Category
📺
TVTranscript
00:00Our universe is violent, deadly. Cosmic bombs are everywhere.
00:09The most crazy, intense, violent explosions you can imagine are happening out there.
00:15The sun spits flares millions of miles high.
00:21Magnetic monsters rip worlds apart.
00:26Galactic flamethrowers fire gamma rays halfway across the universe.
00:33It's like a cosmic blowtorch. The energy of these things is unimaginable.
00:39Megaflares light up the universe.
00:43They illuminate hidden secrets.
00:47They're also a threat.
00:50If you're in the line of sight, watch out.
00:54Our planet is under attack from colossal cosmic firestorms.
01:02Do these deadly megaflares threaten life on Earth?
01:24An ordinary starfield, but home to one of the most extraordinary stars in our galaxy.
01:318.7 light-years from Earth, this is UV-SETI.
01:41This mysterious object can grow five times bigger than the Sun.
01:48This mysterious object can grow five times brighter in less than a minute.
02:02Any planet circling this star would be blasted by the heat, quickly melting its frozen surface.
02:18Then, just seconds later, the Sun dims.
02:28The planet retreats into icy darkness.
02:37But UV-SETI is about to go way further.
02:41The star begins to brighten, but this time, it doesn't stop.
02:48A runaway inferno. In just 20 seconds, it gets 75 times brighter than normal.
03:03UV-SETI has a long way to go.
03:08UV-SETI has unleashed a megaflare.
03:16An immense explosion of energy on the star's surface.
03:26If our Sun fired off a megaflare like this, we'd be toast.
03:35If you were standing on the surface of the Earth, and the Sun were to get 75 times brighter,
03:41even for only a minute or two, it would really probably be the last thing you'd ever see.
03:47The temperature on the Earth would rise up, we'd have huge fires, it would just basically cook everything.
03:54Earth is a long way from UV-SETI.
03:59We're safe from that particular star.
04:04But the more stars we study, the more flares we find.
04:11They fire in all directions.
04:16Sometimes, directly at us.
04:26But the more stars we study, the more flares we find.
04:40The closer a star is to Earth, the greater the danger.
04:46And one star is way closer than all the others.
04:52Our Sun looks stable and calm.
04:58But it's not.
05:04Our Sun looks stable and calm.
05:11But behind the glare,
05:17the Sun is a monster.
05:25Solar observatories capture the violence.
05:32Flares erupt across its surface.
05:40Gigantic explosions on an unimaginable scale.
05:46One flare, one of the most energetic flares on the surface of the Sun,
05:51would be equivalent to over 200 million hydrogen atomic bombs.
05:57It's enough energy to power the entire human race's energy consumption
06:03for something like two million years.
06:13Each flare is as bright as 400 billion trillion light bulbs.
06:20But the visible light is just a fraction of the energy it emits.
06:27Radio waves.
06:31Infrared heat.
06:34Ultraviolet light.
06:37Even X-rays.
06:41Unleashed in every flare, at incredible intensities.
06:49These are the biggest explosions in the solar system.
06:59Yet the force behind them is simple.
07:07Magnetism.
07:14The Sun has an immense magnetic field.
07:20The energy stored in this field powers solar flares.
07:31Vast loops of magnetic force push toward the surface.
07:38Huge magnetic arches rise out into space.
07:57When two field lines cross, it triggers a magnetic short circuit.
08:04This is a solar flare.
08:10All the energy trapped in the magnetic field blasts out at 100 million degrees.
08:19It can hurl hot gas a billion miles out into space.
08:26An eruption 10 million times more powerful than a volcano.
08:41Magnetism.
08:47The same force that powers a simple compass fuels the biggest explosions in the solar system.
08:56Yet by cosmic standards, our Sun is puny.
09:05As we look out into space, we see even more active stars, even more intense magnetism.
09:11And then things really start to get wild.
09:18There are stars and objects in our galaxy and in other galaxies that produce flares at great intensity,
09:28so great they would literally destroy all life on Earth if they were nearby.
09:36Outside our solar system, titanic explosions rock the cosmos on a scale we can barely imagine.
09:48Far beyond the Sun, we enter the realm of megaflares.
10:03Our Sun is violent.
10:09Flares explode with the force of billions of atomic bombs.
10:18But travel out into the cosmos and the explosions get bigger.
10:27Other stars have flares so huge they're planet killers.
10:34Evie Lacerde is 16.5 light-years from Earth.
10:53Every day, flares erupt on its surface.
11:00But one megaflare smashed every record.
11:11The star blasted out 10,000 times more X-rays than the Sun's most powerful flare.
11:20The ultraviolet light was so intense, the star turned blue.
11:30This stellar firestorm, 100 trillion miles away, was visible from Earth with the naked eye.
11:42If our Sun flared like this, we'd be incinerated.
11:49But Evie Lacerde is a very different kind of star.
11:56Compared to our Sun, it is tiny.
12:07This is a red dwarf.
12:13Red dwarfs are stars that have much less mass than the Sun.
12:19They're smaller, they're cooler. These are dinky stars.
12:30They burn so slowly that unlike our Sun, which will last 10 billion years,
12:36some of them will last 10 trillion years.
12:42They're also relatively cold.
12:48They're about 3,000 degrees Fahrenheit, half the temperature of our Sun, and 10,000 times dimmer.
12:58Yet somehow, they're capable of staggering violence.
13:10That's because red dwarfs are immensely magnetic.
13:16The fields which form inside them are enormous, much more powerful than our Sun's.
13:22That means the magnetic field energy that can be released when those fields get twisted up is incredibly intense.
13:28And even though these objects are very dim in visible light, they can produce flares that are thousands of times more energetic than those released by the Sun.
13:36You wouldn't want to be near one of those when it went off.
13:42All red dwarfs flare violently.
13:48But E.V. Lacerde's flares are off the chart.
13:54That's because it's young, just 300 million years old, 15 times younger than our Sun.
14:04In one way, stars are a little bit like people. They're hotheads when they're younger.
14:10And they're spinning very rapidly, and that actually helps generate magnetic fields as well.
14:16The result, a star 100 times more magnetic than the Sun.
14:24When its giant loops cross, the megaflare is colossal.
14:30A torrent of radiation lasting eight hours.
14:44Big flares on our Sun have the energy of billions of atomic bombs.
14:50E.V. Lacerde's monster flare was 10,000 times more powerful.
15:00Incredibly, even these massive flares are just a flicker on the cosmic scale.
15:16There are eruptions millions of times brighter.
15:22Explosions that can light up a whole galaxy.
15:28From a tiny star with unimaginable power.
15:42This is the Australia Telescope Compact Array.
15:48A network of five radio dishes constantly listening to the cosmos.
15:55In 2004, they were struck by a massive blast of energy.
16:06Evidence of a megaflare.
16:12But this was bigger than any we had witnessed before.
16:19The largest burst of power ever recorded from our galaxy.
16:31The object behind it is truly bizarre.
16:37A kind of star we didn't even know existed, until a megaflare gave it away.
16:43I've studied black holes. I've studied stars that explode.
16:49I've talked about rogue planets wandering the galaxy.
16:55For my money, the scariest single object in the galaxy is a magnetar.
17:03Magnetars are the most magnetic objects in the universe.
17:10And this one beats them all.
17:21Its magnetic field is 1,000 trillion times stronger than our sun's.
17:28If it came near our solar system, the effects would be devastating.
17:34The first thing you would notice is its magnetism would wipe every credit card in your pocket.
17:40As you start to get closer, anything metal on you would be ripped away.
17:46Your earrings, your jewellery.
17:52Once you got within a few million miles of the magnetar, its magnetism would be so intense it would actually disrupt the electrical signals in your nerves and your heart would stop beating.
17:59Amazingly, this vast magnetic field comes from an object no bigger than an asteroid.
18:14Our sun is close to a million miles across.
18:20The magnetar? Just ten.
18:27It weighs more than the sun.
18:36This is incredible.
18:42Take the sun and squeeze it down not just to the size of the earth, but down to the size of Manhattan.
18:48The entire mass of a gigantic star packed into a space the size of a city.
18:57You could almost walk around the star in a day except you couldn't because the gravitational field is so intense.
19:03The density of material on these stars is so great that a teaspoon full of material weighs several thousand billion tons.
19:11You would be crushed beyond recognition in a moment.
19:18Dense and compacted, the iron-rich crust is under incredible magnetic pressure.
19:27Something has to give.
19:33Fissures rip across the surface.
19:39The crust splits open.
19:46A starquake.
19:52It's like an earthquake on earth except the crust literally moves a half an inch.
19:58It's just a little tiny shift, but that is a huge amount of energy because of this intense gravity.
20:04It's like a magnitude 30 earthquake.
20:10From the fracture, a trillion-ton cloud of ultra-dense matter blasts into space.
20:26It lasts just a tenth of a second.
20:33But it unleashes more energy than the sun emits over 250,000 years.
20:43The energy emitted when one of these flares from a magnetar is released,
20:49in some cases more than a billion times the energy emitted by the sun.
20:56Megaflares are time machines.
21:02They show us events from long ago.
21:08This magnetar is 50,000 light years from earth.
21:14The flare we observed in 2004 actually happened 50,000 years ago.
21:21It took that long for the light to travel halfway across the galaxy and slam into our atmosphere.
21:37If a similar megaflare exploded near earth,
21:43we wouldn't even see it coming.
21:49If a magnetar were to have another flare like this,
21:55the event is so sudden on the surface and it creates so much energy,
22:01it blasts out at the speed of light and nothing can travel faster than light.
22:07So basically this just happens and that's it.
22:14Thankfully, even the closest magnetar is too distant to threaten us.
22:25We can't see them even with the strongest telescope.
22:31We've only detected these stars in the flash of a megaflare.
22:37These explosions are dwarfed by an even more powerful monster.
22:50Second only to the Big Bang in scale,
22:56this is the ultimate megaflare.
23:08Seven and a half billion years ago,
23:14many galaxies away,
23:20a supergiant star is in trouble.
23:27Its nuclear core has run out of energy.
23:33It's about to implode.
23:57For a few seconds,
24:03the colossal blast shines a million times brighter than our entire galaxy.
24:10This is the most extreme explosion in the universe,
24:16a gamma-ray burster.
24:22Gamma-ray bursters are so powerful
24:28that they can be seen across the universe.
24:34Gamma-ray bursters are so powerful
24:40that they can be seen across the entire universe,
24:46second only to creation itself.
24:52Two intense jets of energy shoot out.
24:59These two beams of gamma rays are the ultimate megaflare.
25:05The energy of these things is just unimaginable.
25:08It's the entire power that the sun puts out
25:10over its entire 10-billion-year lifetime
25:13focused into just these two things that last for maybe a few seconds.
25:17It's like a cosmic blowtorch of gamma rays and matter
25:20that march across the universe.
25:24The most high-energy, intense light is gamma rays.
25:27Gamma rays are naturally produced by things that are billions of degrees hot.
25:34There will never be a hotter type of flare.
25:36This is where it stops. Gamma rays is it.
25:46Seven and a half billion years after the explosion actually happened,
25:52we see it in our skies.
25:56March 2008.
26:03A flare from halfway across the entire universe
26:07shines even more brightly than the closest star.
26:13Something blew up seven billion light-years away
26:16that you could see with your unaided eye on a dark night.
26:20That should tell you something.
26:27It is the biggest flare ever witnessed.
26:32But it is also a sign
26:37of the birth of the most destructive entity in the universe.
26:44A black hole has formed in the core of the collapsing star.
26:54It consumes the star from the inside out.
27:01When the star finally explodes in a catastrophic supernova,
27:07all that remains is a newborn black hole.
27:16Usually, when we look in outer space, we see old black holes.
27:20The black holes are the ones that have been around for thousands of years.
27:26But to see a baby black hole being born, that is an incredible event.
27:32And that's what we think is a gamma ray burster.
27:38Amazingly, these gigantic explosions are common.
27:45We see more than 350 a year.
27:51We see them every day.
27:54Our satellites detect them every few hours in all directions
27:58outside the Milky Way galaxy.
28:04Gamma ray megaflares reveal a new kind of black hole.
28:11Gamma ray megaflares reveal one of the universe's most awesome secrets.
28:18A new black hole is born every single day.
28:26Most of these explosions happened a long time ago, far away from Earth.
28:33But if one went off inside our galaxy,
28:44it could be catastrophic.
28:50If you were to put a gamma ray burst a hundred light years from the Earth,
28:57it would be like igniting a one megaton nuclear bomb
29:03over every square mile of the surface of the Earth facing that event.
29:14It would be blowing up millions and millions of nuclear weapons over the planet.
29:20It would be the end of all life on Earth as we know it forever.
29:29Gamma ray bursts are the most powerful megaflares in existence,
29:35but not the most dangerous for us.
29:41The greatest threat to Earth sits terrifyingly close,
29:47in our solar system.
30:05We were once blissfully ignorant, safe in our solar system.
30:12Now we know Earth sits in a cosmic firing range.
30:22Monster megaflares are everywhere we look.
30:30But the deadliest cosmic weapon of all is right on our doorstep.
30:37Our sun.
30:47We're lulled into thinking that the sun is static, is benevolent, and is our friend.
30:53Wrong.
30:59The sun is dynamic. In some sense, it's alive.
31:05It's a mechanism on a scale that we can only begin to comprehend.
31:11And its most powerful weapon is this,
31:17a coronal mass ejection, or CME.
31:23A colossal solar explosion rips a chunk of the star away
31:29and torpedoes it out into space.
31:33CMEs are related to flares, but they're even larger.
31:39You can sort of think of it as a solar flare being like a tornado,
31:45very powerful, very intense, very short-lived.
31:51And a coronal mass ejection is like a hurricane,
31:57Magnetic arcs emerge from the surface,
32:03glowing with trapped solar matter.
32:09The loops cross, triggering a firestorm of energy.
32:15The sun erupts.
32:22A monstrous cloud of super-hot gas and electric particles.
32:28When one of these huge prominences is shot out,
32:34an energy equivalent of about 10% of the entire luminosity of the sun for a second
32:40is released towards the Earth.
32:4610 billion tons of material is shot out at a speed of over a million miles an hour.
32:57The power of a coronal mass ejection is sort of mind-numbing.
33:03It takes our probes years to get from the Earth to the sun.
33:09A coronal mass ejection can cross that distance in a couple of days,
33:16powerful, but also deadly.
33:22Because sometimes the sun shoots a CME straight toward the Earth.
33:28The crackling, charged cloud plays havoc with our electronics.
33:34It melts power grids, blows fuses, and disrupts communications.
33:41But that's nothing compared to the damage that a really big CME could do.
33:58They can wipe out satellites, GPS, the internet.
34:04All sorts of havoc can take place when this huge tsunami hits the Earth.
34:16The damage to satellites alone would total $100 billion.
34:24Think of a blackout that hits not just one city, but hundreds of cities around the planet Earth.
34:35Property damage would be about $2 trillion.
34:41We're talking about perhaps a collapse of modern-day civilization.
34:47We're going to be thrown back perhaps 50, 100 years into the past, into a world without electricity.
34:56Big solar storms are rare.
35:02On average, a massive CME strikes Earth every 500 years.
35:10But it's happened before, and it will happen again.
35:18In 2003, we had one of the largest coronal mass ejections ever recorded,
35:24but fortunately it missed the Earth.
35:28One of these days, it's going to hit the Earth.
35:31One of these days, one of these rifle bullets will be aimed right at the Earth, and at that point, watch out.
35:38NASA Jet Propulsion Laboratory, California Institute of Technology
35:56Our planet is under attack.
36:02Not just from megaflares in deep space, but from our own star.
36:14The sun fires billions of tons of hot gas and electric particles into space every day.
36:21Deadly solar weapons.
36:32Sometimes pointing straight at us.
36:38What I find amazing is the fact that the Earth is in the middle of a shooting gallery.
36:45But we have survived this onslaught.
36:51We are protected.
36:55The Earth has a magnetic field.
37:01It's incredibly weak, but enough to keep us safe.
37:08Think of an ordinary magnet that you use on your refrigerator.
37:14That has more magnetism than the Earth's magnetic field.
37:25Without our magnetic shield, every CME would strip away Earth's atmosphere.
37:31And we'd be fried by solar radiation.
37:37How do we know?
37:43Because it happened to one of our neighbors.
37:49Look at Mars. Mars is an example of what happens to a planet without a magnetic field.
37:56Mars is a frozen desert.
38:02With an atmosphere only 1% the atmospheric density of the Earth.
38:08It's because it lacks a magnetic field.
38:16Over billions of years, these particles have actually stripped away Mars' air.
38:22And that's why it has very thin atmosphere now.
38:28Here on Earth, we have a magnetic field and we have air.
38:32This is not a coincidence.
38:36So we can breathe because of our magnetic field.
38:42From Earth's surface, safe beneath our magnetic umbrella,
38:48we have our violent sun in the northern and southern lights.
38:59Trillions upon trillions of electric particles strike the Earth every second.
39:05The magnetic shield funnels them to the poles.
39:11They energize gas molecules in our atmosphere,
39:17making them glow.
39:21A chemical light show.
39:25Oxygen shines green.
39:29Nitrogen, blue or red.
39:35The aurorae are evidence of a battle between magnetic fields.
39:42The sun's field creates CMEs.
39:46Earth's field shields us from them.
39:55Magnetism is nature's most mysterious force.
40:01Only now are we beginning to understand how it shapes the cosmos.
40:11Megaflares make magnetism visible.
40:16They shine a light on the incredible power of magnetic fields.
40:22Fields that play a fundamental role in the universe.
40:27They impose order on chaos.
40:34They weave their way through the spiral shapes of galaxies.
40:43Fields hundreds of thousands of light years across,
40:48yet 100,000 times weaker than Earth's.
40:54Smaller magnetic fields exist inside galaxies.
41:01They organize matter into clouds of molecules, spectacular nebulae.
41:10These stellar nurseries are where new stars are born.
41:18Now we've discovered magnetic fields even permeate empty space.
41:24Fields created in the Big Bang,
41:30with just one quadrillionth the strength of Earth's.
41:36This is a magnetic universe.
41:42What's amazing is this thing that's invisible, magnetic fields,
41:46play such an important role in every aspect of the universe,
41:50from the radiation from the sun, to the explosions in red dwarfs,
41:54to magnetars and to the most energetic, violent processes in the entire universe, gamma ray bursts.
42:00Magnetism plays a role on every scale of the universe,
42:04changing the dynamics of objects and making the universe a violent and interesting place.
42:12Megaflares light up the cosmos.
42:16These are things we can't otherwise see.
42:20From the other side of the universe,
42:24or from billions of years in the past,
42:28a black hole is born.
42:32A star dies.
42:36Distant events and hidden mysteries.
42:46In a flash, flares reveal them,
42:52illuminating the awesome secrets of the universe.