WEBVTT

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Humanity has always been
drawn to the night sky.

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We draw pictures in the
stars, track the planets,

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see signs and portents
and celestial objects.

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But so much of the universe
is beyond our reach.

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Vast distances separate
us from the sites

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that might answer some
of our biggest questions.

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How do galaxies form?

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How do stars and
planets come to be?

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Do distant planets have the
conditions necessary for life?

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To construct and
test our theories,

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we need to see what's happening.

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So we build tools to
extend our vision.

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They get bigger, (ECHOING)
more powerful, more advanced.

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As time goes on, astronomy
stops relying on the light

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we can see only with our eyes.

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[JAZZY MUSIC]

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When you look at
the world, you're

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seeing something we
call visible light.

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But visible light is really only
a certain form of radiation.

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Our universe is full of many
different types of radiation.

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It surrounds us.

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Our bodies evolved to detect
visible light with our eyes,

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but they also evolved to detect
another kind of radiation

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called infrared light.

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Our bodies feel
infrared light as heat.

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This infrared radiation was
discovered by the astronomer

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Frederick William Herschel.

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Herschel knew that
a prism could be

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used to break white
light into colors.

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He wanted to know
whether the colors had

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different temperatures.

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They did.

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But then Herschel measured
the empty space just

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beyond the red light.

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Though no sunlight was
visible, it was hot.

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Herschel had just discovered
invisible infrared radiation.

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[CHEERING AND APPLAUSE]

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Humanity now knew that there
were forms of radiation

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that could not be seen.

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[OMINOUS ORGAN MUSIC]

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They could be anywhere,
all around us.

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How many were there?

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What were they up to?

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What were they hiding?

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Obviously, we had to find out.

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A type of energy that
travels through the universe

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in the form of waves is called
electromagnetic radiation.

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The entire range of it
from high-energy gamma

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rays to low-energy
radio waves is called

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the electromagnetic spectrum.

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Although our eyes can
see only visible light,

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we can build tools, like
infrared-detecting cameras,

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to see other forms of radiation.

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These tools are
man-made eyes that

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view invisible radiation for us
and transform it into pictures.

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[RADIATION BUZZING SOUND]

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Objects can emit all
kinds of radiation.

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Huh?

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Observing the entirety
of that radiation

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gives us a true
picture of an object.

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[RADIATION BUZZING SOUND]

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[BURP]

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When we turn these
tools on space,

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they open up the entire cosmos
to us in its full glory.

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When we look at
the night sky, we

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see stars and planets,
galaxies and nebulae

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in the form of visible light.

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But if we could see
in infrared light,

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the sky would appear
very different.

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For one thing, infrared
light's long wavelengths

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penetrate clouds
of gas and dust.

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The shorter wavelengths
of visible light

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are stopped and scattered as
they fight through collections

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of particles.

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So by detecting
infrared light, we

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can see through
clouds of gas and dust

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to warm objects inside
like just-forming stars.

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Objects that don't glow with
any visible light their own,

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like planets, are
still often warm enough

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to radiate infrared
light, perhaps

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allowing us to glimpse them.

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And by observing how infrared
light from a planet's star

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passes through its
atmosphere, we acquire clues

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about the planet's composition.

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The dust left behind by
distant planets as they form

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will also glow in infrared,
helping to show us

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how planets are born.

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So infrared helps us
see objects like these

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in our own galactic
backyard, but it can also

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help us observe the
first objects that

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formed in the universe
after the Big Bang.

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Imagine you gave a
letter to the post office

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in a galaxy billions
of light years

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away and addressed it to Earth.

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It would travel for an
incredibly long time.

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When it finally arrived
at its destination,

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the person who opened
it would be getting news

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from billions of years earlier.

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The light from the first
stars to shine in the universe

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is something like that.

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It left the stars ages ago and
is still out there in space,

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traveling the vast
distances between galaxies.

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If we could see it, we
could see those galaxies

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as they were in
the early universe.

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Essentially, we would
be seeing back in time.

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But we haven't been
able to see it.

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Why?

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Because the universe
is expanding.

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As light travels across space,
it's stretched like taffy

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by the expansion.

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The first stars gave off mostly
visible and ultraviolet light,

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but the stretching changes
those waves into infrared light.

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This is called redshifting.

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The only way to see
that light as it arrives

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in our region of the
universe is to look

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for that faint infrared glow.

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By capturing it, we
will be able to create

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images of the first galaxies
to form in the universe.

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By witnessing the birth of
the first stars and galaxies,

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we deepen our knowledge
of how the universe as we

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know it came to be.

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How did we get from
those first blazing stars

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to the islands of billions
of stars we see today?

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What will we learn about how
galaxies grow and evolve?

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How did the chaos of
the early universe

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transform into
order and structure?

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NASA is currently building the
James Webb Space Telescope.

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[GRACIOUS MUSIC]

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With its huge infrared-capturing
mirror and distant orbit

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far beyond the moon,
Webb will allow

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us to view the cosmos as
we've never seen it before.

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[RECORD SCRATCH]

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Webb will search for
signs of water vapor

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on planets around other stars.

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[RUBBER DUCKY SQUEAKING]

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It will take pictures of
the universe's infancy.

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Webb will reveal the hidden
stars and solar systems forming

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within cocoons of dust.

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The answers to some of the
universe's biggest mysteries

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and more questions we
haven't thought to ask

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are waiting out there for us in
the form of infrared radiation.

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All we have to do is look.

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[GOOFY MUSIC]

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