All language subtitles for The UnXplained s04e15 The Search for Extraterrestrial Life.eng

Shadowy
objects hiding above our planet.

Unidentified vehicles
moving through outer space.

And a strange radio signal

that may have been
sent from another world.

For thousands of years,

humanity has looked to
the stars and wondered,

"Are we alone in the universe?"

Scientists have long theorized

the existence of
life among the stars,

despite the lack of
irrefutable evidence.

But as a new era of
space exploration begins,

are we on the verge
of finally proving

that extraterrestrials exist?

Well, that is what
we'll try and find out.

At Ohio State University's

Big Ear telescope, which
uses a specialized antenna

to detect radio waves
from outer space,

astronomer Jerry Ehman

is poring over a
printout of incoming data

when he notices
something remarkable.

Buried amidst the random static

is a signal of such
extraordinary intensity

that he wrote a single
word in the margin beside it:

"Wow!"

So the Wow!
Signal just leapt off the charts.

It was so strong and so
unique that it didn't seem

to come from any
known human source.

The exciting
thing about the Wow! signal was

it was in a frequency
band which is

forbidden to
broadcast in on Earth.

So it wouldn't be
an Earth signal.

But it looked just
like a transmission.

When we
detected this Wow! signal,

it wasn't random.

It looked like it was planned.

So, people have theorized

maybe it was a message from
an alien civilization in space.

Many researchers
consider the Wow! signal

to be the strongest
evidence to date

of an extraterrestrial
radio transmission.

But almost 50 years
after it was detected,

the signal remains
shrouded in mystery,

in part because it has
never been observed again.

People have looked for the
Wow! signal to come back again,

but the unfortunate thing is
it just hasn't been repeated.

It's a complete unknown
whether we'll find

an intelligent civilization like

our own out there,

but that's one of the
reasons we're looking.

The work that scientists do

to detect radio signals
from outer space

is referred to as the search

for extraterrestrial
intelligence, or SETI.

Since 1984, this research
has been overseen

by the SETI Institute,

which is located in
Mountain View, California.

At the SETI Institute,

all we do is we look at the
kinds of signals coming in,

if we pick up any, and see

if there's any
information in them.

Like the kind of signal
that you would expect

from an extraterrestrial
transmitter.

One of the most modern
radio telescopes we have

for detecting
extraterrestrial signals

is the Allen Telescope Array

operated by the SETI Institute.

So this is an
array of telescopes

that is specifically designed

to look for radio
signals from ET.

There have been dozens
and dozens and dozens

of SETI experiments.

We are curious about knowing

whether we're the only,
you know, only game in town.

The work being done
by the SETI Institute is the latest

in a long line of scientific
efforts to determine

whether or not humanity

is the only intelligent
life in the universe.

Since time
immemorial, we have wondered,

"What's out there?"

Well, that paradigm
is with us today.

Today, we still wonder
what's in the stars.

It's sometimes said that
perhaps the greatest search

in the history of
science is to search for

how we fit in with
regards to the universe.

For thousands of years,

astronomers could only
gaze up at the heavens

and wonder whether there
was life among the stars.

But the idea of
actually finding evidence

of extraterrestrial
life really took hold

in 1774, when astronomer
William Herschel

used new technology

to see other planets up close

for the first time
in human history.

In the 18th century,
William Herschel comes along

and builds the largest
telescope of that time...

48 inches in diameter.

And he, in effect, invented
the field of stellar astronomy.

He's looking at the planets
and other nearby objects

and says, "Well, I think there's
people living on the Moon,

I think there's people
living on other worlds,

and I think there's people
living inside the Sun."

Herschel's influence
was significant.

The Founding Fathers
of the United States,

Thomas Paine, Ben Franklin
and Thomas Jefferson,

all read his work

and agreed with the
potential that there could be life

on other planets.

As telescopes
became more powerful

in the late 19th century,

American astronomer
Percival Lowell

began to focus them on Mars.

And what he observed
on the Red Planet

was nothing short
of extraordinary.

Percival Lowell saw linear lines

going between the light
and dark areas of Mars.

And so he mapped
these meticulously

and he called them canals.

So suddenly, all this
buzz starts coming around

about "Wait a minute,

there are people on
Mars building canals?"

This idea of canals
on Mars, that there was

an intelligent society building

this planet-wide system,
just gripped the world.

People were
obsessed with this idea

of the intelligent Martians
wanting to reach them.

There were plans to
shine a big light to Mars,

somehow signal to the Martians.

As Lowell's documenting
his Mars observations,

he starts writing
popular articles,

which are incredibly
widely read.

Now, it is notable that
this came out right about

the same time as H.G.
Wells' The War Of The Worlds,

which is a wonderful,

journalistically-styled
fiction novel

about the invasion
of Earth by Martians.

This is the time when the idea

of alien cultures
and extraterrestrials

really begins to flourish
and kind of explode.

First published in 1897,

The War of the Worlds
popularized the notion

that humanity could,
in the near future,

encounter hostile beings
from another planet.

War of the Worlds
started this whole trend

that we always think that aliens
are going to enslave humanity

or that they're going to see us
and somehow try to kill us all.

We have a lot of ideas
about what aliens could be,

and they tend to be
very violent images.

By the early 20th
century, aliens had become a staple

of the imaginative
works of science fiction.

But in the 1940's,
eyewitnesses around the world

began to claim that
they had seen real

extraterrestrial
spacecraft flying in the sky.

Our history is
full of UFO reports

and sightings and abductions
and visitation experiences.

And in the last several decades,

people are looking up
and seeing UFO objects

that are moving
through our space.

The UFO phenomenon is real.

There have been
consistently a lot of reports

of unidentified objects.

Recently, there have been

classified briefings
in the U.S. Congress.

On the UFO findings.

This is a matter of
great public interest

and has been for a very
long time to a lot of Americans.

Our government should
not hide the truth from us

for another second.

On June 25, 2021,

the Office of Director
of National Intelligence

delivered a
preliminary assessment

and what the media
and the public have seen

is a nine-page
unclassified summary.

But it essentially says that
this phenomenon is real.

This was a sensational headline.

The U.S. government
is saying, "Watch out!"

Historically, the
burden of proof

was on the true believers

to prove that these
objects are extraterrestrial.

And for the first time, the
burden of proof has shifted.

Of course, we can't
be definite about this,

but I would think that within
the next 50 to 100 years,

the probability that we
actually make contact

with an extraterrestrial
civilization

approaches 100%.

It's thrilling to think that,

someday soon,
we might find proof

that there's intelligent
life in the universe.

But while scientists continue
to search deep space,

many believe there's evidence
to suggest that alien life forms

have already visited Earth.

Inside the
International Space Station,

Russian cosmonaut Ivan Vagner

is recording a video
of the southern lights

when, suddenly,
his camera captures

what appears to be a formation
of unidentified spacecraft

above the Earth.

It was an
amazing piece of footage.

These objects comes into frame,

which seems to
be of five lights,

and then suddenly disappear.

It happens quite
fast in the video.

One minute it's there,
the next one, it's gone.

Vagner immediately
posted the video on Twitter,

and many people claimed
that the clip was evidence

of an extraterrestrial
spacecraft.

The video is very interesting

because when you
look at the video,

it was speeded up.

It turns out that these lights

actually were visible by the
astronaut for about 50 seconds,

which is quite long.

So sometime later,

he comes back with
a second story saying,

"Maybe I misidentified them."

You know?

So we don't know if
really NASA leaned on

this astronaut to say,

"Look, you know, change
your story a little bit."

Or... that he genuinely did
think he made a mistake.

A number
of mainstream scientists

quickly dismissed the lights
as misidentified satellites,

which would have seemed
to put the matter to rest,

except for the fact that
American astronaut Leroy Chiao

had a similar
sighting back in 2005.

We were on a spacewalk

to install navigation antennas

outside of the
International Space Station.

We were in that transition
zone at part of the orbit

where we're going
from night to day,

and right at that moment,

I saw what looked like
five lights flying in formation

in kind of an
inverted checkmark.

There was no time

to take a picture of
it. It just happened

in just a couple of seconds.

Then we burst into sunrise
and everything was gone.

When I saw the lights,

I knew they were unusual,
but I really didn't assign

any, uh, big deal to them.

I just thought they were
a satellite constellation.

And I really didn't give
it any other thought.

And it wasn't till later that
we got these reports that

people reporting, were
reporting that I had spotted UFOs

and there was theories that

that might be an
alien spacecraft.

Is it possible that the various

recent sightings of
strange phenomena

above Earth are evidence

that there is intelligent
life in the universe,

and that extraterrestrials

are secretly
monitoring our planet?

Many researchers claim that the
answer is yes because astronauts

are highly credible witnesses.

When you look at the number of

sightings of UFOs and
anomalous phenomena

by astronauts,

the possibilities
are hugely exciting

because, generally, astronauts
are the sorts of people who,

as witnesses, are unimpeachable.

Astronauts are absolutely

the best observers of
anything that's out there.

Their attention to
detail is incredible,

and they make absolutely
amazing observers.

So when we do get reports of
something strange being seen,

you can pretty much
take that to the bank

because they've kind of
looked at all the possible

rational explanations and
not come up with anything.

The recent sightings

made by astronauts
are not the first time

that mysterious objects

have been encountered
above our planet.

In fact, there are similar
reports that date back

to the beginning
of the space age.

In 1965, during the
Gemini 4 mission,

astronaut Jim McDivitt

reported photographing
a mysterious object

outside his capsule.

Jim McDivitt was one of
the first astronauts to see

something unexplained in space.

He saw what looked like
a cylindrical spacecraft

or cylindrical object with
antennas sticking out.

He didn't know what it was.

He said it was
quite a large object,

and was moving quite
fast towards them,

He described it as a
shape of a can of beer,

with a prong sticking
out of one end.

And he had absolutely
no idea what this thing was.

So he grabs the nearest camera
and snaps it, but he's clever.

In case there's something
wrong with this one,

grabs a second camera and
takes another photograph.

And of course, he relays this
information back to, to NASA.

Two days
after McDivitt's encounter,

the Gemini 4 Mission ended
and the crew returned to Earth.

The film from McDivitt's camera

was then processed
by NASA technicians.

But when McDivitt
reviewed the images,

he didn't see a
cylindrical object

with a large
antenna sticking out.

James McDivitt was curious.

What the hell was up there
that was close to his craft?

So sometime later,

he's looking through
the images of this camera

and he can't find it.

All he can find is
some blue obscurity.

And he thinks to himself,

"Well, is it because the
camera was out of focus?"

So he grabs the images
of the second camera,

and he's looking at
those photographs.

And lo and behold,
it's not on there neither.

Just another obscurity.

The photos
didn't come out really well.

So, what was it?
We still don't know.

Now, a lot of people say, "Wait.

There was a cover
up about this."

That there was
indeed a genuine photo

buried in a vault somewhere
at NASA headquarters.

Is it possible that NASA
has photographic evidence of a real

extraterrestrial spacecraft

that they've kept secret
for more than 50 years?

Perhaps.

But many researchers believe
that another orbital encounter

provides even stronger evidence

of an extraterrestrial
presence around our planet.

On the 155th day
of their mission

aboard the Soviet
space station Salyut 7,

Russian cosmonauts Oleg Atkov,

Leonid Kizim and
Vladimir Solovyov

witness an extraordinary event.

The Salyut 7 sighting
is one of the most

bizarre and
mysterious encounters

that we've had in space.

These Russian cosmonauts
are up there and suddenly,

they report that the
entire space station

is bathed in this
mysterious light.

It's this orangey glow.

And they look out

and they see strange
entities out in space.

There are theories
that it was a hallucination

or something like
that, but, come on.

A shared hallucination where
everyone sees the same thing?

That's not very likely.

So it leaves you
with the impression

maybe this isn't
a hallucination.

Maybe this was real.

Are the numerous sightings by
astronauts of unusual phenomena

in outer space simply
misidentification?

Or are there forces at
work trying to keep the truth

about extraterrestrial life
hidden from the public?

Perhaps the answer lies

with a strange object
orbiting the Earth

which some people think
may be an alien satellite

spying on our planet.

The Soviet
Union shocks the world

by successfully
launching Sputnik,

the first man-made
satellite, into outer space.

In the six decades

since that historic achievement,

more than 70 nations

have sent their own
satellites into orbit

around the Earth.

Today,

there are approximately 6,500
satellites circling our planet.

We send multiton satellites
into outer space all the time.

You can now communicate

with anyone, anywhere, anytime,

on the surface of the Earth

without a telecommunications
network on the ground.

Internet,

weather satellites,

reconnaissance...
All of it can be done

using the satellites
in outer space.

Three,
two, one, zero and lift off.

One unfortunate side effect

of launching so many
satellites into orbit

is the accumulation
of mechanical debris

left over from previous
space missions.

These objects floating
above our planet

are collectively
referred to as space junk.

Experts estimate that there are

128 million pieces of space junk

in orbit.

Every launch we make,

we're putting out
particles and, honestly,

space trash into
orbit around the Earth.

So far, we've been able
to navigate around it.

But if we're not
careful in the future

and we put out too
much space junk,

it's gonna get harder and
harder to launch spacecraft.

Scientists continue to monitor

the millions of objects
surrounding our planet.

But many researchers
believe that there is one

mysterious satellite
orbiting Earth

that was built not by man

but by an
extraterrestrial civilization.

On day nine of their mission

to construct the
International Space Station...

the crew of Space
Shuttle Endeavor

is unpacking new hardware

when they spot
an irregular shadow

floating some distance away.

They quickly take photographs
of the oddly-shaped object,

but its dark color makes
it difficult to identify.

Almost as if it was
meant to be camouflaged

against the darkness of space.

Astronauts took a picture

of some unidentified
object in space.

Once people saw that picture

they were convinced that
it was an alien spacecraft

or some kind of flying saucer.

But then that raises the
question of what it might be.

This really was
something anomalous

because when you
think about satellites,

normally you think maybe
about something spherical

or about something

obviously manufactured.

But this is all
sorts of odd angles

and curved edges.

Like nothing the human mind

could conceive of
or design or build.

After reviewing the photographs,

NASA claimed that
the mysterious object

was simply a thermal
cover that had broken free

from the space station
during construction.

But given the bizarre shape
of the mysterious object,

there are many people
who find that explanation

a little hard to believe.

Instead, they claim that
the images are evidence

of an extraterrestrial
craft in Earth's orbit

that is known as the
Black Knight satellite.

The Black Knight satellite

is one of those really
curious mysteries.

And the theory is

that this thing is-is like a...

a sort of silent
sentinel in space.

And it's very difficult to
pin down how this started.

What's intriguing is nobody
really knows where the name

Black Knight
satellite came from.

We can't find
where the reference

suddenly came into Black Knight.

But in 1954, one of the
major newspapers in the U.S.

released a story about

a gentleman known
as Donald Keyhoe,

and he was a very
well-known UFO investigator,

ex-military.

And he said there
is something up there

traversing the planet
Earth on an orbit,

and it's not built
by human hands.

But if there really
is a satellite circling our planet,

built by
extraterrestrial beings,

then it naturally
begs the question,

what on Earth is it doing here?

The best wildlife documentaries

is when the animals
don't know you're there.

Well, if Earth is being
monitored, we're the animals.

So it is an
extremely logical step

to park a satellite in orbit

up there in space just
watching, recording,

harvesting information about us

and beaming information
and messages about us

back to the alien home world.

When we think about

the space program, we
are doing the same thing

with all the missions that
we're sending out to Mars,

with all the orbiters,

and even the probes at
the edge of the solar system.

Has an
extraterrestrial civilization

sent a probe to
hover above Earth

in order to spy on us?

Perhaps.

But some scientists
argue that a better strategy

would be to observe our
planet from much further away

on distant asteroids

that are known as
co-orbital objects.

A co-orbital object

looks like a distant satellite
of Earth like the Moon,

but much further away.

They were first discovered
about 20 years ago.

We know very little
about them as objects.

It's assumed they're asteroids.

We estimate that there are
several dozen of them at least,

and the nearest
co-orbital object is about

three million miles away.

So if extraterrestrial
intelligence

wanted to observe
Earth and not be seen,

the co-orbitals are
a fine way to do it,

because it will not
be so noticeable.

Could an extraterrestrial
satellite be secretly

monitoring our planet

as I speak?

For now, that question
remains unanswered.

But an even more
compelling mystery

can be found on one
of the moons of Mars,

where researchers
claim there is evidence

of alien technology.

140 million miles from Earth,

after a perilous five-month
journey through space,

NASA's Perseverance rover
gently lands on the planet Mars.

A big part of our
interest in Mars

has always been
looking for life,

whether it's some kind of
small fossilized life in the rocks

or biochemical
signatures in the soil

that prove that there might
have been life on that planet

at one time in its history.

And people are
getting really excited,

because if we do find life

on another planet in
our own cosmic backyard,

that's a massive game changer.

Ever since the
NASA spacecraft Mariner 4

made the first flyby
of Mars in 1964,

more than 40 additional
missions have been launched

to search the Red Planet

for signs of
extraterrestrial life.

But some researchers claim

that if Mars is
indeed harboring life,

we won't find it
on the planet itself.

Instead, they believe
there is evidence

of an extraterrestrial
intelligence

on a Martian moon
that is known as Phobos.

Phobos is just plain weird.

It's only about
seven miles in radius

which is, uh, very, very small.

And it's a really

bizarre and surreal
looking shape.

It's all sorts of odd angles...

A mixture of sharp
and curved edges.

A real jumble.

In the 1950s,

a Soviet Union astrophysicist,

Iosif Shklovsky,

noticed that Phobos
may not be a moon at all.

And he was approached by

Carl Sagan in the 1960s.

The two of them worked
on a book together,

Intelligent Life
in the Universe,

and in that book they both
talk about Phobos possibly being

an artificial structure.

In 1998,

the Mars Global Surveyor
took a picture of Phobos

that has this strange
three-dimensional cubic-looking

monolith structure on it.

And geologists have looked at
it and they can't quite explain it,

although they come
up with some theories.

But there's no real
explanation as to why it's there

and what its purpose
is, or how it was formed.

That's really
intriguing. What is it?

NASA scientists
claim that this monolith

is the result of a crumbled rock

that fell from a
nearby mountain ridge.

There's no such surface
feature in the area.

The surface of
Phobos is very smooth,

which was vindicated
in later images

taken by the Mars
Reconnaissance Orbiter.

It's very shiny,
very flat surface.

It's littered with
small craters,

and there's no surface
features sticking up.

There's no mountains,
there's no ridges,

and we have this weird
obelisk sticking out of the ground

which doesn't belong there.

In looking
at the monolith on Phobos,

we can't tell whether it's
a perfectly square object

or it's just a rocky
protuberance,

but it is seemingly out of place

on what looks like the
smooth surface of this moon.

That means it
might be artificial.

Could the Phobos
monolith really be an artificial structure

built by extraterrestrials?

Some researchers think
so, and for further evidence,

they point to the fact that
Phobos is mysteriously hollow.

The European Space
Agency's Mars Express mission in 2008

explored Mars' moon Phobos.

Using radar sounder technology,

it found that the moon
isn't actually solid.

There are large subterranean
voids in this body.

We have detailed
photographs of Phobos, and it turns out

that Phobos has a
slightly irregular orbit

that deviates from
Newton's laws of motion,

and this is because of the fact

that it's actually
a hollow moon.

So some people say, "Aha.

"Maybe it's a piece
of alien technology

in orbit around Mars."

When you look at Phobos,

when you look at its
comparatively small size,

odd shape,

and apparent partial hollowness,

Phobos could be
not a natural satellite

but an artificial satellite,

perhaps put there by an
extraterrestrial civilization

to hide some sort
of monitoring device,

listening station,
whatever you call it.

There are those
who believe that the best evidence

that Phobos is an
extraterrestrial outpost

was an incident
that occurred in 1989,

when a Soviet satellite
known as Phobos 2

was sent to investigate the moon

and it mysteriously vanished.

In 1989,

the Russians sent the Phobos
1 and 2 probes to Phobos.

And when it got there,

Phobos 2 took a
couple of photos,

sent them back...

and then it quit working.

It disappeared.

We don't know
what happened to it.

But one of the images
is really strange.

There's a cigar-shaped thing
in the middle of the image.

And I find that
quite interesting

that a lot of the UFO sightings
are cigar-shaped objects.

Is that just a
coincidence? I don't know.

Some people speculate
that there's some type of

defensive mechanism on the moon

that was defending itself
against approaching spacecraft.

And when this probe approached
Phobos it was activated

and it destroyed the probe.

Officially, the loss of Phobos 2

was blamed on a malfunction
of the onboard computer,

but the authorities never
came up with a good explanation

for the strange
cigar-shaped object.

And it makes you wonder...

Was Phobos 2 actually shot down,

as some believe?

If Phobos really is some
sort of extraterrestrial artifact,

is it something that's been
put there from a civilization

that's come from
much further away

as a sentinel?

We can't rule
out the possibility.

There's no getting away
from the fact that Phobos 2

was lost.

Is Phobos really an
artificial space station?

And if so, then where did the
aliens who built it come from?

Well, astronomers are
using a powerful telescope

that may reveal the answer
by showing us the home world

of an extraterrestrial
civilization.

Astronomers
from the University of Geneva

announce an incredible discovery

in the pages of
the journal Nature.

They reveal that by analyzing
slight changes in the light

generated by the distant
star known as 51 Pegasi,

they were able to confirm
the existence of an exoplanet

around another star in our
galaxy for the very first time.

An exoplanet is just a planet

around somebody else's star.

It's not orbiting the Sun.

Before 1995, we
thought there might be

a lot of planets out there,
but we didn't know it.

And since then, there
are a lot of exoplanets

that have been found, in
fact, thousands of them.

That's a lot of planets.

Right now, we have
catalogued about 5,000 exoplanets

orbiting other stars,

and that's just
in our own vicinity

of the Milky Way galaxy.

And we have encyclopedias
documenting the size

and the characteristics
of these planets.

Every day, we discover
a new planet out there

that potentially
could carry life.

Since it's true that
our galaxy is teeming with planets,

could some of them be
home to extraterrestrial life?

According to astronomers,
the answer is yes.

And they claim that these
planets can be found in

what is known as
the Goldilocks zone.

In terms of the Goldilocks zone,

that's the right
distance from the star

where you're not too hot
and you're not too cold.

You're just right.

If you're on the
Goldilocks zone,

you can have liquid
water on your surface

without it freezing or
without it boiling off.

And where there's liquid
water, there could be life.

Earth is obviously in
the Goldilocks zone for the Sun.

Those are the kind of
planets you want to find.

Because you probably
need water for life.

And thanks to telescopes,

we know that every
second or third star

has at least one planet

more or less the
same size as our own

in the Goldilocks zone.

Will we ever
be able to prove that planets

located in the Goldilocks zone

are in fact home
to other life forms?

Well, some scientists believe
that we may soon find out.

Today is a historic day.

At an event at the White House,

President Joe Biden
unveils the first image

taken by NASA's James
Webb space telescope.

It's a new window
into the history of our universe.

We can see light from
the oldest galaxies.

The oldest documented light
in the history of the universe,

from over 13 billion years ago.

The ten
billion dollar instrument

is armed with the most powerful

infrared imaging
technology ever created.

And what's even more
remarkable is that the telescope

was specifically designed
to analyze planets that lie

in the Goldilocks zone
for evidence of life.

The James Webb Telescope...

It's an infrared telescope,
so it's sensitive to heat.

But that's really
not the big deal.

The big deal is that it
can look, for example,

at a planet around another
star and actually see it.

It might only look
like a dot on a photo,

but you take the
light from that dot,

put it through a prism,
and you could tell

what's in the
atmosphere of that planet.

The James Webb Space
Telescope is like a magnifying glass.

It's gonna look
in extreme detail.

And the great thing
is, for the first time,

we can actually start to study

the atmospheres
of Earth-size planets.

If we look at a planet
and we can see chemicals

that we know don't occur
naturally in its atmosphere,

that's a really good indication

that they're produced
by industrial processes.

So if we see those
in an exoplanet,

that's a good sign that they're
produced by some alien industry.

It tells you there's very likely

an intelligent
civilization like our own

on that planet producing
those chemicals.

Given the fact that we have
now the Webb Telescope up there

giving us even more information,

given the fact that we
keep on cataloging more

and more exoplanets,

we are now flooded
with information about

potential lifeforms
in the galaxy,

perhaps even intelligent life.

And so this is a game changer.

The mere possibility that
the James Webb Telescope

might reveal life on other
planets is fascinating.

But if it's true,
as some believe,

that extraterrestrials exist
and have already visited Earth,

then how did they cross
the galaxy to get here?

Well, according
to some scientists,

it could be by
harnessing the power

of an entire star.

Astronomer Tabetha Boyajian

and her colleagues
at Yale University

are combing through
data recorded by

the Kepler Space Telescope
when they notice something unusual.

They discover that a star

located approximately
1,500 light years from Earth

is behaving in a
rather strange manner.

Tabetha Boyajian, who was
working at Yale University,

was looking at
some nearby stars,

and she noticed that one
star had a big dip in brightness.

Not one percent or
a tenth of a percent

but 22%, which is enormous.

We call it Tabby's Star

after the person who
began to talk about this.

Stars do vary in intensity

because a planet
moves in front of it.

It maybe drops a half a percent,

but this is the first time in
history that we've seen a star

whose sunlight
diminished by 22%.

That's astounding.

What could be causing
that? We don't know.

But it's an ongoing mystery.

Astronomers studying
Tabby's Star initially theorized

its dimming could be
the result of comet dust

passing in front
of its position.

But according to another theory,

the unusual dimming
could be caused

by a piece of
otherworldly technology

known as a Dyson sphere.

First proposed by physicist
Freeman Dyson in the 1960s,

a Dyson sphere is
a hypothetical device

that extraterrestrials could
be using to harness the energy

of an entire star.

If you're an alien civilization

and you want to
get lots of power,

you might build some really
large solar collectors in space.

So, one theory is that
there could be a civilization

that was maybe starting
to build a Dyson sphere

to harness the star's energy,

and it's blocking out light
as we see it from Earth.

The idea that advanced societies

would collect
energy from their star

is so appealing
and so logical, really,

because with the
amount of energy

they could marshal this way,

they could build a
rocket propulsion system

that is so fast that they can go
from one star system to another

very close to
the speed of light.

Is it possible
that extraterrestrials

could use the power
generated by a Dyson sphere

to travel across the galaxy
and visit other planets?

Perhaps even Earth?
It's an astonishing notion.

And further research on
this potential technology

may allow us to one day

finally get an answer to
the question of whether

we're alone in the universe.

Our galaxy has
hundreds of billions of stars in it,

in addition to our own.

Nearly every one of
those stars has planets

like we have in our
own solar system.

And there are hundreds
of billions of galaxies

in the universe.

That means there
are just trillions

and quintillions of planets
out there in the universe.

It is nearly
statistically impossible

that we're the
only life out there.

So, what do you think?

Are we alone in the universe?

Or is there intelligent
life beyond our planet?

Just like our
ancestors before us,

we'll continue to keep
searching the stars

in hopes of answering
this profound question

that, for now, remains...

unexplained.

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