Original subtitles

which was the first indication that the Sun rotated.

Not only does the Sun rotate,

but sunspots themselves can actually spin like hurricanes on the solar surface.

And when they do, their magnetic field lines become extremely twisted.

Twisted magnetic field lines mean more energy

and more energy means the potential for huge eruptions.

Think of a rubber band as magnetic field line.

If you twist it, and you twist enough it's goin to have all that energy,

and when you let it go it's going to release.

If you just take an untwisted rubber band and release it it's not going to fly.

When a sunspot unleashes its magnetic energy,

what results are the most colossal explosions in the Solar System:

solar flares.

A single flare releases as much as a billion megatons of energy.

The combined power of a million volcanic eruptions on Earth.

They appear as these very...

bright regions and they're so bright because the temperature is so high,

on the order of ten million degrees and they can last for hours.

But the energy is massive.

The whole explosion...

is equivalent to millions of nuclear bombs

leaving the surface of the Sun all at once.

Solar flares don't just explode out into space.

They also funnel high energy particles

down to a layer of the Sun called the cromosphere,

where they quickly transfer their energy

like a cue ball striking the rack in the game of billiards.

So you have a cue ball, actually is like one of these

very high energy particles coming from the flare region.

The cue ball smacks very quickly into the 8-ball rack,

and once it impacts that head ball,

it's going to transfer that energy

to the balls behind it and then

they will all fly out because the energy is transferred to all of them.

If a large flare shoots enough high energy particles at once,

strange things start to happen.

This is actual footage

of a sunquake.

In 1998

there was a solar flare up in the

corona that was so powerful that the material flying down

toward the surface of the Sun

actually slapped the surface and

caused ripples to spread out from there.

While thay may look like ripples on a pot,

these are actually waves two miles high

travelling at a maximum velocity of

250 thousand miles per hour.

The 1998 sunquake

would have measured an 11.3 on the Richter scale.

More than one million times stronger

than the 1989 earthquake that

shook San Francisco.

In order to shake the surface of the Sun that much,

the solar flare had to release a colossal amount of energy.

It turns out it's almost the same amount of energy

as if you cover the entire landmass of the Earth with dinamite,

about a yard thick.

And set it all off at once.

So, these explosions are not small.

Earthquakes aren't the only natural disasters with equivalents on the Sun.

A flare can also kick-off a solar tsunami,

as waves of plasma in the Sun's atmosphere rock it up

at 700 thousand miles per hour,

spreading around the entire face of the star

in a matter of hours.

While sunquakes and solar tsunamis

pose no danger to Earth,

the violent action of a flare

frequently triggers dangerous eruptions

called coronal mass ejections, or CMEs.

In a CME

energy from a flare flings a blob of

highly charged radioactive plasma

out of the solar atmosphere.

Coronal mass ejections

range in speeds, but they can occur

as quick as

800-900 miles per second,

which is extremely fast and they

expell a massive amount of material.

It can be the same amount of mass as, say, mount Everest,

coming out from the Sun and

flying out into space.

Where does this blob of superheated radioactive

plasma go when it leaves the Sun?

Sometimes it sails out harmlessly into space.

Other times it may head closer to home.

Coronal mass ejections from the Sun

are perhaps the most dangerous threat you've never heard of.

Also known as solar storms,

they hurl a large masses of supercharged particles

across 93 million miles of space.

Most take several days to travel from the Sun to the Earth,

but some rocket across the Solar System

at up to 6 million miles an hour,

reaching our planet in less than 16 hours.

These storms can induce currents in the outer atmosphere

knocking out satellites and cross-country power grids

and carry the potential to

wreak just as much havoc on our infrastructure

as a hurricane or a tornado.

But who on Earth is keeping an eye

on this potentially hazardous cosmic blasts?

This is the headquarters

of the National Oceanic and Atmospheric Administration,

home to the US government's national weather service.

Their daily forecasts, watches and warnings

are essential information for everyday life on our planet.

But there is a lesser known group of forecasters working here

in a special division called "The Space Environment Center".

Out primary job is to monitor the Sun

and put out the alerts, watches and warnings

for solar activity.

Good morning and welcome to our *10 briefing.

We have one long duration C-flare from the east limb,

that's a possible CME.

We have not had protons but we have had electrons.

One thing you notice is that this region

produced all the activity in december

so things might be picking up here in the next couple of weeks.

These space forecasters

are on high alert for solar storms

that might disrupt life on Earth.

Solar storm clouds are made up of charged particles,

so they are initially diverted around the planet

by our magnetic field,

just like waves breaking around the bow of a boat.

That turns out to be very important

because if it impacted the outer atmosphere directly,

it would knock little bits of the atmosphere off into space.

One reason why Mars doesn't have an atmosphere

is that it doesn't have a strong internal magnetic field.

And so gradually over

millions or maybe billions of years,

the atmosphere was gradually knocked off into space

by the influence of the solar wind

and by the CMEs that came past the planet.

But our magnetic field is not the perfect force field of sci-fi movies.

Some particles can penetrate it

charging up the upper atmosphere.

Solar storms will even bend and break the magnetic field lines

on the far side of the Earth,

allowing charged particles to zip back down the field lines

toward the north and south poles.

Extremely powerful storms distort the magnetic field

even futher, inducing electric currents

that span the continents.

When this happens technology like long-distance powerlines,

can become overloaded.

It can cause damage to trasformers at either end of the line.

In fact, in 1989

most of the canadian province of Quebec

blacked-out because a transformer was blown out

by a solar event.

If we have that storm that hits our

communication system and hits our

our power companies and all these things that we depend on,

there is all kinds of chaos that can lay out there.

If power operators have time to react,

thay can reduce the current

being sent over their wires

and avert disaster.

Satellite operators can also

prepare for the onslaught

with proper warning.

When there's a big space storm coming,

they'll actually put some of their satellites to sleep,

so that the storm

doesn't cause an electrical short

or otherwise somehow knock out the satellite.

So the more warning time they have, the better.

We wouldn't go sailing

unless we knew what the weather is going to be.

Similarly when we have a large system

like a power system or a telephone grid that can be affected

by the weather in space,

we need to know what the weather is going to be

so that we can try and mitigate it.

Solar storms can also disrupt high frequency radiocommunications

used by aircraft.

In the 1980's

Airforce One was transporting president Reagan on a trip to China

when a solar storm struck.

All communications were lost

for several hours,

effectively severing the head of

the United States government.

The urgency is just like our ERS weather.

When we have a tornado warning

we know the urgency to get that out to the public

to let the people know that this is happening.

The same thing is with space weather.

Users of this information

need to know it and they need to know it now.

Just a few hours back we experienced a coronal mass ejection.

We wanna see where this blast is going out,

and then we can measure that and see

how long it might take from that to reach the Earth from the Sun.

We're seeing a very huge explosion

of material that's coming out

and if you look at this small image here,

here's the Sun that's covered up,

and look at the mass that's being thrown out into space.

So it's huge, very huge.

Because magnetic field lines emanate from the North and South Poles,

energy from solar storms has easy access to those regions.

For that reason, experts worry that airplane passengers

flying over the Poles during a powerful storm,

might be exposed to harmful levels of radiation,

perhaps are those equal to a hundred chest x-rays.

It's not something that we want to mess around with, because we never know

when that radiation might all of a sudden become

a lot more intense while there's an airplane in the sky.

The threat from solar radiation is just one more reason

for scientists to keep a close watch on our Sun.

It matters, especially in modern times, what the Sun is doing.

Earth is not an island.

We are participant in the activities of the Solar System.

Sunspots are the triggers for more severe solar storms,

so forecasters track them carefully,

as they rotate across the surface of the Sun.

Location, location, location. We see CMEs all the time from the Sun.

A lot of them, as the center is rotated around, are from the backside of the Sun.

That would not be face towards the Earth, so that would be less of a concern.

As the Sun rotates around and that active region gets more into the center of the disk,

looking at us, then that's when we would be concerned with.

From the center of the Sun, as it rotates around, is the kill zone.

As the sunspot rotates around and begins to face directly at Earth,

that's when we really have to worry about a storm.

If a big storm leaves off then,

it can aim directly at Earth, and the full force of the storm slams into the planet.

It's like a shotgun aiming at a target.

The more dead on the shot,

the more likely serious damage will be inflicted.

With great danger also comes astonishing beauty.

Solar storms generate majestic planetary lightshows.

The shimmering courtains of colour called the Aurora.

Auroras work like neon signs, on an enormous scale.

In a neon sign, electricity introduces charged particles into a gas-filled tube.

The particles in the gas are excited and start to glow.

If the tube has only neon inside, it will glow red.

By adding other gases, like argon, a whole range of colors can be produced.

The neon sign is driven by the electric field inside the tube,

whereas the Auroras are actually driven by the magnetic field and energy from the Sun.

As the energetic particles in a solar storm

stream along Earth's magnetic field towards the Poles,

they excite elements in our atmosphere causing them to glow.

Oxygen molecules emit a green or red color.

And nytrogen emits pinks, blues and violets.

While these ghostly lights are usually confined to the Poles,

extremely strong solar storms can drive them closer to the Equator.

In 1859 a geomagnetic storm ignited by a huge solar flare

created Auroras as far south as Rome.

The 1859 storm was an unusually powerful event

that some have called "the perfect solar storm".

The 1859 storm taught us a little something about what the Sun can do.

The storm was so intense and the alignment was so perfect,

that it simply overwhelmed Earth's natural defenses.

A huge solar flare erupts on the surface of the Sun.

Less than a day later and 93 million miles away,

the wires the carry communications across the Earth, begin to spark.

Business grinds to a halt worldwide

as wild fires are ignited by the smoldering lines.

At the same time, colorful Auroras light up the skies of cities around the globe.

Earth has just been visited by the perfect solar storm.

The Sun kicked up this just incredible solar flare

and a massive amount of energy headed towards Earth.

Not only was this storm one of the two most powerul on record,

it was also one of the fastest.

Ejecting from a sunspot aimed directly at Earth,

it raced from the Sun to our planet in less than 18 hours.

Now, it takes a really fast rocketship years to get to the Sun.

This storm, this cloud of electrified particles,

managed to get here in less than a day.

That's incredibly fast.

Fortunately, the perfect solar storm took place in 1859,

when the only technology vulnerable to the onslaught was the telegraph.

Since the era in wich we've become dependant on high technology,

we've yet to see another perfect solar storm.

The question remains: Could it happen again?

What if we have another one like that? Can we have another perfect storm?

I'd say yes we can, there's no doubt about that.

The effects that would be on us today compared to 1859 could be devastating.

The effects on Earth and on our communication systems,

we don't exactly know. That's the scary part.

It's likely that our modern technologies would be battered

like beachfront houses during a hurricane.

Imagine if we lost all the satellites that relay cellphone calls,

television signals and bank transactions.

And what if at the same time,

the failure of power grids cascaded whole regions into darkness for hours, or weeks.

If these essential services couldn't be restored quickly,

chaos wouldn't be far behind.

It would definitely be a ripple effect upon society

and every man and woman and child that lives on this Earth.

Solar storms can be as hard to predict as hurricanes.

While forecasters lack the technology to foretell the next pefect storm,

they do know that one would be more likely to hit

at the peek of the Sun's eleven-year sunspot cycle.

What happens is the Sun reverses the direction of its magnetic field

every eleven years.

So in 22 years it reverses and comes back to where it was.

As we near the reversal every eleven years,

the number of sunspots increases and there's a spike in solar activity.

We call that period solar maximum

and those periods are interspersed about 5 years apart

from periods we call solar minimum.

So you have this eleven year back and forth

between the Sun being sometimes very feroscious,

and it goes crazy and it's like the 4th of July with fireworks all the time.

And then it starts to ramp down

and for a few years it gets quieter until we get to

a low point where there is a firecracker now and then but not a lot going on.

Just like hurricane seasons, solar maximums vary in intensity.

Some produce many more powerful storms than others.

Although we're currently at solar minimum, scientists are watching carefully

to see what mayhem the next solar max might unleash.

The last solar maximum was in about 2001

and so the next one ought to be about 2012, but there are different predictions.

The whole field of solar physicists is basically waiting with bated breath

to see what actually happens.

There are some wildly divergent opinions on what's gonna happen.

One group is suggesting that this next solar cycle

could be the strongest in modern times.

If those predictions are correct, Earth could be in for a wild ride.

We might have to worry about a repeat of the 1859 event.

If that would happen today it would wreak untold damage.

We're gonna learn a whole lot about what can happen

to modern technology when the Sun bows its top.

Much of the violence in the Sun erupts here,

in the hellish outer atmosphere known as the corona.

This region has long held one of the great solar mysteries.

Because even though it's half a million miles from the heat-generating core,

it burns at millions of degrees.

This seems to violate the very laws of physics.

That's very strange. I have a thermometer here.

If I hold the thermometer close to the fire,

it reads a very high reading.

Where the probe is right now it's over 200 degrees.

And if I pull the probe out a little farther from the fire,

ok, it drops down to about 90 degrees.

Now, the farther I get from the center, the cooler it gets.

In the atmosphere, the corona of the Sun, the temperature soars as hot as the core.

That's as if, I were to say, well, way off behind me there,

the heat from the fire is as hot as the fire itself,

even though it's very far from the fire.

What force could possibly cause the superheating of the corona?

The answer will rock you.

The hellish solar corona rages at millions of degrees.

For centuries scientists have been baffled

how anything so far from the Sun's core

could still burn so hot.

Recently, as improved satellites offered a closer view of the solar surface,

clues began to emerge.

Below the corona the Sun's surface is literally boiling.

The reason is that the entire surface of the Sun

is covered with convection cells, hot material from the inside of the Sun,

that rises up through, reaches the surface, cools off by glowing,

giving off sunlight and then sinks back down.

Each bubble of material that comes up is about the size of Texas.

It spreads out across the surface, cools off and sinks down in 5 minutes.

So, that's a tremendously violent process

that's happening in, literally, almost a million places

over the entire surface of the Sun, all the time around the clock, 24/7.

This boiling is not only violent, it's also extremely loud.

The Sun is a tremendously loud place.

If you could imagine covering the entire surface of the Sun

with speakers being driven as hard as the loudest rock concert you've ever been to,

that would be comparable to how loud it really is on the surface of the Sun.

The Sun's churning surface creates enough sound energy

to superheat the corona to millions of degrees.

Scientists believe that a combination of these sound waves and energy

from the Sun's magnetic field

is responsible for the extreme temperatures found in the corona.

The only time you can actually see the corona from Earth

is at the climax of one of the most dazzling displays in the Solar System,

a total solar eclipse.

Before scientists understood them,

these awe inspiring events instilled only fear.

The ancient Chinese believed that a dragon was devouring the Sun.

So what's really happening in a solar eclipse?

In simplest terms it's when the Moon blocks our view of the Sun.

Imagine that you're sitting in a movies watching very happily

something going on on the screen and then somebody

in the row in front of you comes across

and blocks your view.

In a movie theater you might not want that person

to come across in front of you, but at...

an eclipse we're very lucky to have the Moon come across the Sun,

and we're lucky to have it come right across the middle.

We're also lucky that the Moon, although it's 400 times smaller than the Sun,

is also 400 times closer to us.

This cosmic coincidence means that the two objects

just happen to be the same apparent size in our sky,

which allows for one to completely block out the other.

This magnificent cosmic event only happens

when the path of the Moon intersects the line between the Earth and the Sun.

The Moon's orbit is tilted slightly about 5 degrees.

If it wasn't we would have an eclipse every month.

And then we'd be bored,

but we're not bored because most months

the Moon goes above or below

the place where the line goes from the Earth to the Sun.

So instead of one every month we get a total eclipse

somewhere on Earth about once every year and a half.

As the Moon slides in front of the Sun,

it casts a shadow onto the Earth.

The outer part, where the shadow is fainter,

is called the penumbra.

If you're standing within the swath traced by the penumbra,

as it moves along the Earth's surface,

then you'll see only a partial eclipse.

But travel to a spot within the path of the dark inner shadow,

called the umbra,

and you'll experience the majesty of a total eclipse.

There's another option if you can't travel to the path of totality,

wait in one place long enough

and a total eclipse will pass right over your head

about once every 300 years.

The Sun, that shining star of our Solar System,

is capable of both astonishing beauty and ferocious violence.

It seems impossible to believe,

but it won't be around forever.

Eventually even the Sun must die.

The Sun has a fixed amount of fuel in its core,

it is undergoing fusion at a rate that you can calculate.

So here's the rate it's using its fuel,

here's how much fuel you have,

so it's a simple calculation to show when the Sun will die,

and that's in about a five billion years.

Well, unfortunately the Sun will not go out with a bang.

It's too small to erupt in a supernova.

However stars do a peculiar thing,

they're one of the few things around that get hotter as they cool off.

As it exhausts its hydrogen fuel, our nearest star will cool

and gradually collapse under the force of gravity.

Energy from this collapse will start heating up the core again

to hundreds of millions of degrees, hot enough to start burning helium.

Onto the extra heat of the helium burning,

the star will expand into a monstrous orb called a red giant.

It'll get so big it will engulf

the entire orbits of Mercury, Venus and Earth.

You don't want to be around for that.

You want to be planet-hopping your way to safety

long before this happens.

The Earth is likely to change its orbit slightly as the star expands,

so that it won't be engulfed.

Still, talking about global warming, you wouldn't want to be here.

The outer layers of our Sun will eventually become so unstable

that they will fly off into space,

leaving behind a small core about the size of the Earth.

So remember we've shrunk most of the Sun,

which is a million miles across, to the size of the Earth which is

more like 6000 miles across.

Our once great star reduced to a slowly cooling cinder.

Life as we know it on Earth will cease to exist.

And that is the death of the Sun.

All of this is bad news for the human race,

but look on the bright side.

We've got five billion years to prepare for this disaster.

For now, humanity basks in the glow of a Sun

in the prime of its life.

Science has uncovered many of the secrets of our nearest star,

but we remain awed by its beauty,

and ever more wary of its wrath.