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  • (Music)

  • Narrator: What safeguards our solar system...

  • is our star.

  • The sun provides a shield, stretching beyond the last

  • planet in its orbit: a force field that deflects these "cosmic

  • rays."

  • But these "solar winds" can be dangerous too, especially during

  • outbursts called coronal mass ejections.

  • Want a vision of earth gone wrong?

  • Just look at what solar storms do our sister planet,

  • Venus. They strip away lighter

  • elements in its upper atmosphere, hydrogen, oxygen

  • and the molecule they form: water.

  • What's left is a witch's brew of noxious chemicals

  • including thick sulfurous clouds.

  • How has Earth avoided the grim fate of Venus?

  • We can see the answer as the solar storm

  • approaches Earth.

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  • Our planet has a protective shield all it's own--

  • A powerful magnetic field

  • generated deep within its core.

  • In fact, that's just our first line of defense.

  • Much of the solar energy that gets through is reflected back

  • to space by clouds, ice, and snow.

  • The energy that Earth absorbs is just enough to power

  • a remarkable planetary engine: the climate.

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  • It's set in motion by the unevenness of solar

  • heating, due in part to the cycles of day and night,

  • and the seasons that cause warm tropical winds

  • to blow toward the poles and cold polar air

  • toward the equator.

  • Wind currents drive surface ocean currents.

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  • This computer simulation shows the Gulf Stream winding its

  • way along the coast of North America.

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  • This great

  • ocean river carries enough heat energy to power the industrial

  • world a hundred times over.

  • It breaks down in massive world pools

  • that spread warm tropical waters over northern seas.

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  • Below the surface they mix with cold deep currents that swirl

  • around under sea ledges and mountains.

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  • Earth's climate engine

  • has countless moving parts: tides and terrain,

  • cross winds and currents-- all working to equalize temperatures

  • around the globe.

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NASA | Dynamic Earth Excerpt: Viz Challenge Winner

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    VoiceTube posted on 2014/02/08
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