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Speaker 1: Welcome to Brainstuff from Hastaff Parks dot com where smart happens. Hi.
Speaker 1: I'm Marshall Brain with today's question, how does the Aurora
Speaker 1: borealis or the Northern lights work? The Aurora borealis has
Speaker 1: always fascinated mankind, and people even travel thousands of miles
Speaker 1: just to see this amazing light show in the Earth's atmosphere.
Speaker 1: The aurora's both surrounding the Northern Magnetic Pole and the
Speaker 1: Southern Magnetic Pole, occur when highly charged electrons from the
Speaker 1: solar wind interact with elements in the Earth's atmosphere. Solar
Speaker 1: winds stream away from the Sun at speeds of about
Speaker 1: one million miles per hour. When they reach the Earth
Speaker 1: some forty hours after leaving the Sun, they follow the
Speaker 1: lines of magnetic force generated by the Earth's core and
Speaker 1: flow through the magnetos sphere, a tear drop shaped area
Speaker 1: of highly charged electrical and magnetic fields. As the electrons
Speaker 1: enter the Earth's upper atmosphere, they encounter atoms of oxygen
Speaker 1: and nitrogen at altitudes from twenty to two hundred miles
Speaker 1: above the Earth's surface. The color of the aurora depends
Speaker 1: on which atom is struck and the altitude of the meeting.
Speaker 1: Green auroras mean that an oxygen atom up to a
Speaker 1: hundred and fifty miles in altitude has been hit by
Speaker 1: an electron. Red auroras mean that an oxygen atom above
Speaker 1: a hundred fifty miles in altitude has been struck. A
Speaker 1: blue aurora means that a nitrogen at them up to
Speaker 1: sixty miles in altitude has been struck, and a purple
Speaker 1: or violet aurora means that a nitrogen atom above sixty
Speaker 1: miles in altitude has been struck. All of the magnetic
Speaker 1: and electrical forces react with each other in constantly shifting combinations.
Speaker 1: These shifts and flows can be seen as the auroras
Speaker 1: appear to dance, moving along with atmospheric currents. The auroras
Speaker 1: generally occur along the auroral ovals, which center on the
Speaker 1: magnetic poles of the Earth. And roughly correspond to the
Speaker 1: Arctic and the Antarctic circles. There are times, though, when
Speaker 1: the lights are further south, usually when there's a lot
Speaker 1: of sun spots. Sun Spot activity follows an eleven year cycle,
Speaker 1: and the next peak will occur in two thousand and
Speaker 1: eleven and two thousand and twelve, so opportunities to see
Speaker 1: auroras outside their normal rain should be good. There are
Speaker 1: many stories about sounds associated with auroras, but there are
Speaker 1: no recordings of these sounds. Scientists can't agree on what
Speaker 1: would produce sounds during an aurora. Do you have any
Speaker 1: ideas or suggestions for this podcast? If so, please send
Speaker 1: me an email at podcast at how stuff works dot com.
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