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Documentary, PBS Nova; At the Edge of Space
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00:01On a stormy night in Denver, a team of scientists takes to the air to investigate a mystery.
00:12I reported it and nobody would believe me.
00:16They're trying to catch a burst of energy so fleeting and hard to see that scientists call it by the
00:24ethereal name of Sprite.
00:26The bolts that cause Sprites are super bolts, the kind of lightning that will blow your TV sky high.
00:34Unlike the brilliant northern lights created in the upper atmosphere by streams of charged solar particles,
00:42Sprites are high-altitude sparks that originate right here on Earth.
00:48They're leading researchers on a chase into the far reaches of the upper atmosphere,
00:53to a little-explored region, home to many mysterious phenomena.
01:00You can see airglow that's more diffuse and just in layers than the curtain-like aurora.
01:06Nova takes to the air on a quest to record these elusive events.
01:12And the effort also continues above, from the vantage point of space,
01:18where the work had its beginning during the ill-fated Columbia mission,
01:23with Israeli astronaut Ilan Ramon.
01:26I asked him, please bring me one Sprite image.
01:30He said, don't worry, I'll get you a couple.
01:34Ramon's colleagues now continue where he left off.
01:37We must take over their work. I thought that was the survivor's duty.
01:41Their dramatic discoveries are revealing that we live on an electrified planet,
01:48surrounded by a global circuit that rings the Earth.
01:53And like a planetary heartbeat, we can now detect it.
01:57It is like taking the EKG of the planet.
02:00High above the air we breathe, at the boundary of a new frontier,
02:04journey with us to the edge of space, right now, on NOVA.
02:26Major funding for NOVA is provided by the following.
02:30The David H. Koch Fund for Science.
02:33Supporting NOVA and promoting public understanding of science.
02:40The Corporation for Public Broadcasting.
02:44And by contributions to your PBS station from viewers like you.
02:51Additional funding from Roger and Vicki Satt.
02:55In the darkness of space, there are violent forces at work.
03:03Cosmic rays shoot across the universe.
03:07Asteroids billions of years old stream towards Earth.
03:10And solar winds wreak havoc.
03:14Their destination, the edge of space.
03:19Our upper atmosphere.
03:22It's Earth's first line of defense against the hurtling space rocks that we see flare into brilliance as meteors.
03:30A protective buffer against the high-energy solar wind that creates the beautiful northern lights.
03:37And crucially, it's a key link in a global electric circuit that blankets the planet from pole to pole.
03:46Far below, the surface of the Earth is hammered by 8 million bolts of lightning every day.
03:54Up to 100 strikes every second.
03:59Most lightning strikes from the clouds towards the surface of the Earth.
04:03But occasionally, the most powerful bolts are accompanied by a ghostly and fleeting flash above the clouds.
04:12Reaching all the way to the very edge of space.
04:16But lasting only milliseconds.
04:19It's been a decades-long challenge to understand these mysterious bursts of light.
04:27Now, from the high vantage of the International Space Station,
04:32it may finally be possible to capture images of these rarely seen events in the boundary between Earth and space.
04:44But what defines this region?
04:47Earth's atmosphere is a thin blanket of gas.
04:51The troposphere is the lowest and densest layer.
04:55All of life as we know it depends on this relatively thin, 5 to 10 mile thick band of protective
05:02air.
05:03Its thickness varies with latitude and the seasons.
05:07This is where most weather occurs, including the towering thunderclouds that generate lightning.
05:15A high-altitude helium-filled balloon ascends quickly through this region and enters the stratosphere,
05:22where most jet planes fly and where the ozone layer is found,
05:28which absorbs the sun's ultraviolet light that can damage living things.
05:35Moving into this hostile environment, the air pressure drops, causing the balloon to expand.
05:43Up here, the lack of oxygen would quickly kill a person.
05:48The stratosphere reaches an altitude of about 30 miles.
05:54Eventually, the balloon cannot rise any higher.
05:58But the ever-thinning upper atmosphere, including the ionosphere, extends another 500 to 600 miles,
06:06even beyond the orbital height of the International Space Station,
06:09which circles Earth at an altitude of between 200 and 270 miles.
06:19From here, the ISS looks down on the planet.
06:24At this altitude, the environment is instantly lethal.
06:28The extremely low pressure would cause a person's body fluids to vaporize in seconds,
06:35while the little air that remains can reach temperatures of more than 2,000 degrees Fahrenheit.
06:42There are also dangers of radiation exposure in this forbidding atmosphere.
06:49But safely aboard the ISS, an international team of astronauts lives and works.
06:57Including, on this mission, Satoshi Furukawa, a native of Yokohama, Japan.
07:03An ardent baseball fan, he takes advantage of zero gravity to play a solo game.
07:13A medical doctor, one of Furukawa's jobs on the station, is to study the effects of microgravity on the human
07:20body.
07:21He often conducts research as both doctor and patient.
07:27He's also the mission photographer.
07:31Using an extremely sensitive high-definition camera,
07:35Furukawa will capture nighttime images of Earth's upper atmosphere.
07:43The ISS is an ideal platform to study the edge of space,
07:47thanks to the cupola observation window.
07:51It offers a priceless view of space and the planet below.
07:56Its heavy shutters open to reveal windows for photography and viewing.
08:05It's from here that Furukawa will aim his camera when the station's orbit takes it into the Earth's shadow,
08:12which it passes into about every 90 minutes as it orbits the planet.
08:19Designed to capture never-before-seen phenomena,
08:22it's so sensitive that it can shoot color images in near total darkness,
08:29bringing to light places once hidden by the blackness of space.
08:37He's hoping to capture images of an elusive and mysterious form of high-altitude lightning,
08:44only recently discovered and still little understood.
08:51The story of these strange lights in the sky began one night in 1973,
08:57when a U.S. Air Force pilot named Ronald Williams was surprised by an unusual sight.
09:05There was a typhoon over the South China Sea.
09:08I happened to be flying over the typhoon.
09:10And as I was going right towards the center of the typhoon, there was a big thunderstorm just off the
09:17center of the typhoon.
09:18All of a sudden, just by accident, I was watching it, because if I'd have been doing anything else, I
09:23wouldn't have saw it.
09:24Williams saw a bolt of lightning go straight up from the top of the clouds.
09:28When it came up, I happened to be watching it, and I just watched it go up.
09:35I reported it, and nobody had believed me.
09:38They said lightning don't go straight up. It has a discharge on something.
09:44But it turned out that Williams was not the only pilot to see lightning emerge from the top of a
09:50cloud and shoot upward towards space.
09:54As sightings accumulated, they became a part of aviation folklore,
09:59rare and unconfirmed events that hovered just outside the boundaries of real science.
10:06Until another chance sighting provided more evidence.
10:10A fellow by the name of Jack Winkler had some detectors out.
10:14He was looking for something else, but he discovered them by accident with equipment that was operated on dark nights
10:20in Minnesota.
10:23While testing a low-light video camera in 1989, Jack Winkler and a team at the University of Minnesota
10:30accidentally captured a black and white image that seemed to show the elusive upward lightning the pilots had described.
10:40Fittingly, this ethereal phenomenon became known as a Sprite.
10:47A whimsical name that captures its fleeting nature.
10:52These giant pillars of light sparked an intensified interest in lightning
10:57and the dangers it presents to spacecraft during launch or landing.
11:08Today, astronaut Satoshi Furukawa is looking for thunderstorms.
11:14Sprites are only found where lightning is present.
11:17But spotting sprites isn't easy.
11:19They only accompany bolts of lightning over ten times more powerful than normal lightning.
11:29In ten minutes, it will be nightfall again.
11:33So Furukawa quickly prepares his camera.
11:40Recorder power is on.
11:42Monitor is on too.
11:52This specialized camera should be able to capture images of the elusive sprites, even in these low-light conditions.
12:01He'll need this extra sensitivity to catch a sprite.
12:10If any sprites appear, they'll be above powerful bursts of lightning.
12:16Across the world, over 2,000 lightning bolts flash every minute.
12:21And over 20 million strike the U.S. each year.
12:26They're four to five times hotter than the surface of the sun.
12:31And the most potent can discharge up to a billion volts of electricity.
12:39Unlike the superheated lightning flashing below the storm clouds,
12:43the sprites above are huge, but electrically much weaker.
12:47And faster.
12:50Disappearing on average in less than 70 milliseconds.
12:57Furukawa maintains his vigil for several hours.
13:03But without much luck.
13:07It's difficult.
13:12His camera recorded a huge number of lightning flashes, but no sprites appeared above them.
13:19I felt like a hunter.
13:22It was impossible to predict where it would appear.
13:26Though the search is frustrating and difficult, he's determined to capture a sprite.
13:31In part, because of a letter he received during training for his ISS flight.
13:38The letter was from an Israeli lightning expert, Yoav Yair, who wrote to inquire about the mission.
13:46He enclosed a photo of Ilan Ramon, Israel's first astronaut,
13:52and a crew member of the ill-fated Columbia mission.
13:56Ramon had brought with him a high-sensitivity black-and-white camera to try to capture images of sprites from
14:03space.
14:04And it's a big day for the Israeli science community.
14:08Ramon's partner in the research was Professor Yoav Yair.
14:13I asked him, please bring me one sprite image.
14:17He said, don't worry, I'll get you a couple.
14:21After capturing over nine hours of thunderstorm footage on board, he succeeded and transmitted several images of sprites back down
14:30to Earth.
14:31But tragically, Columbia never made it home.
14:35It disintegrated upon re-entry.
14:40Though debris was scattered widely, the camera that Ramon had used to capture sprite images somehow survived.
14:48With some of Ramon's work intact.
14:56One image of active lightning over Central Africa shows a bright flash of light above the lightning and arcing up
15:04towards space.
15:06It was a sprite.
15:09Ramon captured images like this one from several vantage points in orbit.
15:15Yair and his research team studied these photos and were surprised to discover how frequently sprite events occurred over large
15:23tropical storms and how widely distributed they were.
15:27But there was still much to learn.
15:32Yair saw Furukawa's mission as a great opportunity to advance the understanding of sprites.
15:47It's so touching. I can feel their passion.
15:52I was there at their scheduled landing spot and looking up the sky.
15:58The Columbia never came back.
16:07They were my friends and my colleagues.
16:10I was very sad to lose them.
16:15At first, it was difficult to get back on track.
16:19I didn't feel like doing anything.
16:22Then I thought, we must take over their work and move forward.
16:27I thought that was the survivor's duty.
16:30So I am honored and happy that I was given this chance in this way.
16:42So nearly 250 miles above Earth, Furukawa is working hard to further Ramon's legacy.
16:51He readies his camera as the flight path takes him towards Europe and into the nighttime darkness, Earth's shadow.
17:02He won't have much time.
17:04He won't have much time.
17:04At ISS speeds, traveling over Paris to Rome takes just two minutes.
17:12Looking down, he sees the lights rimming the boot-shaped peninsula of Italy.
17:20In 10 minutes, he'll be over Central Africa.
17:25Weather patterns and topography make this the world's most lightning-prone region.
17:31Because it's estimated that only one in 10,000 lightning bolts produces a Sprite,
17:37Africa's very active skies make it one of the best places to spot one of these elusive events.
17:44So the first step in capturing a Sprite is to track the kind of extraordinary monster thunderstorms
17:51that produce super bolts of lightning.
17:54And figuring out where they might be is Yoav Yair's job.
18:00He analyzes weather patterns on the ground
18:03and sends the locations of potential Sprite-producing thunderclouds to Furukawa on the space station.
18:10This is a very exciting and emotional thing for me to do
18:14because it reminds me of the things that we did for Ilan Ramon
18:19and the crew of the Columbia in 2003.
18:25With Yair guiding him, Furukawa circles the globe
18:29looking for the kind of monster thunderclouds that could produce a Sprite.
18:35Then, while flying over the Middle East...
18:39Incredible!
18:40...he sees something.
18:45It's clearly a Sprite flashing over the thundercloud and surging towards space.
18:52And it looks like a color version of the one captured by Ilan Ramon
18:56from the Columbia Space Shuttle.
18:59It's the first clear, high-definition color photograph of a Sprite taken from above.
19:07And there are more.
19:08Ahead is Taiwan, Japan, and mainland China.
19:14A giant Sprite appears over Beijing, near the horizon.
19:21The white flash below is an unusually powerful bolt of lightning.
19:31The Sprite above is far off.
19:34It may not look especially large, but some Sprites can be almost 40 miles in height.
19:40Dozens of times taller than ground-striking lightning bolts.
19:46All together, Furukawa captured six Sprites.
19:51It was a real surprise to me.
19:53It's so exciting when something previously invisible to us finally starts to become visible.
20:04The footage was sent to Yoav Yair and an international team of Sprite researchers
20:09who are continuing the work of Ilan Ramon and the Lost Columbia crew.
20:14Oh, that's very nice.
20:17Now it's much more detailed, better camera, color.
20:21We only had back and white, but it was really exciting for me.
20:25Actually, it really moved my heart to see it.
20:28I have to imagine this because they are all not with us, they are all gone.
20:33But I'm sure that if he knew that their mission was accomplished eight years later,
20:41and maybe even going on later, they would feel fulfilled.
20:46He would be proud, I think.
20:50Images like these are helping scientists to understand how a huge storm can generate Sprites.
20:58During a thunderstorm, electric charge builds up in a thundercloud,
21:02causing lightning to emerge from the lower part of the cloud and strike the Earth,
21:08discharging an immense electric current.
21:10But if that lightning bolt is powerful enough,
21:14it can trigger a sympathetic spark above the cloud.
21:18As you go up in an altitude, the density of air decreases.
21:22And so low-density air is easier to make a spark in than high-density air.
21:28So a Sprite is really caused by lightning down in the lower atmosphere
21:34that exerts a stress on the upper, thinner atmosphere and causes a spark up there.
21:41And that spark gives rise to a Sprite.
21:46As the scientists examine the images, there's one that attracts a lot of attention.
21:52Captured in one of Furukawa's pictures, the top of one of the Sprites seems to reach all the way to
21:58the airglow layer.
21:59The airglow is part of the ionosphere, which is a vast sea of electrically charged particles, or ions.
22:08It's these particles, with help from the sun, that create the glow.
22:14Airglow is due to solar radiation at short wavelengths.
22:18Ultraviolet wavelengths, UV, the same stuff that sun burns us if we're outside without our sunblock.
22:22Or X-rays, you know, that we use to image our bones.
22:27And that can transfer energy to the molecules in the atmosphere.
22:31And that energy transfer causes a glow.
22:34But the most important thing about the airglow may not be why it glows, but where it's located.
22:41It's the lowest part of the ionosphere, the uppermost region of the atmosphere.
22:47It begins about 60 miles above Earth and extends over 600 miles to the very edge of space.
22:56The airglow is just the most visible component of the ionosphere,
23:00which is created by radiation from the sun interacting with the topmost layer of Earth's atmosphere.
23:08So the image of a sprite reaching the airglow shows the incredible heights these massive sparks can reach.
23:17But these stunning images from the space station still leave many questions unanswered.
23:24How exactly do sprites form? And what accounts for their peculiar shape?
23:33To answer these questions, the group decides to try something that's never been done.
23:39To fly closer to sprites and to photograph them simultaneously with two different cameras on two different airplanes,
23:46hoping to combine these images digitally and reveal the anatomy of a sprite.
23:54The planes will also be equipped with the same super sensitive color HD camera Furukawa has been using on the
24:02International Space Station.
24:05But their real secret weapon is a high speed black and white camera that shoots 10,000 frames per second
24:12under low light conditions.
24:14It will be able to show the formation of sprites in slow motion.
24:19It will be the first time that we've had two aircraft simultaneously trying to image sprites with high speed cameras.
24:28So it's very exciting for us.
24:34They chose the area where the Great Plains meet the Rocky Mountains as a likely place to hunt for sprites,
24:40because it's famous for very big nighttime thunderstorms.
24:46You can see huge thunderclouds there in the summertime.
24:49The weather is sunny almost 70% of the year.
24:53The intense sunlight heats the ground and causes a strong upward air current.
24:59This, in turn, creates active thunderclouds one after another, producing lightning.
25:06But only the biggest lightning flashes of all produce sprites.
25:13And once again, it will be Yoav Yair's job to help the team in the air find those huge, sprite
25:20-producing thunderclouds.
25:24He and his team will be at the Yucca Ridge Field Station,
25:27a weather observation facility on the Great Plains north of Denver.
25:34They will forecast where a sprite might appear and direct the planes.
25:40All right.
25:41At 5 p.m., the flight team gathers to discuss strategy for tonight's mission.
25:49They call the control station.
25:52Scientist Jeff McHarg, who will be on one of the planes, is asking for the lightning forecast.
25:58We were just looking at the charge moment change map and then the weather map.
26:03But it's not weakening, and the good news is it's moving into some extremely unstable air.
26:09Walt Lyons of the Yucca Ridge Field Station is working with Yair to analyze the weather data.
26:15In this satellite image, clouds are shown in blue.
26:20That day, thunderclouds were developing in a variety of places.
26:23But would they produce powerful enough lightning to produce sprites?
26:30Back at the airport, the pilots talk among themselves.
26:35Usually, they avoid big storms.
26:38But tonight, they'll have to fly in and around the thunderclouds, hunting for the perfect position to capture sprites.
26:46They know it will be a rough and difficult flight.
26:56As soon as it gets dark, thunder begins to reverberate around the airport.
27:04The researchers board the planes on what looks like a promising night.
27:10At 9pm, the two jets take off.
27:16They're heading for thunderclouds 120 miles away that are vigorously producing lightning.
27:23The cabin is in constant communication with Yair and Lyons at Yucca Ridge.
27:28Essentially, they want some kind of a central location.
27:32He evaluates the data and gives the pilots the latitude and longitude of large thunderclouds where sprites might appear.
27:40Our reference will be on this data collection run for about 10 minutes.
27:47Outside the window, they see a huge thundercloud begin to glow with lightning.
27:53Oh, it's here. Lightning. Quite promising.
27:58Somewhere in the darkness above the cloud, they are hoping a sprite will occur.
28:03The high-speed camera is adjusted slightly upwards to shoot the area above the flashing thunderclouds.
28:12Jeff McHard, who has spent 20 years chasing sprites, can barely contain his excitement.
28:19But Yair and Walt Lyons on the ground can see an unexpected change in the thundercloud.
28:25They are here, and if they go like this, they would get this part.
28:30But...
28:31You know, both of them are starting to weaken.
28:34The large thundercloud that was expected to grow has started to split in two.
28:41They've been in the air for five hours, with no sign of those elusive sprites.
28:47And now, the lightning is quickly losing momentum.
28:52Despite the promising forecast and their careful preparation, they have no choice but to return to the airport, defeated.
29:03It was horrible.
29:06Yeah.
29:07I've seen much larger storms, you know, where you get really large sprites that happen pretty often, and this was
29:14just too small.
29:14We'll see. Fingers crossed for the next one.
29:17Good night.
29:18Good night, everyone.
29:19They realize this will not be easy.
29:28On the 4th of July, while people all over America are celebrating, the sprite team hurries to the airport.
29:36They've been waiting for the right kind of weather for a week.
29:41Finally, new storm clouds powerful enough to generate sprites have appeared.
29:46So, if we go like here...
29:48If we don't see lots of sprites, and this starts to get more intense, then I may want to extend
29:54up.
29:55We should just...
29:56Go as soon as they get ready, I would say.
29:58Go.
30:04Both planes take off into a stormy sky.
30:17While Denver watches fireworks below, they prep the cameras and get ready.
30:2330 seconds.
30:26They start to see flashes of lightning below.
30:30On the ground, Yair and Lyons are trying to figure out the best way to position the planes.
30:36But then they would have to turn down, or do you want to circumvent it?
30:40Well, can they punch through and come around the other back?
30:43Go all the way, then...
30:44To about 47 degrees, and see if they can punch through it.
30:47The two thunderclouds shown in deep blue have collided, and major cloud development has begun.
30:53Yeah, maybe it's like...
30:55They send the coordinates of the strongest lightning to the team in the air.
31:00WPRT, and the coordinates are WPRT.
31:0430 degrees, 20 minutes.
31:09Outside, lightning flashes are everywhere.
31:11A monster cloud, with a diameter of more than 300 miles, is releasing electricity with frightening intensity.
31:20The scientists rush to position their gear.
31:24The frustration and anticipation of the previous week is getting to them, and tension in the cabin is high.
31:31Zero, nine, ten...
31:35Sprite!
31:36Sprite!
31:36Wow!
31:37That's a heck of a sprite there!
31:39Did you get it?
31:41For an instant, a giant red flash appeared.
31:44On replay, they can see beautiful shafts of light thrusting upwards towards space.
31:51The mysterious sprite, in all its glory.
31:58Then, the sprites keep coming.
32:08On board, the team reviews the stunning and unique images.
32:14This sprite was shaped like a mangrove tree.
32:18It's been captured in more detail than any sprite until now.
32:24Just like its name, this sprite evokes a fairy with wings.
32:34Yeah, very big jellyfish. It's pretty. Very pretty.
32:41It indeed looks like a jellyfish with many tentacles.
32:48Sprites of many different forms appear, one after another.
32:59Seen up close, they have a variety of shapes.
33:05Eventually, a sprite appears that demands special attention.
33:10This is spectacular!
33:16The umbrella-like top of this sprite reaches an altitude of around 60 miles.
33:23That's the altitude of the air glow layer that appeared in Furukawa's footage from the International Space Station.
33:29The image confirms that sprites interact with the ionosphere.
33:41Now it's time for the high-speed camera.
33:45It's designed so that when a sprite is sighted and the button is released,
33:50the previous three seconds of footage will be saved.
34:15This is the momentary flash of a sprite taken by the super-sensitive camera.
34:20And when shot by the high-speed camera, it looks like this.
34:34In just a few hundredths of a second, countless particles of light rain down.
34:43This is the first time a sprite's formation has ever been revealed in such detail.
34:55During the night, 14 sprites were captured by the high-speed camera.
35:07What else will the footage reveal?
35:11With great expectations, they return to the ground.
35:15Not too bad, huh?
35:21That's amazing!
35:25It was fabulous!
35:27It was amazing!
35:29I haven't seen anything like that ever!
35:35The long night is over, but they know their work is just beginning.
35:43Back in Denver, the team gathers to make some scientific sense out of their spectacular sprite footage.
35:49The halo above and the elf below, and that's just because it's expanded out in front.
35:55At first glance, this sprite may seem to burst up from the storm clouds towards space.
36:02But when seen by the high-speed camera, the movement looks completely different.
36:09Bursts of light appear out of the center, spreading both up and down.
36:16In fact, when examined in slow motion, it appears that sprite formation is more complicated than early reports had indicated.
36:26And what about this sprite shaped like angels' wings?
36:31With this one, too, bursts of light suddenly appear out of darkness.
36:36They go down.
36:38And the next moment, up.
36:41And then down again.
36:43They change their direction as they unfold.
36:48So what is really happening?
36:51Within the sprite, electrons are colliding with charged particles in the atmosphere, creating a pathway for the electrons to travel.
37:00Where they go depends on the concentration of electrons and the composition of the atmosphere.
37:11Sprites are beautiful and intriguing.
37:15But do they actually have a role to play in Earth's upper atmosphere?
37:22Yukihiro Takahashi is investigating the aftermath of a sprite.
37:28Once the electrons cut open a path, the atmosphere around it becomes highly electrified.
37:35Following the sprite's path, a large electric current continues to flow from the thunder cloud to the ionosphere, which shows
37:43up as the air glow in many sprite images.
37:47The sprite flashes only for an instant, but at the moment when it flashes, a conductive pass is created.
37:55The electrified pass doesn't disappear when the flash ends, but stays there for a while.
38:01The effects are thought to last several seconds to minutes.
38:06The result is a massive transfer of electric charge in the space between the cloud and the ionosphere.
38:17The team also successfully captured a sprite from different angles, as they had originally planned, using high-speed cameras placed
38:26on the two aircraft.
38:31By combining the images from the two cameras, the three-dimensional structure of the sprite becomes apparent.
38:41A large number of electrons collide with the atmosphere, creating brilliant bursts of light and opening channels where the electrons
38:49can flow.
38:52Each sprite channel can be hundreds of yards wide.
39:00A sprite event is like a switch that turns on an electric current in the space between the Earth and
39:08the ionosphere.
39:09In fact, our planet is surrounded by electric current from the surface to the edge of space.
39:17Like lightning, sprites help to complete a global circuit, allowing charge to flow continuously around the Earth.
39:28But sprites reach much farther than lightning.
39:31And unlike lightning, sprites can transfer charge into the ionosphere, to the edge of space.
39:38Not only that, but the bolts of lightning that create the sprites are so powerful that they literally reverberate around
39:48the world.
39:49When a sprite occurs, the parent lightning that causes the sprite radiates electromagnetic waves.
39:57Those waves propagate in what we call the global circuit.
40:02Earl Williams of MIT studies sprites from this remote laboratory in western Rhode Island.
40:09Williams and his equipment are nearly off the grid out here.
40:12But they're completely plugged into the biggest circuit of all, the global electric circuit.
40:18We've been monitoring this phenomenon for nearly two decades at this site, trying to look for long-term trends.
40:26In fact, scientists have actually been measuring the global electric circuit on this unusual site since the 1950s,
40:34when the lab was set up by Williams' predecessor, Charles Polk, of the University of Rhode Island.
40:42The antenna immediately behind me is Charles Polk's. The more distant antenna is one that we constructed.
40:48When Polk's antenna was struck by lightning and blew the antenna into many separate fragments all over the meadow we're
40:54sitting in right now.
40:56Williams got involved with early sprite research by collaborating with Walt Lyons of the Yucca Ridge Field Station.
41:03Every time Walt saw a sprite in Colorado, which is roughly 2,000 miles from here, we would see a
41:09big disturbance here in Rhode Island.
41:12The antenna Williams is using measures a very low-frequency wave, like a steady hum, that resonates between the Earth
41:20and the ionosphere.
41:22When a sprite occurs, the lightning that causes the sprite sends waves in that thin cavity around the world two
41:30or three times.
41:31And it is exciting, something called the Schumann resonances.
41:36And the Schumann resonances is a manifestation of what we call the AC global circuit.
41:43Earl's aunt was a prominent violin player, so it's not too surprising that he thinks of it in musical terms.
41:50The vibration of a violin string is very much like what happens with Schumann resonances.
41:55We have a fixed string length, and there's one wave on the string, which has a fixed frequency, say the
42:02A node of 440 hertz.
42:05For Schumann resonance, we have a fixed length, but the length wraps itself around the world.
42:09And for that fixed length and the speed of light, we have a fixed frequency of eight cycles per second.
42:15So they're both examples of resonances, this one being a mechanical resonance, that one being an electromagnetic resonance, but the
42:22same wave phenomena applies.
42:26It's almost like the music of the spheres, or of the Earth at least.
42:31No matter where you are on Earth, if you have an antenna, a vertical antenna, like the one behind me,
42:37you will see an oscillation on that antenna at roughly eight cycles per second.
42:42And that is maintained continuously by all the lightning on the planet.
42:46Every time there's a lightning flash, a small fraction of the energy in that lightning flash feeds into this global
42:53resonance.
42:55The Schumann resonance is present all the time.
42:59It never dissipates, because there's always lightning someplace on Earth.
43:04And when a sprite is produced by a super bolt of lightning, there is a spike in the Schumann resonance
43:10signal.
43:11Every sprite lightning is a bell ringer for the Schumann resonances.
43:16One of these giant lightnings will single-handedly excite the whole Schumann cavity with electromagnetic waves.
43:25And everyone on Earth who has a receiver in the range of frequency of eight cycles per second will detect
43:32a sprite event.
43:34Here on the oscilloscope, we have an example of the Schumann resonance signals.
43:38You can see the characteristic eight cycle per second oscillation continuously.
43:42That's called the background Schumann resonances.
43:46Occasionally you'll see a big increase in the amplitudes.
43:49Those events are the events that make the sprites.
43:53These are the lightning flashes, the very energetic lightning flashes that create sprites in the thin upper atmosphere.
44:01Earl's science may be cutting edge, adding to our understanding of planet Earth.
44:06But his equipment is a little bit old school.
44:11Because the Schumann resonances oscillate at only eight cycles per second, it is kind of a low-tech operation here.
44:18I mean, we do digital recording of the signals, but these are very low-frequency signals you can put on
44:24an oscilloscope,
44:25and you don't need high-band-width equipment to record them.
44:28But you have to be in a quiet place.
44:30You can't do this in the middle of a city.
44:32There's too much background noise.
44:34And that's why we're out here in this very beautiful sight in the middle of nowhere.
44:39And super-powerful lightning produces not only sprites, but other weird phenomena as well.
44:45There are actually a whole zoo of creatures up there that are caused by lightning.
44:50There's something called an Elve, and it's like a pancake of light within the air-glow layer.
44:55And it's caused by the radiation field from lightning.
44:58Then there is a halo, which is also a pancake shape, but at somewhat lower altitude.
45:04And then there are blue jets and pixies and a whole host of other optical phenomena that occur in conjunction
45:12with lightning flashes.
45:16Since the Schumann resonance fluctuates slightly depending upon factors such as the temperature of the Earth,
45:22Williams thinks it's one important way of measuring the health of the whole planet.
45:28It's a natural setup for looking at the entire Earth.
45:32You have one quantity which represents the entire planet.
45:36And it's hard to dream up another such circumstance.
45:40It is like taking the EKG of the planet.
45:46The global electric circuit surrounds everything on Earth and connects us to the edge of space.
45:53Sprites feed into the ionosphere from below.
45:56But from above, the Sun also affects the ionosphere, resulting in the vivid displays of the aurora borealis.
46:07Auroras are light displays caused by the collision of charged particles streaming from the Sun into our atmosphere.
46:18There are two types of auroras.
46:20The discrete aurora like the northern and southern lights have well-defined boundaries that can be seen with the naked
46:28eye.
46:28And diffuse auroras that spread out over a wide area and are less colorful.
46:38Ninety-three million miles away, auroras are born from a landscape of blistering temperatures and violent eruptions.
46:48From the surface of the Sun, huge volumes of solar material in the form of charged particles are blasted into
46:56space.
47:00A fleet of satellites monitors this solar activity.
47:09Stereo-A and Stereo-B satellites are making 3D images of the Sun and also tracking solar activity.
47:22These eyes in the sky paint a detailed picture of the Sun and the powerful forces erupting from its surface.
47:31The constant stream of charged particles.
47:34The solar wind is so violent it would strip away the Earth's atmosphere if it hit our planet directly.
47:41The Sun you can think of as a really big angry hair dryer in a lot of ways.
47:47It's constantly blowing hot, energetic wind out in all directions, not just directly towards the Earth, but in all directions.
47:54And this hot, energetic, fast-moving particle stream hits straight on with the Earth.
48:03Earth's magnetic field blocks and deflects the solar wind, protecting our planet from a full-on assault.
48:12But there is a back door that allows some of the charged particles from the solar wind to reach us.
48:19In the Earth's shadow, there is a region in space where charged particles accumulate.
48:27These particles, though drastically decreased in number, sneak in through small gaps in Earth's magnetic defenses.
48:39The charged particles dash toward Earth and interact with the magnetic field, which deflects and diverts them to the poles.
48:59They rain down, forming luminous rings in the sky.
49:10The beautiful, vibrant colors of the aurora are visible evidence of the particles' interaction with Earth's second line of defense,
49:18the atmosphere.
49:22The aurora are different colors at different altitudes depending on the gases in the atmosphere that the particles are interacting
49:30with.
49:31So it's red at higher altitudes, it's oxygen, and then blue and green with oxygen and nitrogen as it gets
49:38denser into the atmosphere where the gases get thicker.
49:40And then for really, really strong interactions of the particles, energetic particles really penetrating deep into the atmosphere, you may
49:48even see like a pinkish purple color down at the bottom where there's more nitrogen.
49:55But sometimes things can go wrong, really wrong.
50:01Sometimes the blast of charged particles can be so intense that the auroral ring thickens and vibrates explosively.
50:09There are these periodic events, these coronal mass ejections where the gas just is incredibly more intense than it normally
50:17is, and this charged particle cloud will come out, spiral out towards the Earth, and our magnetic field will respond.
50:24The Earth's magnetic field does a good job of protecting us. The more beautiful the aurora, the more intense the
50:33battle at the edge of space.
50:36And even satellites high above Earth can fall victim to the power of our sun.
50:43In 1989, during a period of intense solar turbulence, induced electric currents caused by the aurora shut down the entire
50:54power grid in Quebec, Canada in under two minutes.
50:58The province's largest city, Montreal, was crippled by power outages. Human activity throughout the region came to a halt for
51:08nine hours.
51:10The more recent Halloween storms of 2003 caused hour-long power outages throughout Sweden and impacted satellites and aircraft communications.
51:21But the greatest solar storm on record took place in 1859.
51:28It created auroras so powerful, they illuminated skies as far south as Hawaii and Panama, while playing havoc with telegraph
51:38systems around the planet.
51:39A similar storm today could devastate power grids and communication systems, and cost billions to repair.
51:47In today's wired world, no one is invulnerable.
51:52Solar storms can affect satellite communications in different ways.
51:56Performance of your handheld radio, your GPS receiver, your satellite television receiver, your satellite radio receiver.
52:04All these things can be affected by space weather.
52:10We think of electricity as a modern invention, but the electric Earth has always been with us, surrounding our planet
52:21and connecting us to the edge of space.
52:51This NOVA program is available on DVD. To order, visit shoppbs.org or call 1-800-PLAY-PBS.
52:59NOVA is also available for download on iTunes.
53:18NoVA is also available on Twitch.
53:19NoVA How to earn more présent up Всlle Denger is located in Iinko,
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