1 00:00:00,440 --> 00:00:03,480 Speaker 1: I'm at, I'm no, I'm Ben, and we are stuff 2 00:00:03,520 --> 00:00:06,080 Speaker 1: they don't want you to know. Each week we cover 3 00:00:06,160 --> 00:00:09,719 Speaker 1: the latest and strangest in fringe science, government cover ups, 4 00:00:09,800 --> 00:00:13,399 Speaker 1: allegations of the paranormal, and more. New episodes come out 5 00:00:13,440 --> 00:00:16,880 Speaker 1: every Friday on iTunes, Spotify, Google Play, and anywhere else 6 00:00:16,960 --> 00:00:24,520 Speaker 1: you get your podcasts. Welcome to brain Stuff from How 7 00:00:24,560 --> 00:00:32,120 Speaker 1: Stuff Works. Hey, brain Stuff, this is Christian Sager. We've 8 00:00:32,120 --> 00:00:36,040 Speaker 1: all heard of the Northern lights, right, those beautiful manifestations 9 00:00:36,040 --> 00:00:39,040 Speaker 1: of colors that are in the sky. Well, they've inspired 10 00:00:39,159 --> 00:00:42,920 Speaker 1: many myths. In Viking legends. They were considered the by Frost, 11 00:00:43,080 --> 00:00:46,640 Speaker 1: the many colored bridge between Earth and Asgar, the home 12 00:00:46,680 --> 00:00:49,680 Speaker 1: of the gods, and in Finland they actually believe the 13 00:00:49,760 --> 00:00:52,920 Speaker 1: lights were a sign of the archangel Michael battling the 14 00:00:53,040 --> 00:00:57,920 Speaker 1: devil bills above. Scandinavians believed that they were reflections off 15 00:00:57,920 --> 00:01:01,680 Speaker 1: of the shields of the Valkyries. But despite being observed 16 00:01:01,720 --> 00:01:05,440 Speaker 1: for thousands of years, there are still many misconceptions about 17 00:01:05,480 --> 00:01:08,520 Speaker 1: what the Northern lights are. First of all, it's false 18 00:01:08,720 --> 00:01:11,959 Speaker 1: that their sunlight reflecting off of polar ice caps. It's 19 00:01:12,000 --> 00:01:15,720 Speaker 1: also false that their moonlight reflecting off of ice crystals 20 00:01:15,760 --> 00:01:19,319 Speaker 1: in the air. The Aurora borealis, as it was coined 21 00:01:19,319 --> 00:01:23,840 Speaker 1: by Galileo Galilei and means northern dawn or dawn of 22 00:01:23,880 --> 00:01:27,160 Speaker 1: the North in Latin, is also at the South pole, 23 00:01:27,360 --> 00:01:31,880 Speaker 1: known as the Aurora Australia's. In eighteen nineties six, their 24 00:01:31,959 --> 00:01:37,160 Speaker 1: real origin was discovered by Norwegian scientist Christian Burkeland. He 25 00:01:37,440 --> 00:01:41,759 Speaker 1: tested his theory in controlled experiments and here's the truth 26 00:01:41,760 --> 00:01:45,200 Speaker 1: of the matter. Solar winds stream away from the Sun 27 00:01:45,319 --> 00:01:51,320 Speaker 1: and flow around the Earth's magnetosphere. They're charged electrons interact 28 00:01:51,360 --> 00:01:55,240 Speaker 1: with elements in our atmosphere at points where the magneto 29 00:01:55,320 --> 00:01:59,440 Speaker 1: sphere is weakest, the North and the South poles. So 30 00:01:59,480 --> 00:02:04,200 Speaker 1: these solar winds the Sun's corona continuously amidst them a 31 00:02:04,400 --> 00:02:08,880 Speaker 1: stream of electrically charged particles. They stream away from the 32 00:02:08,919 --> 00:02:13,639 Speaker 1: Sun at speeds of one million miles per hour. They 33 00:02:13,680 --> 00:02:16,639 Speaker 1: reach Earth in forty hours from the Sun. Now, this 34 00:02:16,720 --> 00:02:19,760 Speaker 1: is forty times faster than a spacecraft needs to be 35 00:02:19,919 --> 00:02:24,959 Speaker 1: to escape Earth's gravity. It's pretty fast. Solar activity currently 36 00:02:25,040 --> 00:02:29,200 Speaker 1: follows an eleven years cycle, and longer cycles affect the Aurora, 37 00:02:29,240 --> 00:02:32,120 Speaker 1: and we've actually seen them increased Solar activity in the 38 00:02:32,200 --> 00:02:36,359 Speaker 1: last few centuries. When they get here, though, these solar 39 00:02:36,400 --> 00:02:40,519 Speaker 1: winds strike the magnetic force generated by the Earth's core. 40 00:02:41,080 --> 00:02:44,840 Speaker 1: Then they flow through this magneto sphere, a shield area 41 00:02:44,919 --> 00:02:50,200 Speaker 1: of charged electrical and magnetic fields. This shield is then 42 00:02:50,320 --> 00:02:54,080 Speaker 1: blown into a tear drop shape by the solar winds. 43 00:02:54,520 --> 00:02:59,639 Speaker 1: The magneto sphere protects Earth from dangerous solar and interstellar particles, 44 00:03:00,040 --> 00:03:03,680 Speaker 1: and most are directed away from Earth, but some are 45 00:03:03,720 --> 00:03:07,920 Speaker 1: trapped near the magnetic poles. The electrons from these solar 46 00:03:07,960 --> 00:03:12,600 Speaker 1: winds interact with elements in Earth's atmosphere somewhere between sixty 47 00:03:12,639 --> 00:03:15,840 Speaker 1: to two hundred miles up in the air. This is 48 00:03:15,960 --> 00:03:19,119 Speaker 1: ten times higher, by the way, than most airlines fly. 49 00:03:19,760 --> 00:03:25,200 Speaker 1: These electrons collide with oxygen and nitrogen, transferring energy into 50 00:03:25,240 --> 00:03:29,320 Speaker 1: these gases and making them excited. When they calm down, 51 00:03:29,440 --> 00:03:34,320 Speaker 1: they emit photons and small little bursts of energy form light. 52 00:03:34,960 --> 00:03:38,480 Speaker 1: The shifts and flow of this energy can reach twenty 53 00:03:38,760 --> 00:03:43,720 Speaker 1: million ampiers at fifty thousand volts. Compare that to your 54 00:03:43,760 --> 00:03:48,360 Speaker 1: circuit breaker at home disengaging over fifteen to thirty ampiers 55 00:03:48,360 --> 00:03:52,640 Speaker 1: at one volts. So it's a lot of energy. Now, 56 00:03:52,640 --> 00:03:56,000 Speaker 1: the color of the aurora depends on which element, whether 57 00:03:56,000 --> 00:04:00,080 Speaker 1: it's oxygen or nitrogen, that is struck, and at what 58 00:04:00,240 --> 00:04:04,160 Speaker 1: altitude it's struck at. Since it's dimmer than sunlight, the 59 00:04:04,200 --> 00:04:08,680 Speaker 1: aurora actually can't be seen during the day. But oxygen 60 00:04:08,840 --> 00:04:12,480 Speaker 1: emits either a greenish yellow light somewhere around up to 61 00:04:12,520 --> 00:04:15,000 Speaker 1: a hundred and fifty miles up in the air, or 62 00:04:15,280 --> 00:04:18,159 Speaker 1: a red light over a hundred and fifty miles up 63 00:04:18,160 --> 00:04:22,040 Speaker 1: in the air. Nitrogen, however, emits a blue light up 64 00:04:22,080 --> 00:04:24,719 Speaker 1: to sixty miles up in the air. If you blend 65 00:04:24,720 --> 00:04:28,719 Speaker 1: them all together, however, you can produce purples, pinks, and 66 00:04:28,960 --> 00:04:32,120 Speaker 1: white light. But one note. While some say they have 67 00:04:32,240 --> 00:04:35,839 Speaker 1: quote heard the Northern lights, the air where they're formed 68 00:04:35,880 --> 00:04:39,599 Speaker 1: is actually too thin to conduct sounds, so that's not possible. 69 00:04:39,640 --> 00:04:42,680 Speaker 1: It would be impossible for sound to travel from the 70 00:04:42,760 --> 00:04:46,520 Speaker 1: upper atmosphere to the ground. So you're probably asking yourself, 71 00:04:46,560 --> 00:04:48,680 Speaker 1: these sound pretty cool. Where do I get to see 72 00:04:48,720 --> 00:04:51,679 Speaker 1: the Northern lights? Where do they occur? Well, they center 73 00:04:51,760 --> 00:04:56,520 Speaker 1: around Earth's magnetic poles, not the geographic polls, and they're 74 00:04:56,520 --> 00:05:01,359 Speaker 1: in ring shaped spots called auroral oval. These are between 75 00:05:01,480 --> 00:05:06,119 Speaker 1: five hundred and fifteen hundred kilometers wide and expand during 76 00:05:06,200 --> 00:05:11,480 Speaker 1: geomagnetic storms. These roughly correspond to the Arctic and Antarctic 77 00:05:11,600 --> 00:05:14,919 Speaker 1: circles and can be seen from space, so the best 78 00:05:14,960 --> 00:05:21,279 Speaker 1: places to see them are Central Canada, Alaska, Greenland, northern Scandinavia, 79 00:05:21,520 --> 00:05:25,599 Speaker 1: and northern Russia. And yes, if you're asking, other planets 80 00:05:25,680 --> 00:05:29,839 Speaker 1: also have auroras. They've also been observed on Saturn, Jupiter, 81 00:05:30,240 --> 00:05:38,120 Speaker 1: and Urinus. Check out the brain stuff channel on YouTube, 82 00:05:38,200 --> 00:05:40,359 Speaker 1: and for more on this and thousands of other topics, 83 00:05:40,520 --> 00:05:55,720 Speaker 1: visit how stuff works dot com.