about the Solar System

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Speaker 2: and the universe. Congrats and they pass the exam. But

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Speaker 2: you're right that it is important to understand, like what's

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Speaker 2: out there in the Solar System, where is this stuff

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Speaker 2: coming from? What are the sizes we expect for things

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Speaker 2: that are raining down on the Earth this death from above?

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Speaker 1: Okay, So we've done like an overview of definitions. Let's

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Speaker 1: jump into where asteroids come from and give a little

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Speaker 1: bit more background about where you would find asteroids in particular, and.

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Speaker 2: Go so something that you don't often realize when you

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Speaker 2: look up at the night sky is you mostly see

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Speaker 2: stars and planets, and you think about the Solar System

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Speaker 2: in terms of, you know, like the Sun and the

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Speaker 2: planets and maybe a couple of moons here or there.

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Speaker 2: But the Solar System is much much dirtier than that.

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Speaker 2: You know, there's a whole spectrum of chunks of stuff,

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Speaker 2: from the Sun down to planets, down to moons, down

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Speaker 2: to much smaller rocks. And as the stuff gets smaller,

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Speaker 2: becomes much more numerous. So you've like obviously one Sun,

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Speaker 2: a few planets, dozens of moons, But when you get

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Speaker 2: to smaller chunks of stuff, asteroids and meteoroids and all

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Speaker 2: that stuff, there's zillions and billions and even trillions of

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Speaker 2: these things. But of course they're not luminous, right, They

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Speaker 2: don't glow, and they don't reflect as much light because

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Speaker 2: they're small, so you don't mostly see them in the

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Speaker 2: night sky. They're mostly invisible. So the picture I want

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Speaker 2: to paint in your mind is space being filled basically

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Speaker 2: with dark rocks.

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Speaker 1: Wait, so I have an important question. Yeah, So in

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Speaker 1: Star Wars, this is how all important questions start in

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Speaker 1: Star Wars, when they're like trying to navigate around rocks

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Speaker 1: and space. There's just like they're everywhere and you can't

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Speaker 1: get around them. If you were out in space and

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Speaker 1: you were to stand on like one chunk of something,

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Speaker 1: would you be able to see other chunks of stuff nearby?

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Speaker 1: Or even though there's lots of them, are they still

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Speaker 1: like pretty darn spread out or is it like Star Wars.

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Speaker 2: No, it's a great question. It's not like Star Wars.

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Speaker 2: It turns out Star Wars not a documentary, not a

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Speaker 2: reliable way to plan your space mission.

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Speaker 1: Who you got to know? That would have been embarrassing

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Speaker 1: to say that public.

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Speaker 2: But no, these rocks are pretty big. But they're also

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Speaker 2: very far apart. Because space is vast, especially as you

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Speaker 2: get out into the further reaches of the Solar System,

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Speaker 2: the amount of space between these planets gets enormous, right,

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Speaker 2: The volume of the sphere goes as the radius cube,

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Speaker 2: and so if you're like another million miles away from

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Speaker 2: the Sun, then you create a volume of space which

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Speaker 2: is much much bigger than everything inside of it. And

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Speaker 2: so even though there are lots and lots of asteroids

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Speaker 2: out there, remnants from the formation of the Solar System

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Speaker 2: that didn't pull together into planets or were disturbed by

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Speaker 2: the gravity of Jupiter, for example, to prevent them from coalescing.

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Speaker 2: They're far enough apart that you can't really have that's

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Speaker 2: sort of like exciting space dodgem game.

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Speaker 1: Well, you've dashed a lot of Star Wars related dreams today,

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Speaker 1: but it's important to know, so, all right, So where

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Speaker 1: do you find most.

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Speaker 2: Of these So most of these things are in the

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Speaker 2: asteroid belt, this region between Mars and Jupiter. And that's

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Speaker 2: no accident. You know, as the Solar System is forming,

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Speaker 2: it clumps together, mostly into the Sun and then into

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Speaker 2: the planets, and planets form when you have like a

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Speaker 2: seed of a heavy object, something that can pull stuff

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Speaker 2: together and generate its own gravitational well, rather than just

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Speaker 2: getting sucked into the Sun. But because Jupiter became so big,

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Speaker 2: it's gravity was strong enough that it disrupted the formation

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Speaker 2: of other stuff. And so that's why, for example, these

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Speaker 2: asteroids near Mars Jupiter, even though they've been around for

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Speaker 2: billions of years, they haven't like gradually coalesced into one

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Speaker 2: big object. There's lots and lots of them over there.

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Speaker 1: Oh, it's kind of fun to imagine what it would

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Speaker 1: have been like to have another planet out there. It's

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Speaker 1: like Jupiter.

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Speaker 2: Another way you can see the effect of Jupiter on

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Speaker 2: these asteroids is that there's a bunch of astrailids in

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Speaker 2: orbit with Jupiter. If you draw an ellipse for where

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Speaker 2: Jupiter goes around the Sun, it's not actually totally empty.

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Speaker 2: There's a whole cluster of asteroids that are leading Jupiter

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Speaker 2: and another cluster that are following Jupiter. They're called the

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Speaker 2: Greeks and the Trojans. These two like different camps of asteroids.

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Speaker 1: So I thought that planets were supposed to clear their orbits.

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Speaker 1: Does that okay?

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Speaker 2: All right?

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Speaker 1: But Jupiter is huge, so all right, go on.

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Speaker 2: So if you were like a lawyer for Pluto, you

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Speaker 2: might raise this objection and say, hey, folks, you've been

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Speaker 2: inconsistent here because planets are supposed to clear their orbit.

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Speaker 2: But you know, when planets get big enough, then they

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Speaker 2: can actually collect asteroids in these lagrange points, these points

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Speaker 2: where the Sun and Jupiter's gravity balances out in a

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Speaker 2: way that there's like a little gravitational well there for

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Speaker 2: asteroids to collect in. But it's super cool. We're actually

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Speaker 2: sending a mission to go visit these Trojans pretty soon

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Speaker 2: be a lot of fun.

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Speaker 1: Wait your what.

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Speaker 2: We have a mission that's going to go visit the

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Speaker 2: asteroid belt and one of these trojans.

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Speaker 1: Ooh, that's exciting.

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Speaker 2: Yeah, we had a whole podcast episode about it, Me

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Speaker 2: and you, so check that one out if you're curious

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Speaker 2: about it. But even though you imagine this space to

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Speaker 2: be filled with rocks, and some of these are pretty big,

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Speaker 2: like Series is a whole dwarf planet in this region.

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Speaker 2: It's like nine hundred kilometers in diameter, So that's pretty big.

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Speaker 2: I mean, it's like a tenth or thirteenth of the

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Speaker 2: radius of Earth. That's the biggest thing out there in

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Speaker 2: the asteroid belt. But after that it pretty much falls off.

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Speaker 2: Like half of the mass of the asteroid Belt is

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Speaker 2: in just four big Mama asteroids. After that, it's a

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Speaker 2: bunch of smaller stuff.

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Speaker 1: And those big Mama asteroids are stay input.

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Speaker 2: I hope mostly they stay input. NaSTA does a really

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Speaker 2: good job of tracking these folks and thinking about their trajectory.

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Speaker 2: They can predict them out to about one hundred years

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Speaker 2: from now. After that, it's too chaotic with all the

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Speaker 2: influence from Jupiter and Saturn and the other little bits

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Speaker 2: of the asteroid belt for them to reliably predict where

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Speaker 2: they're going to be. But mostly they know where all

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Speaker 2: the big ones are and they know they're not going

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Speaker 2: to hit us in the next one hundred years.

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Speaker 1: All right, all right, that's that certainty that I can handle.

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Speaker 1: I'll sleep tonight, all right. So, so half of the

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Speaker 1: mass is in those four objects, and how is the

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Speaker 1: rest of the mass distributed?

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Speaker 2: So after that it's lots of tiny little ones. And

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Speaker 2: you know, it used to be much more. It used

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Speaker 2: to be that the asteroid belt had like one hundred

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Speaker 2: or a thousand times as much mass as it does.

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Speaker 2: But when it's so dense over there, they will eventually

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Speaker 2: bump into each other or even just pull on each

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Speaker 2: other gravitationally and fall out of orbit and then plummet

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Speaker 2: into the Sun. So something like ninety nine point ninety

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Speaker 2: percent of the mass of the asteroid belt is gone.

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Speaker 2: It was lost in the first one hundred million years

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Speaker 2: of the Solar System. And what's left is a bunch

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Speaker 2: of smaller asteroids. But even if you add it all

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Speaker 2: up together, it's not even that much stuff. It's like

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Speaker 2: four or five percent the mass of the Moon. If

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Speaker 2: you like gathered it all together into one big ball.

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Speaker 1: So do we need to worry about like so you

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Speaker 1: said most of it has already fallen into the Sun

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Speaker 1: or presumably fallen into Jupiter or something. Is the rest

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Speaker 1: of it? Something like if voyager, you know, was going

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Speaker 1: out past Jupiter, did we have to worry about it

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Speaker 1: running into that stuff? Or there's just not that much

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Speaker 1: of it out there?

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Speaker 2: There's not that much of it out there. Yeah, if

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Speaker 2: you pointed a spaceship through the asteroid belt, you'd have

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Speaker 2: a very small chance of hitting anything.

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Speaker 1: Nice. That's good to hear.

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Speaker 2: Yeah, so you can put your kids on that spaceship

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Speaker 2: and send amount of space without worrying about it.

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Speaker 1: Kelly, No, No, my kids are staying here. I wrote

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Speaker 1: a whole book on why this is a bad idea,

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Speaker 1: four years of my life. My kids are staying here

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Speaker 1: unless they want to go, and then I probably won't stop. Okay,

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Speaker 1: let's take a break. So we've talked about the asteroid

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Speaker 1: belt between Mars and Jupiter. There are other clumps of

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Speaker 1: death from above, and we'll get to that after the break,

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Speaker 1: all right, So, Daniel, where else are these clumps of death?

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Speaker 1: Where else could they be coming from if they're going

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Speaker 1: to be heading towards Earth.

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Speaker 2: So the asteroids are not really something to worry about.

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Speaker 2: We know where most of the big ones are, as

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Speaker 2: we said, and we know where they're going to be.

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Speaker 2: The more dangerous things are further out in the Solar system,

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Speaker 2: out in the Kuiper Belt, like past Neptune, like between

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Speaker 2: thirty and fifty AU, is a bunch of frozen ice cubes,

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Speaker 2: essentially out past the snow line where the Sun is

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Speaker 2: not powerful enough to vaporize. Ice can still be a

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Speaker 2: big factor in the formation of clumps of stuff and

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Speaker 2: also planets. Right, That's why we call Neptune and Urinus

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Speaker 2: the ice giants. So out there in the Kuiper Belt,

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Speaker 2: they're basically a bunch of big frozen snowballs, and sometimes

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Speaker 2: some of them fall towards the center of the Solar system,

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Speaker 2: and those are comets because as they burn their way

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Speaker 2: towards the Sun, the Sun is then boiling stuff off

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Speaker 2: of them, making that tail.

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Speaker 1: And you maybe already said this, and I guess I

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Speaker 1: just didn't understand. What, why are we more at risk

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Speaker 1: from stuff in the Kuiper Belt than the asteroid belt,

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Speaker 1: which is closer is there movement just more chaotic.

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Speaker 2: Well, for two reasons. One is they come from further out,

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Speaker 2: so that by the time they make it into our

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Speaker 2: inner neighborhood of the Solar System, they're moving faster, like

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Speaker 2: they've fallen further into a gravity well. And velocity is

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Speaker 2: important because the faster you're moving when you hit the Earth,

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Speaker 2: the more energy you're depositing, the more the seismic waves,

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Speaker 2: the more stuff you toss up into the atmosphere. Velocity

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Speaker 2: does matter. The other reason is that these things are

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Speaker 2: harder to study. They're further away, so they're harder to spot,

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Speaker 2: and they're more erratic. They're more susceptible to like passing

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Speaker 2: stars that give them a little gentle tug and nudge

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Speaker 2: them in towards the center of the Solar System. And

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Speaker 2: there's so many of them out there that we can't

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Speaker 2: possibly track all of them, so they're harder to spot

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Speaker 2: and higher speeds.

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Speaker 1: I don't like it all.

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Speaker 2: Right, Well, then you're definitely not going to like. The

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Speaker 2: Org cloud, even further away from the Sun is a

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Speaker 2: theoretical cloud of basically icy many planets. We think there

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Speaker 2: might be trillions of objects in there that are more

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Speaker 2: than a kilometer wide, and maybe even billions that are

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Speaker 2: twenty kilometers wide. You said theoretical, Yes, theoretical.

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Speaker 1: I had assumed we knew this about the Ork Cloud already.

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Speaker 1: This is just like stuff we think. I mean, I

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Speaker 1: guess it makes sense. It's really far away, but we're

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Speaker 1: we just think it's out there. We're not sure.

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Speaker 2: We think the Orc Cloud is out there. It makes sense,

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Speaker 2: it's part of all of our simulations. It's been predicted,

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Speaker 2: but we've never actually seen something in the Ork Cloud

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Speaker 2: because it is super duper far away. These things are

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Speaker 2: like one to three light ears from the Sun.

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Speaker 1: But it's on a bunch of the illustrations I've seen.

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Speaker 2: Artists' conceptions. Oh my gosh, I know. No, this is

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Speaker 2: basically an interstellar space. It's not really part of the

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Speaker 2: heliosphere or the Solar system. But we do think it's

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Speaker 2: part of the gravitational system of the Sun, and there's

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Speaker 2: a lot of stuff out there. Theoretically, it's much further

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Speaker 2: out than like even where Voyager one has gone, and

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Speaker 2: it's so far away, and these things are pretty small,

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Speaker 2: so it's hard to spot them directly.

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Speaker 1: Well, Voyager one gets there before it runs out of power.

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Speaker 2: It's going to take like three hundred years for Voyager

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Speaker 2: one to get there, and it basically ran out of power. Recently,

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Speaker 2: I heard that they stopped hearing from it, so we

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Speaker 2: already know the end of that story.

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Speaker 1: Oh oh, that's really sad. I can't believe I missed that. Yes,

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Speaker 1: Christ in Peace one.

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Speaker 2: Exactly, or floating piece or whatever you say out there

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Speaker 2: in space. The Ork Cloud is theoretical. We're fairly confident

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Speaker 2: it's there. We see indirections, and also we think it's

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Speaker 2: the source of the longer period comets. Because these things

402
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Speaker 2: are so far away, they take a long time to

403
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Speaker 2: make it into the Inner Solar System and maybe impact

404
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Speaker 2: on a juicy Inner Solar System planet or not. And

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Speaker 2: so the shorter period comets probably come from the Kuiper Belt,

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Speaker 2: and the longer period comets with even more mass and

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Speaker 2: even more velocity come from the Org Cloud.

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Speaker 1: Have we seen something come closer to us that we

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Speaker 1: think came from ort cloud.

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Speaker 2: Well, we've definitely seen a lot of long period comets,

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Speaker 2: these comments that take centuries sometimes to orbit the Solar System,

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Speaker 2: and so we think that they originated from the Ork Cloud.

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Speaker 2: So yeah, we think those things are visitors from the

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Speaker 2: Ork Cloud. And that's one reason why people are excited

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Speaker 2: to like go sample comets while they're sending probes out

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Speaker 2: there to grab bits of comments to see, like what

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Speaker 2: is it like out there in the Orc cloud. Be

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Speaker 2: awesome to get a sample of the Ork cloud that

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Speaker 2: visited the Inner Solar System.

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Speaker 1: Okay, so we've talked about where these things reside. Let's

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Speaker 1: talk a little bit more about size. So like, if

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Speaker 1: something that's a meter in diameter comes at us, that's

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Speaker 1: not a problem, right, that's going to burn up.

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Speaker 2: That's not a problem. That's actually kind of awesome. Yeah,

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Speaker 2: it makes really nice streak in the sky. It doesn't

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Speaker 2: really do any damage. And also it happens all the time.

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Speaker 2: You know, space, as we said, is filled with dark rocks.

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Speaker 2: Is not just the asteroids that we've cataloged in the

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Speaker 2: asteroid belt. There's rocks out there all over the place,

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Speaker 2: just floating free, tugged by Jupiter here and there. And

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Speaker 2: that's why we see meteor showers. Right, Every meteor shower

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Speaker 2: are a bunch of rocks hitting the Earth. Fortunately, our

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Speaker 2: atmosphere is dense enough to act like a big pillow,

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Speaker 2: and so when they hit the atmosphere, there's friction, they

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Speaker 2: heat up and then they burn up before they hit

436
00:22:18,840 --> 00:22:21,240
Speaker 2: the ground. And so stuff that's less than a meter

437
00:22:21,359 --> 00:22:23,000
Speaker 2: in size, it happens all the time.

438
00:22:23,119 --> 00:22:24,639
Speaker 1: Yeah, a big slammable pillow.

439
00:22:24,920 --> 00:22:25,119
Speaker 2: You know.

440
00:22:25,200 --> 00:22:29,760
Speaker 1: I was when I was researching the spacebook, and we

441
00:22:29,760 --> 00:22:32,560
Speaker 1: were looking at companies that had sort of like out

442
00:22:32,600 --> 00:22:35,960
Speaker 1: there ways of planning to make money on space stuff.

443
00:22:35,960 --> 00:22:39,560
Speaker 1: There was a company that was pitching that they could

444
00:22:39,600 --> 00:22:44,840
Speaker 1: make you essentially like asteroid meteor shower sorts of things

445
00:22:44,880 --> 00:22:47,520
Speaker 1: by like sending masks to space and then having it

446
00:22:47,560 --> 00:22:49,320
Speaker 1: come down at a certain time, and that they could

447
00:22:49,400 --> 00:22:52,359
Speaker 1: like determine the colors that it would be. Wow, so like,

448
00:22:52,600 --> 00:22:56,160
Speaker 1: you know, the most epic birthday present, like a pink

449
00:22:56,240 --> 00:22:58,080
Speaker 1: meteor shower for your Kinsania.

450
00:22:59,200 --> 00:23:02,200
Speaker 2: But anyway, that sounds like there's no way that could

451
00:23:02,240 --> 00:23:06,120
Speaker 2: go wrong. Yeah, absolutely, that doesn't sound dangerous at all.

452
00:23:07,160 --> 00:23:11,679
Speaker 1: No, No, it's great, it's great. Okay, all right, so

453
00:23:12,160 --> 00:23:15,720
Speaker 1: we've got a meter and it's beautiful. When does it

454
00:23:15,760 --> 00:23:18,040
Speaker 1: start becoming less beautiful and more scary?

455
00:23:18,320 --> 00:23:21,240
Speaker 2: Yeah, So there's this trade off. As they get larger,

456
00:23:21,440 --> 00:23:25,879
Speaker 2: they get more dangerous, and fortunately they also get less common. So,

457
00:23:26,000 --> 00:23:29,000
Speaker 2: for example, stuff that's like a meter wide hits the

458
00:23:29,040 --> 00:23:32,360
Speaker 2: Earth around once per day, and that's not that big

459
00:23:32,400 --> 00:23:34,320
Speaker 2: a deal. I mean, you can make a big explosion

460
00:23:34,400 --> 00:23:36,480
Speaker 2: in the sky and it's the kind of stuff that

461
00:23:36,520 --> 00:23:39,480
Speaker 2: you hear about, you know, like the churbulence explosion in

462
00:23:39,560 --> 00:23:43,640
Speaker 2: Russia recently. It's an order magnitude of a meter size thing.

463
00:23:44,320 --> 00:23:47,440
Speaker 2: Often this just happens, you know, over the ocean. Nobody notices,

464
00:23:47,960 --> 00:23:50,240
Speaker 2: but occasionally you get a bigger one. And if you

465
00:23:50,280 --> 00:23:53,760
Speaker 2: had something like ten or twenty meters wide, this happens

466
00:23:53,800 --> 00:23:57,080
Speaker 2: like every ten or fifty years, then you're starting to

467
00:23:57,080 --> 00:24:00,000
Speaker 2: get energies comparable to an atomic bomb explosion.

468
00:24:00,640 --> 00:24:03,600
Speaker 1: WHOA, I feel like we should hear about that more often.

469
00:24:03,600 --> 00:24:05,080
Speaker 1: But I guess I guess you said that it happens

470
00:24:05,080 --> 00:24:06,919
Speaker 1: over the ocean a lot, and so we wouldn't hear

471
00:24:06,920 --> 00:24:07,280
Speaker 1: about it.

472
00:24:07,400 --> 00:24:09,159
Speaker 2: Yeah. I had exactly the same reaction. I was like,

473
00:24:09,200 --> 00:24:12,640
Speaker 2: hold on, a second, nuclear bomb explosions not that common.

474
00:24:13,040 --> 00:24:16,280
Speaker 2: You think you'd hear about it. This is beyond the news.

475
00:24:16,440 --> 00:24:18,879
Speaker 2: You'd feel it or something. But these things tend to

476
00:24:18,880 --> 00:24:21,840
Speaker 2: happen in the upper atmosphere and often over the ocean,

477
00:24:21,960 --> 00:24:23,720
Speaker 2: so they're just not observed or reported.

478
00:24:23,840 --> 00:24:26,479
Speaker 1: But with how much like surveillance equipment we have in space,

479
00:24:27,280 --> 00:24:28,960
Speaker 1: I would expect you'd see it. But I guess that

480
00:24:29,040 --> 00:24:31,800
Speaker 1: surveillance equipment, you know, has only been up there since

481
00:24:32,320 --> 00:24:34,360
Speaker 1: like the sixties or something like that, so we don't

482
00:24:34,359 --> 00:24:39,200
Speaker 1: have that many years of data. Wow, Okay, that's the

483
00:24:39,280 --> 00:24:42,240
Speaker 1: numbers you're giving are much more regular than I would

484
00:24:42,240 --> 00:24:43,560
Speaker 1: have guessed. Let's move on.

485
00:24:44,119 --> 00:24:47,080
Speaker 2: Yeah, and it's also energy deposited in the upper atmosphere,

486
00:24:47,280 --> 00:24:49,200
Speaker 2: so it's not like the equivalent of somebody sitting off

487
00:24:49,200 --> 00:24:52,520
Speaker 2: a nuclear weapon on land or even dropping one in

488
00:24:52,560 --> 00:24:55,800
Speaker 2: the ocean. And so while the military is definitely tracking

489
00:24:55,880 --> 00:24:58,199
Speaker 2: these things, and we talked about like the network of

490
00:24:58,240 --> 00:25:00,960
Speaker 2: satellites that the military has when we're talking recently about

491
00:25:01,000 --> 00:25:03,720
Speaker 2: interstellar asteroids and whether they've hit the Earth and whether

492
00:25:03,800 --> 00:25:07,840
Speaker 2: Avilobe has actually gathered any spherials from them. So we

493
00:25:07,920 --> 00:25:09,760
Speaker 2: know the folks are tracking them, it's just not that

494
00:25:09,800 --> 00:25:12,800
Speaker 2: big a deal. It's like getting your shields zapped with lasers,

495
00:25:12,880 --> 00:25:14,440
Speaker 2: but you know your shields are pretty strong.

496
00:25:14,600 --> 00:25:17,840
Speaker 1: Okay, all right, So these explosions are happening in the atmosphere.

497
00:25:17,880 --> 00:25:21,200
Speaker 1: So have we talked about a size yet that could

498
00:25:21,560 --> 00:25:25,639
Speaker 1: reach the Earth, and is there a relationship between size

499
00:25:25,680 --> 00:25:27,800
Speaker 1: and whether Yeah, there's got to be a relationship between

500
00:25:27,840 --> 00:25:29,520
Speaker 1: size and whether or not it makes it to the

501
00:25:29,560 --> 00:25:30,800
Speaker 1: Earth to impact, right.

502
00:25:30,840 --> 00:25:34,720
Speaker 2: Yeah, So anything above like twenty five or fifty meters

503
00:25:35,119 --> 00:25:38,080
Speaker 2: will probably make it to the surface. Anything smaller than

504
00:25:38,119 --> 00:25:40,680
Speaker 2: that is probably going to burn up in the atmosphere.

505
00:25:41,240 --> 00:25:42,880
Speaker 2: And once you get up to that size, we're talking

506
00:25:42,880 --> 00:25:46,560
Speaker 2: about a significant amount of energy. So like one hundred

507
00:25:46,600 --> 00:25:49,119
Speaker 2: meters size asteroid if it hits, which is something that

508
00:25:49,200 --> 00:25:52,479
Speaker 2: happens every few thousand years, we think has as much

509
00:25:52,640 --> 00:25:55,000
Speaker 2: energy as three thousand atomic bombs.

510
00:25:55,200 --> 00:25:57,880
Speaker 1: Oh my gosh, Okay, so five thousand years. How long

511
00:25:57,920 --> 00:26:01,520
Speaker 1: have we had recorded history? Do we have? And I

512
00:26:01,560 --> 00:26:04,159
Speaker 1: know it could have happened in the ocean and we

513
00:26:04,240 --> 00:26:06,639
Speaker 1: missed it or something, But do we have any recorded

514
00:26:07,280 --> 00:26:09,080
Speaker 1: histories of this sort of thing happening?

515
00:26:09,400 --> 00:26:11,200
Speaker 2: We do, we think, and we're going to dig into

516
00:26:11,200 --> 00:26:12,160
Speaker 2: that in just a minute.

517
00:26:12,400 --> 00:26:13,360
Speaker 1: Who suspenseful?

518
00:26:15,400 --> 00:26:18,600
Speaker 2: And then as the things get larger, like a kilometer wide,

519
00:26:18,640 --> 00:26:22,480
Speaker 2: we're talking about something every half million years. We think

520
00:26:22,520 --> 00:26:26,679
Speaker 2: probably five kilometer wide asteroids happen every twenty to forty

521
00:26:26,800 --> 00:26:31,040
Speaker 2: million years, and basically anything above five or ten kilometers

522
00:26:31,240 --> 00:26:34,720
Speaker 2: is extinction level event. We're talking about creating creators that

523
00:26:34,760 --> 00:26:38,240
Speaker 2: are like one hundred kilometers wide, tossing up enormous amounts

524
00:26:38,240 --> 00:26:43,560
Speaker 2: of stuff into the atmosphere, obliterating a consonant instantly with fireballs,

525
00:26:43,840 --> 00:26:46,760
Speaker 2: so like an enormous amount of energy, but fortunately very

526
00:26:46,880 --> 00:26:47,440
Speaker 2: very rare.

527
00:26:47,560 --> 00:26:49,200
Speaker 1: I don't know what to say other than maybe I'm

528
00:26:49,200 --> 00:26:52,160
Speaker 1: not going to be sleeping tonight. Maybe I take it back.

529
00:26:53,320 --> 00:26:55,159
Speaker 2: And so, of course we're really curious about if this

530
00:26:55,240 --> 00:26:57,200
Speaker 2: is going to happen in the future, and when we

531
00:26:57,440 --> 00:27:00,119
Speaker 2: can also look around the Earth for signs at this

532
00:27:00,119 --> 00:27:03,080
Speaker 2: this happened because it's hit the Moon, it's hit basically

533
00:27:03,119 --> 00:27:06,160
Speaker 2: every surface in the Solar System. The Earth is not special.

534
00:27:06,359 --> 00:27:09,359
Speaker 2: The Earth also gets hit with this stuff, but only

535
00:27:09,440 --> 00:27:12,000
Speaker 2: the larger ones make it down to the surface and

536
00:27:12,119 --> 00:27:13,480
Speaker 2: cause impact craters.

537
00:27:13,560 --> 00:27:15,959
Speaker 1: So now I'm realizing that I would love to know

538
00:27:16,000 --> 00:27:19,920
Speaker 1: how we figured out these frequency data that you said.

539
00:27:19,960 --> 00:27:21,879
Speaker 1: You know, how do we know that you get a

540
00:27:21,960 --> 00:27:25,600
Speaker 1: five meter size one almost every five years? And how

541
00:27:25,680 --> 00:27:29,119
Speaker 1: can we search the Earth for evidence of how often

542
00:27:29,119 --> 00:27:31,400
Speaker 1: it got hit? Are you saying that we don't bother

543
00:27:31,480 --> 00:27:34,239
Speaker 1: searching the Earth because it's easier to just look at

544
00:27:34,240 --> 00:27:34,600
Speaker 1: the Moon.

545
00:27:34,840 --> 00:27:37,880
Speaker 2: These are extrapolations from our stimulations of like what's out

546
00:27:37,920 --> 00:27:40,160
Speaker 2: there in the Solar system, how often do we expect

547
00:27:40,160 --> 00:27:43,120
Speaker 2: stuff to hit the Earth. We can also verify those

548
00:27:43,119 --> 00:27:46,000
Speaker 2: and a lot of those stimulations are built on studies

549
00:27:46,040 --> 00:27:48,959
Speaker 2: of impact craters on the Moon and other objects, the

550
00:27:48,960 --> 00:27:51,800
Speaker 2: Moon just being super close by and like riddled with

551
00:27:51,880 --> 00:27:54,760
Speaker 2: impact craters, and they do all sorts of cool studies

552
00:27:54,800 --> 00:27:56,720
Speaker 2: to see like the age of craters on the Moon,

553
00:27:56,720 --> 00:27:59,159
Speaker 2: by seeing how they're layered, Like if you have a

554
00:27:59,520 --> 00:28:02,760
Speaker 2: fresh then it's gonna have no other craters inside of it,

555
00:28:02,960 --> 00:28:05,000
Speaker 2: whereas an old crater is gonna have lots of other

556
00:28:05,119 --> 00:28:08,160
Speaker 2: small craters within it. And so you can tell the

557
00:28:08,200 --> 00:28:10,400
Speaker 2: age of these craters on the Moon by like how

558
00:28:10,440 --> 00:28:12,720
Speaker 2: many other craters have been layered on top of them.

559
00:28:12,800 --> 00:28:13,639
Speaker 2: It's super cool.

560
00:28:13,960 --> 00:28:16,560
Speaker 1: That is super cool. And if we couldn't do that

561
00:28:16,640 --> 00:28:18,800
Speaker 1: on Earth because that stuff gets covered up too fast,

562
00:28:18,840 --> 00:28:19,280
Speaker 1: is that right?

563
00:28:19,359 --> 00:28:22,119
Speaker 2: No, we do actually have evidence of craters here on Earth,

564
00:28:22,680 --> 00:28:25,119
Speaker 2: though it is more complicated because we have weather and

565
00:28:25,160 --> 00:28:27,560
Speaker 2: we have an atmosphere, and so only the bigger stuff

566
00:28:27,840 --> 00:28:30,280
Speaker 2: leaves evidence. But there's lots of cool ways that people

567
00:28:30,359 --> 00:28:34,800
Speaker 2: have figured out that formations on Earth are due to impact,

568
00:28:35,160 --> 00:28:38,320
Speaker 2: Like there's certain kinds of rock that are only formed

569
00:28:38,640 --> 00:28:43,000
Speaker 2: when you get a super high energy impact, Like shocked quartz.

570
00:28:43,360 --> 00:28:46,560
Speaker 2: This is a structure of quartz that's only formed under

571
00:28:46,720 --> 00:28:50,800
Speaker 2: extremely high pressure. Like you squeeze quartz hard enough and

572
00:28:50,880 --> 00:28:54,600
Speaker 2: it changes its crystal structure and it stays that way

573
00:28:54,640 --> 00:28:56,520
Speaker 2: even after you remove the pressure.

574
00:28:56,760 --> 00:28:59,360
Speaker 1: I like that name shocked quartz. It was like, Oh,

575
00:28:59,680 --> 00:29:01,920
Speaker 1: that's a surprising explosion.

576
00:29:02,600 --> 00:29:06,520
Speaker 2: It sucks. We only actually discovered it recently in nuclear

577
00:29:06,560 --> 00:29:10,280
Speaker 2: testing craters, Like when we started creating these conditions, these

578
00:29:10,360 --> 00:29:13,960
Speaker 2: nuclear bombs, we discovered this shock courts. Then we found

579
00:29:13,960 --> 00:29:16,280
Speaker 2: it in other places on Earth. We're like, oh, wow,

580
00:29:16,720 --> 00:29:19,440
Speaker 2: this must have been a big explosion too, thousands of

581
00:29:19,520 --> 00:29:23,040
Speaker 2: years ago. So it's kind of cool how modern technology

582
00:29:23,120 --> 00:29:25,800
Speaker 2: has enabled us to discover the secrets of the past.

583
00:29:26,280 --> 00:29:31,640
Speaker 1: So many positives to nuclear bomb testing.

584
00:29:32,240 --> 00:29:34,960
Speaker 2: But earlier you were asking whether we have evidence for

585
00:29:35,120 --> 00:29:38,080
Speaker 2: like these sort of smaller collisions in the recent past,

586
00:29:38,640 --> 00:29:42,080
Speaker 2: And maybe my favorite one is in Estonia. This evidence

587
00:29:42,080 --> 00:29:44,600
Speaker 2: in Estonia of an impact that left a crater that's

588
00:29:44,600 --> 00:29:47,800
Speaker 2: like one hundred meters wide, and they think it happened

589
00:29:47,840 --> 00:29:51,040
Speaker 2: in fifteen hundred BC, So this is just a few

590
00:29:51,120 --> 00:29:53,800
Speaker 2: thousand years ago, you know, as we were saying, like,

591
00:29:53,920 --> 00:29:57,719
Speaker 2: we expect one hundred meter wide impactors every few thousand years.

592
00:29:58,200 --> 00:30:00,120
Speaker 2: So do we have any written history of this? And

593
00:30:00,200 --> 00:30:01,360
Speaker 2: this is a great candidate.

594
00:30:01,800 --> 00:30:05,840
Speaker 1: Go on, So is it the ancient Egyptians? They did

595
00:30:05,840 --> 00:30:06,560
Speaker 1: a lot of writing.

596
00:30:07,280 --> 00:30:10,080
Speaker 2: The ancient Egyptians did a lot of writing. But these

597
00:30:10,120 --> 00:30:13,280
Speaker 2: are lakes in Estonia that they're pretty certain were caused

598
00:30:13,320 --> 00:30:16,320
Speaker 2: by an impact. They're like these big circular lakes, and

599
00:30:16,360 --> 00:30:19,400
Speaker 2: they suspect that they may actually appear in Estonian and

600
00:30:19,440 --> 00:30:22,960
Speaker 2: Finnish mythology. So now this is very tenuous, of course,

601
00:30:23,240 --> 00:30:25,600
Speaker 2: but you know, you're wondering, like ancient peoples when they

602
00:30:25,600 --> 00:30:28,240
Speaker 2: saw this thing, what did they think? How they describe it?

603
00:30:28,320 --> 00:30:31,280
Speaker 2: How would it appear in their records? Because they're not

604
00:30:31,320 --> 00:30:34,200
Speaker 2: all doing astronomy. I mean, the ancient Chinese have like

605
00:30:34,240 --> 00:30:37,480
Speaker 2: astronomical records way way back then, but we don't have

606
00:30:37,520 --> 00:30:40,880
Speaker 2: astronomical records from everybody. You, of course, are familiar with

607
00:30:40,920 --> 00:30:43,120
Speaker 2: the famous work of literature of Beowulf.

608
00:30:43,400 --> 00:30:47,280
Speaker 1: I am indeed yeh, because you're the best adaptation ever

609
00:30:47,360 --> 00:30:50,080
Speaker 1: has been written by my husband for children, because who

610
00:30:50,160 --> 00:30:52,760
Speaker 1: didn't want the Beowolf for children version?

611
00:30:53,040 --> 00:30:57,200
Speaker 2: Yes, well exactly, And so spoiler alert, Beowulf dies in

612
00:30:57,240 --> 00:31:00,800
Speaker 2: the end, and he dies the hands of a fiery dragon.

613
00:31:01,400 --> 00:31:03,760
Speaker 2: And in the text they call it the sky Plague,

614
00:31:03,800 --> 00:31:06,480
Speaker 2: a long creature that flew at night over the coast

615
00:31:06,560 --> 00:31:10,400
Speaker 2: of Greystone Cliffs, and in the poem it uses its fiery,

616
00:31:10,480 --> 00:31:14,680
Speaker 2: poisonous breath to scorch and depopulate the countryside. And some

617
00:31:14,720 --> 00:31:17,320
Speaker 2: people think I read a sociology paper that says that

618
00:31:17,360 --> 00:31:20,280
Speaker 2: the description of the dragon and the devastation it causes

619
00:31:20,480 --> 00:31:24,160
Speaker 2: has a lot in common with this impact site in Collie,

620
00:31:24,640 --> 00:31:28,400
Speaker 2: And there are indeed Greystone Cliffs dearby, and so it

621
00:31:28,440 --> 00:31:32,000
Speaker 2: could be that, like some fiery impact left its traces

622
00:31:32,000 --> 00:31:34,880
Speaker 2: in the local mythology and ended up in the text

623
00:31:34,880 --> 00:31:35,640
Speaker 2: of Beowulf.

624
00:31:35,760 --> 00:31:37,600
Speaker 1: WHOA, that's pretty cool.

625
00:31:38,880 --> 00:31:40,880
Speaker 2: And you know this is not scientific, of course, it's

626
00:31:40,880 --> 00:31:43,240
Speaker 2: always very easy to come up with a connection where

627
00:31:43,280 --> 00:31:46,000
Speaker 2: there isn't one. But it's fun to imagine how these

628
00:31:46,000 --> 00:31:49,840
Speaker 2: people might have thought about these huge, devastating impact And

629
00:31:49,840 --> 00:31:52,440
Speaker 2: it's something you can go and visit today. It's called Kali.

630
00:31:52,560 --> 00:31:56,680
Speaker 2: I'm sure, I'm pronouncing it incorrectly kaa l I. And

631
00:31:56,720 --> 00:31:59,400
Speaker 2: it's a site in Estonia with obvious impact craters.

632
00:32:00,120 --> 00:32:04,080
Speaker 1: It's a wonderful work of fiction, particularly if you're reading

633
00:32:04,120 --> 00:32:06,880
Speaker 1: the version written by my husband called be Wolf.

634
00:32:07,560 --> 00:32:09,640
Speaker 2: Exactly, and it may have inspired some of the great

635
00:32:09,680 --> 00:32:13,080
Speaker 2: literature of our civilization. But you don't actually have to

636
00:32:13,120 --> 00:32:15,920
Speaker 2: travel to Estonia to see impact creators. We have an

637
00:32:15,920 --> 00:32:17,280
Speaker 2: awesome one right here in.

638
00:32:17,200 --> 00:32:20,200
Speaker 1: The US, and after a break, we'll tell you where

639
00:32:20,240 --> 00:32:35,080
Speaker 1: you can find it. All right, So, for your listeners

640
00:32:35,080 --> 00:32:37,720
Speaker 1: who reside in the United States, if we want to

641
00:32:37,800 --> 00:32:41,280
Speaker 1: visit our nation's crater, where would we go?

642
00:32:42,680 --> 00:32:46,040
Speaker 2: So in Arizona, there's a place well named. It's called

643
00:32:46,320 --> 00:32:49,360
Speaker 2: Meteor Crater, and it's the side of an impact from

644
00:32:49,520 --> 00:32:53,600
Speaker 2: forty seven thousand BC, so this is like almost fifty

645
00:32:53,680 --> 00:32:56,720
Speaker 2: thousand years ago. But it's not a small site. This

646
00:32:56,760 --> 00:32:59,960
Speaker 2: crater is more than a kilometer across, and it's just

647
00:33:00,000 --> 00:33:01,840
Speaker 2: it's like out there in the desert. It's just like

648
00:33:02,000 --> 00:33:04,880
Speaker 2: huge vast plains and then all of a sudden, enormous

649
00:33:04,960 --> 00:33:08,640
Speaker 2: impact crater. You can see this thing one flying over Arizona.

650
00:33:08,720 --> 00:33:10,040
Speaker 2: It's like very obvious.

651
00:33:10,400 --> 00:33:13,920
Speaker 1: This one. I happened to know is nickel iron if

652
00:33:13,920 --> 00:33:17,320
Speaker 1: it had been ice but it was the same size

653
00:33:17,320 --> 00:33:20,000
Speaker 1: and going the same speed, would it matter or is

654
00:33:20,040 --> 00:33:21,600
Speaker 1: it about size and speed and mass?

655
00:33:22,040 --> 00:33:25,240
Speaker 2: Yeah, great question, It wouldn't matter so much. Like you

656
00:33:25,320 --> 00:33:27,600
Speaker 2: get a similar impact crater, but this one actually left

657
00:33:27,600 --> 00:33:30,680
Speaker 2: a meteor right because it's made of nickel an iron.

658
00:33:30,800 --> 00:33:33,200
Speaker 2: A lot of it survived, like half of it was

659
00:33:33,320 --> 00:33:36,440
Speaker 2: vaporized when it came through the atmosphere and smashed into

660
00:33:36,480 --> 00:33:39,680
Speaker 2: the earth, but huge chunks of it are still lying around.

661
00:33:40,120 --> 00:33:42,600
Speaker 2: They have found chunks of this asteroid before it came

662
00:33:42,640 --> 00:33:45,640
Speaker 2: a meteor and now the chunks of it are called meteorite,

663
00:33:45,720 --> 00:33:47,200
Speaker 2: so we can actually study it.

664
00:33:47,280 --> 00:33:49,880
Speaker 1: Whoa dude like, is this something you can buy online?

665
00:33:49,960 --> 00:33:50,800
Speaker 1: Is there that much of it?

666
00:33:51,520 --> 00:33:55,280
Speaker 2: There's not that much of it. It's very scientifically valuable.

667
00:33:55,480 --> 00:33:58,480
Speaker 2: But it also played an important role in understanding how

668
00:33:58,560 --> 00:34:01,680
Speaker 2: to date geological events. Like one way we figure out

669
00:34:01,720 --> 00:34:04,720
Speaker 2: how old things are, how old a rock is when

670
00:34:04,760 --> 00:34:07,440
Speaker 2: it went from lava to some sort of like crystal,

671
00:34:08,080 --> 00:34:10,960
Speaker 2: is by looking at the uranium inside of it. We

672
00:34:11,000 --> 00:34:13,879
Speaker 2: can use uranium dating to figure out when a rock

673
00:34:14,120 --> 00:34:14,960
Speaker 2: was made.

674
00:34:15,000 --> 00:34:18,160
Speaker 1: And did this have uranium in it or does stuff

675
00:34:18,160 --> 00:34:20,320
Speaker 1: in space have different amounts of uranium.

676
00:34:20,440 --> 00:34:22,359
Speaker 2: This stuff has uranium and it so we can use

677
00:34:22,400 --> 00:34:25,520
Speaker 2: this technique to figure out like when the original chunk

678
00:34:25,560 --> 00:34:28,120
Speaker 2: of stuff was made before it hit the earth. But

679
00:34:28,160 --> 00:34:30,640
Speaker 2: it actually also has a really cool story connected to

680
00:34:30,760 --> 00:34:33,759
Speaker 2: gasoline because when they were trying to figure this stuff out,

681
00:34:34,080 --> 00:34:36,560
Speaker 2: they need to understand where all the lead was in

682
00:34:36,600 --> 00:34:40,200
Speaker 2: the atmosphere. The way this dating system works is that

683
00:34:40,280 --> 00:34:43,960
Speaker 2: when these little crystals form inside the rock, these Zerokon crystals,

684
00:34:44,239 --> 00:34:47,839
Speaker 2: they allow uranium in, but they strongly reject lead. Like

685
00:34:47,840 --> 00:34:50,840
Speaker 2: the chemistry of it says lead is not allowed inside

686
00:34:50,880 --> 00:34:55,200
Speaker 2: these crystals, but uranium decays into lead, and so after

687
00:34:55,320 --> 00:34:58,520
Speaker 2: millions or billions of years, the uranium has transformed itself

688
00:34:58,520 --> 00:35:01,200
Speaker 2: into lead. So the more the lead you find inside

689
00:35:01,200 --> 00:35:03,880
Speaker 2: these crystals, the older the rock is. It's like a

690
00:35:03,880 --> 00:35:07,200
Speaker 2: little clock turning uranium into lead. And you know there's

691
00:35:07,200 --> 00:35:09,480
Speaker 2: no lead to start with because the crystal's repel it.

692
00:35:10,120 --> 00:35:11,680
Speaker 2: So if you can measure the amounts of lead and

693
00:35:11,719 --> 00:35:14,440
Speaker 2: then mounted uranium, then you can tell how old stuff is.

694
00:35:14,880 --> 00:35:17,080
Speaker 2: So the chemist who was figuring this stuff out, he

695
00:35:17,160 --> 00:35:19,799
Speaker 2: was trying to calibrate this and he was discovering, Oh

696
00:35:19,800 --> 00:35:22,839
Speaker 2: my gosh, this lead everywhere. Like every time he tried

697
00:35:22,840 --> 00:35:25,400
Speaker 2: to get a lead free environment just to like calibrate

698
00:35:25,440 --> 00:35:28,279
Speaker 2: his measurements and do some tests, he was totally unable to.

699
00:35:28,719 --> 00:35:31,200
Speaker 2: He had to actually go to Arizona and study a

700
00:35:31,239 --> 00:35:33,400
Speaker 2: piece of this meteorite to try to get like an

701
00:35:33,440 --> 00:35:37,160
Speaker 2: unspoiled piece of rock that didn't have like lead everywhere

702
00:35:37,200 --> 00:35:39,040
Speaker 2: in it. And that, of course was because we had

703
00:35:39,120 --> 00:35:41,960
Speaker 2: lead in our gasoline and we were pumping a huge

704
00:35:41,960 --> 00:35:45,840
Speaker 2: amount of lead into our atmosphere and into our children's mouths.

705
00:35:46,000 --> 00:35:48,719
Speaker 2: There's lead everywhere in the seventies, and he actually led

706
00:35:48,719 --> 00:35:51,680
Speaker 2: the charge to get lead out of gasoline, not just

707
00:35:51,719 --> 00:35:54,000
Speaker 2: because it was making everybody dumber, but also because he

708
00:35:54,040 --> 00:35:56,319
Speaker 2: didn't like having a lead polluted atmosphere. It made it

709
00:35:56,360 --> 00:35:59,279
Speaker 2: harder for him to make these measurements. And he's one

710
00:35:59,280 --> 00:36:01,319
Speaker 2: of the first people to measure the age of the.

711
00:36:01,239 --> 00:36:03,320
Speaker 1: Earth accurately better living through science.

712
00:36:03,440 --> 00:36:06,200
Speaker 2: Yeah, and this meteorite helps us all have a safer

713
00:36:06,280 --> 00:36:09,640
Speaker 2: environment for our children and understand uranium dating.

714
00:36:09,920 --> 00:36:13,840
Speaker 1: Wow. Well, okay, so that's that's a positive thing for once.

715
00:36:14,960 --> 00:36:17,000
Speaker 1: Maybe my children can listen to that chunk. But I'll

716
00:36:17,040 --> 00:36:18,799
Speaker 1: just take out the lead is everywhere a part.

717
00:36:19,760 --> 00:36:21,840
Speaker 2: Well, lead is no longer everywhere, thankfully.

718
00:36:22,080 --> 00:36:25,000
Speaker 1: All right, So let's go even further back in time.

719
00:36:25,680 --> 00:36:29,799
Speaker 1: Presumably we'll talk about an even big asteroid. Where are

720
00:36:29,800 --> 00:36:30,800
Speaker 1: we going to find this one?

721
00:36:30,880 --> 00:36:32,680
Speaker 2: So for the next biggest one, we got to go

722
00:36:32,719 --> 00:36:37,640
Speaker 2: to Kazakhstan. There's a site in zamashin Kazakhstan where an

723
00:36:37,680 --> 00:36:43,160
Speaker 2: impact left a crater fourteen kilometers wide about a million

724
00:36:43,360 --> 00:36:44,040
Speaker 2: years ago.

725
00:36:44,239 --> 00:36:48,879
Speaker 1: Oh okay, so how many hiroshimas would that produce? That's

726
00:36:48,880 --> 00:36:49,680
Speaker 1: gotta be a lot.

727
00:36:50,320 --> 00:36:53,600
Speaker 2: That was a really big impact. Absolutely. They think that

728
00:36:53,719 --> 00:36:57,480
Speaker 2: this is essentially the most recent impact that would have

729
00:36:57,560 --> 00:37:01,520
Speaker 2: produced a huge nuclear winter. Not large enough to cause

730
00:37:01,520 --> 00:37:04,480
Speaker 2: a mass extinction, but large enough to really have a

731
00:37:04,520 --> 00:37:08,279
Speaker 2: serious impact on the Earth's climate for many years. So

732
00:37:08,360 --> 00:37:11,280
Speaker 2: this was a really large event. I mean, fourteen kilometer

733
00:37:11,360 --> 00:37:13,760
Speaker 2: wide crater is like nothing to joke about.

734
00:37:13,840 --> 00:37:15,919
Speaker 1: I'm a little surprised you can have a nuclear winter

735
00:37:16,080 --> 00:37:20,200
Speaker 1: without a mass extinction, but uh, I guess nature's kind

736
00:37:20,239 --> 00:37:20,880
Speaker 1: of resilience.

737
00:37:22,080 --> 00:37:23,960
Speaker 2: By then, the mammals were already in charge, and we'd

738
00:37:24,000 --> 00:37:26,279
Speaker 2: already survived from one big nuclear winter. So you know,

739
00:37:26,840 --> 00:37:29,040
Speaker 2: grow out that fur coat and hunker down for a

740
00:37:29,080 --> 00:37:31,279
Speaker 2: few years we.

741
00:37:31,360 --> 00:37:34,719
Speaker 1: Got this figured out. Now can I buy any of

742
00:37:34,760 --> 00:37:36,279
Speaker 1: this online?

743
00:37:36,440 --> 00:37:39,279
Speaker 2: Actually you can. This one is so big that it

744
00:37:39,400 --> 00:37:42,120
Speaker 2: left fragments everywhere, and people just go like and pick

745
00:37:42,200 --> 00:37:44,799
Speaker 2: up the stuff and sell it online. And some of

746
00:37:44,840 --> 00:37:47,920
Speaker 2: it is really spectacular, Like you can buy this stuff

747
00:37:47,960 --> 00:37:52,000
Speaker 2: called glass foam, which shows you that the original impactor

748
00:37:52,239 --> 00:37:55,440
Speaker 2: was kind of fluffy. It had these like big chunks

749
00:37:55,440 --> 00:37:57,799
Speaker 2: of silicon with huge air bubbles in it. We still

750
00:37:57,800 --> 00:38:01,040
Speaker 2: don't really understand exactly how it was full. And in

751
00:38:01,080 --> 00:38:03,080
Speaker 2: some of these chunks of glass foam you can see

752
00:38:03,120 --> 00:38:06,719
Speaker 2: the melt, like there's unspoiled chunks of glass foam. Then

753
00:38:06,760 --> 00:38:09,600
Speaker 2: the other side of the rock is like melted glass

754
00:38:09,600 --> 00:38:12,680
Speaker 2: foam as it passed through the atmosphere and the plasma

755
00:38:12,719 --> 00:38:15,239
Speaker 2: from the friction actually melted the edge of this thing.

756
00:38:15,400 --> 00:38:18,080
Speaker 2: It's really pretty spectacular. So yeah, you can just go

757
00:38:18,120 --> 00:38:21,400
Speaker 2: online and buy Zamanschite.

758
00:38:20,640 --> 00:38:23,960
Speaker 1: Quite the conversation piece, And you know, there's a lot

759
00:38:24,000 --> 00:38:25,399
Speaker 1: of studio science surrounding this stuff.

760
00:38:25,400 --> 00:38:27,640
Speaker 2: People think it's mystical. I look for some of this

761
00:38:27,680 --> 00:38:30,400
Speaker 2: stuff for sale, and it was advertised as having the

762
00:38:30,440 --> 00:38:34,680
Speaker 2: capacity to quote blast away bad forces and negative people

763
00:38:34,719 --> 00:38:37,960
Speaker 2: who block your life's path. So I'm not sure that

764
00:38:37,960 --> 00:38:48,279
Speaker 2: sounds great big if true, right right, Yeah, so we'll see.

765
00:38:48,280 --> 00:38:50,520
Speaker 2: I'm not going to endorse those claims, but it is

766
00:38:50,600 --> 00:38:53,520
Speaker 2: pretty cool to own a chunk of stuff that came

767
00:38:53,560 --> 00:38:56,640
Speaker 2: from space that like floated around the Solar System for

768
00:38:56,719 --> 00:38:59,759
Speaker 2: a while and then decided to end its days here

769
00:38:59,800 --> 00:39:00,359
Speaker 2: on Earth.

770
00:39:00,560 --> 00:39:02,960
Speaker 1: That is pretty cool, all right. And so now we're

771
00:39:02,960 --> 00:39:08,279
Speaker 1: going to another stan. We're heading to Jikastan. Tell us

772
00:39:08,320 --> 00:39:09,000
Speaker 1: about this one.

773
00:39:09,120 --> 00:39:12,600
Speaker 2: Yeah, So Karakul to Jikastan is the site of a

774
00:39:12,680 --> 00:39:17,040
Speaker 2: disputed impact. It's basically a huge leak. And when people

775
00:39:17,080 --> 00:39:19,520
Speaker 2: first went to space and saw pictures of him from space,

776
00:39:19,560 --> 00:39:21,600
Speaker 2: they were like, hold on a second, look at the

777
00:39:21,640 --> 00:39:24,480
Speaker 2: shape of that thing. That looks like an impact crater.

778
00:39:24,800 --> 00:39:26,120
Speaker 1: And that's because it's very circular.

779
00:39:26,320 --> 00:39:28,920
Speaker 2: It's mostly circular. It's actually got like a big peninsula

780
00:39:29,000 --> 00:39:31,560
Speaker 2: in the middle. Some people think is also part of

781
00:39:31,600 --> 00:39:34,400
Speaker 2: the evidence, because when a rock hits the Earth, it

782
00:39:34,440 --> 00:39:37,759
Speaker 2: can have all sorts of weird seismic bounce backs, So

783
00:39:37,800 --> 00:39:41,200
Speaker 2: some people think it's consistent with a crater. Some people

784
00:39:41,239 --> 00:39:43,720
Speaker 2: are like, nah, you're just imagining it. It's like staring

785
00:39:43,760 --> 00:39:47,239
Speaker 2: at clouds. But If it is an impact crater, it's

786
00:39:47,239 --> 00:39:51,920
Speaker 2: an enormous one. This thing is fifty kilometers wide, and

787
00:39:52,080 --> 00:39:55,400
Speaker 2: they think it probably happened somewhere between five and twenty

788
00:39:55,600 --> 00:39:59,000
Speaker 2: million years ago. So this would have been big news

789
00:39:59,040 --> 00:39:59,839
Speaker 2: a long time ago.

790
00:40:00,080 --> 00:40:02,239
Speaker 1: So why do we have to dispute this? Why can't

791
00:40:02,239 --> 00:40:04,000
Speaker 1: we know for sure? Why can't we look for like

792
00:40:04,120 --> 00:40:06,120
Speaker 1: shocked quartz or tech tight or something.

793
00:40:06,280 --> 00:40:08,040
Speaker 2: Yeah, people have done that, but you know, these things

794
00:40:08,040 --> 00:40:10,680
Speaker 2: aren't easy to find when it's so old. Even the

795
00:40:10,680 --> 00:40:12,360
Speaker 2: big crater like the one we'll talk about next that

796
00:40:12,440 --> 00:40:14,799
Speaker 2: killed the dinosaur, it took a long time before people

797
00:40:14,880 --> 00:40:17,680
Speaker 2: were able to like find the evidence for it. So

798
00:40:17,719 --> 00:40:19,959
Speaker 2: this one was discovered fairly recently, and people are still

799
00:40:19,960 --> 00:40:22,480
Speaker 2: studying and still trying to find those pieces of evidence

800
00:40:22,520 --> 00:40:23,319
Speaker 2: that might be out there.

801
00:40:23,560 --> 00:40:24,920
Speaker 1: All right, all right, so then let's move on to

802
00:40:24,960 --> 00:40:25,799
Speaker 1: the dinosaur killer.

803
00:40:27,000 --> 00:40:30,080
Speaker 2: So probably the most famous impact site on Earth is

804
00:40:30,320 --> 00:40:33,080
Speaker 2: Do you know how to pronounce this one? Kelly? No,

805
00:40:33,880 --> 00:40:35,399
Speaker 2: do you want to try on air?

806
00:40:36,719 --> 00:40:37,359
Speaker 4: Uh?

807
00:40:37,600 --> 00:40:38,240
Speaker 1: Chick kloop?

808
00:40:38,640 --> 00:40:39,799
Speaker 2: All right, We're gonna go with that.

809
00:40:39,920 --> 00:40:42,040
Speaker 1: I think I had a Russian in there. I'm not

810
00:40:42,040 --> 00:40:42,920
Speaker 1: sure that belongs.

811
00:40:43,560 --> 00:40:45,799
Speaker 2: Sorry, this is the one in the Yucatan. You know

812
00:40:45,840 --> 00:40:49,160
Speaker 2: how Mexico basically has that little swoop in it, and

813
00:40:49,200 --> 00:40:51,439
Speaker 2: they think that that's the edge of an impact crater,

814
00:40:51,600 --> 00:40:55,120
Speaker 2: the one that probably took out the dinosaurs sixty five

815
00:40:55,200 --> 00:40:58,480
Speaker 2: million years ago. And this one's enormous, right, it's one

816
00:40:58,560 --> 00:41:02,399
Speaker 2: hundred and fifty kilometers wide, and they think that an

817
00:41:02,400 --> 00:41:06,480
Speaker 2: impactor like ten kilometers wide hit the Earth and left

818
00:41:06,520 --> 00:41:09,400
Speaker 2: that impact crater. One we can see now from space.

819
00:41:09,480 --> 00:41:10,440
Speaker 2: It's pretty amazing.

820
00:41:10,600 --> 00:41:12,920
Speaker 1: But we do have shocked quarts and tech tights from

821
00:41:12,920 --> 00:41:13,319
Speaker 1: this one.

822
00:41:13,360 --> 00:41:15,920
Speaker 2: From this one, we actually do have very specific evidence.

823
00:41:15,960 --> 00:41:18,080
Speaker 2: You can see in the ring around the edge, shock

824
00:41:18,200 --> 00:41:20,840
Speaker 2: quarts everywhere, and they have tech tights, which are these

825
00:41:20,880 --> 00:41:23,160
Speaker 2: little bits of glass that are created during the impact

826
00:41:23,200 --> 00:41:27,080
Speaker 2: and then thrown everywhere that are different from volcanic glass

827
00:41:27,080 --> 00:41:30,560
Speaker 2: and also like don't have the geology of the local environment,

828
00:41:30,640 --> 00:41:34,279
Speaker 2: so they seem very obviously like created from some impactor.

829
00:41:34,800 --> 00:41:37,160
Speaker 2: So here we have very strong evidence that there really

830
00:41:37,360 --> 00:41:40,560
Speaker 2: was an impact sixty five million years ago. People still

831
00:41:40,719 --> 00:41:44,200
Speaker 2: argue about whether it's the reason the dinosaurs went extinct,

832
00:41:44,200 --> 00:41:46,800
Speaker 2: et cetera, et cetera, et cetera, but we're pretty confident

833
00:41:46,800 --> 00:41:49,520
Speaker 2: that it happened, and it would lead to crazy things

834
00:41:49,640 --> 00:41:54,560
Speaker 2: like tsunamis a kilometer high clouds of dust and ash

835
00:41:54,600 --> 00:41:58,960
Speaker 2: and steam, including like twenty five trillion tons of material,

836
00:41:59,400 --> 00:42:02,720
Speaker 2: some of which escaped the Earth and is still floating

837
00:42:02,760 --> 00:42:06,719
Speaker 2: around in the Solar system, like explosive dust from this

838
00:42:06,840 --> 00:42:08,359
Speaker 2: impact is still out there.

839
00:42:08,400 --> 00:42:10,400
Speaker 1: It's crazy, right, that's intense.

840
00:42:10,600 --> 00:42:12,960
Speaker 2: Yeah, So this is the most famous impact crater on

841
00:42:13,000 --> 00:42:15,320
Speaker 2: Earth when people know about the most, but it's actually

842
00:42:15,360 --> 00:42:19,560
Speaker 2: probably not the biggest, the most dramatic impact in Earth's history.

843
00:42:19,719 --> 00:42:22,719
Speaker 1: No, this is the biggest one that I know about,

844
00:42:22,800 --> 00:42:25,520
Speaker 1: and I feel pretty good because I think for the listeners,

845
00:42:26,200 --> 00:42:27,879
Speaker 1: this was the one that most of them talked about

846
00:42:27,880 --> 00:42:31,600
Speaker 1: as well. So which one is bigger?

847
00:42:31,920 --> 00:42:35,640
Speaker 2: So there's an impact crater in South Africa. It's called Redifort.

848
00:42:35,719 --> 00:42:39,080
Speaker 2: I'm sure I'm mispronouncing it. And this one is three

849
00:42:39,160 --> 00:42:42,960
Speaker 2: hundred kilometers wide, so it's twice as wide as the

850
00:42:42,960 --> 00:42:46,000
Speaker 2: one that killed the dinosaurs, Oh my gosh. But this

851
00:42:46,080 --> 00:42:48,799
Speaker 2: one is also much much older. They date this one

852
00:42:48,840 --> 00:42:52,520
Speaker 2: to like two billion years ago, so when life was

853
00:42:52,680 --> 00:42:56,520
Speaker 2: very very primitive, and because it's so old, it's been

854
00:42:56,560 --> 00:43:00,800
Speaker 2: eroded significantly, like mostly it looks like like a partial

855
00:43:00,920 --> 00:43:03,760
Speaker 2: ring of hills and there's a dome in the middle

856
00:43:03,800 --> 00:43:05,799
Speaker 2: of it. You have to sort of like squinch your

857
00:43:05,800 --> 00:43:07,359
Speaker 2: eyes a little bit to even see it.

858
00:43:07,520 --> 00:43:11,560
Speaker 1: Why is there a dome? Why are rolling hills the

859
00:43:11,680 --> 00:43:14,719
Speaker 1: sign of an impact crater. I would think that like

860
00:43:14,760 --> 00:43:17,560
Speaker 1: Ohio being flat would be the sign of an impact crater,

861
00:43:17,680 --> 00:43:20,680
Speaker 1: But I don't associate hills with impact craters.

862
00:43:20,920 --> 00:43:23,520
Speaker 2: Yeah, so the dome is really fascinating. When a really

863
00:43:23,560 --> 00:43:25,920
Speaker 2: big impact or hits the Earth, you don't just get

864
00:43:25,960 --> 00:43:28,320
Speaker 2: a crater for a huge one, you actually get to

865
00:43:28,400 --> 00:43:31,080
Speaker 2: bounce back in the center. The Earth is like a

866
00:43:31,120 --> 00:43:34,120
Speaker 2: big waterbed. Right you hit it, it's gonna bounce back

867
00:43:34,239 --> 00:43:36,320
Speaker 2: a little bit. And so if it's big enough, you

868
00:43:36,360 --> 00:43:39,279
Speaker 2: get this bounce back, this dome in the center. And

869
00:43:39,320 --> 00:43:42,160
Speaker 2: then you also don't just get like one circle. You

870
00:43:42,200 --> 00:43:46,240
Speaker 2: can have multiple rings. It's like the seismic waves travel

871
00:43:46,280 --> 00:43:49,280
Speaker 2: through the Earth and they get frozen in several places.

872
00:43:49,600 --> 00:43:52,399
Speaker 2: It's not actually something that's understood very well. You can

873
00:43:52,400 --> 00:43:55,040
Speaker 2: see it in a few other places around the Solar System,

874
00:43:55,280 --> 00:43:58,839
Speaker 2: impact craters with multiple rings around them, but geologists are

875
00:43:58,840 --> 00:44:01,920
Speaker 2: still trying to understandactly how that happens. But if you

876
00:44:01,960 --> 00:44:04,759
Speaker 2: look at these sets of hills in South Africa, you

877
00:44:04,800 --> 00:44:07,920
Speaker 2: can see that there are multiple rings surrounding this dome.

878
00:44:08,280 --> 00:44:10,960
Speaker 2: So that looks a lot like a huge impact.

879
00:44:10,880 --> 00:44:13,520
Speaker 1: The bounce back that you're talking about. That that's the

880
00:44:13,760 --> 00:44:15,680
Speaker 1: like you said, the lake in Tajikastan has like an

881
00:44:15,719 --> 00:44:18,200
Speaker 1: island in the middle. That's the that's the bounce back

882
00:44:18,400 --> 00:44:21,320
Speaker 1: that you were talking about. Okay, got it, Yeah exactly.

883
00:44:22,000 --> 00:44:24,600
Speaker 2: But because it's so old, it's not really complete anymore.

884
00:44:24,680 --> 00:44:26,320
Speaker 2: Like if you've seen this thing when it was fresh,

885
00:44:26,560 --> 00:44:28,360
Speaker 2: you probably would see like a big dome in the

886
00:44:28,360 --> 00:44:32,240
Speaker 2: middle and then complete rings around it, multiple complete rings.

887
00:44:32,640 --> 00:44:35,920
Speaker 2: But because it's been two billion years since the incident,

888
00:44:36,400 --> 00:44:38,640
Speaker 2: a lot of those have just eroded away. So now

889
00:44:38,680 --> 00:44:42,560
Speaker 2: you have incomplete rings of hills, so partial rings of

890
00:44:42,680 --> 00:44:43,880
Speaker 2: hills around the dome.

891
00:44:44,680 --> 00:44:46,839
Speaker 1: But the good news is that all of this has

892
00:44:46,880 --> 00:44:50,440
Speaker 1: happened in the past half the day. Listeners, it's been

893
00:44:50,560 --> 00:44:51,560
Speaker 1: nice having you here.

894
00:44:52,120 --> 00:44:55,320
Speaker 2: Sleep well, and then you know, as the listeners mentioned,

895
00:44:55,400 --> 00:44:59,080
Speaker 2: maybe the most dramatic incident in Earth history was the

896
00:44:59,080 --> 00:45:01,840
Speaker 2: formation of the moon. Right, we think that the Earth

897
00:45:01,920 --> 00:45:04,520
Speaker 2: was hit by a proto planet billions and billions of

898
00:45:04,640 --> 00:45:08,040
Speaker 2: years ago, which essentially obliterated the entire planet, turned the

899
00:45:08,239 --> 00:45:12,200
Speaker 2: entire surface into lava, which spun out and turned into

900
00:45:12,239 --> 00:45:14,880
Speaker 2: the Earth and the Moon. So this is probably the

901
00:45:14,920 --> 00:45:18,080
Speaker 2: most dramatic event in Earth's history, so dramatic that it

902
00:45:18,080 --> 00:45:20,200
Speaker 2: doesn't even leave an impact crater, right, It just like

903
00:45:20,400 --> 00:45:24,319
Speaker 2: vaporizes the whole planet. But they actually think that they

904
00:45:24,480 --> 00:45:28,920
Speaker 2: found in the Earth's core some evidence of this impact.

905
00:45:29,040 --> 00:45:30,040
Speaker 1: And what is the evidence.

906
00:45:30,239 --> 00:45:32,080
Speaker 2: They look inside the Earth, you know, to like the

907
00:45:32,160 --> 00:45:35,520
Speaker 2: lower most mantle, and they find that some chunks of

908
00:45:35,520 --> 00:45:37,880
Speaker 2: the mantle look a little bit different. It's like a

909
00:45:37,920 --> 00:45:41,040
Speaker 2: different composition, different density, and they think that what they're

910
00:45:41,040 --> 00:45:43,920
Speaker 2: seeing there is mantle from the impact or from FEA

911
00:45:44,160 --> 00:45:47,080
Speaker 2: that made its way down to proto Earth's lower mantle.

912
00:45:47,400 --> 00:45:50,279
Speaker 2: So basically, like the inner core of our planet is

913
00:45:50,360 --> 00:45:53,840
Speaker 2: partially from the inner core of this huge impactor.

914
00:45:54,040 --> 00:45:54,920
Speaker 1: That's incredible.

915
00:45:55,280 --> 00:45:58,840
Speaker 2: Yeah, So the blobs, the density patterns inside the Earth

916
00:45:59,280 --> 00:46:03,680
Speaker 2: show this tell tail sign of this crazy cataclysmic impact,

917
00:46:04,040 --> 00:46:06,279
Speaker 2: even more dramatic than the one that killed the dinosaurs,

918
00:46:06,320 --> 00:46:09,240
Speaker 2: even more dramatic than this one that left these eroded

919
00:46:09,320 --> 00:46:10,640
Speaker 2: rings in South Africa.

920
00:46:10,760 --> 00:46:14,040
Speaker 1: Glad I wasn't there, and I sure do like the mood.

921
00:46:15,040 --> 00:46:17,640
Speaker 2: And as much as these all seem scary, Kelly, these

922
00:46:17,800 --> 00:46:20,440
Speaker 2: all were crucial in life turning out the way that

923
00:46:20,480 --> 00:46:23,360
Speaker 2: it did. Right. If things had happened differently, we wouldn't

924
00:46:23,400 --> 00:46:26,040
Speaker 2: be here. And so we can say thank you to

925
00:46:26,080 --> 00:46:29,440
Speaker 2: the solar system for raining death down on other people's

926
00:46:29,480 --> 00:46:31,040
Speaker 2: ancestors for so many years.

927
00:46:31,280 --> 00:46:34,440
Speaker 1: Yes, thank you for this past, but never again in

928
00:46:34,480 --> 00:46:38,680
Speaker 1: the future. Right, there's no risk of this happening, say,

929
00:46:38,880 --> 00:46:41,440
Speaker 1: I don't know in the next decade or so.

930
00:46:41,880 --> 00:46:44,600
Speaker 2: There's actually an asteroid that's a few hundred meters across

931
00:46:44,920 --> 00:46:47,759
Speaker 2: that's likely to make a close pass in April of

932
00:46:47,840 --> 00:46:51,880
Speaker 2: twenty twenty nine. It's called Apofis, and they predict that

933
00:46:51,920 --> 00:46:55,040
Speaker 2: it's going to come by Friday the thirteenth in April

934
00:46:55,080 --> 00:46:57,160
Speaker 2: twenty twenty nine. But it's just supposed to make a

935
00:46:57,160 --> 00:46:57,759
Speaker 2: clut us.

936
00:46:59,120 --> 00:46:59,640
Speaker 4: But it's not.

937
00:47:00,200 --> 00:47:02,640
Speaker 1: It's not coming on Friday the thirteenth, Are you kidding?

938
00:47:02,719 --> 00:47:05,240
Speaker 2: I am not making that part of that part is real.

939
00:47:06,520 --> 00:47:08,719
Speaker 2: You gotta wonder what it's like to be that scientist,

940
00:47:08,760 --> 00:47:10,840
Speaker 2: like predicting the day it's going to be the closest

941
00:47:10,840 --> 00:47:16,279
Speaker 2: approach and having to be like Friday the thirteenth.

942
00:47:16,920 --> 00:47:19,320
Speaker 1: Or I wonder if you have like a Cassandra syndrome

943
00:47:19,360 --> 00:47:21,239
Speaker 1: sort of thing, like, no one's gonna believe me if

944
00:47:21,239 --> 00:47:23,040
Speaker 1: I say it's coming on Friday the thirteen.

945
00:47:23,600 --> 00:47:24,160
Speaker 2: That's right.

946
00:47:24,440 --> 00:47:26,680
Speaker 1: How close is close when you say it's going to

947
00:47:26,719 --> 00:47:27,520
Speaker 1: make a close pass?

948
00:47:27,920 --> 00:47:31,080
Speaker 2: You know, astronomically speaking, anything that comes like with between

949
00:47:31,120 --> 00:47:33,719
Speaker 2: the Earth and the Moon is pretty close. But that

950
00:47:33,760 --> 00:47:35,960
Speaker 2: doesn't mean it's very dangerous. The Earth is still a

951
00:47:36,080 --> 00:47:40,000
Speaker 2: very small target compared to the vastness of space, and

952
00:47:40,040 --> 00:47:42,680
Speaker 2: it's hard to predict these things years out. So as

953
00:47:42,719 --> 00:47:45,680
Speaker 2: time gets closer, they'll predict it more accurately, and very

954
00:47:45,800 --> 00:47:46,880
Speaker 2: likely we'll all be fine.

955
00:47:46,960 --> 00:47:50,239
Speaker 1: But it's like within the range of error right now

956
00:47:50,280 --> 00:47:51,360
Speaker 1: that Earth could get hit.

957
00:47:51,360 --> 00:47:53,799
Speaker 2: Depends how generous you want to be with range of error.

958
00:47:53,840 --> 00:47:56,840
Speaker 2: There's always systematic uncertainties that haven't accounted for that increase

959
00:47:56,880 --> 00:48:00,000
Speaker 2: the envelope to include the Earth. So yeah, it's possible

960
00:48:00,160 --> 00:48:02,080
Speaker 2: it could hit the Earth. Maybe we should be thinking

961
00:48:02,120 --> 00:48:03,759
Speaker 2: about Plan B Kelly, what do you think?

962
00:48:04,600 --> 00:48:09,280
Speaker 1: I don't know, mostly because I think there's zero chance

963
00:48:09,280 --> 00:48:11,760
Speaker 1: that we could have a self sustaining settlement on Mars

964
00:48:11,800 --> 00:48:14,080
Speaker 1: by twenty twenty nine. So if Earth is going to

965
00:48:14,120 --> 00:48:17,600
Speaker 1: be destroyed in twenty twenty nine. You know, a Mars

966
00:48:17,640 --> 00:48:21,240
Speaker 1: settlement would just be like a couple years behind. Maybe

967
00:48:21,239 --> 00:48:23,279
Speaker 1: you'd buy us a couple more years or something, but

968
00:48:23,400 --> 00:48:25,920
Speaker 1: I doubt it. For more information, check out A City

969
00:48:26,000 --> 00:48:29,480
Speaker 1: on Mars by Kelly and Zach Widersmith.

970
00:48:30,000 --> 00:48:31,920
Speaker 2: I mean, if Earth's civilization is going to be destroyed

971
00:48:31,920 --> 00:48:33,680
Speaker 2: in five years anyway, might as well spend all your

972
00:48:33,719 --> 00:48:35,000
Speaker 2: money on books right now.

973
00:48:35,280 --> 00:48:38,799
Speaker 1: That's exactly well, it's a good deal, even if there's

974
00:48:38,800 --> 00:48:40,840
Speaker 1: not a world ending cataclysm coming.

975
00:48:42,640 --> 00:48:45,640
Speaker 2: Well, it's fun to think about the crazy history of

976
00:48:45,719 --> 00:48:49,040
Speaker 2: the Earth. You know. It hasn't just been bubbling oceans

977
00:48:49,080 --> 00:48:51,799
Speaker 2: and hot tubs and all sorts of cozy times. It's

978
00:48:51,800 --> 00:48:55,160
Speaker 2: been dramatic and cataclysmic. And we can find the evidence

979
00:48:55,280 --> 00:48:58,120
Speaker 2: of those impacts on the surface of other objects in

980
00:48:58,160 --> 00:49:01,480
Speaker 2: the Solar System, but also year on Earth. And I

981
00:49:01,520 --> 00:49:05,160
Speaker 2: love when geologists unearth the evidence here on Earth for

982
00:49:05,320 --> 00:49:07,120
Speaker 2: crazy events in our deep history.

983
00:49:07,239 --> 00:49:11,000
Speaker 1: Way to go, geologists, don't let it happen again.

984
00:49:13,400 --> 00:49:19,120
Speaker 2: It's on you, exactly. We're counting on you, well, all right,

985
00:49:19,160 --> 00:49:21,640
Speaker 2: even if we do nothing about it's knowing how this

986
00:49:21,719 --> 00:49:24,239
Speaker 2: works and knowing the history of the impacts. Maybe you

987
00:49:24,280 --> 00:49:26,319
Speaker 2: will help us figure out how to prevent them in

988
00:49:26,360 --> 00:49:29,160
Speaker 2: the future. Thanks very much everybody for listening, and thanks

989
00:49:29,239 --> 00:49:30,279
Speaker 2: Kelly for joining us today.

990
00:49:30,360 --> 00:49:32,360
Speaker 1: Thanks for having me on the show. It was quote

991
00:49:32,400 --> 00:49:34,080
Speaker 1: unquote fun as always.

992
00:49:37,719 --> 00:49:44,960
Speaker 2: All Right, everyone, tune in next time for more science

993
00:49:45,000 --> 00:49:47,759
Speaker 2: and curiosity. Come find us on social media where we

994
00:49:47,800 --> 00:49:52,080
Speaker 2: answer questions and post videos. We're on Twitter, Discord, Instant,

995
00:49:52,080 --> 00:49:55,800
Speaker 2: and now TikTok. Thanks for listening and remember that Daniel

996
00:49:55,840 --> 00:49:59,240
Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio.

997
00:49:59,560 --> 00:50:04,719
Speaker 2: For more podcast from iHeartRadio, visit the iHeartRadio Apple Apple Podcasts,

998
00:50:04,840 --> 00:50:07,200
Speaker 2: or wherever you listen to your favorite shows.