The Secret Life of the Sun

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90 million miles from us

is the power that shapes our world.

Our very own star.

The sun.

We see it shine in the sky above us.

But beyond our sight,

something dramatic is happening.

The sun is going into overdrive.

Our star is more active now

than it's been for a decade.

It's sending

eruptions of superheated plasma

and vast waves of radiation

towards our planet,

with the potential

to disrupt our lives

in completely unexpected ways.

At the same time,

a new generation of satellites

is showing us the sun

in more detail than ever before.

It's almost pulsating.

I'm Kate Humble.

And I'm Helen Czerski.

Together, we're going to unravel

what's happening to our sun.

From Britain's leading centre

for solar research,

we'll use the latest satellite images

and a team of world-class experts

to decode the sun's inner workings.

Something in the sun's atmosphere

snapped.

We'll explore the sun's

most spectacular displays.

I love your laboratory,

it's brilliant!

Investigate its mysterious

cycles of activity.

So it took seconds to get from the

sun to the satellite. That's right.

And discover how our sun

is behaving right now.

70 miles west of London

lies Britain's answer to NASA.

This is the Rutherford Appleton

Laboratory in Oxfordshire.

At RAL, satellite instruments

are designed and tested

before they're launched into space.

And scientists are analysing

the latest information

these satellites beam down

around the clock.

It's one of the most important

centres of solar research

in the world.

We've set up inside one

of RAL's giant research facilities

so that we can talk to some

of Britain's leading solar scientists

and see for ourselves

the extraordinary images

they're using to study our star.

We can't look directly at the sun

without damaging our eyesight,

but a new fleet of satellites

are allowing scientists here at RAL

for the first time

to get a unique picture of the sun.

In 2006, NASA launched

the twin STEREO spacecraft

to observe the sun

from two sides simultaneously.

The Solar Dynamics Observatory

followed four years later.

It's able to visualise the sun in

high resolution for the first time.

These satellites show the sun

as far more than simply the burning

disc in the sky that we see.

Here at RAL, head of space science

Richard Harrison

is responsible

for analysing those images.

So, Richard,

how are these new satellites

advancing our knowledge of the sun?

Well, the whole point

is that we have now built up

a fleet of spacecraft, an

international fleet of spacecraft,

that are really studying the sun

in phenomenal detail.

We can see the sun from both sides.

We can see a complete star,

and we'd never done that before.

And these satellites can detect

types of light from the sun

that are invisible to the naked eye.

The brighter regions here

are what we call active regions,

and they're regions

a bit like volcanoes and earthquakes

on the Earth, if you like,

regions where the sun is active,

and there's a lot of interesting

stuff happening in here.

You can see it with your own eyes,

it's so complex,

it's moving all the time,

like a plate of writhing spaghetti.

And I mean,

this is an extraordinary image.

We can see several colours

put together,

showing you the full complexity

in all of its glory, if you like,

the truly complex atmosphere

writhing in front of your eyes.

And this sort of illustrates it,

puts it in a nutshell,

how fantastic it is

to be studying the sun

as it approaches a peak in activity

with this wonderful fleet

of spacecraft.

This peak in activity

is known as a solar maximum.

It's the high point in a cycle

the sun goes through

on average every 11 years.

From relative calm...

..to intense activity...

..and back again.

A cycle that's fundamental

to how the sun works.

Understanding this solar cycle

will help us discover

the secret life of the sun.

But for most of us on Earth,

the sun is something we rarely

examine in any sort of detail.

To begin to understand

its extraordinary power

and its changing cycles of activity,

we need the help

of one of the most dramatic events

in the astronomical calendar,

a total solar eclipse.

And to see that, I had to travel

to the other side of the world.

November 2012.

I've come to Cairns, Australia.

I'm joining people

from across the globe

because in 48 hours,

there's going to be a total eclipse.

But this one is special

because it promises to reveal

something crucial about our sun.

Cairns is a relatively small town

in Australian terms.

It's home to about 130,000 people.

But that number could swell

by as much as 50,000

in the next couple of days,

and all for an event

that's going to last

just two minutes and two seconds.

It's an emotional experience, it's a

lovely way to sort of see the world.

Everyone is happy. It's fanta...

It's a natural spectacle of science.

I'm getting excited, yeah!

I've never seen

a total eclipse before

and we've got our glasses,

and we're all set to go.

We've got our fingers crossed

for clear skies.

You can't safely view an eclipse

unless you have glasses

with powerful filters.

Hi. Hello.

That's what I'm after.

The very last pair.

No way! Three dollars.

Did you want some as well? Oh, yeah,

we've been searching everywhere!

This is the very last pair in Cairns.

I'm really sorry.

Oh, you're joking!

We could share them.

Don't film this. This is horrible.

This is like breaking my heart!

No...

It's once every 50 years or so,

so make the most of it.

Thank you very much. Thanks, bye!

Seriously, your last pair?

Last pair. No more, all gone!

To get an eclipse, the moon

must drift between the sun and us.

At what's called first contact,

the moon begins to block it.

But what's extraordinary

is what happens

when the sun is completely covered.

That moment of totality

reveals something that's normally

hidden by the sun's glare -

the sun's faint atmosphere,

the corona.

And it's the corona that's key

to what this eclipse can tell us.

The corona is due to reveal itself

at precisely 6.38 in the morning

the day after tomorrow.

But the fact that we get

total eclipses in the first place

is thanks

to an astonishing coincidence.

Earth is the only planet

in the solar system

from where you can witness

a total eclipse,

and the reason for that

is down to pure luck.

The moon is 400 times smaller

than the sun.

But it's also 400 times closer

to the Earth.

So when the moon's orbit brings it

between the Earth and the sun,

it appears to be

exactly the same size as the sun,

and it's able to block out

its entire surface from our view.

There's a total eclipse

on average every 18 months,

so they're not exactly rare.

But catching one isn't easy.

The narrow shadow paths

they trace on the Earth's surface

are far more likely

to pass over uninhabited regions,

such as the oceans,

than a populated area like Cairns.

And the timing of this eclipse

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