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Our Universe is violent, deadly.

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00:00:04,258 --> 00:00:08,208
Cosmic bombs are everywhere.

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And the most crazy,
intense, violent explosions

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you can imagine
are happening out there.

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The Sun spits flares
millions of miles high.

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Magnetic monsters
rip worlds apart.

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Galactic flamethrowers

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fire gamma rays
halfway across the Universe.

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00:00:32,667 --> 00:00:34,835
It's like a cosmic blowtorch.

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00:00:34,837 --> 00:00:38,508
The energy of these things
is unimaginable.

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Mega-flares
light up the Universe.

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They illuminate hidden secrets.

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They're also a threat.

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If you're in the line of sight,
watch out.

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Our planet is under attack

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from colossal, cosmic
firestorms.

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Do these deadly mega-flares
threaten life on Earth?

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An ordinary star field,

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but home to one of
the most extraordinary stars

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in our galaxy.

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8.7 light-years from Earth,
this is UV Ceti.

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This mysterious object

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can grow five times brighter
in less than a minute.

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Any planet circling this star
would be blasted by the heat,

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quickly melting
its frozen surface.

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Then, just seconds later,
the sun dims.

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The planet retreats
into icy darkness.

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But UV Ceti is about to go
way further.

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The star begins to brighten,
but this time, it doesn't stop.

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A runaway inferno,
in just 20 seconds,

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it gets 75 times brighter
than normal.

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UV Ceti has unleashed
a mega-flare...

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00:03:15,050 --> 00:03:19,923
...an immense explosion
of energy on the star's surface.

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If our Sun fired off
a mega-flare like this...

35
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...we'd be toast.

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If you were standing
on the surface of the Earth

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and the Sun were to get
75 times brighter,

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even for only a minute or two,

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it would really probably be
the last thing you'd ever see.

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The temperature on the Earth
would rise up.

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We'd have huge fires. It would
just basically cook everything.

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Earth is a long way
from UV Ceti.

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We're safe
from that particular star.

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But the more stars we study...

45
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...the more flares we find.

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They fire in all directions...

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...sometimes, directly at us.

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The closer a star is to Earth,
the greater the danger.

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And one star is way closer
than all the others.

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00:05:03,379 --> 00:05:06,810
Our Sun looks stable and calm.

51
00:05:10,139 --> 00:05:12,536
But behind the glare...

52
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...the Sun is a monster.

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Solar observatories
capture the violence.

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Flares erupt
across its surface...

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...gigantic explosions
on an unimaginable scale.

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One flare,
one of the most energetic flares

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on the surface of the Sun
would be equivalent

58
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to over 200 million
hydrogen atomic bombs.

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It's enough energy

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to power the entire human race's
energy consumption

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for something like
2 million years.

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Each flare is as bright

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as 400 billion trillion
light bulbs.

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But the visible light

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is just a fraction
of the energy it emits.

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Radio waves...

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Infrared heat...

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Ultraviolet light...

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even X-rays...

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...unleashed in every flare
at incredible intensities.

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These are the biggest explosions
in the solar system...

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...yet the force behind them
is simple...

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...magnetism.

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The Sun has an immense
magnetic field.

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The energy stored in this field
powers solar flares.

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Vast loops of magnetic force
push toward the surface.

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Huge magnetic arches
rise out into space.

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When two field lines cross,

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it triggers a magnetic
short circuit.

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This is a solar flare.

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All the energy
trapped in the magnetic field

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blasts out
at 100 million degrees.

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It can hurl hot gas

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a billion miles
out into space...

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...an eruption 10 million times
more powerful than a volcano.

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Magnetism -- the same force
that powers a simple compass

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fuels the biggest explosions
in the solar system.

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Yet by cosmic standards,
our Sun is puny.

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As we look out into space,
we see even more active stars,

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even more intense magnetism,

91
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and then things
really start to get wild.

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There are stars and objects

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in our galaxy
and in other galaxies

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that produce flares
of great intensity --

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so great, they would literally
destroy all life on Earth

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if they were nearby.

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Outside our solar system,

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titanic explosions
rock the cosmos

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on a scale
we can barely imagine.

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Far beyond the sun, we enter
the realm of mega-flares.

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Our Sun is violent.

102
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Flares explode with the force
of billions of atomic bombs.

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But travel out into the cosmos,

104
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and the explosions get bigger.

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Other stars have flares so huge,
they're planet killers.

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EV Lacertae
is 16.5 light-years from Earth.

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Every day,
flares erupt on its surface.

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But one mega-flare
smashed every record.

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The star blasted out
10,000 times more X-rays

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than the sun's
most powerful flare.

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The ultraviolet light
was so intense,

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the star turned blue.

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This stellar firestorm
100 trillion miles away

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was visible from Earth
with the naked eye.

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If our sun flared like this,
we'd be incinerated.

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But EV Lacertae is
a very different kind of star.

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Compared to our sun, it is tiny.

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This is a red dwarf.

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Red dwarfs are stars that have
much less mass than the Sun.

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They could be a tenth to about
four-tenths the mass of the Sun.

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They're smaller. They're cooler.
These are dinky stars.

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They burn so slowly
that, unlike our Sun,

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which will last
10 billion years,

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some of them
will last 10 trillion years.

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They're also relatively cold.

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Their surface is just
5,000 degrees Fahrenheit --

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half the temperature
of our Sun --

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and 10,000 times dimmer.

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Yet somehow, they're capable
of staggering violence.

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That's because red dwarfs
are immensely magnetic.

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The fields which form
inside them are enormous,

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much more powerful
than our suns.

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That means
the magnetic-field energy

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that can be released
when those fields get twisted up

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is incredibly intense.

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And even though these objects
are very dim in visible light,

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they can produce flares

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that are thousands of times
more energetic

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than those released by the Sun.

140
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You wouldn't want to be near
one of those when it went off.

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All red dwarfs flare violently,

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but EV Lacertae's flares
are off the chart.

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That's because it's young --
just 300 million years old...

144
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...15 times younger
than our Sun.

145
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In one way, stars
are a little bit like people.

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They're hotheads
when they're younger.

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When stars are first born,
they're spinning very rapidly,

148
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and that actually helps generate
magnetic fields, as well.

149
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The result --

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a star 100 times more magnetic
than the Sun.

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When its giant loops cross,
the mega-flare is colossal...

152
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...a torrent of radiation
lasting 8 hours.

153
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Big flares on our Sun

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have the energy
of billions of atomic bombs.

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EV Lacertae's monster flare
was 10,000 times more powerful.

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Incredibly,
even these massive flares

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are just a flicker
on the cosmic scale.

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There are eruptions
millions of times brighter...

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...explosions that can light up
a whole galaxy...

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From a tiny star
with unimaginable power.

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This is the Australia
telescope compact array --

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a network of five radio dishes

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constantly listening
to the cosmos.

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In 2004, they were struck
by a massive blast of energy...

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...evidence of a mega-flare.

166
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But this was bigger than any
we had witnessed before...

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...the largest burst of power
ever recorded from our galaxy.

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The object behind it
is truly bizarre --

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a kind of star
we didn't even know existed

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until a mega-flare gave it away.

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I've studied black holes.
I've studied stars that explode.

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I've talked about rogue planets
wandering the galaxy.

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For my money, the scariest
single object in the galaxy

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is a magnetar.

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Magnetars
are the most magnetic objects

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in the Universe.

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And this one beats them all.

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Its magnetic field

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is 1,000 trillion times stronger
than our sun's.

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If it came near
our solar system,

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the effects
would be devastating.

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The first thing you would notice
is its magnetism

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would wipe every credit card
in your pocket.

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As you start to get closer,

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anything metal on you
would be ripped away --

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your earrings, your jewelry.

187
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Once you got within a few
million miles of the magnetar,

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its magnetism
would be so intense,

189
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it would actually disrupt
the electrical signals

190
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in your nerves, and your heart
would stop beating.

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Get even closer, and the
magnetism would be so intense,

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it would rip apart every atom
in your body.

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Amazingly,
this vast magnetic field

194
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comes from an object
no bigger than an asteroid.

195
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Our Sun is close
to a million miles across.

196
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The magnetar, just 10.

197
00:18:22,885 --> 00:18:25,585
But it's unimaginably dense.

198
00:18:32,026 --> 00:18:36,629
It weighs more than the Sun.
This is incredible.

199
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Take the Sun and squeeze it down

200
00:18:39,334 --> 00:18:41,501
not just to the size
of the Earth,

201
00:18:41,503 --> 00:18:43,603
but down to the size
of Manhattan.

202
00:18:45,772 --> 00:18:48,774
The entire mass
of a gigantic star

203
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packed into a space
the size of a city.

204
00:18:56,380 --> 00:18:59,349
You could almost
walk around the star in a day,

205
00:18:59,351 --> 00:19:01,551
except you couldn't,
because the gravitational field

206
00:19:01,553 --> 00:19:02,885
is so intense,

207
00:19:02,887 --> 00:19:06,088
the density of material
on these stars is so great,

208
00:19:06,090 --> 00:19:08,457
that a teaspoonful of material

209
00:19:08,459 --> 00:19:11,059
weighs several thousand
billion tons.

210
00:19:11,061 --> 00:19:14,462
You would be crushed
beyond recognition in a moment.

211
00:19:19,367 --> 00:19:22,503
Dense and compacted,
the iron-rich crust

212
00:19:22,505 --> 00:19:26,573
is under incredible
magnetic pressure.

213
00:19:26,575 --> 00:19:29,610
Something has to give.

214
00:19:34,216 --> 00:19:38,419
Fissures rip across the surface.

215
00:19:42,591 --> 00:19:45,893
The crust splits open --

216
00:19:45,895 --> 00:19:48,395
a starquake.

217
00:19:50,397 --> 00:19:52,160
It's like an earthquake
on Earth,

218
00:19:52,162 --> 00:19:54,522
except the crust literally moves
a half an inch.

219
00:19:54,524 --> 00:19:56,090
It's just a little, tiny shift,

220
00:19:56,092 --> 00:19:57,992
but that is a huge amount
of energy

221
00:19:57,994 --> 00:19:59,927
because of this intense gravity.

222
00:19:59,929 --> 00:20:02,463
It's like
a magnitude-30 earthquake.

223
00:20:07,436 --> 00:20:10,538
A flare erupts
from the fracture.

224
00:20:16,011 --> 00:20:19,246
A trillion-ton cloud
of ultra-dense matter

225
00:20:19,248 --> 00:20:21,014
blasts into space.

226
00:20:24,318 --> 00:20:28,121
It lasts
just a tenth of a second.

227
00:20:33,694 --> 00:20:35,962
But it unleashes more energy

228
00:20:35,964 --> 00:20:40,933
than the Sun emits
over 250,000 years.

229
00:20:43,704 --> 00:20:46,839
The energy emitted
when one of these flares

230
00:20:46,841 --> 00:20:48,608
from a magnetar is released --

231
00:20:48,610 --> 00:20:50,310
in some cases,
more than a billion times

232
00:20:50,312 --> 00:20:51,544
the energy emitted by the Sun.

233
00:20:57,718 --> 00:21:01,087
Mega-flares are time machines.

234
00:21:01,089 --> 00:21:05,758
They show us events
from long ago.

235
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This magnetar is 50,000
light-years from Earth.

236
00:21:10,599 --> 00:21:13,801
The flare we observed in 2004

237
00:21:13,803 --> 00:21:17,741
actually happened
50,000 years ago.

238
00:21:21,413 --> 00:21:23,314
It took that long for the light

239
00:21:23,316 --> 00:21:26,184
to travel
halfway across the galaxy

240
00:21:26,186 --> 00:21:29,654
and slam into our atmosphere.

241
00:21:37,363 --> 00:21:41,433
If a similar mega-flare
exploded near Earth...

242
00:21:43,136 --> 00:21:45,871
...we wouldn't
even see it coming.

243
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We would have no warning

244
00:21:47,708 --> 00:21:50,209
if a magnetar were to have
another flare like this.

245
00:21:50,211 --> 00:21:52,111
The event is so sudden
on the surface

246
00:21:52,113 --> 00:21:53,612
and it creates so much energy,

247
00:21:53,614 --> 00:21:55,514
it blasts out
at the speed of light,

248
00:21:55,516 --> 00:21:57,649
and nothing can travel faster
than light.

249
00:21:57,651 --> 00:22:01,820
So, basically, this just
happens, and that's it.

250
00:22:01,822 --> 00:22:05,757
Any life within
10 light-years of the blast

251
00:22:05,759 --> 00:22:08,293
would be vaporized.

252
00:22:10,002 --> 00:22:13,004
Thankfully,
even the closest magnetar

253
00:22:13,006 --> 00:22:16,175
is too distant to threaten us.

254
00:22:16,177 --> 00:22:17,910
We can't see them,

255
00:22:17,912 --> 00:22:21,113
even with
the strongest telescope.

256
00:22:21,115 --> 00:22:26,018
We've only detected these stars
in the flash of a mega-flare.

257
00:22:26,020 --> 00:22:28,754
Yet these explosions are dwarfed

258
00:22:28,756 --> 00:22:32,357
by an even more powerful
monster.

259
00:22:40,098 --> 00:22:43,869
Second only to the Big Bang
in scale,

260
00:22:43,871 --> 00:22:47,874
this is the ultimate mega-flare.

261
00:23:05,600 --> 00:23:09,303
7.5 billion years ago,

262
00:23:09,305 --> 00:23:12,206
many galaxies away...

263
00:23:16,678 --> 00:23:19,848
...a supergiant star
is in trouble.

264
00:23:26,822 --> 00:23:30,758
Its nuclear core
has run out of energy.

265
00:23:32,660 --> 00:23:35,396
It's about to implode.

266
00:23:46,942 --> 00:23:50,946
For a few seconds,
the colossal blast shines

267
00:23:50,948 --> 00:23:55,951
a million times brighter
than our entire galaxy.

268
00:24:12,369 --> 00:24:16,506
This is the most extreme
explosion in the Universe...

269
00:24:19,343 --> 00:24:21,945
...a gamma-ray burster.

270
00:24:24,181 --> 00:24:26,449
Gamma-ray bursters
are so powerful

271
00:24:26,451 --> 00:24:30,653
that they can be seen
across the entire universe,

272
00:24:30,655 --> 00:24:33,823
second only to creation itself.

273
00:24:36,761 --> 00:24:40,764
Two intense jets
of energy shoot out.

274
00:24:48,173 --> 00:24:53,343
These two beams of gamma rays
are the ultimate mega-flare.

275
00:24:53,345 --> 00:24:56,613
The energy of these
things is just unimaginable.

276
00:24:56,615 --> 00:24:58,181
It's the entire power

277
00:24:58,183 --> 00:25:01,585
that the Sun puts out over its
entire 10-billion-year lifetime,

278
00:25:01,587 --> 00:25:03,687
focused into
just these two things

279
00:25:03,689 --> 00:25:05,789
that last for maybe
a few seconds.

280
00:25:05,791 --> 00:25:08,992
It's like a cosmic blowtorch
of gamma rays and matter

281
00:25:08,994 --> 00:25:10,861
that march across the Universe.

282
00:25:12,564 --> 00:25:14,932
The most
high-energy, intense light

283
00:25:14,934 --> 00:25:16,399
is gamma rays.

284
00:25:16,401 --> 00:25:18,034
Gamma rays
are naturally produced

285
00:25:18,036 --> 00:25:20,336
by things that are billions
of degrees hot.

286
00:25:23,173 --> 00:25:25,408
There will never be
a hotter type of flare.

287
00:25:25,410 --> 00:25:27,778
This is where it stops.
Gamma rays is it.

288
00:25:35,219 --> 00:25:37,286
7.5 billion years

289
00:25:37,288 --> 00:25:41,423
after the explosion
actually happened,

290
00:25:41,425 --> 00:25:45,194
we see it in our skies...

291
00:25:45,196 --> 00:25:48,664
March 2008.

292
00:25:52,302 --> 00:25:56,506
A flare from halfway across
the entire Universe

293
00:25:56,508 --> 00:26:00,544
shines even more brightly
than the closest star.

294
00:26:02,681 --> 00:26:05,984
Something blew up
7 billion light-years away

295
00:26:05,986 --> 00:26:09,221
that you could see with your
unaided eye on a dark night.

296
00:26:09,223 --> 00:26:10,757
That should tell you something.

297
00:26:16,637 --> 00:26:20,407
It is the biggest
flare ever witnessed.

298
00:26:22,343 --> 00:26:26,713
But it is also a sign...

299
00:26:26,715 --> 00:26:29,916
of the birth
of the most destructive entity

300
00:26:29,918 --> 00:26:31,384
in the Universe.

301
00:26:39,727 --> 00:26:41,695
A black hole has formed

302
00:26:41,697 --> 00:26:45,636
in the core
of the collapsing star.

303
00:26:47,340 --> 00:26:51,410
It consumes the star
from the inside out.

304
00:27:01,289 --> 00:27:06,827
When the star finally explodes
in a catastrophic supernova,

305
00:27:06,829 --> 00:27:11,264
all that remains
is a newborn black hole.

306
00:27:15,403 --> 00:27:17,904
Usually when we look
in outer space,

307
00:27:17,906 --> 00:27:19,372
we see old black holes --

308
00:27:19,374 --> 00:27:22,309
black holes that have been
around for millions of years.

309
00:27:22,311 --> 00:27:25,679
But to see a baby black hole
being born --

310
00:27:25,681 --> 00:27:28,015
that is an incredible event,

311
00:27:28,017 --> 00:27:30,418
and that's what we think
is a gamma-ray burster.

312
00:27:33,254 --> 00:27:38,292
Amazingly, these
gigantic explosions are common.

313
00:27:43,898 --> 00:27:47,901
We see more than 350 a year.

314
00:27:49,136 --> 00:27:51,638
We see them every day.

315
00:27:51,640 --> 00:27:53,807
Our satellites
detect them every few hours

316
00:27:53,809 --> 00:27:58,011
in all directions
outside the Milky Way galaxy.

317
00:28:01,315 --> 00:28:03,450
Gamma-ray mega-flares reveal

318
00:28:03,452 --> 00:28:06,653
one of the Universe's
most awesome secrets --

319
00:28:06,655 --> 00:28:12,425
a new black hole is born
every single day.

320
00:28:15,495 --> 00:28:19,532
Most of these explosions
happened a long time ago,

321
00:28:19,534 --> 00:28:21,267
far away from Earth.

322
00:28:28,175 --> 00:28:32,345
But if one went off
inside our galaxy...

323
00:28:36,612 --> 00:28:39,545
...it could be catastrophic.

324
00:28:41,548 --> 00:28:43,082
If you were to put
a gamma-ray burst

325
00:28:43,084 --> 00:28:44,517
100 light-years
from the Earth...

326
00:28:49,089 --> 00:28:52,425
...it would be like igniting
a one-megaton nuclear bomb

327
00:28:52,427 --> 00:28:54,894
over every square mile
of the surface

328
00:28:54,896 --> 00:28:56,596
of the Earth facing that event.

329
00:29:05,039 --> 00:29:08,075
You would be blowing up millions
and millions of nuclear weapons

330
00:29:08,077 --> 00:29:09,642
over the planet.

331
00:29:09,644 --> 00:29:13,779
It would be the end of all life
on Earth as we know it forever.

332
00:29:18,086 --> 00:29:20,020
Gamma-ray bursts

333
00:29:20,022 --> 00:29:24,224
are the most powerful
mega-flares in existence,

334
00:29:24,226 --> 00:29:27,294
but not the most dangerous
for us.

335
00:29:28,896 --> 00:29:33,332
The greatest threat to Earth
sits terrifyingly close,

336
00:29:33,334 --> 00:29:38,038
right at the heart
of our own solar system.

337
00:29:53,130 --> 00:29:56,499
We were once
blissfully ignorant,

338
00:29:56,501 --> 00:29:59,468
safe in our solar system.

339
00:30:02,607 --> 00:30:06,644
Now we know Earth sits
in a cosmic firing range.

340
00:30:12,017 --> 00:30:15,787
Monster mega-flares
are everywhere we look.

341
00:30:19,959 --> 00:30:22,661
But the deadliest cosmic weapon
of all

342
00:30:22,663 --> 00:30:25,698
is right on our doorstep...

343
00:30:27,167 --> 00:30:28,801
...our Sun.

344
00:30:36,375 --> 00:30:39,711
We're lulled into thinking
that the Sun is static,

345
00:30:39,713 --> 00:30:42,113
it's benevolent,
and is our friend.

346
00:30:42,115 --> 00:30:43,247
Wrong.

347
00:30:48,486 --> 00:30:50,186
The Sun is dynamic.

348
00:30:50,188 --> 00:30:52,956
In some sense, it's alive.

349
00:30:52,958 --> 00:30:54,759
It creates magnetism on a scale

350
00:30:54,761 --> 00:30:57,261
that we can only begin
to comprehend.

351
00:30:59,832 --> 00:31:04,569
And its most powerful
weapon is this --

352
00:31:04,571 --> 00:31:09,207
a coronal mass ejection, or CME.

353
00:31:10,610 --> 00:31:15,514
A colossal solar explosion
rips a chunk of the star away

354
00:31:15,516 --> 00:31:18,750
and torpedoes it out into space.

355
00:31:20,052 --> 00:31:22,621
Coronal mass ejections
are related to flares,

356
00:31:22,623 --> 00:31:24,223
but they're even larger.

357
00:31:24,225 --> 00:31:25,725
You can sort of think of it

358
00:31:25,727 --> 00:31:28,061
as a solar flare
being like a tornado --

359
00:31:28,063 --> 00:31:30,496
very powerful, very intense,
very short-lived.

360
00:31:30,498 --> 00:31:33,132
And a coronal mass ejection
is like a hurricane --

361
00:31:33,134 --> 00:31:36,269
much more energy, much bigger,
and can last for days and days.

362
00:31:41,307 --> 00:31:45,678
CMEs start
with a magnetic short circuit.

363
00:31:45,680 --> 00:31:50,015
Magnetic arcs emerge
from the surface...

364
00:31:51,885 --> 00:31:55,754
...glowing with
trapped solar matter.

365
00:31:57,090 --> 00:32:01,561
The loops cross, triggering
a firestorm of energy.

366
00:32:01,563 --> 00:32:05,032
The Sun erupts.

367
00:32:05,034 --> 00:32:09,737
Solar matter explodes from
the surface out into space...

368
00:32:10,973 --> 00:32:12,606
...a monstrous cloud

369
00:32:12,608 --> 00:32:16,610
of super-hot gas
and electric particles.

370
00:32:17,812 --> 00:32:21,682
When one of these
huge prominences is shot out,

371
00:32:21,684 --> 00:32:24,084
an energy equivalent
of about 10%

372
00:32:24,086 --> 00:32:26,920
of the entire luminosity
of the Sun for a second

373
00:32:26,922 --> 00:32:29,189
is released towards the Earth.

374
00:32:34,095 --> 00:32:37,731
Over 10 billion tons of material
is shot out

375
00:32:37,733 --> 00:32:40,301
at a speed
of over a million miles an hour.

376
00:32:46,274 --> 00:32:48,442
The power
of a coronal mass ejection

377
00:32:48,444 --> 00:32:50,378
is sort of mind-numbing.

378
00:32:50,380 --> 00:32:53,114
It takes our probes years to get
from the Earth to the Sun.

379
00:32:53,116 --> 00:32:54,716
A coronal mass ejection

380
00:32:54,718 --> 00:32:56,851
can cross that distance
in a couple of days,

381
00:32:56,853 --> 00:33:00,055
sometimes in only a couple of
hours or even faster than that.

382
00:33:00,057 --> 00:33:03,158
So these are tremendously
powerful events.

383
00:33:07,964 --> 00:33:12,000
Powerful, but also deadly.

384
00:33:12,002 --> 00:33:15,237
Because sometimes,
the Sun shoots a CME

385
00:33:15,239 --> 00:33:18,140
straight toward the Earth.

386
00:33:18,142 --> 00:33:21,243
The crackling, charged cloud

387
00:33:21,245 --> 00:33:24,012
plays havoc
with our electronics.

388
00:33:24,014 --> 00:33:27,515
It melts power grids,
blows fuses,

389
00:33:27,517 --> 00:33:30,285
and disrupts communications.

390
00:33:32,889 --> 00:33:35,824
But that's nothing
compared to the damage

391
00:33:35,826 --> 00:33:39,061
that a really big CME could do.

392
00:33:49,373 --> 00:33:52,809
They can wipe out
satellites, GPS, the Internet.

393
00:33:52,811 --> 00:33:55,145
All sorts of havoc
can take place

394
00:33:55,147 --> 00:33:59,649
when this huge Tsunami
hits the Earth.

395
00:34:04,955 --> 00:34:07,524
The damage to satellites alone

396
00:34:07,526 --> 00:34:11,828
would total $100 billion.

397
00:34:13,131 --> 00:34:16,566
Think of a blackout
that hits not just one city,

398
00:34:16,568 --> 00:34:21,671
but hundreds of cities
around the planet Earth.

399
00:34:26,376 --> 00:34:30,212
Property damage
would be about $2 trillion.

400
00:34:30,214 --> 00:34:31,981
We're talking about perhaps

401
00:34:31,983 --> 00:34:35,052
a collapse
of modern-day civilization.

402
00:34:35,054 --> 00:34:39,056
We can be thrown back perhaps
50, 100 years into the past

403
00:34:39,058 --> 00:34:41,859
into a world
without electricity.

404
00:34:45,764 --> 00:34:48,366
Big solar storms are rare.

405
00:34:51,337 --> 00:34:55,207
On average,
a massive CME strikes Earth

406
00:34:55,209 --> 00:34:57,709
every 500 years.

407
00:34:58,945 --> 00:35:01,446
But it's happened before...

408
00:35:01,448 --> 00:35:04,749
And it will happen again.

409
00:35:06,786 --> 00:35:09,754
In 2003,
we had one of the largest

410
00:35:09,756 --> 00:35:13,458
coronal mass ejections
ever recorded,

411
00:35:13,460 --> 00:35:17,128
but fortunately,
it missed the Earth.

412
00:35:17,130 --> 00:35:19,765
One of these days,
it's gonna hit the Earth.

413
00:35:19,767 --> 00:35:21,834
One of these days,
one of these rifle bullets

414
00:35:21,836 --> 00:35:24,136
will be aimed
right at the Earth,

415
00:35:24,138 --> 00:35:26,338
and at that point, watch out.

416
00:35:44,613 --> 00:35:47,214
Our planet is under attack...

417
00:35:49,818 --> 00:35:52,920
...not just from mega-flares
in deep space...

418
00:35:54,556 --> 00:35:57,357
...but from our own star.

419
00:36:01,897 --> 00:36:04,265
The Sun fires billions of tons

420
00:36:04,267 --> 00:36:06,601
of hot gas
and electric particles

421
00:36:06,603 --> 00:36:09,471
into space every day...

422
00:36:15,310 --> 00:36:18,645
...deadly solar weapons...

423
00:36:20,648 --> 00:36:24,784
...sometimes pointing
straight at us.

424
00:36:26,052 --> 00:36:28,153
What I find amazing is the fact

425
00:36:28,155 --> 00:36:31,123
that the Earth is in the middle
of a shooting gallery.

426
00:36:34,428 --> 00:36:38,331
But we have survived
this onslaught.

427
00:36:40,267 --> 00:36:42,769
We are protected.

428
00:36:44,038 --> 00:36:46,940
The earth has a magnetic field.

429
00:36:50,044 --> 00:36:54,715
It's incredibly weak,
but enough to keep us safe.

430
00:36:57,452 --> 00:36:59,520
Think of an ordinary magnet

431
00:36:59,522 --> 00:37:01,489
that you use
on your refrigerator.

432
00:37:01,491 --> 00:37:05,292
That has more magnetism
than the Earth's magnetic field.

433
00:37:13,635 --> 00:37:16,303
Without our magnetic shield,

434
00:37:16,305 --> 00:37:21,842
every CME would strip away
Earth's atmosphere,

435
00:37:21,844 --> 00:37:26,513
and we'd be fried
by solar radiation.

436
00:37:28,683 --> 00:37:31,719
How do we know?

437
00:37:31,721 --> 00:37:35,423
Because it happened
to one of our neighbors.

438
00:37:35,425 --> 00:37:37,258
Look at Mars.

439
00:37:37,260 --> 00:37:39,594
Mars is an example
of what happens

440
00:37:39,596 --> 00:37:42,464
to a planet
without a magnetic field.

441
00:37:45,835 --> 00:37:48,803
Mars is a frozen desert

442
00:37:48,805 --> 00:37:50,538
with an atmosphere

443
00:37:50,540 --> 00:37:54,308
only 1% the atmospheric density
of the Earth.

444
00:37:57,413 --> 00:38:00,081
It's because
it lacks a magnetic field.

445
00:38:05,356 --> 00:38:07,591
Over billions
of years, these particles

446
00:38:07,593 --> 00:38:10,294
have actually stripped away
Mars' air,

447
00:38:10,296 --> 00:38:14,098
and that's why it has
a very thin atmosphere now.

448
00:38:15,334 --> 00:38:18,837
Here on Earth, we have a
magnetic field, and we have air.

449
00:38:18,839 --> 00:38:20,772
This is not a coincidence.

450
00:38:20,774 --> 00:38:24,944
So we can breathe
because of our magnetic field.

451
00:38:28,315 --> 00:38:30,583
From Earth's surface,

452
00:38:30,585 --> 00:38:34,955
safe beneath
our magnetic umbrella,

453
00:38:34,957 --> 00:38:37,825
we see the power
of our violent Sun

454
00:38:37,827 --> 00:38:41,094
in the northern
and southern lights.

455
00:38:47,035 --> 00:38:51,472
Trillions upon trillions
of electric particles

456
00:38:51,474 --> 00:38:54,442
strike the earth every second.

457
00:38:54,444 --> 00:38:58,712
The magnetic shield funnels them
to the poles.

458
00:39:00,315 --> 00:39:04,784
They energize gas molecules
in our atmosphere,

459
00:39:04,786 --> 00:39:08,220
making them glow --

460
00:39:08,222 --> 00:39:11,424
a chemical light show.

461
00:39:12,926 --> 00:39:16,962
Oxygen shines green.

462
00:39:16,964 --> 00:39:20,699
Nitrogen, blue or red.

463
00:39:24,071 --> 00:39:29,008
The aurorae are evidence of a
battle between magnetic fields.

464
00:39:30,110 --> 00:39:33,713
The Sun's field creates CMEs.

465
00:39:33,715 --> 00:39:36,816
Earth's field shields us
from them.

466
00:39:42,856 --> 00:39:46,926
Magnetism is nature's
most mysterious force.

467
00:39:50,063 --> 00:39:52,598
Only now are we beginning
to understand

468
00:39:52,600 --> 00:39:55,401
how it shapes the cosmos.

469
00:39:59,372 --> 00:40:03,542
Mega-flares
make magnetism visible.

470
00:40:03,544 --> 00:40:04,944
They shine a light

471
00:40:04,946 --> 00:40:08,547
on the incredible power
of magnetic fields...

472
00:40:11,185 --> 00:40:13,584
...fields that play
a fundamental role

473
00:40:13,586 --> 00:40:15,415
in the Universe.

474
00:40:15,417 --> 00:40:18,146
They impose order on chaos.

475
00:40:22,884 --> 00:40:24,452
They weave their way

476
00:40:24,454 --> 00:40:28,156
through the spiral shapes
of galaxies...

477
00:40:31,561 --> 00:40:35,564
...fields hundreds of thousands
of light-years across,

478
00:40:35,566 --> 00:40:40,469
yet 100,000 times weaker
than Earth's.

479
00:40:42,205 --> 00:40:46,709
Smaller magnetic fields exist
inside galaxies.

480
00:40:49,179 --> 00:40:53,115
They organize matter
into clouds of molecules --

481
00:40:53,117 --> 00:40:56,185
spectacular nebulae.

482
00:40:59,122 --> 00:41:03,760
These stellar nurseries
are where new stars are born.

483
00:41:06,130 --> 00:41:08,998
Now we've discovered
magnetic fields

484
00:41:09,000 --> 00:41:12,534
even permeate empty space...

485
00:41:15,438 --> 00:41:17,973
...fields created
in the Big Bang

486
00:41:17,975 --> 00:41:22,344
with just one quadrillionth
the strength of Earth's.

487
00:41:23,446 --> 00:41:27,249
This is a magnetic universe.

488
00:41:28,918 --> 00:41:30,752
What's amazing is this thing

489
00:41:30,754 --> 00:41:33,088
that's invisible --
magnetic fields --

490
00:41:33,090 --> 00:41:36,625
play such an important role
in every aspect of the Universe,

491
00:41:36,627 --> 00:41:39,694
protecting us from the radiation
from the Sun

492
00:41:39,696 --> 00:41:41,829
to explosions and red dwarfs,
to magnetars,

493
00:41:41,831 --> 00:41:45,332
and to the most energetic,
violent processes

494
00:41:45,334 --> 00:41:47,802
in the entire Universe --
gamma-ray bursts.

495
00:41:47,804 --> 00:41:51,239
Magnetism plays a role
on every scale of the Universe,

496
00:41:51,241 --> 00:41:53,641
changing the dynamics of objects

497
00:41:53,643 --> 00:41:57,578
and making the universe
a violent and interesting place.

498
00:41:59,749 --> 00:42:03,485
Mega-flares light up the cosmos.

499
00:42:03,487 --> 00:42:07,722
They show us things
we can't otherwise see

500
00:42:07,724 --> 00:42:10,758
from the other side
of the Universe...

501
00:42:12,694 --> 00:42:16,130
...or from billions of years
in the past.

502
00:42:16,132 --> 00:42:19,800
A black hole is born.

503
00:42:21,169 --> 00:42:24,671
A star dies.

504
00:42:29,177 --> 00:42:33,380
Distant events
and hidden mysteries.

505
00:42:37,218 --> 00:42:41,721
In a flash,
flares reveal them...

506
00:42:44,192 --> 00:42:49,295
...illuminating the awesome
secrets of the Universe.