[Narrator] A mathematical message
encoded on opposite sides of the globe.
Complex crop circles
designed to convey sound frequencies.
And colossal figures
that can only be seen from the sky.
♪ ♪
When author and ancient astronaut theorist
Erich von Däniken wrote Chariots of the Gods?
he presented a groundbreaking theory.
He suggested that extraterrestrials
not only came to Earth in the distant past,
but that they left hidden messages for us to discover
once we had developed the right technology to decipher them.
One compelling example are geoglyphs,
massive shapes and figures carved into the landscape
that are only fully visible from the sky.
[Narrator] Saudi Arabia. 2004.
While exploring the ancient lava fields of Harrat Khaybar,
amateur archaeologist Dr. Abdullah Al-Saeed
comes upon a number of what appear to be stone walls,
each approximately three feet high.
From the ground level, Dr. Al-Saeed concludes
that the structures have no discernable pattern or purpose.
That is, not until four years later,
when he obtains satellite photos of the very same area.
What he sees astounds him.
There, detectable from the sky,
are a vast collection of more than 400 stone enclosures.
Known to the local Bedouin as "The Works of the Old Men,"
these mysterious structures are quickly examined
and are revealed to stretch for hundreds of miles.
[Andrew Collins] They were within what's referred to as--
as a lava field of activity.
And are generally described
either as kites...
...or as gates,
which are more rectilinear forms of them.
And there are literally hundreds of these.
In fact, they stretch all the way from Saudi Arabia
right away across to Jordan
and into Syria.
[Hugh Newman] They're kind of like angular pyramids, almost,
going off into the distance like runways,
widening at one end to being short at the other end.
[Narrator] Although no record exists
indicating when these structures were built,
who built them, or why,
the predominant theory among mainstream archaeologists
is that they were constructed for hunting purposes,
many thousands of years ago.
What we think they are, are prehistoric hunting sites,
where gazelle and other animals
would be driven into the enclosure,
and then, on the outsides of the enclosure,
pits were dug, and the animals would fall into the pits.
The kites, when you visit them on the ground,
are really hard to find.
In the air, you get the whole pattern.
There are literally thousands of them.
And they must have been in use for thousands of years.
And why did they fall into disuse?
That's an answer we haven't yet got.
[Narrator] Although the theory that
the stone structures were used
for hunting purposes is compelling,
ancient astronaut theorists argue
that if these structures were really used
for hunting gazelle,
the walls would have needed to be more than three feet high,
since a gazelle can leap more than ten feet into the air.
Instead, they suggest
that because the structures are only viewable from the air,
they should be considered geoglyphs.
[Paul Bahn] A geoglyph is just, basically,
a drawing on the landscape.
Usually quite large-scale.
Most geoglyphs are in deserts,
and in deserts you get a phenomenon
which we call desert varnish.
It's just a natural dark patina that builds up on the surface.
And so, if you move the dark parts to one side,
expose the lighter soil or sand underneath,
that is one way of making a drawing.
The second basic technique
is to use the dark stones
and pile them together to make shapes,
geometric shapes, animal shapes or whatever.
And the third basic technique
is simply a combination of the two.
You move things to one side to expose lightness,
you use the dark stones to make patterns.
So you get very nice combination of the two.
In recent years, thanks to modern technology,
and particularly satellite photographs,
there has been an explosion in new discoveries
of-of geoglyphs that we didn't know about before.
[Collins] The interesting fact about all of these
is that they point towards the sky.
And what might this tell us?
Well, the first thing is that many of the geoglyphs
that we know today were only discovered
once aerial survey started in around the 1920s.
All of them were only really revealed
once aircraft got up into the air.
And this tells us something very, very important.
[Bahn] Most geoglyphs really only make sense from above.
It therefore seems that they would be messages
to something non-human, something up there.
[Narrator] When the now-legendary Nazca Lines
of Peru were first discovered in 1927,
they were considered a unique phenomenon.
But now, with the benefit of satellite imagery,
thousands of ancient geoglyphs are being found
all over the world:
in Kazakhstan,
in the southwestern United States,
in the Atacama Desert of Chile
and in Bolivia.
[Collins] Almost everywhere around the world,
we find what are known as geoglyphs,
whether they be the Nazca Lines in Peru,
British geoglyphs,
to those in the Middle East,
they're something that are virtually universal
around the world,
and they've been appearing for many hundreds of years.
[Narrator] But why would ancient people
in so many different locations around the world
all be making signs that can only be seen from above?
We don't know for sure what
ancient peoples were trying to communicate through geoglyphs,
but the most important thing is
the amount of time and effort that went into building them.
They're not quick sketches.
They're, many of them, whole community projects.
And the time that you spend working on them
is time not spent gathering food,
not spent defending your land.
It's time not spent looking after your children.
So, the first thing that they communicate
is to the community itself,
what is important to the community.
[Narrator] But could there be another,
even more incredible explanation?
Is it possible that these ancient geoglyphs
were created not for a terrestrial purpose
but for an extraterrestrial one?
Ancient astronaut theorists say yes,
and suggest further clues can be found
by examining similar shapes and symbols
that occur on a much smaller scale.
Geoglyphs are gigantic-sized versions of
what we know as petroglyphs,
the most obvious being the rock art that we'd see
on surfaces of stone rock around the world
that date back many, many thousands of years.
Petroglyphs are images carved into stones
or incised or hammered away.
They occur all over the world,
from Australia up through Asia,
Europe, Africa, through the Americas.
[Narrator] Perhaps more intriguing
than the petroglyphs themselves
are the eerie similarities between them
and their geoglyphic siblings.
We see certain symbols recurring again and again.
There are many geometric forms.
These take the form of spirals,
of concentric rings,
and other more rectilinear or abstract designs.
They're something that are virtually
universal around the world.
One of the most interesting geoglyphs
that you have at Nazca is the Sun, Star, Cross geoglyph,
which is really a very complicated,
huge mandala of interconnected stars and triangles.
And it's something we see all over the world,
and in Tibet and India as mandalas, and even yantras.
So, things like this,
that are so geometrically complicated
and are found all over the world,
indicates that there was some kind of
worldwide symbolic language
that was brought here by a higher intelligence,
probably extraterrestrials.
In 2005, an unusual feature
was discovered in central Canada
that some believe contains the best evidence yet
of a hidden message left by extraterrestrial visitors.
It's a colossal geoglyph that has become known
as the Badlands Guardian.
[Narrator] Gravelbourg, Saskatchewan.
2005.
53-year-old grandmother Lynn Hickox
is scanning GPS driving directions to a local museum
on satellite view when something catches her eye:
a geographical feature that bears a striking resemblance
to a human face.
It looks so much like a man-made structure
that she posts the image on a message board.
Almost overnight, the image goes viral
and becomes known far and wide
as "the Badlands Guardian."
It is quite striking.
It is clearly a face.
The brow, the nose, the lips, the chin are well-formed.
The headdress, a little less so,
but clearly could be seen as feathers.
The Badlands Guardian appears to be
a huge geoglyph near Alberta, Canada.
And to see it from Google Earth or from satellite imagery,
you would think it was created by people many, many years ago.
[William Saunders] Badlands Guardian is a bust,
or a head and shoulders presentation,
of a male Indigenous person.
It is so striking because that is
the Indigenous people of the area.
It doesn't look like a Scotsman wearing a kilt,
doesn't look like an African warrior,
it looks like an Indigenous, uh, native to the area.
[Narrator] Is it possible that the likeness of a human face
naturally formed in the earth?
Many who have examined the Badlands Guardian
suggest that, based on the amount of detail it displays,
this is highly unlikely.
When the mainstream scientific community looks
at the Badlands Guardian,
their first explanation is that
it was created by weathering, rain and water runoff.
But there's just so much detail
that we're seeing in this formation
that it goes way beyond anything nature could make.
It not only has basic facial features,
it has secondary facial features, such as the eyelid.
The only thing missing from
the Badlands Guardian is an ear feature.
Now, the interesting thing about that is,
the local government in Canada,
they had found a gas deposit there.
Right where the ear should be.
There might have been an ear there at one time,
but now, because they put an access road there
and they built this gas feature, that was all erased.
Archaeologists are often mistaken about ancient sites.
And what is actually a pyramid
that's now, say, covered in soil
and has a forest on it
can be mistaken for just a natural hill.
This has happened in... in South America, in China.
Archaeologists are continually
finding that things they think are natural
are actually artificial.
[Narrator] Some of the geoglyphs found
around the world were formed
simply by removing the top layer of soil
to expose the lighter-colored dirt underneath.
But if the Badlands Guardian is also a geoglyph,
creating it would have been an enormous undertaking.
The massive, concave formation
is almost half a mile long,
and is over 1,100 feet wide.
For comparison, the Mount Rushmore National Monument
in South Dakota, which was completed in 1941,
is approximately 80 feet tall and 200 feet wide.
And while it is only a fraction of the size
of the Badlands Guardian, constructing it required
an enormous amount of work,
even with modern technology.
The carving officially started in 1927,
and it was considered complete in 1941.
My grandfather was on the mountain
approximately from 1933 to 1941.
He was chief carver on Mount Rushmore.
It took about 400 workers.
It took 14 years.
And when I think about the amount of time and effort
that it took for people in the '30s
to create Mount Rushmore,
I can't even begin to imagine
what the person or persons had to do
working on something the size of the Badlands Guardian.
I-I can't even wrap my head around it.
How was it possible that the people that carved these,
thousands of years ago,
were able to see what they were doing
or know what they were doing?
They must have had assistance by extraterrestrial beings.
[Tsoukalos] The Badlands Guardian can only be
fully appreciated from the sky.
So you have to wonder: why?
Well, then, the answer is people on the ground
wanted to signal someone up in the sky.
[Narrator] For ancient astronaut theorists,
the Badlands Guardian could offer
some of the most compelling new evidence
that extraterrestrial intervention
occurred on Earth in the distant past...
that is, if it really is an artificial structure.
Boston, Massachusetts.
February 2019.
Aerospace engineer and satellite imaging expert Mark Carlotto
has spent countless hours examining
the Badlands Guardian to see if he can determine for certain
whether it is something other than a natural formation.
[Mark Carlotto] The image of the Badlands Guardian is
very striking as this Native American figure,
and some properties that are unusual.
So I did some analysis, uh, using some imaging software
and the height map of the feature.
So we'll start with an overview of
the Badlands Guardian image here.
We see the figure in the middle of the image here.
And notice the surrounding landform
is very similar in morphology.
So now what we'll do is we'll zoom up on the figure.
You can see it a little bit more clearly, the, um...
this iconic face.
So what can we do to bring out, you know, some information?
So, we ran a program that extracts the height
or elevation from the figure.
And the way it's depicted here is...
is dark is low and bright is high.
So now, when we've-- after we've taken the image
and texture-mapped it onto the elevation surface,
we can view it in 3D.
And, um, now I'm moving around it
and viewing it like we might see it in a drone.
And as you can see, when you're looking
straight down on the Badlands Guardian,
it's, uh, this uncanny resemblance
to a Native American.
But as we look off-angle
and as we look at it from ground level,
simulated ground level,
you see the illusion disappears.
So, clearly, this feature, if it was created,
was meant to be viewed from above.
[Travis Taylor] To me, the Badlands Guardian
looks artificial.
It doesn't look like a trick of nature
and that I'm suffering from apophenia.
All humans do have apophenia,
meaning they see patterns where patterns are not.
That's why we see Mickey Mouse in the clouds and so on.
But this looks too specifically like
some type of Native person with a headdress on.
Looking at this picture,
you can see the natural patterns of erosion.
So, it's clear to me from this picture
that this is an artificial structure.
High in the arid desert of Peru
is a strange, mile-long earthwork
made up of over 5,000 shallow holes
dug out of the dirt.
What purpose this Band of Holes served
and why it was created remains a mystery.
But some researchers believe
that the pattern there contains a hidden message
and point to a nearly identical design
found thousands of miles to the east,
in France.
[Narrator] Central Peru.
Just outside of Pisco,
at an elevation of 11,000 feet,
stretches an arid desert
known as the Cajamarquilla Plain.
Here, thousands of holes of varying dimensions and depths
have been dug into a mountain range
in a pattern that runs north and south for almost two miles.
This mysterious formation
has baffled archeologists for decades,
and, like the Nazca Lines,
the holes can only be appreciated in their entirety
from high above the ground.
[Tsoukalos] In the mountains of Peru,
we have what's commonly referred to as the Band of Holes.
It is one of the coolest places
in relation to the ancient astronaut theory,
because who in their right mind
would go ahead and dig all these holes?
For what?
They're a incredible mystery,
a very long-lived mystery.
Some people think it looks like some kind of machine
was running over the territory.
Some people think it was some kind of
systematic mining operation.
Some people say it was just pot-hunters,
you know, looting, looking for burials.
None of the explanations make good sense.
[Narrator] While the Band of Holes
continues to defy explanation,
some ancient astronaut theorists believe
it may represent a type of message,
a message that can also be found
at another site 6,000 miles away.
The northwest coast of France.
Here, just south of Brittany,
lie the legendary Carnac stones...
...an arrangement of over 3,000 megalithic rocks
that stretch for more than two miles across the countryside.
The megaliths of Carnac in Brittany are just amazing.
Some of them stand about 30 or 40 feet tall.
There are multiple avenues of stones going right over hills.
And no one's really worked out exactly what their purpose is.
[Narrator] Like the Band of Holes in Peru,
the Carnac stones continue to defy explanation.
But ancient astronaut theorists suggest
that the clue to understanding both mysterious sites
might be found by comparing them side by side.
The Band of Holes runs for approximately two miles.
So do the Carnac stones.
The width of the Band of Holes measures eight holes across,
occasionally deviating by one or two holes.
This, too, is often the case with the Carnac stones.
And when viewed from high above,
the layout of the two sites is eerily similar.
[Childress] It would appear, in my mind,
that there's some connection
that's between Carnac, France and Peru,
and a special code put there for us
to find at a-- at a future time
when we could understand these codes.
[Narrator] Some ancient astronaut theorists
have even gone so far
as to suggest that the Band of Holes
may have once held some sort of standing totems...
...similar to what is believed to have existed
at Stonehenge,
and that those totems may have disappeared
because they were made of wood.
There are a series of postholes that were found
all around Stonehenge
in which you can stick sticks in the holes.
But they degraded over time
and it gradually crumbled away,
and perhaps the same thing happened
in the Nazca Plain in Peru with these holes.
[Narrator] Could there really be a connection
between the Carnac stones in France
and the Band of Holes in Peru,
as ancient astronaut theorists suggest?
And if so, is it meant to convey a message?
[Wilcock] If you look at the stones at Carnac,
you see curious alignments.
And these alignments actually duplicate
the Pythagorean triangle.
This appears to have happened as much as 3,000 years before
Pythagoras allegedly invented the Pythagorean triangle.
What you're seeing is remarkable mathematical symbolism
and encoding messages
that seem to suggest somebody wanted us to know
it was built with technology
far in excess of what we have now.
[Erich von Däniken] Some thousands of years in the past,
the extraterrestrials who visited our planet
left a proof behind.
They knew that in the far future
the humans will see these stone patterns.
They will realize that this is high geometry.
And sooner or later the questions comes up,
"Have we maybe been visited by beings from outer space?"
[Narrator] Is it possible that these two ancient sites
are both conveying a message
left behind by extraterrestrials?
And was it their intention
that it would one day be deciphered by mankind?
Ancient astronaut theorists say yes,
and claim that further clues can be found
by investigating magnetic anomalies
within mysterious, colossal stone heads
unearthed in the jungles of Central America.
A key tenet of the ancient astronaut theory is
that extraterrestrials left information for us
within megalithic structures and monuments.
And a recent breakthrough suggests
that some of the largest statues ever built
could possibly be
ancient hard drives.
[Narrator] La Democracia, Guatemala.
June 2019.
A team of researchers from MIT, Harvard, and Yale announce
that they have discovered unusual magnetic anomalies
within the colossal stone heads attributed to the Monte Alto,
a Mesoamerican civilization
that emerged around 1800 BC.
[Childress] Some of these statues
have very strong magnetic fields.
The creators of these statues
were totally aware
of these magnetic fields.
And that is something that shocked modern archaeologists,
that this rather primitive culture, they thought,
was aware of magnetism
and that they actually chose certain rocks
because of the magnetic field.
[Narrator] In Mexico, similar statues
created by the Olmec civilization
were also found to emit magnetic anomalies.
These intricately carved heads
vary in height from nearly five feet
to over 11 feet tall,
the largest weighing approximately 50 tons.
Like the Monte Alto sculptures,
most of these heads were made from basalt.
Basalt has large quantities
of-of iron and magnesium in 'em.
The Olmec were so precise
with knowing where the magnetic fields were
that they actually carved the structure
around these anomalies.
So, when scientists use a magnetometer
around the stone statue,
they notice the nose or the cheeks,
around the chin, the magnetic fields are strongest there.
[Collins] The great heads of the Olmec are made of basalt.
Basalt is a volcanic substance.
And the closest source to many of these heads
is anything up to a hundred miles away.
Now, this is interesting,
because I don't think it's simply the case
that the basalt was easy to sculpt
into the forms of heads.
[Williams] Basalt is dense.
It's very, very heavy, thick rock
and it's very difficult to work with,
let alone carve with rudimentary tools
like flint.
Because they range higher on Mohs test
as far as density.
And flint is a much softer material than basalt.
So, it's difficult to understand how
they carved these things.
And the intricate detail on some of them
is just incredible.
[Newman] With these stone giants,
it really is a question as to why they chose
these specific types of rock.
Like granite we find, it's very crystalline.
It's also electrically conductive.
We find basalt, which is volcanic.
Again, this is very magnetic.
And so, again, it can be conductive
for various different purposes.
And so what's going on here?
Were they specifically choosing
certain types of rock
for technological reasons?
[Childress] When we look at how the ancients were selecting
certain stones that were magnetic
or had certain energies,
we wonder how they could know
about all of the-the properties of these stones.
Are they getting this information
from extraterrestrials?
[Narrator] Extraterrestrials?
Is it possible that the ancient people of Mesoamerica
were given instructions
to sculpt these giant basalt heads
by alien visitors?
But if so, why?
As far as ancient astronaut theorists are concerned,
the answer is simple:
they were intended to be used for data storage.
In 2017, IBM made a huge breakthrough in data storage.
They figured out how to store
201 gigabytes of data on a square inch of tape.
That means a magnetic tape reel,
the size of the palm of your hand,
can hold as much data as you would have
in 330 laptops.
[Williams] Mag tape, mag stripe tape,
is made out of, basically,
very, very tiny magnetic particles.
And what they do is they-they adhere them
to the back of a-a thin strip.
And the way it works is
the little metal filings, which are very microscopic,
they would all align in a certain pattern,
kind of like the grooves on a record player.
And it would take another piece of equipment,
similar to the one that actually aligned them,
to interpret how those particles are lined up.
And we still use it to this day for backup data storage.
[Childress] And so, once again,
we have to ask ourself if these statues...
were in fact devices
that had recorded information.
And information could be extracted from them.
Like a computer hard drive or something like that.
[Nova Spivak] We've been looking at these objects
primarily at the macroscopic level.
What do they look like?
But maybe there's information inside them,
encoded using nanotechnology.
Why is that likely?
Because we ourselves are doing the same thing.
By trying to store information
for thousands or millions of years,
you end up going to
the same physical materials and solutions
that the hypothetical ancient aliens may have also
figured out how to use.
Across the globe,
farmers have discovered massive images in their crops.
These formations, known as crop circles,
often appear overnight
and look like they were created by an otherworldly force.
Curiously, some researchers believe
that these complex patterns contain hidden messages
that are encoded as sounds.
[Narrator] Yarnbury Castle. Wiltshire, England.
July 26, 2020.
An intricate formation of concentric circles,
featuring a number of smaller semi-circles,
appears in a field of wheat.
While the design may seem random,
some researchers believe it contains a message
that can be both seen and heard...
...because it is a perfect match
for what is known as a cymatic pattern.
When we talk about cymatic patterns,
we're talking about a frequency
that will create a image that has a complexity to it.
So, specific frequencies relate to specific patterns.
[Narrator] The origins of cymatics
among human civilizations
can be traced back more than ten centuries to West Africa.
There, tribal rituals
involved sprinkling grains of sand
on the surface of drums.
Striking the drums created specific audio tones,
causing the sand to be instantly shaped
into distinct formations.
From the resulting formations on the drum's surface,
tribal elders believed it was possible
to predict future events.
[Childress] With cymatics, you have these patterns
that are a visualization, really,
of-of sound and vibration.
And physicists tell us
that the entire universe comes down
to vibration and sound patterns,
and these patterns that can be visualized.
[Narrator] In 1787,
German physicist and musician Ernst Chladni
offered a breakthrough on the subject
when he published "Discoveries in the Theory of Sound."
In the writing, Chladni revealed
that specific tones consistently create
the same visual pattern.
By applying sound vibrations to metal plates covered in sand,
he identified the images produced
by various frequencies.
[Henry] When we look at so many crop circles,
they're consistent with what we see in research on cymatics.
We find the same shapes
that are created on Chladni plates.
We find the same shapes
that are created in sound experiments.
So, there's a very key connection
that is to be made here.
[Narrator] But why would cymatic patterns
appear in crop circles?
Could extraterrestrials be using audio frequencies
as a method of communication?
Ancient astronaut theorists suggest
further clues can be found by examining the teachings
found in ancient Hindu religious texts
known as Vedas.
[Dominic Steavu] The word "veda" means
"knowledge" in Sanskrit.
There is this close association with
a special type of wisdom or knowledge
that is transmitted through the Vedas.
Now, originally, the Vedas were revealed by the gods
to a certain class of spiritual elect.
And they contain, again, these primordial sounds
that are associated with the creation
of the universe and its proper functioning.
[Narrator] In the Vedic texts, it is said
that the gods gave humankind a visual guide to sacred sounds
in the form of elaborate patterns called "mandalas."
Like Chladni's experiments,
the mandalas translate sound into visual patterns,
but for a profound and otherworldly purpose.
In Hinduism, mandalas are considered to be
visual translations of primordial sounds.
And these are the sounds
that gave rise to the universe,
and to the very nature of reality.
They are divine,
they were uttered cosmically
by supernatural beings, by gods.
[Henry] The Vedas tell us
that the gods taught humans how to chant.
How to pray and to sing
in order to communicate with the gods.
[Narrator] The most powerful Hindu mantra
is the sound "Om,"
which is visually represented by a simple circle
with a dot in the middle...
the fundamental element of a mandala.
Incredibly, when the "Om" frequency
is applied to a Chladni plate,
the exact same pattern emerges.
Higher-toned frequencies result in more complex arrangements...
...that also identically match
the ancient mandala symbols.
[Collins] Is it conceivable
that the writers of the ancient Vedic texts
were given advanced knowledge
on how sound frequencies
can be converted into visual patterns?
Some of the crop circle designs
are very clearly
reflections of sound.
Is it therefore possible
that what we are looking at is sound signatures,
communication with such higher intelligences?
[Narrator] Many cultures around the world
believe it is possible to commune with a higher realm
through ritualistic chanting,
singing, and prayer.
Like mandalas, could crop circles contain
an otherworldly message for humanity,
one that is based on sacred sounds?
[Tsoukalos] I certainly think that
crop circles are messages by...
other beings who are trying to
make contact with us,
or at least letting us know they're there.
And the entire basis of the universe is vibration,
and sound is vibration.
When we talk about different ways
with which to communicate with different civilizations,
scientists have proposed
that can be achieved with sound frequencies.
[Childress] What they're doing is
putting sound and vibration
into a communication device of some sort,
but exactly what they're trying to communicate to us
is the big question.
The idea that an alien civilization
has left us hidden messages
may strike some as sounding more like
science fiction than fact.
But in 2001, a crop circle appeared in England
that many believe was sent
by extraterrestrials.
[Narrator] Arecibo Observatory, Puerto Rico.
November 16, 1974.
Scientists, dignitaries and other public officials
gather to watch as astronomers send out
the first official radio communication
directed to extraterrestrials,
using the largest,
most powerful telescope in the world.
[Seth Shostack] The message was just a series
of, you know, dots and dashes, if you will,
but you could order them into a-a matrix
and actually get a picture.
It's a way of sending
a greeting card, if you will, from Earth.
[Narrator] Designed by renowned scientists
like Carl Sagan and Frank Drake,
the Arecibo message contains binary encoded information
including the numbers one through ten,
an image of human DNA,
a human figure,
and a graphic of the solar system,
highlighting the position of Earth.
[Nick Pope] This was a calling card from Planet Earth.
It was really reaching out across the galaxy
and saying, "We're here."
Now, some scientists condemned it,
and, in fact, SETI has been very controversial
when it moves into active-- what's called METI,
messaging to extraterrestrial intelligence.
Some people have said it's like a suicide note to the universe,
because if there's a super predator species out there,
you were saying, "Come and get us."
Now, SETI scientists say, "Well, it's too late.
We've been a detectable civilization for decades
because of our radio and television broadcasts,"
but it's still controversial.
[Narrator] In August 2001,
almost three decades after the Arecibo message was sent,
there was an extraordinary development.
Workers at the Chilbolton Observatory
in Hampshire, England
discovered a mysterious crop circle in a nearby field
that was an almost exact replica
of the Arecibo message.
It's actually called, sometimes, the Arecibo reply,
because it-it's essentially very similar
to the Arecibo message, but with some subtle changes.
For example, the DNA swaps out carbon for silicon,
and also there's a-a representation of a figure,
but it's not a human.
It looks like an alien.
Instantly, the astronomers proclaimed this a hoax.
And as people started to investigate this,
they realized that maybe it was possible
that it came from extraterrestrials.
One reason why was that the message was so perfect.
How likely is it that some crop circle hoaxer
could have duplicated that message in a crop circle?
Crop circles are a very important
potential way that an extraterrestrial intelligence
could use to communicate with us.
They're very public,
and they have caught the curiosity of humanity.
Was the so-called "Arecibo reply" sent to Earth
by an alien civilization?
It's entirely possible.
But perhaps the better question is,
are we ready to receive the information contained
in these hidden messages that are all around us?
One thing is clear:
whether they are massive geoglyphs...
towering monoliths...
or elaborate crop circles...
once these extraordinary sites are decoded,
we may be one step closer to learning the truth
of our extraterrestrial past.
CAPTIONING PROVIDED BY A+E NETWORKS