WILLIAM SHATNER: 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!"
JEFF COUGHLIN: 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.
JAMES BENFORD: 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.
MICHIO KAKU: 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.
♪ ♪
SHATNER: 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.
SHATNER: 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.
SETH SHOSTAK: 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.
SHATNER: 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.
KAKU: 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.
SHATNER: 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.
ROD PYLE: 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.
SHATNER: 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.
PYLE: 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?"
TEITEL: 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.
SHATNER: 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.
TEITEL: 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.
SHATNER: 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.
D'ANTONIO: 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.
SHATNER: 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.
MERA: 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.
SHATNER: Vagner immediately posted the video on Twitter,
and many people claimed that the clip was evidence
of an extraterrestrial spacecraft.
MERA: 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.
SHATNER: 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.
LEROY CHIAO: 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.
SHATNER: 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.
POPE: 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.
MERA: 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.
SHATNER: 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.
MERA: 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.
SHATNER: 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.
MERA: 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.
POPE: 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.
SHATNER: 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.
POPE: 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.
SHATNER: 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.
LAUNCH DIRECTOR: Three, two, one, zero and lift off.
SHATNER: 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.
COUGHLIN: 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.
SHATNER: 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.
TEITEL: 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.
POPE: 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.
SHATNER: 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.
POPE: 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.
SHATNER: 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.
SHATNER: 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.
BENFORD: 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.
SHATNER: 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.
SHATNER: 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.
HAAS: 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.
TAYLOR: 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?
HAAS: 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.
D'ANTONIO: 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.
SHATNER: 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.
TEITEL: 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.
KAKU: 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."
POPE: 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.
SHATNER: 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.
TAYLOR: 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.
HAAS: 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.
SHATNER: 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?
POPE: 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.
SHATNER: 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.
KAKU: 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.
SHATNER: 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.
COUGHLIN: 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.
SHOSTAK: 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.
SHATNER: 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.
SHATNER: At an event at the White House,
President Joe Biden unveils the first image
taken by NASA's James Webb space telescope.
JOE BIDEN: 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.
SHATNER: 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.
SHOSTAK: 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.
KAKU: 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.
SHATNER: 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.
KAKU: 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.
SHATNER: 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.
SHOSTAK: 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.
SHATNER: 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.
COUGHLIN: 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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