Nova (1974–…): Season 45, Episode 1 - Eclipse Over America - full transcript

On August 21, 2017, millions of Americans witnessed the first total solar eclipse to cross the continental United States in 99 years. As in all total solar eclipses, the moon blocked the sun and revealed its ethereal outer atmosph...

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August 21, 2017.

From coast to coast,

Americans witness
their first total solar eclipse

since 1979.

A total eclipse is one of
nature's greatest spectacles.

It has filled people with wonder
since earliest times.

Well, it's just tremendously
exciting to be outside

while the universe darkens
all around you.

And that's a primeval thrill.

Scientists seize these
precious seconds of darkness

to explore a region of the sun
normally invisible...



Its outer atmosphere,
the solar corona.

It's this crown around the sun,
this beautiful halo.

The corona is also the source
of huge solar storms

that can strike Earth
with enough energy

to plunge cities into darkness.

All of our technology

is susceptible to these storms.

Can we learn to predict
when they will occur?

These dangerous solar storms
are just one of the mysteries

that a total solar eclipse
can help scientists to solve.

While millions enjoyed
the spectacle,

scientists were among
the most avid eclipse chasers,

on the ground and in the air.

To better understand



our most important
celestial neighbor.

"Eclipse Over America."

Right now on NOVA.

Major funding for NOVA is
provided by the following.

93 million miles away from us,

the sun is the source
of all life on Earth.

The sun is the most important
star

to us here on Earth.

It's responsible for the warmth
that we receive,

the food that we eat,
the water that we drink.

It's essential to our being.

But every so often,

in one of nature's
most dazzling spectacles,

the sun dramatically disappears.

A total eclipse is,

it's almost miraculous.

Since earliest times,

total eclipses have
filled people with wonder

and dread.

The ancient Chinese thought
a dragon swallowed the sun.

The ancient Babylonians saw them

as an omen that could herald
the death of a king.

But as the age of superstition
gave way to an era of reason,

scientists discovered
a hidden region of the sun

only visible
during a total eclipse:

its outer atmosphere, or corona.

The corona has tantalized people

ever since
it was first observed.

And mystified them, as well,

because the corona,
the sun's outer atmosphere,

is hotter
than the surface itself.

It's a few million degrees,

much hotter than the surface
of the sun,

and we don't really understand
why that is.

And even from millions
of miles away,

it's dangerous.

It can hurl powerful
electromagnetic storms

towards our planet.

When they impact the Earth,

they affect our satellites,

they can cause power grids
to go down,

because that's where the energy
is being deposited

from these storms.

With so much at stake,
can we protect ourselves?

We would love to improve
our capability

to predict this stuff.

A unique opportunity
to unravel these mysteries

arrives with the total
solar eclipse

of August 21, 2017.

10:15 a.m.

Salem, Oregon, is plunged
into darkness

as the total eclipse begins.

Over the next hour-and-a-half,

the path of totality sweeps
across 14 states.

On its way, it blankets

the south side of St. Louis
and the whole of Nashville

in total darkness

before finally passing
over Charleston

and heading out to sea.

Astronomers from all over
the country

have been making feverish
preparations for months.

We've got the telescopes

pointing
in the same direction...

Jay Pasachoff is one

of America's most seasoned
eclipse scientists.

I've now seen 65 solar eclipses.

This is number 66.

They're just wonderful things
to see.

He's setting up his equipment
in Salem, Oregon.

There are certainly
dozens of telescopes.

It includes a suite
of instruments

designed to reveal the hidden
structure of the corona.

Only on the days of eclipses
do we see the corona appear,

so we want to take advantage
of that as much as possible.

Farther along the eclipse path,
on Casper Mountain in Wyoming,

Steve Tomczyk hopes to find out

how the corona triggers
those destructive solar storms

that can strike Earth.

His team has been preparing
for months,

but finally, they're ready.

So here we are,

at Casper Mountain, Wyoming,

and the weather is great.

And we're getting very excited

as we're leading up
to first contact

in about an hour.

We have a team
of about 15 people

that have been working hard.

Everybody's ready,
the equipment's working.

So we're very excited
about our prospects

for getting some good data.

But what if it's cloudy?

Over southern Illinois,
scientist Amir Caspi has a plan.

Two NASA jet aircraft,
fitted with telescopes,

will fly at 50,000 feet
above the clouds,

to ensure image quality.

But there are no guarantees.

I'm very nervous.

It's game day, it's hard
to describe how I feel.

He hopes his data
will shed light

on why the corona
is so much hotter

than the surface of the sun.

All three teams
are taking advantage

of an extraordinary
astronomical fluke.

A total solar eclipse
occurs only

when the Earth, moon, and sun
are perfectly aligned,

so the moon blocks
the sun's light.

The diameter of the moon

is actually 400 times smaller
than that of the sun.

But by an amazing coincidence,

the moon is also 400 times
closer to the Earth,

so it appears the same size
in the sky as the sun.

When it passes
in front of the sun,

it completely blocks
the sun's light,

casting a shadow on the Earth

that plunges
everywhere it passes

into darkness.

It requires
this precise alignment

between the Earth, the moon,
and the sun.

It doesn't happen
all of the time,

but occasionally we get lucky.

If the moon were any closer
to Earth, or any larger,

it would obscure the object

the scientists are trying
to study:

the sun's outer atmosphere,
its corona.

9:00 a.m. in Salem, Oregon.

The first scientist to get
to study the eclipse

is Jay Pasachoff.

Okay, we see, we see an eclipse.

I see it!

First contact.

Oh, there it is!

The first of the four stages
of an eclipse

is first contact.

This is where the moon first
kisses the edge of the sun.

First contact.

In other words, we can just
look up through a filter,

and we see a bite out
of the sun,

and that's going to gradually
grow bigger

for the next hour-and-a-quarter.

To view this stage
of the eclipse safely,

it's essential to use specially
designed solar filters.

Ah, it's so cool.

It looks like someone
took a bite out of the sun.

Although the moon is traveling
in its orbit

at over 2,000 miles an hour,

it will take roughly 80 minutes

before it completely covers
the sun.

When that moment comes,
known as second contact,

it will be the start
of the total eclipse.

But how do we know
when and where

a total solar eclipse
will happen?

The last time one was visible

from the continental
United States

was in February 1979.

Jimmy Carter was president,

and the first personal computers
were just going on sale.

That was 38 years ago.

But the gap
between total eclipses

can be much shorter.

January 25.

Nature cooperating
with ballyhoo.

Elaborate preparations
were made...

In 1925, American astronomers
watched a total eclipse

as it passed from the middle
of the country

to the East Coast.

Some even flew in an airship
to make observations.

This fortunate generation

had already seen
two total solar eclipses

in the previous seven years...

And would see another
only seven years later.

Despite this apparent
randomness,

there is a complex pattern
behind eclipses.

And astonishingly,

it was discovered
over 2,000 years ago.

Ancient Babylon,

situated in what is now
modern Iraq.

For centuries, astronomers here
kept meticulous records

of their observations.

They reveal that,
for Babylonian kings,

eclipses were a matter
of life and death.

The British Museum holds

over 4,000 of these ancient
astronomical texts.

Whatever was seen in the sky

was considered to be
of relevance

for the fate of the king,

especially eclipses.

They could announce war,
they could announce his death.

When an eclipse came,
the king would stand down,

and one of his subjects
was appointed king in his place.

But this new job
came with a catch.

Here is a letter
in which the king asks,

"How long is this fellow going
to sit on the throne?

When can I return?"

And then the scholar replies,

"Well, with the next full moon,
he can go to his fate."

Meaning the substitute king
would be killed

and the actual king
would return to the throne,

and the evil would have passed.

To protect the king,

astronomers had to be able
to predict an eclipse.

For hundreds of years,

they recorded every occasion
an eclipse was reported.

Eventually,
around the fifth century BC,

they spotted a pattern.

Some very clever
Babylonian astronomers

figured out that solar eclipses
are governed by a cycle.

This is the so-called
Saros cycle.

Today we know
that a total solar eclipse

will take place
somewhere on Earth

about once every 18 months.

But with centuries of data,

the Babylonians realized
there was a larger pattern.

Every 18 years,

the time between eclipses
would repeat.

They could actually make
an entire calendar

of eclipse predictions

simply by projecting
these past eclipses

into the future.

Astonishingly,
the Babylonian predictions

were accurate to within
an average of four hours,

but they couldn't tell
where in the world

the eclipse would take place.

It would take
another 2,000 years

before astronomers worked out
how to do that.

At Harvard University,

locked in the Houghton Library's
special collection,

is a rare document.

It showed for the first time

that the path of totality
could be accurately predicted.

In 1715, the British astronomer
Edmond Halley

became the first person

to correctly predict
a total solar eclipse

by using the mathematics

of his good friend Isaac Newton

to calculate the orbit
of the moon around the Earth,

and therefore where its shadow
would fall

across the countryside.

In April of 1715,
Halley published this map,

forecasting
that in two weeks' time,

an eclipse would pass
over London.

Halley had studied records
of past eclipses

and rediscovered
the Saros cycle,

lost since ancient times.

This told him
an eclipse was due.

He then used new, accurate
observations of the moon's orbit

to calculate its path.

Among the things he had to take
into account

was the unusual orbit
of the moon,

which is tilted by five degrees.

So most of the time,

the moon's shadow
misses our planet,

which makes eclipses rare.

He also had to factor in
the gravitational effect

of the Earth and the sun,

which subtly alters
the moon's position.

By luck, Newton's new theory
of gravity

gave him just the tool he needed

to accurately calculate
the path of the eclipse

across England.

From comparing the maps

that Edmond Halley made
of the 1715 eclipse

both before and after,

based on the observations
by the public,

we find that he was actually
within about 20 miles...

Amazingly precise.

And Halley's estimate
of the time of the eclipse

was off by just four minutes.

Today, with
more accurate observations

of the moon's orbit,

astronomers can predict exactly
where an eclipse will occur

and when, to the nearest second.

Six months before the eclipse
over America,

Jay Pasachoff has come
to Argentina.

He's here to witness
another type of eclipse.

I saw my first eclipse

the beginning
of my freshman year at Harvard,

and it's just a thrill

when the universe darkens
around you.

They're just so fascinating,
I just want to see them all.

For Jay, eclipses
are a clear demonstration

of the predictive power
of modern science.

The most remarkable thing is,

we've come halfway around
this side of the world.

Beautiful blue sky, perfect,
normal conditions here,

and yet I confidently believe
that in half an hour,

something is going to start
going in front of the sun.

Exactly as predicted,

the moon starts its journey
across the face of the sun.

The filter on the camera
darkens the sky,

which is still bright.

The eclipse Jay has come to see
is not a total eclipse.

It's called an annular eclipse,

and it results from the shape
of the moon's orbit.

The moon's orbit
isn't a perfect circle.

It's very slightly elliptical.

So when the moon is farther away
from the Earth,

it appears smaller and doesn't
completely cover the sun,

creating an annular,
or "ring of fire," eclipse.

Look at the quality
of the light.

The color is a little eerie.

It's clear that something
strange is going on.

I see a bead.

Even though the moon blocks out
99% of the sun's light...

the experience for spectators,

while still exciting,

is different
from a total eclipse.

This is an annular eclipse.

Here it's only going to get
100 times darker.

So that's dramatic in some way,
and it's fun to look at...

But the total eclipses
are the exciting one,

when it really gets
a million times darker

in the middle of the day.

Only the darkness
of a total eclipse,

like this one
in Svalbard, Norway,

enables scientists
to see a part of the sun

normally invisible.

Its outer atmosphere,
the corona.

This elusive pearly white cloud

is made from a state of matter
rarely found on Earth,

called plasma.

You know, every day
in our lives,

we interact with solids,
liquids, and gases,

but there's another one,
and that's called plasma.

If you heat a gas
to a high enough temperature,

some of the electrons
in its atoms fly off,

leaving positively charged ions.

This super-hot mixture
of ions and electrons

is known as a plasma.

It's an electrically
charged gas.

And occasionally we see examples
of it, like lightning.

You know, lightning is a plasma,
and we can see it,

but it's incredibly short-lived.

In the corona, the natural state
of matter is in a plasma.

Although rare on Earth,

plasma is the most common state
of matter in the universe.

Most stars we can see are made
from it, including our sun.

1.3 million times larger
than the Earth,

our sun is a dense ball
of plasma,

made from hydrogen, helium,

and smaller amounts
of other elements.

The heat that creates
this plasma

is generated inside the sun,
at the sun's core.

Here, the extreme pressure
of gravity

forces the hydrogen atoms
to fuse together,

creating helium

and releasing vast amounts
of energy

as photons of light.

This nuclear fusion
heats the core

to 27 million degrees
Fahrenheit.

From here, the photons of light

pass through the dense
inner layer of the sun.

The temperature of the plasma
gradually drops

as the photons reach
the sun's visible surface,

known as the photosphere.

Here, rising and sinking plasma
forms a seething surface

of light and dark areas.

Around the photosphere
is the corona,

the sun's outer atmosphere
of extremely diffuse plasma,

extending far into space.

The word corona is a Latin word,
meaning "crown."

It's this crown around the sun,
this beautiful halo.

But it's not as dense
as the sun,

and so ordinarily,
we can't see it.

Because the sun, it's so bright,

we have to find a way
to diminish the starlight

so we can see the details
on its surface.

A total eclipse does just that.

But when the moon cancels out
the disc of the sun,

this beautiful halo is revealed

and we can then study that
in detail.

In Salem, Oregon,
Jay Pasachoff's team

is only minutes away
from second contact,

when the moon completely covers
the sun.

There is onl minutes to go.

There is only a very thin
crescent now.

Now it's looking weirder.

It just looks strange.

It's hard to explain.

You just know that something
weird is happening.

It's just tremendously exciting
to be outside

when the universe darkens
all around you.

And that's a primeval thrill.

As the moon closes over the last
remaining crescent of the sun,

tiny spots of light appear...
Like a string of beads.

The English astronomer,
Francis Baily,

almost 200 years ago,
saw bright little dots

along the edge of the sun.

And we now know that those are
the everyday sun

shining through the deepest
valleys on the edge of the moon.

And we call them Baily's beads
after their discoverer.

Fifteen seconds.

Five seconds.

Bailey's beads!

Diamond ring!

Corona!

Yay!

Wow!

Look at the corona.

Look at the shape there.

The total eclipse has arrived.

Jay Pasachoff's team has just

one minute and 55 seconds
of darkness

to photograph the corona.

We can see it on the imaging.

We've got a good exposure!

We're looking at the corona
here.

It means it's working.

The sensitivity is fine.

There's a big streamer
coming down.

Two streamers going up.

It's just beautiful.

Jay's plan is to capture
enough detail

to reveal the structure
of the corona.

Because the brightness
of the corona falls off

the farther it is
from the sun's surface,

it's impossible to capture
its detail

in a single photograph.

So one of Jay's cameras

takes a series of images
at varying exposures

to capture the different parts
of the corona.

Combining these photographs

reveals the corona is full
of astonishing detail.

Every time we look at the sun,
it's different.

There are all kinds of streamers
and little loops.

The lines of plasma in the sun's
corona are vast.

They would dwarf the Earth.

The force that drives
their shape and motion

is the sun's magnetic field.

We now know

that those are
the magnetic field of the sun

holding this hot gas in place.

We're familiar with
magnetic fields on the Earth.

They give us
our north and south poles.

But the sun also has
magnetic fields,

and they are far stronger.

As the sun turns,

electrically charged plasma,
beneath the surface, moves,

generating powerful
magnetic fields.

Because the plasma is moving
faster in some regions,

it bends and twists
these magnetic fields...

until some break through
the sun's photosphere

into the corona,

where they form giant arches
called coronal loops.

Because these magnetic fields

trap electrically charged
plasma,

they show up
as the bright lines and loops

we see in the corona.

The sun's complex
magnetic field,

revealed during an eclipse,

can directly affect us on Earth

through a process called
a coronal mass ejection.

You can see these huge
magnetic flux loops,

and occasionally,

these magnetic flux loops
can break.

In a coronal mass ejection,

the corona can throw
over a billion tons of plasma

out into space

at speeds of up to 2,000 miles
per second.

When a coronal mass ejection
heads our way,

the Earth's magnetic field
normally protects our planet.

It deflects most
of the highly charged particles.

But a large
coronal mass ejection

can overwhelm
our magnetic defenses

with devastating consequences.

These storms can impact
our technology.

They affect our satellites.

They can cause power grids
to go down.

Powerful coronal mass ejections

can cripple the power
and communication systems

our modern society relies on.

When they impact the Earth,

they interact with the Earth's
magnetic field.

They cause the magnetic field
to bounce.

Now, this causes currents.

As these currents surge
through power lines,

they can knock out transformers

and in an instant
put a city off-grid.

We really want to be able
to ultimately predict

when these storms
are going to occur.

This group of scientists
is on the front line

of predicting
a coronal mass ejection.

From Boulder, Colorado,

they use a fleet of satellites
to monitor the sun 24/7.

The biggest event they ever saw
happened in 2012.

This is what we saw.

All of a sudden
that flare occurs,

the eruption occurs,

and that blast,
it was tremendous.

Very big, very, very fast.

If it had hit the Earth,
it would have been a disaster,

but fortunately,
it wasn't in the right place.

But of course, the key is,

it has to be facing Earth
for us to feel it.

Near the middle of the sun,

there's a window we often
refer to as the kill zone.

When it occurs inside that zone,
then it's Earth-directed.

Then we're going to feel
the effects.

Had it occurred a week earlier,

the impact would have been
here on Earth,

and it could have been
very significant.

A large storm like this
very rarely hits our planet,

but in the last 40 years,

smaller storms have damaged
or disabled

over a dozen satellites,

and in 1989, one knocked out
the power supply

to the Canadian province
of Quebec.

To minimize the risk
of devastating damage,

Bill and the team must predict

when a powerful coronal
mass ejection will strike.

We would love to improve
our capability to predict.

If we can better model

what the magnetic
field might look like

within the eruption,

then we'd be in a great place.

And a total solar eclipse
is essential to this effort.

25 minutes after the eclipse
reached Salem, Oregon,

it arrives at Casper Mountain
in Wyoming.

Here, at 8,000 feet,

scientist Steve Tomczyk
is setting up an experiment

to see how these coronal
mass ejections

are created by the sun's
magnetic field.

We're trying to find out

how the corona is oriented

and that's important
because energy is stored

in the coronal magnetic fields.

Steve hopes his new camera
will help him understand

these magnetic fields.

So magnetism is very important
in controlling the plasma

and causing the plasma to erupt
in coronal mass ejections.

It's magnetism that triggers
these violent events.

The corona contains
highly charged plasma

trapped in magnetic fields.

When these magnetic fields
become twisted,

they can rise up,
stretching other magnetic fields

until they suddenly snap
and reconnect,

releasing huge amounts of energy

as the plasma blasts into space
as a coronal mass ejection.

You can remove them.

This is where the new camera
helps.

It will reveal evidence
of the twisted magnetic fields,

which are a sign that a coronal
mass ejection is about to erupt.

This camera allows us to measure
the polarization in the corona

over the entire corona,

and allow us to possibly
eventually predict

when coronal mass ejections
will occur.

Wow.

To the west of Casper Mountain,
the moon's shadow

races across the plains
at over 1,600 miles an hour.

The eclipse is moments away.

As the sky darkens,
the air begins to chill.

During a total solar eclipse,

the temperature can drop
as much as 28 degrees.

Moments later, the total eclipse
reaches Casper Mountain.

Steve's gamble has paid off.

The conditions are perfect
to carry out his observations.

Mid-eclipse.

C3 plus 40 is flash,
so I think we're done.

And we're starting to saturate,
so I think we're good.

You can cover flash now.

Just catch my breath, okay?

Diamond ring.

Here at Casper Mountain,
totality lasts

only two minutes and 26 seconds.

But is there a way to extend
the viewing time?

Ellington Airfield,
Houston, Texas.

8:00 a.m.

A NASA crew prepares
an audacious mission

to view the eclipse
for three times longer

than anywhere on the ground.

Their plan is to use telescopes

attached to the nose cones
of two WB-57 jets,

to track the sun
and record video of the corona.

Amir Caspi is
the scientist in charge.

At 50,000 feet we're going to be

above 85% to 90%
of the atmosphere,

which will make our image
quality much better

than it would be
if we were on the ground.

From Houston, the two NASA jets
fly to southern Illinois,

where they will line up
50 miles apart

and fly along the eclipse path.

As the moon's shadow
races over the jets,

they will observe the eclipse...

One after the other.

And the idea is
that they pick up the track

and follow the track
straight through.

The jets aren't fast enough

to keep up
with the eclipse shadow,

traveling around 1,600 miles
an hour,

nearly three times as fast
as the planes.

By flying two jets,

Amir hopes to extend
the viewing time

to over seven minutes.

By having two airplanes,
we can stage them in such a way

that when the shadow finishes
passing over that airplane,

it starts passing
over the second airplane.

And so then we can put
those two data sets together

and get a longer observation.

Amir and the team are trying
to solve a mystery

that has baffled scientists
for decades.

In the late 1800s,
an American astronomer

studying the corona
during an eclipse

made an astonishing discovery.

In 1869,
there was a total solar eclipse

visible from the United States.

Charles Young, an astronomer
at Dartmouth College,

led an expedition to Iowa
in order to use

the brand-new technology
of spectroscopy.

A spectroscope uses a prism

to divide white light
into its constituent colors,

or wavelengths.

If you heat an element
strongly enough,

its gas emits light
in very specific wavelengths.

Viewed through a spectroscope,

each element has its own unique
pattern of colored lines.

By pointing a spectroscope
at the corona during an eclipse,

Young hoped to find the elements
it contained.

What he discovered was
a mysterious spectral line

no one had ever seen coming
from any element on Earth.

He noticed there was
a special green line,

green light emitted
from the corona.

And since it matched up
with no known element,

people naturally assumed that
there must be some new element

not existing here on the Earth
that hadn't been discovered.

Scientists gave this strange
new element a name:

coronium, because it had been
discovered in the corona.

For the next 70 years,

astronomers sought to identify

what this mystery element
might be.

What they found, in fact,

iron...

Iron at such a high temperature

that 13 of its 26 electrons
had been ripped away.

Astonishingly,
the corona was so hot,

it had turned the metal iron
into a plasma

with a spectral line
completely different

from iron found on Earth.

Only under extraordinarily
high temperatures

is this ever possible.

So when you see
a total solar eclipse

and you witness
that amazing corona,

you are seeing an object
at a million degrees.

It is the hottest thing you will
ever see with the human eye.

And that's the problem.

The surface of the sun is only
about 10,000 degrees Fahrenheit.

How can the sun's
outer atmosphere

be hotter than its surface?

It seems to defy
the basic laws of physics.

The energy in the sun

is being generated at its core,

in the center.

Now, as you move away
from the core,

you expect things to get cooler.

You're moving away
from the source of the energy.

Same thing, as I'm sitting here
close to the fire, it's hot.

If I were to move away,
it would get cooler and cooler.

And that does happen
up until the surface of the sun,

but then all of a sudden,

as you move further away
from the surface,

it gets really hot again.

We do not understand
what is causing

this extreme change
in temperature.

So, what is heating the corona?

One of the leading theories

is this theory of nanoflares,
which are small,

what we call impulsive events.

They happen very quickly.

Nanoflares are thought to be
explosions on the sun

that are too small
to be seen directly

by ground-based telescopes,

but there is evidence
they exist.

Recently, at the White Sands
Missile Range in New Mexico,

this group of scientists

launched a research rocket
into space to study nanoflares.

I've been launching rockets
for 30 years.

When you fly
a satellite program,

you spend weeks aligning it,
focusing it, calibrating it.

The biggest challenge
with rockets is,

it's only a five-minute flight,

so it has to work
right when you open the door.

On board is a modern electronic
version of Young's spectroscope.

It will briefly photograph
the sun

before the rocket falls back
to Earth.

We spend years developing
the instrument,

but actually seeing it work
and fly it in space

is really the icing on the cake.

The advanced spectrograph is
designed to analyze the light

from brief flashes
of extremely hot plasma...

The signature of nanoflares.

According to the theory,

the trigger for nanoflares comes
from the sun's magnetic fields.

Like most interesting phenomena
on the sun,

they involve magnetic fields
in a fundamental way.

So these fields are much,
in fact, like rubber bands.

They can be stretched
and twisted and stressed,

and eventually they reach
a breaking point.

And when they do, they snap.

The arches of plasma that rise
from the sun's surface

can be made up
of many magnetic field lines.

As the sun's plasma churns
at the surface,

it can twist and tangle
these magnetic field lines,

creating stresses that build up

until eventually the lines break

and reconnect
in a simpler configuration.

This releases huge amounts
of energy

in a nanoflare.

Millions of nanoflares

are thought to be going off
each second,

beginning at the sun's surface,

and reaching into the corona

to heat it
to over a million degrees.

Each nanoflare is the equivalent
of a 50-megaton hydrogen bomb.

They're happening
at a tremendous rate,

a million or so per second
across the sun,

so collectively
they really pack a wallop.

At White Sands,

the spectrograph...
Designed to find nanoflares...

Will soar 200 miles
above the Earth.

50 seconds and counting.

The rocket will take it beyond
the Earth's atmosphere,

which would absorb the light
they're trying to detect.

All stations,

this is MM calling
for go status... Navy?

Navy, go.

TM is go.

We're go.

Ten,

nine, eight, seven, six,

five, four, three, two, one,
lift off.

Come on, second stage.

Yes!

After five minutes in space,
the spectrograph lands safely.

The mission is a success.

Outstanding.

It will take the team months
to process the results.

So we have any broken?

But the first indication
that nanoflares really do exist

came from a flight like this
in 2013.

That rocket captured images

that indicate
a surprisingly hot plasma.

The emission that we see here
indicates very, very hot plasma.

It's a very faint emission,

and we in fact expect it to be
very faint, but it's there,

and that is
the smoking gun of nanoflares.

Spectral lines provided evidence

of iron stripped
of 18 electrons.

And that can only happen
at 16 million degrees...

Hotter than even the corona,

and a temperature

that it's thought
only nanoflares can produce.

So far signs of nanoflares
had been found

only near the sun's surface.

But during the eclipse,
Amir's team will use its planes

to look for nanoflares thousands
of miles above the surface,

in the corona.

We don't know
where they might be occurring.

There could be nanoflares
occurring

higher up in the corona.

Because we can't see them...

We can only see the results
of these nanoflares...

It's hard to know.

And that's one of the things
that we hope to learn

from this eclipse observation.

In Houston, Amir Caspi
anxiously awaits

the live video feed from the
telescopes on the NASA jets.

I'm not sure what's going on.

Two minutes to eclipse.

Planes are in position,

although the live streams
are a little flaky.

Right now, the first plane,
the westward plane,

should be in the path
of totality.

It should be experiencing
a total solar eclipse.

Unfortunately we don't have
the live video feed right now.

Oh...

Just then, the video feed
comes in.

That looks great.

We've got the overlap.

That is beautiful.

That is beautiful!

We got observations.

We got totality.

So, had a little bit
of a touch and go

with the live feed there, but
we got some great observations.

I'm... I'm pumped.

See that streamer
coming out of here?

The operation is a success.

Yeah, there's one
over there too, that's right.

Until we get the scientific
quality data on the ground,

we won't know for sure if we saw
what we were hoping to see.

On the other hand, whatever we
see is going to be interesting.

It's going to teach us
about how energy gets

from the center of the sun
out to the solar corona,

how it heats the solar corona.

It will take a little while to
extract all of that information,

but we got what we came for.

All right!

For sheer spectacle,

it's hard to beat the end
of a total eclipse.

The last moment of totality
is called third contact...

the moment when the moon

starts to reveal
the sun's light again.

As soon as this happens,

the sun creates
a brief but dazzling spectacle.

When the first rays of sunlight
reappear,

they sparkle
like a brilliant jewel.

Since the 1920s,
this moment of the eclipse...

The glowing circle of the corona

welded to a bright spot
of light...

Has been known
as the diamond ring.

The name comes from the eclipse

that passed over the East Coast
in January 1925.

From New York to Washington,
D.C., people flocked to see it.

President Coolidge watched it
from the White House.

One of the things they reported
was a diamond ring,

a bright point of light

set in this diaphanous circle
of corona.

And so it's come down to us
today, this term,

which I still find to be one
of the most beautiful sights

to see during a total
solar eclipse.

Diamond ring!

Salem, Oregon.

At 10:19 local time,

the moon moved away
from the edge of the sun,

revealing the diamond ring.

It's the end of totality.

Just gorgeous.

Congratulations, everybody!

For the scientists,

it's time to check their
observations of the corona.

Today's view of the sun will be
one of the best ever in history.

It's such an amazing experience.

Jay has the first images
from the eclipse.

But he won't be able to see
the details in the corona

until he has processed the data.

We had predictions based on

what the corona might look like,
and now we'll go back

and compare what it actually did
look like, and prove the theory.

So we're... we'll be analyzing
that for a long time.

Yeah.

Good, your first eclipse.

Glad it came back.
Your first eclipse.

On Casper Mountain, the moon's
shadow passes on its way,

throwing the land
into light again.

The diamond ring appears.

And the total eclipse is over.

Interesting.
Really interesting.

It's the moment of truth
for Steve Tomczyk.

Did the new camera work?

Data look really good.

We're going to have a lot of fun
the next few months

analyzing the data.

Really exciting.
Very exciting.

Good job, everybody.

Fabulous.

It's another small step towards
understanding the forces

that trigger
coronal mass ejections.

The 2017 total solar eclipse

was the first to cross
the United States

from coast to coast
in nearly a hundred years.

Its path,
over several major cities,

meant that millions of people
were able to experience

this unique spectacle.

This is the coolest thing
I've ever seen.

It's awesome.

It's spiritual, it's emotional.

When I watched it,
my jaw was completely open.

There are scientists here.

There's people
from all over the world,

different languages
being spoken.

I think we're all just united

by this amazing
kind of cosmic event

that reminds us kind of where
we are in the universe.

For 90 minutes, the eclipse
transfixed the nation.

And, if you missed it, in 2024,

another total solar eclipse
will cross America,

once again reminding us
of our special connection

with our nearest star, the sun.

This NOVA program
is available on DVD.

NOVA is also available
for download on iTunes.