Original subtitles

[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 D�niken 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 D�niken] 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.

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