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Picture this, the early solar system.

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It's just a swirling, chaotic mess of dust and gas.

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Out of this maelstrom, tiny rocky bodies emerge asteroids.

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Now, you might think they're just cosmic debris,

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leftover bits from planet formation, Rid.

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Yeah, you could think that.

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But you'd be surprised to learn how crucial these asteroids

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were in shaping the solar system we know today.

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Absolutely.

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Welcome to Cosmos and a Pod's Space and Astronomy series.

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OK.

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Today, we're taking a deep dive into the world of asteroids,

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unearthing their secrets, and exploring

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how these leftovers, as we call them,

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actually laid the groundwork for our cosmic neighborhood.

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OK.

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So let's start with the basics.

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What exactly are asteroids?

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I mean, we've all seen pictures, but what defines them

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scientifically?

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Well, you're right to think of them as leftovers.

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OK.

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But they're more like the building blocks that never

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quite made it into the final structure.

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They're remnants from the very beginning of the solar system,

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planetesimals that never grew large enough to become planets.

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Planetesimals.

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Yeah.

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OK, that's a new one for me.

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Think of them as the seeds of planets.

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OK.

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In the early solar system, you had this massive cloud

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of dust and gas.

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Right.

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Over time, these tiny particles started clumping together,

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forming larger and larger bodies.

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Right.

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Those are the planetesimals.

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OK.

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Some of them kept growing, eventually becoming

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the planets we know today.

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Right.

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But others, well, they remained as asteroids.

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So kind of like a cosmic game of who can

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gather the most dust bunnies.

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That's a fun way to think about it.

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And just like dust bunnies, they come in all shapes and sizes.

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Some are just meters across, while others

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can be hundreds of kilometers in diameter.

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Wow.

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And then in the solar system, the largest asteroid

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is so big, it's actually considered a dwarf planet.

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So there's a whole range of sizes.

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Yeah.

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What about their composition?

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Are they all just big chunks of rock?

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Not at all.

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They're incredibly diverse in their makeup,

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which is one reason they're so fascinating to study.

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You've got your rocky asteroids, of course.

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Right.

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But they're also metal-rich asteroids

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packed with iron and nickel.

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And then there are the carbon-rich asteroids.

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OK.

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And these are particularly intriguing,

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water and organic compounds.

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Wait, hold on.

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Organic compounds.

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Are you talking about the building blocks of life?

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Exactly.

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And that leads to one of the most exciting possibilities

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in asteroid research.

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Which is?

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The idea that these objects may have

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played a role in delivering the ingredients for life to Earth.

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OK.

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Now, that's a story I want to hear more about.

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Sure.

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But first, can we rewind a bit?

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OK.

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You mentioned the early solar system,

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the swirling cloud of dust and gas.

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Right.

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How did we go from that to planets A and D asteroids?

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That's all about gravity, really.

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OK.

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Imagine this giant rotating disk of dust and gas

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about 4.6 billion years ago.

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Right.

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As particles move within this disk,

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they collided and stuck together, growing larger and larger

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over time.

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Yeah.

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Gravity played a key role here, pulling in more and more

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material.

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The larger these clumps grew, remember

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talking about those planetesimals,

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the stronger their gravitational pull became.

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So it's like a snowball effect.

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Yeah.

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The bigger they get, the faster they grow.

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Exactly.

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And that's how you go from tiny particles

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to planet-size objects.

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OK.

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But here's the catch.

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What's that?

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Not all planetesimals had the same fate.

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You mean not all of them became planets.

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Right.

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Some, for various reasons, never reached that critical mass

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needed to become full-fledged planets.

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They remained as smaller bodies, asteroids.

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They're like snapshots of that early stage of solar system

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formation phrasing in time.

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Fascinating.

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So we've got these leftover planetesimals hanging around.

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Right.

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But how did they actually influence

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the formation of the planets we see today?

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Right.

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Were they just passively floating around,

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or did they play a more active role?

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Oh, they were far from passive.

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Really?

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Their role was crucial in several ways.

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Like what?

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First and foremost, they provided the building materials

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for planets to grow.

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OK, so like supplying the bricks for a planet

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for a construction project.

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Precisely.

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The early solar system was a chaotic place

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with collisions happening constantly.

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Right.

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Asteroids smashed into each other,

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merging into larger and larger bodies.

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Yeah.

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This process of accretion is how planets gradually bulked up.

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I can imagine it was quite the cosmic demolition

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derby back then.

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You could say that, but those collisions

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weren't just about destruction.

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They were about creation, too.

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OK.

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And remember those carbon-rich asteroids I mentioned?

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The ones with water.

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The ones with water and organic molecules.

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Right.

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Well, there's a strong possibility

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that they played a vital role in delivering

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those essential ingredients for life to Earth.

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So these asteroids might have literally

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brought us the building blocks of life.

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That's incredible.

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It is, isn't it?

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It paints a picture of our early Earth being bombarded

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by these water-rich asteroids seeding our planet

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with the essential ingredients for life to emerge.

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That's mind-blowing.

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It's like a cosmic delivery service bringing us

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the essentials.

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So it sounds like asteroid impacts played a major role

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in shaping the early solar system.

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They absolutely did.

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And their influence went beyond just delivering

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water and organic molecules.

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Those metal-rich asteroids we talked about earlier.

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They played a key role in forming planetary cores.

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You mean like the Earth's core?

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Exactly.

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The iron and nickel from those metal-rich asteroids

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drawn by gravity sank to the centers of young planets,

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helping to form those dense metallic cores.

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And those cores are crucial.

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In what way?

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They generate magnetic fields which shield planets

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from harmful solar radiation.

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Wow, so asteroids weren't just providing the building

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blocks for planets.

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No.

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They were also shaping their internal structures.

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They were the interior designers of the solar system.

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That's a great analogy.

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And let's not forget about the rocky asteroids, which

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also contributed to the formation of planetary crusts.

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It was a complex interplay of different types of asteroids,

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each playing a role in shaping the planets we see today.

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It really makes you appreciate the interconnectedness

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of everything in the solar system, doesn't it?

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It does.

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I'm starting to see asteroids in a whole new light.

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But speaking of seeing things, what about all those craters

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we see on planets and moons?

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Right.

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Are those all from asteroid impacts?

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Many of them are, yes.

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It's a constant reminder that the solar system

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is a dynamic place even today.

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While those giant planet-forming collisions

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are mostly a thing of the past, smaller asteroids

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and meteoroids still collide with planets and moons

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all the time.

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So it's like a constant cosmic rain of pebbles and rocks.

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In a way, yes.

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Most of these impacts are harmless, really.

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They add a bit of dust and minerals to a planet's surface.

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But every now and then, a larger object comes along.

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That's when you get those impressive craters.

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Like the one that wiped out the dinosaurs.

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Exactly.

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The Chicxulub impact about 66 million years ago

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is a sobering reminder of the power

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that even a single asteroid can wield.

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Just how big was that asteroid?

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Estimates vary, but it was somewhere between 10 and 80

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kilometers in diameter.

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Wow.

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To put that in perspective, that's larger than many cities.

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That's huge.

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No.

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No wonder it caused so much devastation.

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The energy released upon impact was unimaginable.

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It triggered earthquakes, tsunamis, wildfires.

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Oh my gosh.

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And sent a massive cloud of dust and debris into the atmosphere.

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Wow.

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This dust cloud blocked out the sun,

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leading to a global cooling effect that dramatically

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changed the Earth's climate.

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And that's ultimately what led to the extinction

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of the dinosaurs, right?

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That's the prevailing theory, yes.

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It's a stark illustration of how a single asteroid impact can

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reshape the course of life on Earth.

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It makes you wonder if another large asteroid could

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threaten Earth in the future.

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It's a valid concern and one that scientists

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take very seriously.

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There are ongoing efforts to track and monitor

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near-Earth asteroids, those whose orbits bring them

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close to our planet.

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So we're keeping an eye on the cosmic neighborhood just in case.

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Exactly.

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We want to be prepared should another potentially hazardous

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asteroid come our way.

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That's reassuring.

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But let's switch gears a bit.

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OK.

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You mentioned earlier that asteroids

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are like time capsules from the early solar system.

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Right.

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What exactly can they tell us about that time period?

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Well, they preserve a record of the conditions

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that existed billions of years ago.

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OK.

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By analyzing their composition, we

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can glean insights into the chemical makeup

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of the original protoplanetary disk,

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the swirling cloud of dust and gas

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from which our solar system formed.

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It's like having a sample of the raw ingredients

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from the cosmic kitchen.

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A perfect analogy.

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And we're not just looking at them from afar anymore.

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No.

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Thanks to missions like Hayabusa 2 and OSIRIS-REx,

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we've actually brought back samples from asteroids

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to Earth.

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Wait, we've actually got pieces of asteroids here on Earth.

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We do.

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And those samples are a treasure trove of information.

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They're allowing us to study these ancient objects up close

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in unprecedented detail.

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We can analyze their chemical makeup, determine their age,

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and even look for signs of organic molecules.

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It's like having a piece of the early solar system

279
00:09:24,200 --> 00:09:25,520
right here in our labs.

280
00:09:25,520 --> 00:09:26,840
It really is.

281
00:09:26,840 --> 00:09:28,480
And the more we study these samples,

282
00:09:28,480 --> 00:09:31,000
the more we learn about the processes that

283
00:09:31,000 --> 00:09:33,320
led to the formation of planets and ultimately

284
00:09:33,320 --> 00:09:35,080
to the emergence of life itself.

285
00:09:35,080 --> 00:09:39,280
It's amazing how these seemingly insignificant objects

286
00:09:39,280 --> 00:09:42,280
can hold so much information about our cosmic past.

287
00:09:42,280 --> 00:09:43,080
It is, isn't it?

288
00:09:43,080 --> 00:09:43,600
Yeah.

289
00:09:43,600 --> 00:09:45,800
But as I often say, the most exciting discoveries

290
00:09:45,800 --> 00:09:47,640
are the ones we haven't made yet.

291
00:09:47,640 --> 00:09:49,560
Despite all we've learned, there are still

292
00:09:49,560 --> 00:09:53,040
many unanswered questions about asteroids and their role

293
00:09:53,040 --> 00:09:54,400
in planetary formation.

294
00:09:54,400 --> 00:09:55,480
Like what?

295
00:09:55,480 --> 00:09:58,800
What are some of the mysteries that still puzzle scientists?

296
00:09:58,800 --> 00:10:01,600
Well, one of the big ones is, why didn't all asteroids

297
00:10:01,600 --> 00:10:02,760
become planets?

298
00:10:02,760 --> 00:10:03,240
Right.

299
00:10:03,240 --> 00:10:05,160
And what factors tipped the scales

300
00:10:05,160 --> 00:10:07,680
in favor of planet formation for some,

301
00:10:07,680 --> 00:10:09,920
while others remained as asteroids?

302
00:10:09,920 --> 00:10:11,600
That's a great question.

303
00:10:11,600 --> 00:10:14,280
I mean, if gravity was pulling everything together,

304
00:10:14,280 --> 00:10:16,520
why didn't they all just clump into giant planets?

305
00:10:16,520 --> 00:10:19,000
Well, there are a few possible explanations.

306
00:10:19,000 --> 00:10:20,960
Location plays a big role.

307
00:10:20,960 --> 00:10:21,440
OK.

308
00:10:21,440 --> 00:10:24,040
Planetesimals that formed closer to the sun,

309
00:10:24,040 --> 00:10:27,160
where the protoplanetary disk was denser,

310
00:10:27,160 --> 00:10:29,520
had more material available to them.

311
00:10:29,520 --> 00:10:31,560
They could grow faster and more easily.

312
00:10:31,560 --> 00:10:34,800
The cosmic game of real estate location is everything.

313
00:10:34,800 --> 00:10:36,960
You could say that.

314
00:10:36,960 --> 00:10:39,200
But there's more to it than just location.

315
00:10:39,200 --> 00:10:40,040
Like what?

316
00:10:40,040 --> 00:10:42,840
The composition of the planetesimals themselves,

317
00:10:42,840 --> 00:10:47,320
their initial size, the presence of other large objects nearby.

318
00:10:47,320 --> 00:10:49,280
All of these factors could have influenced

319
00:10:49,280 --> 00:10:52,560
whether a planetesimal went on to become a planet

320
00:10:52,560 --> 00:10:54,440
or remained as an asteroid.

321
00:10:54,440 --> 00:10:56,520
It sounds like there's a complex interplay of forces

322
00:10:56,520 --> 00:10:57,240
at work here.

323
00:10:57,240 --> 00:10:57,880
Absolutely.

324
00:10:57,880 --> 00:11:00,360
And then, of course, there's the influence of giant planets,

325
00:11:00,360 --> 00:11:01,480
like Jupiter.

326
00:11:01,480 --> 00:11:01,980
Yes.

327
00:11:01,980 --> 00:11:02,880
The king of the planets.

328
00:11:02,880 --> 00:11:03,400
Right.

329
00:11:03,400 --> 00:11:05,280
How does it fit into all of this?

330
00:11:05,280 --> 00:11:07,120
Well, Jupiter's immense gravity has

331
00:11:07,120 --> 00:11:09,680
had a profound effect on the asteroid population.

332
00:11:09,680 --> 00:11:10,160
OK.

333
00:11:10,160 --> 00:11:13,640
Its gravitational pull has shaped the asteroid belt,

334
00:11:13,640 --> 00:11:15,960
herding asteroids into specific orbits

335
00:11:15,960 --> 00:11:18,920
and preventing them from coalescing into larger objects.

336
00:11:18,920 --> 00:11:21,320
So Jupiter's kind of like a cosmic sheepdog

337
00:11:21,320 --> 00:11:22,600
herding the asteroids.

338
00:11:22,600 --> 00:11:24,120
That's a great way to put it.

339
00:11:24,120 --> 00:11:27,080
But Jupiter's influence goes beyond just hurting.

340
00:11:27,080 --> 00:11:28,000
In what way?

341
00:11:28,000 --> 00:11:31,480
Its gravity can also disrupt asteroid orbits,

342
00:11:31,480 --> 00:11:35,040
sending some careening into the inner solar system,

343
00:11:35,040 --> 00:11:37,280
where they might collide with planets like Earth.

344
00:11:37,280 --> 00:11:38,640
So it's a double-edged sword.

345
00:11:38,640 --> 00:11:39,160
Right.

346
00:11:39,160 --> 00:11:41,360
Jupiter keeps the asteroid belt in check.

347
00:11:41,360 --> 00:11:43,280
But it can also fling some of them our way.

348
00:11:43,280 --> 00:11:44,400
Exactly.

349
00:11:44,400 --> 00:11:47,400
And that brings us back to the question of water delivery.

350
00:11:47,400 --> 00:11:48,120
OK.

351
00:11:48,120 --> 00:11:50,000
We know that asteroids played a role

352
00:11:50,000 --> 00:11:52,120
in bringing water to Earth.

353
00:11:52,120 --> 00:11:54,520
But how much did they actually contribute?

354
00:11:54,520 --> 00:11:56,040
That's what I was wondering earlier.

355
00:11:56,040 --> 00:11:58,400
Is it possible to know how much of our water

356
00:11:58,400 --> 00:12:02,440
came from asteroids versus other sources like comets?

357
00:12:02,440 --> 00:12:03,880
It's a tricky question.

358
00:12:03,880 --> 00:12:06,040
But scientists are getting closer to an answer.

359
00:12:06,040 --> 00:12:08,720
They're using a technique called isotopic analysis

360
00:12:08,720 --> 00:12:10,440
to trace the origin of water.

361
00:12:10,440 --> 00:12:11,880
Isotopic analysis.

362
00:12:11,880 --> 00:12:13,560
Now, that sounds complicated.

363
00:12:13,560 --> 00:12:14,040
It is.

364
00:12:14,040 --> 00:12:15,320
But the basic idea is this.

365
00:12:15,320 --> 00:12:15,640
Yeah.

366
00:12:15,640 --> 00:12:18,080
Different sources of water have slightly different ratios

367
00:12:18,080 --> 00:12:21,160
of isotopes, which are atoms of the same element

368
00:12:21,160 --> 00:12:22,960
with different numbers of neutrons.

369
00:12:22,960 --> 00:12:23,440
OK.

370
00:12:23,440 --> 00:12:26,600
So you're saying that water from asteroids

371
00:12:26,600 --> 00:12:28,920
has a different isotopic fingerprint than water

372
00:12:28,920 --> 00:12:29,720
from comets.

373
00:12:29,720 --> 00:12:30,560
Exactly.

374
00:12:30,560 --> 00:12:34,240
And by comparing the isotopic composition of Earth's water

375
00:12:34,240 --> 00:12:36,680
to water from asteroids and comets,

376
00:12:36,680 --> 00:12:39,040
we can start to piece together the story of where

377
00:12:39,040 --> 00:12:40,240
our oceans came from.

378
00:12:40,240 --> 00:12:43,400
It's like a cosmic detective story using isotopes as clues.

379
00:12:43,400 --> 00:12:44,360
Precisely.

380
00:12:44,360 --> 00:12:47,440
And the evidence so far suggests that asteroids likely

381
00:12:47,440 --> 00:12:50,600
played a significant role in delivering water to Earth,

382
00:12:50,600 --> 00:12:53,280
though the exact proportion is still being debated.

383
00:12:53,280 --> 00:12:55,440
So it's a cosmic mystery still being solved.

384
00:12:55,440 --> 00:12:56,200
It is.

385
00:12:56,200 --> 00:12:58,520
But it's incredible to think that something as essential

386
00:12:58,520 --> 00:13:01,200
as water might have come to us from these rocky wanderers

387
00:13:01,200 --> 00:13:01,960
of space.

388
00:13:01,960 --> 00:13:02,680
It is, isn't it?

389
00:13:02,680 --> 00:13:04,360
And it highlights just how much we still

390
00:13:04,360 --> 00:13:07,040
have to learn about asteroids and their impact

391
00:13:07,040 --> 00:13:09,560
on our planet and the solar system as a whole.

392
00:13:09,560 --> 00:13:10,840
Well, I'm certainly feeling a lot more respect

393
00:13:10,840 --> 00:13:12,120
for asteroids now.

394
00:13:12,120 --> 00:13:12,640
Yeah.

395
00:13:12,640 --> 00:13:14,320
They're not just boring rocks.

396
00:13:14,320 --> 00:13:17,400
They're architects of planets, deliverers

397
00:13:17,400 --> 00:13:21,160
of life's ingredients, and keepers of cosmic secrets.

398
00:13:21,160 --> 00:13:22,400
I couldn't agree more.

399
00:13:22,400 --> 00:13:24,440
They're a testament to the beauty complexity

400
00:13:24,440 --> 00:13:26,880
and constant evolution of our universe.

401
00:13:26,880 --> 00:13:30,480
It really makes you wonder what other secrets are out there

402
00:13:30,480 --> 00:13:34,200
locked away in these asteroids just waiting to be discovered.

403
00:13:34,200 --> 00:13:34,720
Absolutely.

404
00:13:34,720 --> 00:13:37,000
And remember, we've only been talking about the asteroids

405
00:13:37,000 --> 00:13:37,920
in our solar system.

406
00:13:37,920 --> 00:13:38,640
Right.

407
00:13:38,640 --> 00:13:42,280
Imagine the possibilities out there and the vastness of space.

408
00:13:42,280 --> 00:13:43,680
You mean around other stars?

409
00:13:43,680 --> 00:13:44,720
Yeah.

410
00:13:44,720 --> 00:13:47,600
Could there be asteroids playing similar roles

411
00:13:47,600 --> 00:13:49,880
in shaping other planetary systems?

412
00:13:49,880 --> 00:13:51,280
It's almost a certainty.

413
00:13:51,280 --> 00:13:51,840
Really?

414
00:13:51,840 --> 00:13:55,680
We know that planetary systems are incredibly common

415
00:13:55,680 --> 00:13:57,120
throughout the galaxy.

416
00:13:57,120 --> 00:13:59,920
And if the processes that formed our solar system

417
00:13:59,920 --> 00:14:03,040
or any indication, asteroids are likely

418
00:14:03,040 --> 00:14:05,840
to be key players in the formation of the systems

419
00:14:05,840 --> 00:14:06,560
as well.

420
00:14:06,560 --> 00:14:09,680
So the story of asteroids isn't just a solar system story.

421
00:14:09,680 --> 00:14:10,200
No.

422
00:14:10,200 --> 00:14:12,640
It's a galactic one, maybe even a universal one.

423
00:14:12,640 --> 00:14:13,920
Precisely.

424
00:14:13,920 --> 00:14:16,800
And with every new exoplanet we discover,

425
00:14:16,800 --> 00:14:18,360
with every new observation we make,

426
00:14:18,360 --> 00:14:20,920
we're getting a clearer picture of just how

427
00:14:20,920 --> 00:14:23,800
widespread and influential asteroids might be.

428
00:14:23,800 --> 00:14:26,160
It's mind boggling to think about all those asteroids

429
00:14:26,160 --> 00:14:29,240
out there orbiting distant stars, perhaps even contributing

430
00:14:29,240 --> 00:14:31,520
to the formation of habitable worlds.

431
00:14:31,520 --> 00:14:32,040
It is.

432
00:14:32,040 --> 00:14:33,640
And it opens up a whole new realm

433
00:14:33,640 --> 00:14:37,040
of possibilities for the search for life beyond Earth.

434
00:14:37,040 --> 00:14:40,080
If asteroids played a role in delivering the ingredients

435
00:14:40,080 --> 00:14:42,360
for life to our planet, could they

436
00:14:42,360 --> 00:14:45,000
have done the same for other planets out there?

437
00:14:45,000 --> 00:14:46,640
That's a fascinating thought.

438
00:14:46,640 --> 00:14:48,800
It makes you wonder what other amazing discoveries

439
00:14:48,800 --> 00:14:52,200
are waiting to be made as we continue to explore the universe.

440
00:14:52,200 --> 00:14:53,200
Absolutely.

441
00:14:53,200 --> 00:14:55,320
We've only just scratched the surface of what there

442
00:14:55,320 --> 00:14:56,960
is to know about asteroids.

443
00:14:56,960 --> 00:14:57,520
Yeah.

444
00:14:57,520 --> 00:15:00,360
They've gone from being overlapped space rocks

445
00:15:00,360 --> 00:15:03,400
to objects of intense scientific interest.

446
00:15:03,400 --> 00:15:04,080
Right.

447
00:15:04,080 --> 00:15:05,600
And I have a feeling that we're only

448
00:15:05,600 --> 00:15:08,040
at the beginning of this journey of discovery.

449
00:15:08,040 --> 00:15:10,600
Well, I, for one, am excited to see what the future holds

450
00:15:10,600 --> 00:15:12,200
for asteroid research.

451
00:15:12,200 --> 00:15:12,680
Yeah.

452
00:15:12,680 --> 00:15:14,400
Who knows what groundbreaking insights

453
00:15:14,400 --> 00:15:15,720
are waiting to be unearthed.

454
00:15:15,720 --> 00:15:16,880
Indeed.

455
00:15:16,880 --> 00:15:19,080
The universe is full of wonders, and asteroids

456
00:15:19,080 --> 00:15:21,000
are proving to be some of the most intriguing

457
00:15:21,000 --> 00:15:22,960
and insightful object we've encountered.

458
00:15:22,960 --> 00:15:24,240
So keep looking up.

459
00:15:24,240 --> 00:15:24,720
Right.

460
00:15:24,720 --> 00:15:27,440
Keep exploring, and never stop asking questions.

461
00:15:27,440 --> 00:15:30,600
Thank you so much for taking us on this deep dive

462
00:15:30,600 --> 00:15:31,760
into the world of asteroids.

463
00:15:31,760 --> 00:15:32,800
Oh, you're welcome.

464
00:15:32,800 --> 00:15:35,160
I feel like I've gained a whole new appreciation

465
00:15:35,160 --> 00:15:36,680
for these cosmic wanderers.

466
00:15:36,680 --> 00:15:38,160
It's been my pleasure.

467
00:15:38,160 --> 00:15:40,480
And remember, this is just the beginning.

468
00:15:40,480 --> 00:15:43,200
There's a whole universe of knowledge out there

469
00:15:43,200 --> 00:15:45,080
waiting to be explored.

470
00:15:45,080 --> 00:15:46,680
And don't forget to follow and subscribe

471
00:15:46,680 --> 00:15:49,520
to Cosmos in a Pod and our YouTube channel

472
00:15:49,520 --> 00:16:17,520
for more fascinating explorations of the universe.