Prática de Shadowing: What If You Lived on Mars 1 Billion Years Ago? - Aprenda a falar inglês com vídeo
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Scientists finally did it.
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They've discovered life on Mars.
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Maybe.
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To fully understand what they've found and what this discovery means for you, let me take you back in time.
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But I'm not just going to take you back one billion years.
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We're going to start much, much further back in history.
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Billions of years ago, Mars wasn't a simple, lifeless red rock.
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It had a thick atmosphere, pleasant temperatures, and liquid surface water.
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Think beachfront.
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Back then, Mars might have been a better location for life to take hold than Earth.
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And maybe it did have living organisms on it.
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So let's start at the beginning.
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And by that, I mean the beginning of the planets in our Solar System, around 4.5 billion years ago.
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On Mars, this period is known as the pre-Noachian.
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Mars has just formed from dust and gas in the protoplanetary disk, just like Earth did.
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Pieces of debris clamped into a planet with a dense core, a rocky mantle, and a crust.
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And this planet was slammed with swirling space rocks.
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In its early years, Mars had a very dense atmosphere, atmosphere, and an ocean so big it covered one-third of the planet.
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At first, the planet was super hot, but slowly, between 4.3-4.4 billion years ago, it cooled down.
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Fast forward to the Noachian period, about 4 billion years ago.
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This was a time of heavy asteroid and comet bombardments, and widespread volcanic activity.
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So basically, everything that could blast gas, vapor, and dust into the atmosphere was doing it.
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It was a perfect place for life to put down roots.
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All these gases created a thick atmosphere, and the planet heated up thanks to the good old greenhouse effect.
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Suddenly, Mars had clouds, valleys, lakes, and even rain.
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Likely acid rain.
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And this acid rain wasn't just destructive, it may have been useful.
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As it dissolved Martian rocks, it released minerals and nutrients into rivers and lakes, providing a chemical buffet for any microbes trying to survive.
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Not harsh for you, but a probable paradise for tiny alien life.
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Then, somewhere between 4.1 and 3.7 billion years ago, things started going downhill.
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the interior of Mars cooled off, and its magnetic field dissipated.
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Now, that's a problem for life.
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You might not think about magnetic fields very often, but without them, planets die.
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That's because without a magnetosphere, nothing is protecting the planet from solar wind.
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And that wind strips planets of their atmosphere.
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How does it do it?
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Well, solar wind isn't like the wind you know.
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It's a stream of charged particles coming from the Sun.
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These particles slam into the air molecules and knock off their electrons.
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Without electrons, air molecules become ionized and get knocked into space.
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Oof!
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There's no air left on the planet.
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So that's how Mars started to lose its atmosphere. So what?
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Well, keep in mind, without an atmosphere, there's no way to keep the temperature stable, and no way to keep water on the ground.
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That meant that the hotspots for life to arise on Mars became smaller.
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The clock was ticking.
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But the conditions for life were holding on.
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All is not lost.
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You still got this, Mars.
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Now, not long in cosmic terms, after losing its magnetic field, Mars started to look more like Earth today.
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Yeah, 3.7 billion years ago was a great time for this red rock.
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It was the beginning of the Hesperian period.
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Mars may still have had a northern ocean around this time, though scientists think it was shrinking fast.
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Still, it was the perfect place for Mars to be teeming with tiny early Martians.
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At this very same time, Earth kick-started primitive life on its surface.
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It was the beginning of the chain reaction for all life on our planet.
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It's also the period of time between 3.2 and 3.8 billion years ago, when something mysterious happened on Mars.
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Something that left potential biosignatures on the Martian rocks.
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When scientists discovered these biosignatures, they knew they were onto something big.
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Well, I actually have one of the scientists who worked on the discovery Right here with me, Dr. Ed Clutis.
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So, Dr. Clutis, is there life on Mars?
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We haven't found life on Mars.
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We found possible remains of life on Mars.
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And when we analyzed it in detail, we detected things like organic molecules, which is always a sign of possible life.
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Where we find this assemblage of minerals and organic molecules on Earth, it's inevitably associated with biology.
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This discovery started when NASA's Perseverance rover was out cruising the Jezero Crater, which used to be a huge Martian lake and river delta.
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Perseverance rolled through the Naretva Vallis, which is basically Martian for the now-dry Naretva Valley.
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We call it Vallis instead of Valley for the same reason we call Martian days Sols and not Days.
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Because it's Latin, and it sounds cooler.
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Anyway, Naretfa Valis is about 400 metres wide.
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That's 1,300 feet.
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Back in the day, it had a big river flowing through it.
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And it was here that Perseverance investigated sedimentary rocks like clay and silt,
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which are really good at preserving evidence of previous microbial life.
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Perseverance poked around some odd-looking mudstone rocks found what could be the signatures of two iron-rich minerals,
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vivianite and greigite.
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These colorful leopard spots in this image could be fossilized signs that microbial life existed on Mars billions of years ago.
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Yeah, that's right, microbes.
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That's what's at the core of the excitement around this core sample that Perseverance investigated.
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When we look at these spots, we could be looking at evidence of ancient life on Mars.
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Now, one thing NASA's rovers can't do is go back in time
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and capture Mars exactly like it was 3.5 billion years ago.
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Which is fine, because on What If? we don't have a Mars rover.
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We have something better or worse.
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Uh, definitely better.
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Hey Chase heads, so uh, this is Mars.
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3.5 bill years ago, uh, 3.5 billion years before Chase.
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Before humanity.
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Before uh, I don't know, like big numbers ago.
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Pre-dino, pre-robot, pre-robot chicken?
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You know, all that stuff.
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It actually looks pretty sweet, you know? But life?
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Nah, I don't see it.
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Nothing.
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Well, nobody said there would be walking,
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talking aliens, but you're looking at a river that's potentially churning with all kinds of single cell organisms.
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I mean, it's cool here.
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I always think of Mars as like, you know, red, but it's like beautiful.
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It's like blue skies, you know, water.
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Check it out.
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I mean, I guess the dirt is still pretty red, but like, you know, look, Martian clouds.
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Pretty cool.
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The air's...
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...unbreathable.
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You still need a spacesuit.
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But it's pretty, you know?
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And thankfully, seems pretty safe.
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Look, okay.
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You guys wanted me to show you what life was like in this potentially historical spot, right?
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So, here you go!
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It's a bunch of dirt and stuff.
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You can't see anything without a proper microscope.
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So honestly, disappointing.
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Very disappointing.
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Yeah, that appearance was disappointing.
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It's true, even though this recent discovery was the best proof of ancient life on Mars,
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it's very unlikely that life was anything but microbes.
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And while Perseverance has collected a number of samples, we still have to get those samples back to Earth so we can study them properly.
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The current plan is a sample return mission in 2030, and I believe the samples would come back to Earth in 2031.
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Yeah, getting those rocks back is a complicated process.
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NASA is looking at sending a whole team of robots to get these samples
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and bring them back to Earth on a European Space Agency orbiter.
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But until that happens, we won't know for sure if there was ancient life on Mars.
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But we do know that back in this Hesperian period, Mars was still rocking active volcanoes, only not for long.
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As its magnetic field dissipated, the temperature dropped, Mars was losing its atmosphere, and water became locked into ice.
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Whenever asteroids smashed into Mars,
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the impacts superheated the underground water and created explosive flash floods, Martian tsunamis.
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And here's something cool to think about.
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We know that billions of years ago, chunks of Mars often got blasted off the planet and landed on Earth.
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We have over 400 pieces of space rock with Martian origins.
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Which means, if life was common on Mars back 3.5 billion years ago, Could you yourself be from Mars?
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It'd be wild, but anything is possible.
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There's a theory that life on Earth originated from microbes that immigrated to our planet, traveling on space dust, meteoroids,
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asteroids, comets, or even spacecraft.
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Now, Earth didn't see the first multicellular animals until about 800 million years ago.
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And those were just sponges.
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They could be sponges from Mars. Who knows?
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But I'm going to carry it away now.
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And this video is called What If You Lived On Mars 1 billion years ago, not 3 billion years ago.
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So as exciting as this time was for Mars, let's fast forward a little more.
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By the end of the Hesperian Period, things started going downhill for Mars.
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While its neighbor Earth was welcoming life, changing its atmosphere and reshaping its surface,
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Mars was losing all the things that life could hold onto.
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2.9 billion years ago, the Martian magnetosphere was gone.
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And without it, solar winds did what solar winds do and stripped much of the atmosphere.
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The air had become thinner and could no longer retain heat.
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Very quickly, Mars was becoming cooler and drier.
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And that's bad news for the water on its surface.
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As the temperatures fell well below freezing, liquid water was disappearing.
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But it was still there.
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Yeah, at this point, Mars still had some of its briny, salty water in isolated areas.
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But if you look around, you'll see that most of the oceans, rivers, lakes are gone.
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Volcanoes were on their way out too.
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As Mars was cooling off, the volcanoes became less frequent.
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But you could still see Olympus Mons erupting occasionally.
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And these eruptions temporarily made Mars just a little warmer.
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Yeah, every time Olympus Mons erupted, it didn't just spread lava.
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It spewed out greenhouse gases.
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For a short while, Mars may have warmed up, melting ice and unleashing sudden floods.
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These eruptions could be seen as the planet's last attempt to stay habitable.
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Now, what about all that potential life?
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Well, it's horrible news for those microbes, too.
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Now, back on Earth, microbes were thriving.
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Cyanobacteria started photosynthesis and pumped oxygen into the air.
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this began changing the composition of Earth's atmosphere.
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But Mars wasn't going in that direction.
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It started to get a cold, red desert vibe.
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Even if microbial life did exist 3.5 billion years on Mars, now, well, it was dying in this increasingly hostile environment.
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The only chance it had of surviving would be underground, protected from the harsh surface.
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If anything could survive on Mars, it'd have to be tough as hell, and it would probably have to be below the surface, maybe a meter, a few meters.
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If any Martian microbes survive, they likely abandoned the surface and retreated underground into aquifers,
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caves, or close to geothermal hotspots, shielded from the radiation or freezing air above.
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OK, finally, we fast forward to one billion years ago.
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That's what you've been waiting for, right?
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Well, that's too bad, because this is when Mars was inevitably becoming what it is today.
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A red, lifeless rock.
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This period of Martian history is called the Amazonian.
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It started 2.9 billion years ago, and it's still going on as of today.
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Yeah, that's right.
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Mars has looked like this for a very long time.
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Dry, dusty, rusty red.
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whether it was two billion years ago, or one billion, or two years ago.
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If you lived on Mars, life would be the same.
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To be clearer, there wouldn't be any, at least not that we know of.
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So here you are, in the middle of the Red Desert.
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The atmosphere is thin, composed mostly of carbon dioxide, and the surface pressure is low, about 1% of Earth's.
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surface water doesn't exist, or if it does, it doesn't last, it vaporizes.
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Plus, it's freezing.
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By now, the average surface temperature has plummeted to about minus 60 degrees Celsius.
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That's negative 76 degrees Fahrenheit.
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But occasionally Olympus Mons erupts and warms up the surrounding area.
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If you don't know, Olympus Mons isn't your average volcano.
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At about 22 kilometers or 14 miles high, it's the largest volcano in the solar system.
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Yeah, three times taller than Mount Everest and about the size of the entire state of Arizona.
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It started forming three and a half billion years ago.
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For billions of years, it was growing, turning into a giant.
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It was able to do this without any interference because
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Mars doesn't have plate tectonics beneath its crust to move this mountain around.
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And one billion years ago, it was still active.
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Not as active as in its best years, but it wasn't dormant.
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It spewed lava for hundreds of kilometers and reshaped and warmed the Martian surface around it.
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Back then, it could have been a Martian's last resort.
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All that underground heat could have created hydrothermal systems, which are a really good place for microbes to hide from the harsh surface conditions.
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Today, Olympus Mons is silent, just a giant pimple on the Martian surface, one that's visible from space.
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I had one of those before senior prom.
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From this point on, Mars didn't change much.
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Now, without an atmosphere or water, its surface is primarily changed by erosion, some late-stage volcanism, and lava flows.
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Strong winds also shaped Mars, creating sand dunes and flattening the plains.
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There could be underground water, but no oceans.
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And here and there, there's faint evidence of life, like these leopard spots on rocks that shouldn't have spots.
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You know, the search for life on Mars is going to get harder as time goes on.
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The spacecraft we send now, we decontaminate them as much as we can so that if we do find organic molecules or possible biosignatures,
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we're pretty sure that it's not contamination brought from the Earth.
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But once you start sending people up there, I mean, we're just bags of microbes and germs, right?
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So once we start sending people up there, finding unambiguous signs of life is going to be harder
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because we're not going to be sure that it's not contaminants that we brought ourselves to Mars.
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Mars action!
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Oh, look.
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Storm's coming.
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That's not obvious at all.
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Maybe one day you'll set foot on Mars, build a base, grow some potatoes, try your best to last longer than five seconds here.
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But that's a story for another WHAT IF.
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Vocabulário e dicas de fala para esta lição
Esta aula de conversação de nível B2 usa o vídeo “What If You Lived on Mars 1 Billion Years Ago?”. As palavras que mais se repetem: Mars, billion, Martian, atmosphere, surface. Este vídeo tem 222 frases e 2460 palavras para praticar shadowing. A fala dura 18:32. O falante mantém um ritmo estável de cerca de 133 palavras por minuto, confortável para o shadowing. Apenas 78% das palavras estão entre as 3.000 mais comuns do inglês, por isso o vocabulário é exigente.
Vocabulário principal deste vídeo
As 15 palavras mais avançadas do vídeo, com pronúncia e significado:
| Palavra | Pronúncia | Significado |
|---|---|---|
| microbe substantivo | /ˈmaɪkɹoʊb/ | micróbio |
| molecule substantivo | /ˈmɑ.lɪ.kjul/ | molécula |
| volcano substantivo | /vɑlˈkeɪ.noʊ/ | vulcão |
| magnetic adjetivo | /mæɡˈnɛtɪk/ | magnético |
| erupt verbo | /ɪˈɹʌpt/ | entrar em erupção, erupcionar |
| microbial adjetivo | /maɪˈkɹəʊ.bi.əl/ | microbial, micróbico |
| asteroid substantivo | /ˈæst(ə)ɹɔɪd/ | asteroide, planetoide |
| disappoint verbo | /ˌdɪsəˈpɔɪnt/ | desapontar, decepcionar |
| lava substantivo | /ˈlɑvə/ | lava |
| mineral substantivo | /ˈmɪn.ə.ɹəl/ | mineral |
| freeze verbo | /ˈfɹiːz/ | gelar, congelar |
| harsh adjetivo | /ˈhɑɹʃ/ | áspero |
| magnetosphere substantivo | /mæɡˈni.təˌsfɪr/ | magnetosfera |
| eruption substantivo | /ɪˈɹʌpʃən/ | erupção |
| sponge substantivo | /spʌnd͡ʒ/ | esponja |
Phrasal verbs que você vai ouvir
| Palavra | Pronúncia | Significado |
|---|---|---|
| warm up verbo | /ˌwɔː(ɹ)m ˈʌp/ | aquecer, esquentar |
| cool down verbo | /kuːl ˈdaʊn/ | esfriar, arrefecer |
Frases que vale a pena repetir
Frases curtas e completas do vídeo que você pode usar na conversa do dia a dia:
- Before uh, I don't know, like big numbers ago.
- Nah, I don't see it.
- I mean, it's cool here.
- It's like blue skies, you know, water.
- You can't see anything without a proper microscope.
Gramática neste vídeo
As estruturas que o falante mais usa, com as palavras exatas do vídeo:
| Estrutura | No vídeo |
|---|---|
| Frases condicionais if + oração, will/would + verbo — uma condição e seu resultado | if you look around, you'll see · If you lived on Mars, life would be |
| Present perfect have/has + particípio passado — uma ação passada que ainda importa agora | They've discovered · they've found · has just formed |
| Voz passiva be + particípio passado — o foco está no que acontece, não em quem faz | is known · was slammed · is not lost |
| Orações relativas who / which + oração — informação extra sobre uma pessoa ou coisa | molecules, which is · Vallis, which is · systems, which are |
Pronúncia para ficar de olho
O falante usa 36 contrações e formas reduzidas, como don't, wasn't, we're. Diga-as na forma curta, do jeito que você ouve.
- Os sons de “sh” e “zh”: harsh /ˈhɑɹʃ/, eruption /ɪˈɹʌpʃən/, erosion /ɪˈɹəʊʒən/, contamination /kənˌtæm.əˈneɪ.ʃən/, smash /smæʃ/
- Palavras longas — acerte a sílaba tônica: microbial /maɪˈkɹəʊ.bi.əl/, magnetosphere /mæɡˈni.təˌsfɪr/, organism /ˈɔɹ.ɡəˌnɪz.əm/, inevitably /ɪˈnɛvɪtəbli/, contaminant /kənˈtamɪnənt/
Sons difíceis para falantes de português:
- Consoante final — sem acrescentar um “i” depois: microbe /ˈmaɪkɹoʊb/, magnetic /mæɡˈnɛtɪk/, erupt /ɪˈɹʌpt/, asteroid /ˈæst(ə)ɹɔɪd/, disappoint /ˌdɪsəˈpɔɪnt/
- /l/ final — a língua toca o céu da boca, não vira “u”: molecule /ˈmɑ.lɪ.kjul/, microbial /maɪˈkɹəʊ.bi.əl/, mineral /ˈmɪn.ə.ɹəl/, downhill /ˌdaʊnˈhɪl/, particle /ˈpɑɹtək(ə)l/
- /h/ — um sopro suave, diferente do “r”: harsh /ˈhɑɹʃ/, downhill /ˌdaʊnˈhɪl/, greenhouse /ˈɡɹːnˌ(h)aʊs/, hostile /ˈhɑstəl/
Como praticar com este vídeo
- Ouça o vídeo inteiro uma vez sem falar e anote as palavras que você não conhece.
- Faça shadowing frase por frase na velocidade normal, repetindo cada uma até o seu ritmo ficar igual ao do falante.
- Grave a sua voz e compare com o original, prestando atenção a palavras como microbe, molecule, volcano.
O que é a Técnica de Shadowing?
Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.