Alien Worlds

The Earth, home to millions of species.

But what might live... beyond?

There are countless planets throughout the universe.

If life exists on only a fraction of them,

then the universe must be... alive.

All living things have the same needs.

To feed...

reproduce...

and evolve.

By applying the laws of life on Earth

to the rest of the universe...

it's possible to imagine

what could live...

on alien worlds.

All life forms need a planet to live on.

But how many planets are there in the universe?

Think about our star,

the Sun,

with Earth, Mars, Jupiter orbiting it.

For centuries,

people have asked themselves, "What about the other stars?

Uh, do they have planets as well?"

And 24 years ago,

I found one!

Didier Queloz is a superstar astrophysicist.

He has won the Nobel Prize for discovering the first planet

beyond our solar system.

I was 28 years old when I found the planet.

I was about to finish my PhD,

and my PhD adviser gave me the key of the equipment.

And after observing a couple of times, the star 51 Peg,

I realized that something was going on on that star.

And frankly, I just panicked at that time.

I thought something was really wrong with my equipment.

And the more I wanted to understand this, the less it made sense.

Until the point I got convinced it must be a planet.

That's likely to be a planet over there.

Could be Jupiter over there.

It's pretty cool.

Distant planets are invisible to telescopes

because they don't emit any light.

But if a planet passes in front of a star,

it casts a tiny shadow,

and there's a minuscule dimming of the star's brightness.

When astronomers detect this dip in light level,

they have found a new planet.

Hello, guys.

Uh... Oh, hey. Here is what the telescope is looking at.

This is a picture of the telescope right now.

Uh, in the middle, you have the... the target we're observing.

So, you analyze this whole field, you process the data,

and, um, if you're lucky enough, you detect this.

There's a little bit of a decrease of the flux,

and this tells me that there is a planet orbiting that star.

We know there are a huge number of planets in the universe.

There must be a zillion kinds of different life.

Let's imagine that this is the Earth, here...

Right?

So, imagine that one meter is 20 light-years.

So, I've made two meters as 40 light-years.

This is where you have 51 Peg, where the first planet was detected.

Each of these tiny lights represents a star

where a planet has been found.

Over the next few years,

planets were turning up everywhere.

It looks pretty cool right now.

A horizon of stars and planets...

all around.

Planets beyond our solar system are called exoplanets.

Astronomers have found over 4,000 of them.

And they keep finding more.

They now believe there's at least one planet for every star in the universe.

That means over a million, billion, trillion exoplanets.

More than all the grains of sand on Earth.

A vast canvas for the evolution of life.

The distances are mind-boggling.

The nearest exoplanets are trillions of miles from us.

But they're all subject to the same force that holds the Earth in place.

Gravity.

Imagine a world double the size of Earth,

with twice as much gravity.

This is Atlas.

How would life adapt on such a world?

Gravity pulls vegetation to the planet's surface.

And yet, seeds can float in the sky.

That's because gravity here is so strong.

Air molecules are densely packed together...

creating a thick, buoyant atmosphere for seeds to drift through.

And where there are seeds...

there are sky grazers.

Giant herbivores with six wings

to ride on the dense pillow of air.

Because of the extra gravity,

they weigh twice as much as they would on Earth.

But they don't fall from the sky.

The atmosphere is thick enough to keep them airborne.

Whether on Atlas or on Earth,

flying is always a battle to overcome gravity.

You might say I have a pretty complicated relationship with gravity.

And you can really feel that gravity is a force pulling you down

as you struggle your way up.

But ultimately, my dream has always been to be able to fly.

Whoo-hoo-hoo!

The thing I love most about paragliding is that it's so simple and intuitive.

It's just you and the air.

Like the sky grazers on Atlas,

paragliders use their wings to generate lift.

But the atmosphere is less dense on Earth...

so it takes more effort to stay airborne.

Most people don't see air as a substance.

But for me, when I'm flying,

I really see it as a fluid that's moving up and down the valleys

and along the ridges.

It would be really weird to fly in a very dense atmosphere.

You could just be gliding around the whole time, effortlessly.

The best way to gain altitude is to find an updraft,

known as a "thermal."

When you hit the thermal, it's very similar

to when you're in an elevator and it starts.

You feel a push upwards.

Yeah, there we go!

Just the power of nature to pull me up.

When I'm flying and I see a bird circling up,

it means there must be a thermal there.

So we're always constantly looking at them.

You can really feel the balance between the gravity pulling you down

and the air lifting you up.

You can then use your bodyweight to gain speed,

and use that speed to generate more energy

and feel that you're moving through the air.

Gravity may be weaker on Earth than on Atlas...

but the thinner atmosphere means there's less buoyancy.

So, eventually, everything falls.

On Atlas, the sky grazers never need to land.

Their front and back wings are for direction and thrust.

Their long middle wings are for catching thermals.

Despite their weight,

the air is thick enough for them to live a life

in the sky.

But it's not always a peaceful life.

As on Earth, grazers attract predators.

Using hydrogen-producing bacteria to inflate their air sacs,

they take to the skies.

Alone, they're no match for their prey...

so they hunt in a pack...

waiting for a sky grazer to stray from the group.

Target sighted, they expel their gas...

and attack from above.

The fastest predator on Earth

uses the same tactic.

My interest in flying falcons is...

their predatory instinct coupled with the speed factor...

and how they use that speed to their advantage.

But just watching a top predator do its thing...

is perfection.

I probably have 30-some birds at this moment.

Each bird is a different personality.

What I love about falcons

is how evolution has made the most perfect specimen.

- -

I do have a relationship with these guys.

Certainly from my end, I do.

I don't think the falcons see it that way,

but they certainly see me as part of the team.

Vahe Alaverdian trains captive-bred falcons how to hunt.

These birds are genetically programmed

to be the top-notch avian predators that they are.

What we do as falconers

is try to awaken that predatorial nature in the bird.

Lure training is the very first step.

Come on, buddy! Hup, hup, hup, hup, hup!

I want to put that lure in front of the bird,

and get the falcon to coordinate eye to foot...

Hup, hup!

...and throw its feet out as if it's gonna grab it.

As that happens, I try to pull that away from the falcon

to get it to shoot up in the air and repeat this process again.

I wanna see that bird drop down as vertical as it can.

That's something that they later on will apply to hunting game.

When the falcons are ready, Vahe introduces a prey target...

a racing pigeon.

The falcon can't keep up with the pigeon in a chase,

so its best bet is to drop on it...

using gravity.

When the bird thinks that he's got the advantage,

that's when the wings will get tucked in.

They stoop into a little teardrop shape...

coming down from the heavens.

The kinetic energy of a falcon hitting a pigeon

would be as if you were hit by a cannonball.

In training, the pigeon invariably gets away,

because the falcon is made to stoop from less than a thousand feet.

When hunting for real,

it'll drop from a greater height...

to lethal effect.