Name: オーロラの科学と美しさ (The Science and Beauty of Auroras)
Uploaded: 2021-01-14T06:32:42.000Z
Duration: 4 min 54 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Here's a story: Now imagine there's an invisible force field around our planet. And now imagine that

for billions of years, that force field has been protecting us from a beam of supercharged

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plasma that otherwise wipe out life on Earth as we know it. You might think this

is some kind of science fiction story, but it's all true. And it's what gives us this:

So the auroras are one of mankind's oldest mysteries, and we've come up with some pretty crazy theories

of how to explain it along the way. Take Aristotle, he thought they aurora was the sky vomiting

little bits of flame! But it wasn't until the 1600's that we figured out two key things

that helped us explain the aurora. One,  Earth is really just one big magnet,

and second, it turns out the sun gives of a lot more than just light.

Long before any sunlight hits Earth, it's born at the edge of the Sun. And the edge

of the Sun, the corona, is a busy, beautiful place, full of churning whirlpools of plasma

and huge magnetic arcs. All of that action is constantly releasing waves of energized

particles, creating what we call the "solar wind". A few days after leaving the Sun,

travelling at a whopping 400 kilometers per second, that blast of charged particles reaches

Earth. But luckily, we've got a secret weapon on our side: Earth's swirling, molten core.

Our core is the key to life on Earth. It creates a magnetic

force field around us that deflects that solar wind up and away, making life down here much

more enjoyable. Then because that magnetic field we have nice things like an atmosphere and we're much less burnt-to-a-crisp

thanks to wave after wave of planet-sterilizing radiation. But despite all that . . . A

tiiiiiny bit of that solar wind does hop on the magnetic field and rided

it up or down to the Earth's poles, and that's where we get the auroras.

When those energized particles smash into gases wayyyyy up high in our atmosphere, they

"excite" them, which means the gas atoms grab on to a bit of energy. But they don't

stay excited for long. They give off that stored energy in a bright burst of

light. Different atoms in our atmosphere each give off different colors.

Excited oxygen would give off that familiar green and red that most of us think of when

we hear "aurora". But there's also nitrogen up there, and it can give off a really cool

mix of red and blue light that makes the sky glow this incredible purplish-pink. Now, we

can only see this happening at night, but it's happening 24 hours a day, every day of every year! It's

Sometimes the Sun takes that wind and turns up to eleven, and that can be a very dangerous sight

to behold. Extreme solar storms called coronal mass ejections can erupt into space almost

without warning, unleashing huge waves of charged particles. If they happen to be pointed

These storms are incredibly powerful. Astronauts that are working outside of the Earth's magnetic field

say that if you close your eyes during one of these solar storms, you see bright

flashes of light when the charged particles reacting with the fluid inside your eye. In 1859, a storm

so powerful hit Earth that it powered a telegram from Boston to Portland, Maine

But, when those rare violent storms hit Earth's magnetic field and ride up to the

polar atmosphere, we are treated to an aurora show like no other. Now these images are more than just

works of art, they give scientists to study how solar storms affect life here on

Earth, like our electronics and communications. Some of the best views of Earth's auroras

have been captured from the International Space Station, the Space Station passes near the north

and south poles of our planet about once every 90 minutes. So if they pass by the poles while

it's dark? The auroras are close enough to touch! Although I wouldn't recommend that.

NASA makes sure that the astronauts that work on the ISS are highly trained photographers.

And artists down here on Earth are taking their photos and remixing them into creations

This celestial light show has been burning bright for perhaps billions of years, and

it's more than just Earth's private art show. It's painted by this invisible

force surrounding our living planet, a force that catches wind from the Sun, and turns

it into light. It gives humans a constant reminder of the beauty of the night sky, and

it's right in our planetary backyard. And that's pretty awesome.