1 00:00:00,160 --> 00:00:03,440 Speaker 1: Audible dot com is the leading provider of downloadable digital 2 00:00:03,480 --> 00:00:07,160 Speaker 1: audio books and spoken word entertainment. Audible has over one 3 00:00:07,200 --> 00:00:10,080 Speaker 1: hundred thousand titles to choose from to be downloaded to 4 00:00:10,119 --> 00:00:13,680 Speaker 1: your iPod or MP three player. Go to audible podcast 5 00:00:13,760 --> 00:00:16,120 Speaker 1: dot com slash brain stuff to get a free audio 6 00:00:16,160 --> 00:00:18,560 Speaker 1: book download of your choice when you sign up today. 7 00:00:19,480 --> 00:00:31,560 Speaker 1: Welcome to Brainstuff from Hastaff Parks dot com where smart happens. Hi. 8 00:00:31,600 --> 00:00:34,920 Speaker 1: I'm Marshall Brain with today's question, how does the Aurora 9 00:00:35,040 --> 00:00:40,000 Speaker 1: borealis or the Northern lights work? The Aurora borealis has 10 00:00:40,080 --> 00:00:44,720 Speaker 1: always fascinated mankind, and people even travel thousands of miles 11 00:00:44,720 --> 00:00:48,040 Speaker 1: just to see this amazing light show in the Earth's atmosphere. 12 00:00:48,640 --> 00:00:52,479 Speaker 1: The aurora's both surrounding the Northern Magnetic Pole and the 13 00:00:52,640 --> 00:00:57,520 Speaker 1: Southern Magnetic Pole, occur when highly charged electrons from the 14 00:00:57,640 --> 00:01:02,280 Speaker 1: solar wind interact with elements in the Earth's atmosphere. Solar 15 00:01:02,320 --> 00:01:05,920 Speaker 1: winds stream away from the Sun at speeds of about 16 00:01:06,319 --> 00:01:09,679 Speaker 1: one million miles per hour. When they reach the Earth 17 00:01:10,040 --> 00:01:13,640 Speaker 1: some forty hours after leaving the Sun, they follow the 18 00:01:13,760 --> 00:01:17,520 Speaker 1: lines of magnetic force generated by the Earth's core and 19 00:01:17,680 --> 00:01:21,480 Speaker 1: flow through the magnetos sphere, a tear drop shaped area 20 00:01:21,600 --> 00:01:26,400 Speaker 1: of highly charged electrical and magnetic fields. As the electrons 21 00:01:26,520 --> 00:01:30,720 Speaker 1: enter the Earth's upper atmosphere, they encounter atoms of oxygen 22 00:01:30,760 --> 00:01:34,720 Speaker 1: and nitrogen at altitudes from twenty to two hundred miles 23 00:01:34,760 --> 00:01:38,440 Speaker 1: above the Earth's surface. The color of the aurora depends 24 00:01:38,560 --> 00:01:42,440 Speaker 1: on which atom is struck and the altitude of the meeting. 25 00:01:43,160 --> 00:01:46,880 Speaker 1: Green auroras mean that an oxygen atom up to a 26 00:01:47,000 --> 00:01:49,520 Speaker 1: hundred and fifty miles in altitude has been hit by 27 00:01:49,520 --> 00:01:53,960 Speaker 1: an electron. Red auroras mean that an oxygen atom above 28 00:01:54,040 --> 00:01:57,320 Speaker 1: a hundred fifty miles in altitude has been struck. A 29 00:01:57,440 --> 00:02:00,560 Speaker 1: blue aurora means that a nitrogen at them up to 30 00:02:00,640 --> 00:02:03,720 Speaker 1: sixty miles in altitude has been struck, and a purple 31 00:02:03,960 --> 00:02:08,280 Speaker 1: or violet aurora means that a nitrogen atom above sixty 32 00:02:08,280 --> 00:02:11,720 Speaker 1: miles in altitude has been struck. All of the magnetic 33 00:02:11,800 --> 00:02:17,600 Speaker 1: and electrical forces react with each other in constantly shifting combinations. 34 00:02:17,639 --> 00:02:21,400 Speaker 1: These shifts and flows can be seen as the auroras 35 00:02:21,400 --> 00:02:26,120 Speaker 1: appear to dance, moving along with atmospheric currents. The auroras 36 00:02:26,280 --> 00:02:30,600 Speaker 1: generally occur along the auroral ovals, which center on the 37 00:02:30,639 --> 00:02:33,960 Speaker 1: magnetic poles of the Earth. And roughly correspond to the 38 00:02:34,080 --> 00:02:37,920 Speaker 1: Arctic and the Antarctic circles. There are times, though, when 39 00:02:38,000 --> 00:02:41,320 Speaker 1: the lights are further south, usually when there's a lot 40 00:02:41,320 --> 00:02:45,440 Speaker 1: of sun spots. Sun Spot activity follows an eleven year cycle, 41 00:02:45,760 --> 00:02:48,079 Speaker 1: and the next peak will occur in two thousand and 42 00:02:48,120 --> 00:02:51,760 Speaker 1: eleven and two thousand and twelve, so opportunities to see 43 00:02:51,800 --> 00:02:55,760 Speaker 1: auroras outside their normal rain should be good. There are 44 00:02:55,840 --> 00:03:00,080 Speaker 1: many stories about sounds associated with auroras, but there are 45 00:03:00,080 --> 00:03:04,320 Speaker 1: no recordings of these sounds. Scientists can't agree on what 46 00:03:04,480 --> 00:03:08,600 Speaker 1: would produce sounds during an aurora. Do you have any 47 00:03:08,639 --> 00:03:12,320 Speaker 1: ideas or suggestions for this podcast? If so, please send 48 00:03:12,320 --> 00:03:15,600 Speaker 1: me an email at podcast at how stuff works dot com. 49 00:03:15,720 --> 00:03:18,000 Speaker 1: For more on this and thousands of other topics, go 50 00:03:18,120 --> 00:03:20,920 Speaker 1: to how stuff works dot com and be sure to 51 00:03:21,000 --> 00:03:23,200 Speaker 1: check out the brain stuff blog on the how stuff 52 00:03:23,240 --> 00:03:29,680 Speaker 1: works dot com home page. Streaming TV shows and movies 53 00:03:29,720 --> 00:03:32,400 Speaker 1: directly to your home is a breeze with Netflix. As 54 00:03:32,400 --> 00:03:35,080 Speaker 1: a Netflix member, you can instantly watch TV and movies 55 00:03:35,120 --> 00:03:38,400 Speaker 1: on your PC, mac, mobile device, or television. Get a 56 00:03:38,440 --> 00:03:41,560 Speaker 1: free thirty day trial membership. Go to Netflix dot com 57 00:03:41,640 --> 00:03:43,160 Speaker 1: slash stuff and sign up today.