WEBVTT - How  do the Northern Lights work?

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<v Speaker 1>Welcome to Brainstuff from Hastaff Parks dot com where smart happens. Hi.

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<v Speaker 1>I'm Marshall Brain with today's question, how does the Aurora

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<v Speaker 1>borealis or the Northern lights work? The Aurora borealis has

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<v Speaker 1>always fascinated mankind, and people even travel thousands of miles

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<v Speaker 1>just to see this amazing light show in the Earth's atmosphere.

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<v Speaker 1>The aurora's both surrounding the Northern Magnetic Pole and the

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<v Speaker 1>Southern Magnetic Pole, occur when highly charged electrons from the

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<v Speaker 1>solar wind interact with elements in the Earth's atmosphere. Solar

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<v Speaker 1>winds stream away from the Sun at speeds of about

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<v Speaker 1>one million miles per hour. When they reach the Earth

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<v Speaker 1>some forty hours after leaving the Sun, they follow the

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<v Speaker 1>lines of magnetic force generated by the Earth's core and

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<v Speaker 1>flow through the magnetos sphere, a tear drop shaped area

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<v Speaker 1>of highly charged electrical and magnetic fields. As the electrons

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<v Speaker 1>enter the Earth's upper atmosphere, they encounter atoms of oxygen

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<v Speaker 1>and nitrogen at altitudes from twenty to two hundred miles

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<v Speaker 1>above the Earth's surface. The color of the aurora depends

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<v Speaker 1>on which atom is struck and the altitude of the meeting.

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<v Speaker 1>Green auroras mean that an oxygen atom up to a

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<v Speaker 1>hundred and fifty miles in altitude has been hit by

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<v Speaker 1>an electron. Red auroras mean that an oxygen atom above

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<v Speaker 1>a hundred fifty miles in altitude has been struck. A

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<v Speaker 1>blue aurora means that a nitrogen at them up to

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<v Speaker 1>sixty miles in altitude has been struck, and a purple

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<v Speaker 1>or violet aurora means that a nitrogen atom above sixty

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<v Speaker 1>miles in altitude has been struck. All of the magnetic

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<v Speaker 1>and electrical forces react with each other in constantly shifting combinations.

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<v Speaker 1>These shifts and flows can be seen as the auroras

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<v Speaker 1>appear to dance, moving along with atmospheric currents. The auroras

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<v Speaker 1>generally occur along the auroral ovals, which center on the

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<v Speaker 1>magnetic poles of the Earth. And roughly correspond to the

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<v Speaker 1>Arctic and the Antarctic circles. There are times, though, when

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<v Speaker 1>the lights are further south, usually when there's a lot

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<v Speaker 1>of sun spots. Sun Spot activity follows an eleven year cycle,

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<v Speaker 1>and the next peak will occur in two thousand and

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<v Speaker 1>eleven and two thousand and twelve, so opportunities to see

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<v Speaker 1>auroras outside their normal rain should be good. There are

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<v Speaker 1>many stories about sounds associated with auroras, but there are

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<v Speaker 1>no recordings of these sounds. Scientists can't agree on what

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<v Speaker 1>would produce sounds during an aurora. Do you have any

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<v Speaker 1>ideas or suggestions for this podcast? If so, please send

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<v Speaker 1>me an email at podcast at how stuff works dot com.

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