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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}Narrator: What safeguards our solar system...
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}is our star.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}The sun provides a shield, stretching beyond the last
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}planet in its orbit: a force field that deflects these
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}"cosmic rays." But these
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}"solar winds" can be dangerous too,
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}especially during outbursts called coronal mass ejections.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}Want a vision of earth gone
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}wrong? Just look at what solar storms do our
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}sister planet, Venus. They strip away lighter
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}elements in its upper atmosphere, hydrogen, oxygen
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}and the molecule they form: water.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}What's left is a witch's brew of noxious
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}chemicals including thick sulfurous clouds.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}How has Earth avoided the grim fate of Venus?
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}We can see the answer as the solar storm
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}approaches Earth.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}Our planet has a protective shield
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}all it's own-- A powerful magnetic field 
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}generated deep within its core.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}In fact, that's just our first line of
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}defense. Much of the solar energy that gets through 
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}is reflected back to space by clouds, ice,
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}and snow. The energy that Earth absorbs
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}is just enough to power a remarkable planetary 
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}engine: the climate.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}It's set in motion
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}by the unevenness of solar heating, due in part to the 
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}cycles of day and night, and the seasons that cause warm 
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}tropical winds to blow toward the poles and cold
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}polar air toward the equator.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}Wind currents
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}drive surface ocean currents.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}This computer simulation shows the
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}Gulf Stream winding its way along the coast of North America.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}This great ocean river carries enough heat energy
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}to power the industrial world a hundred times
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}over. It breaks down
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}in massive world pools that spread warm tropical 
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}waters over northern seas.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}Below the surface they mix
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}with cold deep currents that swirl around 
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}under sea ledges and mountains.
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}Earth's climate engine has countless moving parts:
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}tides and terrain, cross winds and currents--
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}all working to equalize temperatures around
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{font:Arial}{size:14}{Plain}{textColor:65535, 65535, 65535}the globe.
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