跟读练习: What NASA Found on Io - 通过YouTube学习英语口语
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Out here, deep into space and far away from the sun,
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Out here, deep into space and far away from the sun,
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you might expect everything to be frozen and lifeless.
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And yet, we find images like this,
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captured by one of NASA's most advanced research probes,
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that shows us these bizarre structures seemingly created by a process that is unlike anything we know on Earth.
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Earth.
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Jupiter's moon Io is more alive than any other body in our solar system.
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Its rocky surface is caught up in a raging battle between fire and ice.
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Meanwhile, scientists on Earth have only just begun to uncover the hidden forces that are driving this chaos.
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The Jupiter system is home to nearly 100 officially recognized moons,
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a number that continues to grow as we discover new objects orbiting the giant planet.
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Most of them are very small,
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but four are exceptionally large.
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We call these the Galilean moons,
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as they were first recognized by the 16th century astronomer Galileo Galilei using one of the first telescopes ever made.
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The outer two moons are the largest, Callisto and Ganymede.
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Both are solid orbs of ice and rock with dead, heavily cratered surfaces.
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Second in line is Europa,
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which is made from a thin,
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smooth sheet of ice floating on a vast ocean of liquid water.
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It's one of the most promising locations in the solar system to find extraterrestrial life.
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And then closest to Jupiter is Io,
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just 350,000 kilometers above the clouds of the gas giant,
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not much further than the distance between Earth and our moon,
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and about the same size,
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just a little bigger and heavier.
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Io is actually the most dense moon in our solar system,
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and that's because it's made almost entirely of rock and metal,
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while most of the other large moons out here are made of ice and rock.
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The difference is so extreme
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that Io is believed to have the lowest water content of any known body in the solar system,
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even drier than Mercury, the closest planet to the sun.
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But what really makes Io special is the action on its surface.
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This is the only location outside of the Earth where we know that volcanoes are erupting on a regular basis.
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Io is actually the most volcanically active place in our entire solar system,
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with up to 400 active volcanoes dotting the entire surface of the Moon.
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This discovery was first made by the Voyager 1 probe during its Jupiter flyby in 1979.
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Even from a distance of 20,000 kilometers and using primitive,
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low-resolution cameras, Voyager was able to see nine distinct volcanic eruptions blasting out from the moon's surface.
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These raging lava flows exist in stark contrast to a world that is consumed by a deep freeze.
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Outside of the volcanic zones,
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the surface temperature of Io drops down to negative 130 degrees Celsius.
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We know that the Sun is too far away to contribute any warmth to the Jupiter system,
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so where does all of this heat come from?
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First, we need to appreciate that Io is caught up in a very treacherous location.
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At this close distance to Jupiter,
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it's just far enough away to avoid getting sucked in or even torn apart by the planet's massive gravity.
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But that doesn't mean that Io is in a safe place either.
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The extreme gravity from Jupiter still pulls on the moon's surface hard enough to stretch the rock and distort its shape.
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And then on the other side there are these three other large Galilean moons,
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and they exert their own force of gravity.
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Not nearly as strong as Jupiter,
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but still enough to pull Io in the opposite direction,
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which disrupts its orbit around Jupiter.
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So instead of moving in a circular pattern,
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Io orbits in an oval shape,
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meaning sometimes it's really close to Jupiter and other times it's further away.
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So it never gets an even exposure to that extreme gravity,
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and it cycles back and forth about once every two days,
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constantly being stretched and released and changing shape as it moves along.
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The result is that Io experiences some pretty massive tidal bulging.
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This is the same effect that we see with the ocean on Earth.
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Our own moon has enough gravity to pull up on the water,
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causing high and low tides.
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The rise of the ocean on Earth is only about half a meter on average.
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Different coastal locations will experience varying amounts of tidal change based on their geography,
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but in the middle of the ocean the change is very small.
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On I.O., the gravity of Jupiter does something insane,
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lifting the surface by as much as 100 meters when the two bodies are at their closest distance.
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And that is not just pulling up water,
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That's stretching solid rock and essentially giving the moon itself a slight egg shape.
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All of this stretching and squeezing acts like a pump
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that drives energy into the center of Io and powers all of this volcanic activity.
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But these volcanoes do not function in the same way that we see on Earth.
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If you think about a volcanic eruption,
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you probably imagine a big pointy mountain with lava and ash shooting out from the top.
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These tend to form along areas where tectonic plates collide,
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and force rock up from below the surface.
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I.O doesn't have plate tectonics,
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so lava just tends to erupt from cracks that form as a result of the constant gravitational stretching.
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The initial release of energy can throw lava dozens of kilometers above the moon's surface,
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and above that, a plume of sulfur gas can rise for hundreds of kilometers.
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Sulfur is always present in volcanic activity on Earth as well.
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If you ever see a lava rock that has all of these round holes all over it,
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those are created by trapped pockets of sulfur gas.
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The result of this is a sulfur atmosphere that surrounds Io.
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Depending on the level of volcanic activity at any given time,
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the atmosphere can range from about one-third the density of Earth's to nearly double.
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Most of the sulfur that gets released will eventually settle back down and cover the moon's surface.
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This is what creates the range of vibrant colors that we see from orbit.
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The yellow regions are sulfur that has been crystallized by the low temperatures, essentially snow.
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The white and blue patches are frozen sulfur dioxide that exist in the coldest shadow regions of the moon.
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The green areas are sulfur monoxide which is created by interactions with Jupiter's radiation belt in the upper atmosphere.
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And then, the red areas are hot spots of recent volcanic activity where the sulfur is still being actively heated.
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Going back to what we mentioned earlier,
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volcanic activity on Io does not create mountains or raised shield structures like it does on Earth.
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Instead, after the initial violence of the eruption,
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the moon's surface tends to collapse down and molten rock fills the void to create these giant lava lakes.
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The biggest one is named Lohipatara.
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It's 200 kilometers in diameter,
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and in the center, there's a big island of solidified rock surrounded by an active churning lake of molten rock.
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Now because of all this volcanic activity,
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you might think that Io is composed just like the Earth,
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with a solid crust layer floating on top of a magma ocean.
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But we are pretty sure that's not the case.
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Probes sent to the Jupiter system have been able to measure the gravity field of the Moon,
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and what they notice is a very uneven pull of gravity around the surface.
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That tells us the magma is not evenly distributed,
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it's probably trapped in localized pockets of molten rock
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that are created in the areas that experience the largest amount of tidal flexing.
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So what you end up with are hundreds of separate volcanic engines hidden underground,
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which means every volcano is going to behave a little differently.
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Okay, here's another mystery.
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If volcanoes and plate tectonics aren't creating mountains on I.O.,
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then where did this thing come from?
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This is called Steeple Mountain.
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At somewhere between 5 and 7 kilometers in height,
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it's one of the most iconic views associated with I.O.,
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mostly because it looks a lot like the spire of a church steeple,
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or the Eye of Sauron.
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We are able to see such detailed images like these thanks to data collected by NASA's Juno spacecraft,
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which arrived at Jupiter in 2016 on a five-year mission to study the atmosphere of the gas giant.
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After completing that goal, Juno was repurposed to investigate the four Galilean moons.
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The probe completed two close flybys of Io,
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the first in December 2023 and a second in February 2024,
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coming within 1,500 kilometers of the surface.
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What Juno saw out there is possibly the most unique landscape in our solar system.
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It quickly found that Steeple is actually just one of many tall,
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spiky mountains dotted around the surface of Io.
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The tallest of them rises 18 kilometers,
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or about double the height of Mount Everest.
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And what's really interesting is that unlike Everest,
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these structures on Io are all just kind of lone wolves.
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There are no dense groupings or mountain ranges to be found,
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just these seemingly random peaks stabbing straight up into the air.
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That tells us that these mountains did not form slowly over time.
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Instead, they burst from the ground suddenly,
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like an alien from a guy's chest in that movie Alien.
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Now, we're pretty sure that this is all still linked to volcanic activity,
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just in a very unusual way.
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So earlier, we talked about how the lava flow tends to cause the surface of Io to collapse
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and form these giant lakes.
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The idea is that this downward pressure into the surface actually causes a nearby area of rock to get pushed up.
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Imagine if every time a sinkhole opened on the Earth,
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a new mountain just sprung up right beside it.
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That is kind of what we're looking at here.
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The result would be unlike any mountain you've ever seen before,
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and this is the kind of bizarre natural process that has been playing out on I.O for billions of years,
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with the surface in a constant state of rise and fall thanks to the relentless pull of Jupiter's gravity.
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Sadly though, these images could be the last we ever see of Io.
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With NASA's Juno spacecraft slowly running out of fuel,
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it's set to be replaced by two new robotic explorers of the Jupiter system.
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One is called JUICE, which stands for the Jupiter Icy Moons Explorer.
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It was made by the European Space Agency and launched in 2023.
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When it arrives at Jupiter in 2031,
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JUICE will investigate three of the Galilean moons, Ganymede, Callisto, and Europa.
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Europa, looking specifically at their icy surfaces and hidden oceans of liquid water.
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Then there is NASA's latest deep space probe,
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the Europa Clipper, which launched in 2024 and will arrive at its destination in 2030.
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As you can probably tell from the name,
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this mission is directed specifically at the moon Europa
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and will be primarily looking for signs of alien life in the watery depths below its surface.
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That leaves Io as the odd one out.
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There is no probe heading there any time in the near future,
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and that's not because IO isn't deeply fascinating in its own right,
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it's largely
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because we didn't realize just how interesting the moon was until we saw these Juno images just a couple of years ago.
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Also it definitely doesn't have aliens,
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which automatically drops down to priority level.
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But priorities are changing at NASA.
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There is exciting new leadership coming in,
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there are unprecedented new rocket technologies emerging,
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and sometime in the not-so-distant future,
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we could be studying the deep solar system just as thoroughly as we investigate Mars and the Moon.
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Until then, we'll always have Steeple Mountain.
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关于本课程
在本课程中，您将通过一段关于木卫一（Io）及其独特气候现象的研究内容，不仅提高您的英语发音，还能增强您的听力理解能力。我们将重点练习与太空、火山活动及其他天体相关的词汇和短语，帮助您在讨论这些主题时更加自信。同时，您将学习如何运用shadowing site技术，通过跟读视频中的发音与语调来改善您的口语表达。
关键词汇与短语
- 木卫一 (Io) - 木星最大的卫星，以其火山活动闻名。
- 火山 (volcano) - 地表喷发的地质构造，木卫一上活跃度非常高。
- 极端温度 (extreme temperature) - 木卫一的表面温度可达-130摄氏度。
- 液态水 (liquid water) - 发现外星生命的重要元素，木卫二（Europa）含有。
- 引力 (gravity) - 木星对木卫一的强大引力影响其表面形状。
- 天体 (celestial body) - 包含行星、卫星等天体，木星系统中有近100颗卫星。
- 探测器 (probe) - 用于研究太空环境的科学仪器，例如旅行者一号。
- 宇宙 (universe) - 包含所有天体和空间的整体。
练习技巧
为了有效利用本视频的内容并改善您的英语口语能力，您可以采用shadow speech技术。在观看视频时，尽量模仿讲解者的语速和语调。建立一个适合自己的时间间隔，例如10到15秒，先听一段，然后反复跟读几次。这样的跟读练习不但能提高您的语音语调，也能增强您的语感，最终帮助您在真实交流中应用。在练习时，要专注于发音的清晰度，尽量做到每个单词、每个语调都尽量与视频中的讲解者一致。此外，不要害怕反复播放视频，多练习几遍以达到最佳效果。通过这些方法，您可以有效地提高英语发音，并掌握与天文学相关的专业词汇，增强口语表达能力。
什么是跟读法？
跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。