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It's one of the biggest questions
in science - is there,

somewhere out in the cosmos,
life waiting to be discovered?

And what will it be like?

But what's less reported is the work
being done to determine what happens

if we do discover aliens.

How could we communicate with them?
What should we say?

And, most importantly,
should we talk to them at all?

This month, The Sky At Night team
are investigating

the controversial world of
extraterrestrial communication.

We follow one of astronomy's most
contentious figures, Doug Vakoch,

on a research trip to the UK...

This isn't the ordinary
kind of signal.

I think they're trying
to get our attention.

..to meet experts in animal
and alien communication.

We can say that any alien
civilisation that has technology

must have a language.

Exoplaneteer George Dransfield

discovers how we listen
for messages from outer space.

Something out there has made that
technology to produce that signal

and therefore, we're going to assume
that's an intelligent,

extraterrestrial civilisation.

And Pete Lawrence tells us
how to see this month's supermoon

and Perseid meteor shower.

Welcome to The Sky At Night.

This is Professor Doug Vakoch.

He's an astrobiologist and he's
trying to communicate with aliens.

I have no doubt that aliens
have to exist somewhere out there.

If there's no-one else out there
it would be a miracle

and I don't believe in miracles.

Vakoch spent much of his career
working at the SETI Institute,

an acronym which stands for the

Search for Extraterrestrial
Intelligence. But in 2015,

he decided to stop waiting
for the aliens to come to us.

The SETI organisations that exist
have avoided the controversy

of sending messages into space.

And yet, maybe that's what we need
to do to make first contact.

And so that's how
METI International came to be.

He's now the president
of METI International,

which stands for Messaging
Extraterrestrial Intelligence.

They use a powerful transmitter
to send a signal out into space

in the hope that aliens
will find it and respond.

The goal of METI
is to establish first contact.

We've always assumed the aliens
will take the initiative.

Maybe it's the audacious young
civilisation like earthlings

who have to reach out
to make first contact.

Vakoch collaborates
with like-minded scientists,

linguists and philosophers
around the world

to answer crucial questions.
And that's why he's here in the UK.

The Sky At Night have been invited
to follow some of these meetings

to gain a better understanding
of the world of METI.

I want very practical answers to
questions that seem very esoteric -

how to communicate with aliens.

I want to figure out how to create
a message that might actually

be understood and then how
to remember that message

in case, centuries from now,
we get a reply.

But if we can't even communicate
with our nearest animal relatives,

what chance do we have
with an alien?

First stop on his trip
is a slightly unusual zoologist.

I mean, if you go to his website,
University of Cambridge,

Dr Arik Kershenbaum -
"animal vocal communication

"and the evolution of language

"and xenolinguistics and the search
for extraterrestrial intelligence."

This is a zoologist I need to meet.

Dr Arik Kershenbaum,
from the University of Cambridge,

specialises in the communication
of wolves and dolphins.

He's also a member of the Cambridge
Institute for Exo-Language.

How does a zoologist
come to get interested in aliens?

I think that what zoologists do
is understand mechanisms.

We're always thinking evolution.

What is it that made this,
gives this an advantage?

I don't know exactly what

a creature on another planet
is going to look like.

But I can make general predictions

about how evolution will always
work out - that they will need food,

they'll need to search for energy.

So you would expect from that,

them to live in groups
with related individuals.

How about something like language
or communication?

Do you have to have that?

Well, all animals on Earth
communicate, all of them,

every single one.
And that's not a coincidence.

It's nothing special about Earth.

Is there any reason to think that
aliens would talk with one another

in a way similar
to what we're doing?

We can say that any alien
civilisation that has technology,

the kind of technologies
that we're familiar with,

must have a language because there
needs to be something like language

to allow them to say to each other,
"Give me the screwdriver,"

or, you know... And if you can't
say, "Give me a screwdriver,"

you're not going to build a radio
transmitter, a radio receiver.

Exactly. So these are the aliens
we're interested in.

At least, I'm interested in,
the ones I can talk with.

If we're talking about
an intelligent, technological,

alien civilisation that's looking
for us, just like we're looking

for them, hopefully they'll be
trying to teach us their language,

just as we should be trying
to teach them our language.

Arik records animal vocalisations

in the search for patterns
that could be universal.

So, this is an example of a dolphin
whistle. And I'll play this.

DOLPHIN CLICKS AND WHISTLES

If you compare that
to a wolf howl...

So, this is an example
of a wolf howling.

WOLF HOWLS

That very typical rise in pitch
and then fall.

Played at normal speed, dolphins and
wolves sound completely different.

But Arik believes
that their communication

is much more similar than
we might think.

This, on the left,
is the same dolphin whistle

but slowed down by about 30 times.
It sounds like this.

SLOW, LOW-PITCHED WAIL

So they're using the same method,
that varying of the frequency,

varying of the pitch,
high pitch, low pitch,

to send messages
over long distances.

It's a very reliable way to send
information in a noisy environment,

and it's constrained by the physics
of the world they live in.

So, if you go to another planet,
the details of the planet

may be different, but the physics
is going to be the same.

The physics is the same.
And that means that the constraints

on the evolution of these animals
are the same.

The constraints that determine,

should this animal
have words and sentences,

should this animal have continuous
howls going up and down in pitch?

So there's hope of understanding
alien...if not language,

at least vocalisations. I think
there's hope of understanding

whatever language
we might encounter, wherever it is.

I came into our conversation
wondering whether our attempt

to send human greetings into space
is completely meaningless.

But what I'm getting from you

is that if we look
at the physics of sound,

that's something that we might
be able to communicate to an alien,

and they should be able
to figure out

that it's a language of some sort.

Doug Vakoch and his METI colleagues

are not the first to attempt
communication with aliens.

These messages have taken on
a variety of forms over the years,

a record of us shouting
into the cosmos.

The first transmission
intended for aliens was sent in 1962

by Soviet scientists

who aimed a radio transmitter
at the planet Venus.

It contained three words
spelled in Morse code.

"Mir" - which is Russian
for peace or world -

"Lenin" and "USSR".

The aliens didn't reply,

presumably because
they don't understand Morse code.

A decade later, Pioneer probes 10
and 11 carried small metal plaques

showing our location in the galaxy

and, perhaps because it was
the '70s, naked human figures.

It's a rather narrow view
of humanity, a gesture to the cosmos

made by a white man, hardly
representative of life on Earth.

This project, like so many attempts
to communicate, ends up telling us

more about ourselves than
whoever or whatever is out there.

Then in 1974,
Carl Sagan and Frank Drake

used the upgrade of the
Arecibo telescope, in Puerto Rico,

to send a radio message
of binary code to M13.

But M13, the target cluster,
is nearly 25,000 light years away.

So even if the Arecibo message
is received by aliens,

we'll have to patiently wait
50,000 years for their response.

In 1977, Sagan and Drake teamed up
again to place the Golden Record

aboard Voyager 1 and 2.

The ambitious international
time capsule contained music,

a greeting in Welsh, a selection of
whale song and some more Morse code.

Voyager 1 is currently the furthest
away human-made object in space,

and it would be nearly impossible
for another civilisation to find it.

But as Carl Sagan said,

"The launching of this bottle
on the cosmic ocean

"says something very hopeful about
life on this planet."

And then there were the more recent
attempts to share popular culture

with outer space.

In 2008, NASA broadcast
The Beatles song Across The Universe

to the star Polaris.

And in the same year,
the ice cap radar on Svalbard

was used to transmit a powerful,
deliberate signal

to hungry extraterrestrials
in the Ursa Major constellation.

It was an advert for Doritos.

One reason to think about messaging
aliens is that THEY might call US.

Finding signals from space
is the work of SETI,

the Search for Extraterrestrial
Intelligence.

Exoplaneteer George Dransfield

is at the Jodrell Bank Observatory
to investigate.

In my work, I search for potentially
habitable exoplanets,

that is, planets
outside the solar system

that could possibly sustain life.

However, while I am hunting
for these brand-new worlds,

there's a whole other set
of astronomers

who are listening to them,
searching for potential signs

of advanced civilisations
out there in the universe

that could maybe
be looking down at us.

Professor Tim O'Brien

is Associate Director at the Jodrell
Bank Centre for Astrophysics.

The radio telescopes here
have been used to search for aliens.

What kind of telescopes
around the world are focusing

and working on SETI right now? Yeah,
I mean, it's a sort of golden age

for SETI, I would say. I mean,
it started... It began, really,

in the early 1960s
with just a few sort of pioneers.

And now we've actually got a major
effort, the best SETI programmes

we've ever had, particularly
the Breakthrough Listen programme,

which is using telescopes
in the USA.

It's also using the
Parkes telescope, in Australia.

We're part of that programme
as well.

SETI scientists like Tim
are looking for technosignatures -

signs of distant,
advanced civilisations.

Technosignatures is a...
In our case, a radio signal

that's produced by technology.

So of course, one of the reasons
SETI people would be interested

in that is because we think,
if we detect such a signal

coming from distant space, something
out there has made that technology

to produce that signal and
therefore, we're going to assume

that's an intelligent,
extraterrestrial civilisation.

All objects in space
that emit energy, emit radio waves.

Most of these signals
are naturally occurring,

but certain types could
be a sign of alien technology.

How can you distinguish
between technosignature

and radio signatures
produced by nature?

The key difference really is that
natural radio signals

tend to produce radio waves across
a really wide part of the spectrum

the very broad band signals,

whereas technosignatures
from technology

are often very narrow lines
in the spectrum.

And I've got a sort of example here,

this very bright feature
that runs down the middle,

that's actually a natural signal,

that's actually a broad line
from hydrogen in space.

But you might also spot, just
sitting in the background... Yeah!

..there's some little faint spikes.

Now, those are some sort of
interference,

which is basically
a technosignature,

but likely from nearby. Right.
From the Earth, effectively.

The challenge is distinguishing
a technosignature from outer space

from technology here on Earth.

How do you know that they're not
going to be false positives

if you find them in space?
Yeah, this is a classic problem.

Modern world, full of technology

producing these sorts
of radio signals.

And you've got to distinguish
a so-called sort of alien signal

from a human-made one.

And so there's a number of sort of
clever ways we can do that.

One way is to look at the exoplanet
direction you're interested in

and then shift your telescope off
to one side and just do that

sort of on-and-off sequence. Yeah.

If there's something local around us

that's producing this
technosignature

it would also be
in the off direction.

And if it's just coming
from the exoplanet direction,

you only see it in your own data.

Another sign of a technosignature
is random patterns,

but these can also be misleading.

What if you find something
that looks exactly like

a technosignature,
as you'd expect it to be,

how do you know that there's nothing
in nature that can produce it?

Yeah. I mean, the pulsars were
an interesting case.

I mean, discovered in 1967
by Jocelyn Bell.

What they saw was a signal that went
on and off repeatedly and, you know,

that seemed unnatural.

And they did call that first pulsar

LGM-1, where LGM stood for
Little Green Man.

The scientists soon realised
that the signal

wasn't little green men,
it was a pulsar.

This can occur when a large star
collapses in on itself

at the end of its life.

It starts to spin, shooting out
powerful beams of light.

This is a recording we made
with the Lovell Telescope here,

and here we go. Wow, yeah.

So, these are
the repetitive flashes,

about three a second,
something like this, in this case.

So, this is a dead star
the size of a city,

spinning around something
like three times a second,

which is pretty, pretty incredible.

I mean, you can see why
when you first find that,

you would think that
that is not natural. Yeah.

Tim might listen for messages from
outer space, but he is less keen

on actually sending one from Earth.

I wouldn't send out messages
deliberately.

I mean, some people will say
that they'd not be keen because

why would you advertise
your presence so deliberately

to a potential extraterrestrial
civilisation when you have no idea

what they might be like?

So you might end up with
an Independence Day scenario

or some such thing where you are...
Mars Attacks! Mars Attacks! indeed.

For me, it's more to
do with what to say. Yeah.

Is it just people like me who
happen to have access

to a big radio telescope who speaks
on behalf of the planet? Yeah.

We're speaking on behalf of the
planet... Of course, yeah.

..in these sorts of situations.
Yeah. So what you say matters.

I think that's an interesting
challenge

because we're in that situation now.
We have the technology

and we'll probably very soon have
the potential targets.

So, Tim's told us that we are now
entering a golden age of SETI.

My hope is that, in the next few
decades, we might find some sort of

technosignature from one of
the many, many exoplanets

that people in my field
are so keenly looking for.

Astronomers are still searching
for the man on the moon.

But in the meantime,
The Sky At Night's stargazing expert

Pete Lawrence is here to tell us

why it looks particularly
impressive in July.

This month, we're talking about
a special full moon

and a dramatic meteor shower
that could be breathtaking.

We get a full moon when it's on the
opposite side of Earth to the sun.

When it's in position
closest to Earth,

it's called a perigee full moon,

sometimes referred to
as a supermoon.

A perigee full moon occurs
several times a year,

and the next one will happen
on the evening of the 31st of July

into the morning
of the 1st of August.

As we move towards mid-August,
the full moon will be slimming down,

ensuring perfect conditions

for the peak of a spectacular
meteor shower, the Perseids.

I've been observing the Perseid
meteor shower since 1977.

It's one of my favourite showers.

Now, the climb to maximum
is pretty steep, and that occurs

on the nights of the 12th, 13th
into the 13th, 14th of August.

Now, the best time to look out
for them is from 1:00am BST -

that's midnight GMT - because after
that time, the Earth has turned

to face the particles which form
the meteor trails head on.

The Perseids are one of
the more plentiful showers.

They have a peak zenithal rate
of around 100 meteors per hour.

The particles in the Perseid stream

originate from comet
109P/Swift-Tuttle.

The small area of sky that the
meteors appear to emanate from

is called the shower's radiant.

The Perseid shower gets its name
because when it's most active,

its radiant is in the constellation
of Perseus.

The location of the radiant
moves over time,

activity beginning
when it's in Cassiopeia.

As it moves into Perseus,

it reaches the peak.

But shortly afterwards

it slips into neighbouring

Camelopardalis,

a faint constellation

representing a giraffe.

It's not difficult to set up
a camera to photograph meteors.

The tricky part is pointing
the camera at the right area of sky

at the right time
to catch a bright meteor trail.

That's down to luck, I'm afraid.

If you want to try your hand
at capturing the Perseids,

check out our guide on The Sky At
Night website for my top tips.

If you manage to get any photographs
of a Perseid meteor trail

or even the perigee full moon,
we'd love to see them.

Upload them
to our Sky At Night Flickr

and we'll pick our favourites and
showcase them in next month's show.

Since our last episode,
we have been receiving

your amazing images of the sun

and its incredible surface.

Scientists from around the world
are waiting and listening

for a message from aliens.
But in the meantime,

others are already
making the first move.

In 2017, Professor Doug Vakoch and
his fellow METI scientists

worked with the EISCAT antenna,
in Norway,

to send an interstellar message
in binary code.

At METI, we identify
a couple of principles

that we want to communicate -

things like time,
things like radio signals -

and then explain them
in great depth.

We sent our message to a little
red dwarf star called Luyten's Star,

12 light years from Earth.

And it means, in 24 years,
we could get a message back.

BEEPING

But who should speak for Earth?
And what should they say?

Vakoch's next appointment
is trying to figure this out.

I'm excited to meet with Paul
because he may just have the answer

to one of the biggest challenges
we face at METI -

to create a message

that is really, adequately
representative of humankind.

This is Paul Quast.
He's a researcher on the council

of a charity called the
Beyond the Earth foundation.

I want to learn about this project

that you've had going on
for a while.

We are currently trialling
a project which we call

The Companion Guide To Earth.
We're looking at

this small physical time capsule
that we're hoping

to attach with bolts
to a geosynchronous satellite.

And who do you hope
will receive this?

If extraterrestrials are coming to
Earth long after humans have left,

What would posterity need to know
about here and now that might be

of some benefit to them?

Paul's Companion Guide To Earth

is very different to previous
messages we've sent into space.

A lot of the messages
that we've sent out have been

greetings from Earth,
they have been shining portraits.

What we're documenting is some
of the more left-out subjects

that are of pertinent interest
for those people

who will one day inherit this world.

So how does the content
of your archive

compare with the messages
that we've sent out into space?

We've branched into
two different segments.

One is "do not go"
and the other one is "need to know".

So, in terms of "do not go" - things
like pollution histories and such.

"Do not go to this
nuclear waste site."

Ideally,
"Do not go dig up this ground.

"Do not go into these landscapes

"because there's still
some radioactive isotopes there."

The "need to know" side of the guide
is slightly more positive.

It includes information about
long-term science experiments

that aliens or future humans
might want to continue.

Another key component is an archive
of the messages

we've sent to extraterrestrials
in the past.

So, we sent out a message
to a nearby exoplanet.

You have a case where it takes ten,
20, 100 years for a round trip

of light to reach there and back.

And how do we remember
what we even sent?

Indeed. I've developed The
Profile Of Humanity Catalogue.

It's documenting well over
70 signals.

I'm impressed by what you're doing.
I don't know of anyone else

who's taking this seriously. And if
I may, I would love to give you

a copy of the message
that METI sent out in 2017.

And so, here is the date
that we hope to get a reply back.

It is the summer solstice in 2043.

And there's one thing
you have to promise me, though,

you're going to upload that,
because 20 years from now,

no-one's going to be using a
thumb drive like that. Very true.

Past messages we've sent out
have whitewashed human history.

Paul emphasises, we need to talk
about some of the things

we're not as proud of,
so we need to take the next step

and explain something
about what makes us human.

An increasing number of individuals
and organisations

are getting excited about contacting
extraterrestrial intelligence.

But many scientists,
including Stephen Hawking,

have expressed their concerns.

And I have to say
that I remain unconvinced.

The idea of communicating
with aliens,

of deliberately sending messages out
into the cosmos, is controversial.

Some people think
it might be dangerous,

that it might attract hostile
attention. Others, like me,

think the universe is so vast

that the odds of succeeding
have to be low.

Before Doug heads back to the US,

I've asked him for a chat
in one of our earthling cafes.

Why do you want to talk to aliens?
Because, so far, we have been

locked into just talking with
other human beings,

so we really have a
narrow perspective on the world.

To me, talking with aliens
is like going to another culture

here on Earth. You learn
different ways of doing things,

you have to call into question,

my way of doing things
isn't the only way.

So, why haven't we found this kind
of message

from another civilisation?
Why are they so hard to find?

That's been the hope of SETI,

in fact, that maybe they've heard
we're here and now they're going

to say, "Welcome to the galactic
club." Yeah, yeah, yeah.

My problem is, maybe
to get into the galactic club,

you actually have to apply and
pay your dues. Right.

So that's what we're doing with the
message. I mean, my big fear is that

aliens are going to be
kind of like my cat.

I mean, they know we're here,
they just really don't care.

But there are these ideas around,
aren't there,

particularly in recent science
fiction, you know, things like

the idea of a dark forest
of a galaxy where you don't want to

draw attention to yourself

because there may be predators
lurking out there between the trees.

Does that worry you?
I think it would be a nice illusion

to think that somehow we can kind of
curl up and protect ourselves.

Sorry, the cat's already
out of the bag.

We have already been
blasting our existence into space

by radio and TV signals
for the last century.

And so, what do you think of those
efforts that have been made already

to send messages out? For the most
part, they've been symbolic.

NASA sent a message
to the North Star

to celebrate its 50th anniversary,
Across The Universe.

The Beatles song. The Beatles, yeah,
yes. But to really have a chance,

we have to do it over and over and
over again, cos it's probably not

going to be in the North Star
or any individual star.

It could be that we have to transmit
to hundreds or thousands,

maybe millions of stars.

So, how do we anticipate
who we're talking to?

How do we craft a message for
an unknown audience?

What if they don't like The Beatles?
If they don't like The Beatles,

we need to send them
some other stuff.

I like the idea of a selection.
We can just do,

"Press one if you want to hear
greetings from humanity. Press two

"for a selection of music."

That's the enticement to get them
to send back again.

"Yes, we would be glad
to send you more of that.

"Send us some of your favourites."

But I think the biggest inhibition
is, are we willing to take the risk

of listening and listening and
waiting for century after century

and hearing absolutely nothing?

And I think we do, because what that
will tell us is, you know,

all this time we've been looking
for an advanced civilisation,

someone that we can learn
something from,

but eventually we're going to
realise that, you know,

by doing this project
of transmitting and listening,

we've turned into the civilisation

we were looking for out
there all along.

For METI to make sense,
you need to believe in Doug's vision

of a galaxy filled with benevolent,

technologically advanced
civilisations just sitting out there

waiting for us to call them.

Personally, I don't know how likely
that is, but if they are out there,

it's good to think that there are
people here trying to talk to them.

That's all we've got time for
this month, but join us next month

when we'll be taking a deep dive
into black holes. Goodnight.