All language subtitles for HTUW S05x09 Strangest Alien Worlds

SUB BY : DENI AUROR@
https://aurorarental.blogspot.com/

For 25 years,

astronomers have been scouring the night sky,

looking for a holy grail,

the ultimate hope ... a planet like our own.

They've found thousands of other worlds,

but most are nothing like we expected...

And many are truly bizarre.

WoThe universe has a vivid imagination.

Orphan planets without stars,

worlds made from diamond

and perhaps even giant eyeballs

circling their suns.

If humans ever get to visit a planet like this,

we're gonna lose our darn minds.

Could any of these worlds be an earth-like twin

with earth-like life?

Or is there really no place like home?

captions paid for by discovery communications

over 400 years ago,

a brave philosopher first posed the question,

if the stars in the night sky are like our sun,

could they have planets, too?

The modern hunt for exoplanets ...

alien worlds orbiting distant stars ...

began in earnest in the 1990s.

Pioneering astronomers expected to find planetary systems

much like our own.

But from the very first,

what they found shocked the world of science.

Of course, we thought,

"well, if there are other solar systems,

they've gotta be just like us, right?

And now we're finding, actually,

there's a really wide diversity of planetary systems.

They are nothing like us.

We're finding planets that I would've thought,

if I saw in a movie, I'd go, "oh, yeah.

That's ... that's cute. That makes for a pretty scene.

But come on. That's not really gonna happen."

And then, boom, we're finding 'em.

The shocks came early.

The very first confirmed planet

found outside our solar system

wasn't orbiting anything like our sun.

It was orbiting one of the most violent

and mysterious objects in the universe:

A pulsar.

It defied logic.

If you were to wake me up

in the middle of the night and say,

"where's the last place you would ever,

ever, ever find planets?"

I probably would've said, "orbiting a pulsar."

A pulsar is honestly one of

the most dramatic things the universe offers.

A teaspoonful of the star

has about as much mass as mount Everest.

And they can rotate hundreds of times a second.

Can you imagine a monster like that?

Pulsars are incredibly compact.

Imagine roughly the entire mass of the sun

squeezed down to an object no bigger than Manhattan.

As they spin, pulsars spit out light

and beams of radiation.

But it's the birth of these violent stars

that makes them such an unlikely home for planets

because pulsars are born in the cosmic fires

of supernova explosions.

These explosions are so powerful

that if one occurs near an ordinary planet

like the earth,

it would be vaporized in the blast.

Finding planets orbiting a pulsar after

a supernova explosion

is like going to the site of a devastating earthquake

and then finding a China shop

with all the plates and everything ...

everything is perfectly intact, not a scratch on 'em.

It just doesn't make any sense.

For a planet to survive a supernova blast,

it would have to be made of incredibly tough material.

But what?

A clue came in 2011,

when astronomers found a strange planet

closely orbiting a rapidly spinning pulsar

in the serpens constellation.

The planet is big,

3,000 times the size of the pulsar it orbits.

But the real surprise is its composition.

The planet appears to be very rich in carbon

but so dense it could only be in diamond form.

If you told me 20 years ago we'd be talking about a ...

a giant diamond orbiting pulsar,

I would ask, uh, "what were we drinking?"

If humans ever get to visit a planet like this,

we're gonna lose our darn minds.

People love diamonds.

They pay huge amounts of money for it.

And now, we're finding that there

is an entire planet that's a diamond.

The diamond planet

could be one of the most spectacular places

in the universe,

shining like a 37,000-mile-wide dirty disco ball.

For planetary geologist jani radebaugh,

the closest thing we have to the surface

of the diamond planet here on earth

is the shimmering black volcanic flood plain in Iceland.

WoImagine we're standing on the surface of a diamond planet.

You can see that it's really flat, really uniform.

And yet it's a little bit shiny.

I think it would be really beautiful.

However beautiful, a diamond planet

is not a place you want to visit.

The planet's immense density exerts a gravitational

pull over 15 times stronger

than that on the earth,

making life extremely uncomfortable for any visitors.

So we're standing on a very high-mass body.

This means that the gravity is extremely large.

It's so big that we'd probably

just be squished flat to a paste.

So how did the diamond planet form?

Scientists believe there can only be one explanation.

It must've started life as a star

but one in a binary partnership

with a much larger companion.

We're actually sort of rare.

Our solar system only has one star.

Most solar systems have more than one.

And the stars orbit around each other.

Billions of years ago,

the diamond planet is a yellow star,

much like our sun.

Its much larger binary partner quickly

burns through its fuel supply

and then explodes in a violent supernova,

leaving behind a remnant, a pulsar.

The sun-like star is big enough to survive the blast.

But billions of years later,

it too runs out of fuel and dies,

leaving behind a burnt-out core known as a white dwarf.

The gravity of the pulsar starts

to steal the lighter elements,

hydrogen and helium,

from the outer layers of the white dwarf

until pretty much all that's left are

the molecules of carbon

the dead star produced during its lifetime.

The pressures in the leftover ball

are so intense that the carbon crystallizes,

turning it into a compacted diamond.

But it turns out these cosmic diamonds aren't forever.

The gravity of the pulsar pulls on the diamond planet,

hauling inwards on a slow

and ever-decreasing death spiral.

At some point, as it gets closer and closer to that pulsar,

it's feeling a harder and harder gravitational stretching.

When it gets very close, that force will get so strong,

it will rip that planet apart.

Imagine the view

as a 10-thousand-billion- billion-billion-karat diamond

is ripped to pieces.

Gravity cannot hold the body together anymore.

And it ... it basically gets torn apart.

And now, what you have is a ... a shower of diamonds.

I mean, that sounds amazing.

Extreme diamond planets forged

from the hearts of dead stars

fire the imagination.

But what exoplanet hunters

really want to find are worlds like our own.

Astronomers, in general, are looking for exoplanets

because they're cool.

But come on. We're human beings.

And we want to find another planet like earth.

And in 2016, astronomers are shocked

when they discover a potentially earth-like planet

orbiting our closest neighboring star.

Stunned scientists wonder,

will this new exoplanet

have what it takes to give birth to life,

intelligent life,

even civilizations?

Take a look at the night sky.

We now know that planets probably surround

almost every point of light you see.

But there's more.

For every star we can see,

there are countless others too dim

for our eyes to pick out.

These are the red dwarfs,

far smaller than the sun

but home to planets by the truckload.

And many of these worlds

are made from rock like the earth.

There are more red dwarfs

than any other kind of star in the galaxy.

And these stars have planets, too.

So the most common type of planet in our galaxy

is one that lives around a red dwarf.

Of the billions of red dwarfs in the milky way,

more than one in 20 have planets

that orbit at just the right distance

for liquid water to collect on the surface.

Any closer, the temperature would be too hot,

and the surface water would boil.

Any farther away and the water would freeze.

It's often called the goldilocks zone

because it's just right for oceans to form,

just as they did on the earth.

Could one of these warm,

wet worlds provide a habitat for life like us?

That's kinda the holy grail of this whole thing,

to find something that looks like home.

For one thing, that means that it could have life on it.

It could be habitable.

And that's something that we've always wanted

are we alone?

These rocky, wet planets

may seem like dead ringers for the earth.

But there's a catch.

Many red-dwarf worlds

orbit so closely to their demo stars

that the same side of the planet

would always face inwards,

held in place forever by the star's immense gravity.

Scientists call this phenomenon tidal locking.

We're all familiar with the fact that the earth spins on its axis

and gives us night and day.

But if you move in closer to a star, eventually,

the gravitational interaction will stop that rotation.

One side of the planet will always face the star.

One side will always face away.

And you're tidally locked.

If you land on this planet and look around,

you're gonna see stuff that's very different depending on

where you are.

If you're on the point on the planet

that is underneath the star

so that, when you look up, that star is straight up,

that's where it's always gonna be.

It never rises. It never sets.

It never moves.

That's where the star is.

Now, if you're on the other side of the planet,

it's always nighttime ... you look up,

you never see your host star in the sky.

In 2016, astronomers discovered

a potentially earth-like planet

orbiting the sun's closest neighboring star,

proxima centauri.

The planet, dubbed proxima b,

sits close enough to its host

to have oceans like the earth.

But scientists suspect its tidally locked.

The result: Proxima b may be staring at its parent star

like a giant eyeball.

The night side is a dark, frozen wilderness,

the day side, a sunblasted desert.

But between the two lies hope for life.

A long, thin strip of land in permanent dusk wraps

around the planet like a ribbon.

Jani radebaugh pictures an eerie twilight zone

where dark glaciers melt

to fill vast lagoons

just as earth's glaciers do during the summer.

Radebaugh: The boundary between these two

completely different landscapes

is something like what we're sitting on right now.

Basically, we would have liquid water

flowing off of these glaciers, pouring off the glaciers

and heading out into the wasteland

and icebergs calving off into this beautiful bay.

We've got liquid water.

We've got energy from this burning sun.

And so this is exactly the kinda place

where we would look for life.

A ring of hope for life on a planet

orbiting the sun's nearest neighbor.

Could proxima b really be home to alien civilizations?

Until we go there, the jury's out.

But red dwarfs burn for trillions of years.

And they outnumber the other stars

in the sky three to one.

If advanced alien civilizations

really are out there,

the planets of red dwarf stars

could be ideal places to find them.

Let's say that we were sitting on a planet around

one of these red dwarfs, maybe a trillion years from now.

We could still be sitting here.

We've never seen a red dwarf die.

And so if that's true, then there's plenty of time

for life to have gotten started.

So not only do we have microbial life,

but maybe even more complex life

and then take it a step further.

We might even have intelligent life in these locations.

It's amazing that even tiny stars

can have potentially habitable rocky planets,

no matter how weird these worlds may turn out to be.

But when astronomers turn their telescopes

to bigger stars,

the surprises keep coming.

These sun-sized stars have planets, too.

And some of them could be the weirdest yet.

Imagine a gas planet

so black it appears to be eating light.

For over two decades,

astronomers have scanned the heavens for alien worlds.

And they've found them

pretty much everywhere they've looked.

They hope to discover multiple planets

just like the earth.

But instead, they've uncovered

a galaxy filled with the bizarre.

When you search for all of these exoplanets,

you can see that the universe has a vivid imagination.

Some of them have super gravity.

Others have two stars and not one.

There are all kinds of interesting configurations.

In 2011, astronomer David kipping

was reviewing data on a gas giant

that was closely orbiting a distant star.

As he studied the brightness of the parent star,

he found something really weird.

It looked like the orbiting planet was eating light.

When I first saw this data,

I actually thought we'd made a mistake.

I thought, "we must've screwed up in our analysis."

David was measuring the brightness of the star

as it went from its day side to its night side.

It had been predicted that the brightness

would drop significantly.

But instead, there was only a tiny drop in the light levels.

The only explanation was that the planet

was barely reflecting any light at all.

This planet, tres-2b,

reflects less than 1 percent of the light which hits it.

So that's darker than black acrylic paint.

That's darker than a piece of coal

that you might hold in your hand.

And it's darker than virtually any material

you will ever encounter in your life.

And for that reason, we started

to nickname this planet the dark knight.

Black objects appear black

because they absorb most of the light that hits them.

The more light an object absorbs,

the blacker it appears.

But the dark knight is so intensely black,

it almost appears to be eating the light around it.

And this weird planet has another secret:

It sits so close to its star

that its atmosphere reaches

incredible temperatures ...

2,000 degrees fahrenheit,

hot enough to melt gold.

Could the dark knight's scorching

atmosphere help explain its weird,

ultra-dark appearance?

Kipping: There is some very alien chemistry

happening in the atmosphere of this exoplanet.

You're gonna have vaporous sodium,

vaporous potassium,

maybe even titanium oxide in the atmosphere.

These substances are solid on earth.

But here, it is so hot, they are gases.

And these gases, like sodium,

are excellent absorbers of light,

creating the dark knight's weirdly shadowy appearance.

Normally, this absorption

is limited to a very narrow color

such as yellow light.

But this planet is so hot

that that absorption feature gets broadened out.

And this absorption feature then spans

the entire visible wavelength of light.

And the planet basically looks extremely dark.

Planets like the dark knight

fascinate astronomers because

these star-skimming giant planets

aren't expected to form so close to their star.

When young stars burst into life,

they blow away the gas

and dust that surrounds them,

leaving little material behind to build gas planets

the size of Jupiter.

Instead, the dark knight must've started life far away

from the heat of its star,

where ice and gas was abundant,

and then gradually spiraled inwards

to its current position.

We think these hot jupiters form much

like the planets in our solar system.

You have a massive planet

that's orbiting very far from the star,

building up material from this disc of gas

and dust swirling around the star.

But as it's moving through this disc of material,

it's slamming into it.

And that's acting like a drag.

So very slowly, over millions of years,

it's going to spiral into the star,

get closer and closer and closer.

And what you're left with is a massive planet

orbiting very close to its star, a hot Jupiter.

Tres-2b most likely started life

looking much like Jupiter does today,

bright in color

and with a raging, stormy atmosphere.

But as it moved closer to its hot star,

the planet's atmosphere began to cook.

It blackened and became the dark knight.

So this shows us how dynamic

planetary systems must be.

Planets migrate.

Where we see planets today

may not be where they formed.

In fact, we're pretty sure it's not where they formed.

Thanks to strange worlds like tres-2b,

we now know for sure that gas giant planets

can drift in towards their star.

But could the opposite be true?

Could they sometimes drift out?

Astronomers turn their telescopes

to the spaces between stars.

And they're amazed to find scores

of exoplanets set adrift in open space.

And one of these lonely orphan worlds

could be the weirdest exoplanet we've ever seen.

2013 ... a group of astronomers

scan the night sky for a mysterious class of object

called a brown dwarf.

Brown dwarfs are failed stars,

too small for fusion

to fully ignite in their cores.

But these dim, gassy balls do radiate some heat,

allowing the astronomers to pick them out

with infrared telescopes.

A star is just a big ball of hydrogen

that happens to have enough mass that the interior

gets hot enough inside to start a nuclear reaction.

Now, the universe is perfectly capable of producing things

that just didn't quite have enough mass

to get those nuclear reactions going.

And we call that a brown dwarf.

The astronomers get a hit

on their infrared detectors.

But it's not what they were expecting.

The object they see is too low-mass

to be a brown dwarf.

It had to be a gas planet.

But its host star was nowhere to be seen.

The planet appeared to be set adrift in open space.

The astronomers had stumbled across one

of the most mysterious objects in the galaxy:

A lonely, orphaned, rogue planet.

A planet, by definition,

in some sense, you might've thought,

is something that orbits a star.

These are planets that don't have a star.

The idea of a rogue planet is just crazy.

That's bonkers. And if ...

but yet we've seen them.

So these things exist. I mean, that already is crazy.

Our galaxy could be home to billions of

rogue planets wandering across interstellar space.

Without a star to keep them warm,

you'd expect rogue planets to be cold.

But the planet discovered in 2013 is seriously weird.

It's hot.

The clouds in the planet's deep,

gassy atmosphere burn at over 1,400 degrees fahrenheit.

It's hard to imagine a more hostile place to visit.

Now, if you were to try to get into this planet,

if you could protect yourself from the massive amounts

of pressure of the atmosphere

squeezing on you and the huge amount of heat

trying to basically vaporize you,

it still would be a pretty rough neighborhood.

This thing almost certainly has incredible weather,

tremendous storms,

huge parcels of hot air rising and cold air falling.

Not only that, we found that, in a lot of these objects,

if they're hot enough,

iron and other metals can be vaporized.

As they cool though, this stuff can rain out.

And you can imagine droplets of molten iron

falling out of the sky.

This is not a great place to, you know, buy a condo.

Diving deep below the searing clouds,

pressure builds

until the pressure of gravity is so great,

hydrogen gases transform into a weird liquid metal.

But where did this planet come from?

And how did it get so hot?

The planet's scorching heat reminds scientists

of infant gas giants in the hot,

violent crossfire

of a newly forming planetary system.

Is it possible this rogue planet

was actually a baby thrown from its nursery

by its jealous planetary siblings?

Planets obviously form in the vicinity of a star.

But, you know, they're in a nest with other planets.

And when they get too close in the early days,

their gravitational tugs

will usually slow one of the planets down

and speed the other planet up.

And if it speeds up enough,

that planet can escape the interstellar system

altogether and go out into the depths of space-Ace-Ace.

An orphan baby gas giant cast out into the cosmos.

But this world may not be truly alone.

It could have companion moons.

In our solar system,

families of icy moons swing around Jupiter

and saturn on elliptical orbits.

And scientists have discovered icy exteriors

that cover vast liquid water oceans.

As we've seen in the moons in our solar system,

uh, they can be very active.

If they're icy, the gravitational interaction

with their host planet can stretch them

and squeeze them and heat them up.

These so-called tidal forces could power hot

volcanic vents just like the vents found

deep in the earth's oceans.

On our planet, ocean vents support

all kinds of strange life

without the benefit of sunlight.

Could something similar be happening

on the tidally heated moon of a rogue planet?

It's entirely possible, hugely speculative,

and let me be clear about that,

but it's possible that you could have life

arising on the moon of a sunless planet.

You could have these moons kind of snuggled up

around this exoplanet,

keeping warm through its gravity.

So even with no star around,

there's still possibility for life.

Weird rogue planets allow us

to dream of interstellar alien life.

But it's hard to imagine these deep-sea creatures

developing into advanced,

complex, intelligent life

on the meager energy of volcanic vents.

To find evidence of civilizations,

we need to look elsewhere.

And it's just possible the weird behavior

of a distant star

has provided our first clue

that these advanced civilizations

could really exist.

We used to think our galaxy

was only filled with stars.

We now know those stars have planets, too,

hundreds of billions of them.

Astronomers call these alien worlds exoplanets.

WoWe didn't even know that there were exoplanets.

And now, it's just mind-blowing

to think about how much we've learned about our universe

just in the last, you know, 10 to 15 years.

This is a really fundamental shift

in our understanding of what is out there.

Since 2009,

a planet-hunting space observatory

called kepler has revolutionized

the search for exoplanets,

locating more than all

the telescopes on earth combined.

Kepler's success is due to its ability

to keep watch on 150,000 stars simultaneously.

If kepler spots the light from one of those stars

dimming just for a moment,

an exoplanet could be crossing its path.

And the greater the drop detected,

the bigger the exoplanet could be.

But in 2011 and 2013,

kepler spots dips in brightness

that are off the scale.

The mystery star is dubbed tabby's star,

named for the astronomer

who investigated its strange behavior.

And that behavior has forced scientists to consider

a completely universe-changing possibility.

The tabby star is really interesting because we know

there's an object that's orbiting it.

And it's blocking a really large amount of the light.

That's how we know it's there.

But it's much more than a planet typically would block.

If you have a Jupiter-sized planet

orbiting a normal star,

you block a percent of the light.

It's a very, very small dip.

But with tabby's star, what we're seeing are huge dips

where 20 percent of the light is being blocked.

If kepler's readings are right,

something huge is moving around tabby's star.

And there's an outside chance

that something is the remnants of a planet

taken apart by aliens

and repurposed as a giant solar power plant.

What really advanced societies

would do is just take apart some worthless planet,

like Neptune in our own solar system,

and rebuild it as a giant sphere

outside the orbit of their planet,

collect all that sunlight and then use that.

WoThe best energy source anywhere is your star.

So you might build giant structures

to actually harvest the energy.

Freeman Dyson called this a Dyson sphere.

Could we have found a Dyson sphere?

If the remains of an exoplanet

are blocking the light from tabby's star,

the aliens have been busy.

Their megastructure would need to be vast to account

for the dimming seen by scientists.

A Dyson sphere is the stuff of Sci-Fi dreams.

But how can we prove it's real?

Astronomers at SETI turn their telescopes to tabby's star

in the hopes of eavesdropping on the radio chatter

of its alien builders.

As soon as we heard about tabby's star,

we swung the antennas

of our Allen telescope array in the direction of that star.

And we spent about a week or two actually looking at it

over a wide range of the radio dial,

looking for any signals. Well, we didn't find any.

We also used a telescope down in Panama

to look for flashing laser lights.

We didn't find those either.

If a type of Dyson sphere

is being constructed around tabby's star,

its workforce is suspiciously quiet.

WoEvery big claim requires big proof.

Just seeing a change in a light profile

is interesting and is intriguing

but is not compelling

and is not evidence to me yet.

I think that just tells us

we have to keep looking and keep learning.

I would love for it to be aliens.

That would be job security for me.

But honestly, I'm trying to be realistic about this.

But if it's not aliens repurposing a planet,

what else could be causing the dramatic dimming in light?

Could it be stellar activity?

Could it be there's a disc around the star?

Could it be disintegrating planets?

But probably, right now, the leading contender

is a family of comets which are orbiting this star

and causing these dips.

Comets are vast, dirty snowballs left over

from the formation of planetary systems.

But if a giant cluster

of comets exists around tabby's star,

they could appear a whole lot bigger.

If they get close to their star,

that ice can heat up,

turn into a gas and expand.

And that expanding cloud

can then be much larger than a planet.

We see that in our own solar system.

And it could be something like that that's blocking the star.

It makes sense.

And it explains a lot of what we're seeing.

But it doesn't explain everything that we're seeing.

A vast cloud of comets could be

blocking the light from tabby's star.

But there's a problem: It's unlikely there would be enough

comets to account for these dips.

And the infrared signature

hasn't been anything out of the ordinary.

So either we've missed it.

That dust disperses relatively rapidly, which is possible,

or there's something more going on here

than just comets breaking up.

None of the current theories

can fully solve the mystery of tabby's star.

So for now, an alien megastructure built

from a planet remains an intriguing

if distant possibility.

We've seen worlds made of diamond, planets

where molten iron rains

from the sky and, perhaps now,

the first signs of alien intelligence.

But there's another planet in the galaxy

that could be the weirdest of them all,

because, no matter how hard we look,

we simply can't find another to match it.

Our hunt for exoplanets

has revealed a galaxy filled

with bizarre planetary systems

and strange alien worlds.

But the biggest surprise is how few of these worlds

look like our planet, the earth.

So far, we haven't found many, if any, solar systems

that are kind of identical to ours.

We always assumed there'd be small planets

on the inside, big planets on the outside like ...

like our own solar system. We don't find too many of those.

What we have found is that

the most common type of planet around other stars

is what's called a super earth.

These super earths

have atmospheres that are too thick,

creating pressures too high to support life like us.

So why does our small planet,

with its exposed continents and relatively thin atmosphere,

appear to be so rare?

A new, radical idea suggests the earth

could be a second-generation planet,

built from the remains of a demolition derby

between giant rocky worlds

that once dominated the early solar system.

WoThere may have been planets before the ones

we know that were destroyed,

that were kicked out or sent careening into the sun.

That makes the earth a second-generation planet.

We may have had brothers and sisters

that we never knew about.

Imagine the scene ... 4.6 billion years ago,

the planets in our solar system begin to form

from a vast disc of dust and debris.

Giant Jupiter is the first to form.

And it settles into a distant orbit.

Where the earth sits today,

a band of super earths are born,

vast worlds up to 10 times the mass of the earth

and with thick crushing atmospheres.

The gravity of these giant,

inhospitable worlds dominates

the inner solar system,

preventing smaller, earth-sized planets

from forming...

That is, until Jupiter joins the party.

We believe that this first generation of planets

was driven

onto the surface of the young sun

by the migration of our big bully

in the solar system ... Jupiter.

A few million years

after the birth of the solar system,

the gravity of the protoplanetary disc

slows Jupiter down.

And it starts to spiral in towards the sun.

As it moves inwards,

it pushes waves of asteroids

and debris towards the super earths.

The incoming debris disturbs

the orbits of the giant planets.

Some may smash each other to pieces.

Others are sent hurtling into the sun.

Once the planetary carnage is over,

Jupiter is tugged back out

by the gravity of the newly formed saturn.

The solar system that is left behind is a place

that's depleted in solid material and gaseous material.

It is a place where ...

where debris will coalesce

over hundreds of millions of years

into the terrestrial planets

that we have today.

Planetary building starts over

in the inner solar system.

But the new planets feed on scraps,

growing much smaller than their predecessors,

with thinner atmospheres and lower pressures.

Among them is our own planet, the earth,

a second-generation planet primed for life.

For so long, we've been trying to identify

all the different factors

that make life likely on a planet.

We know that it has to be warm. It has to be stable.

Well, maybe we've got a new one now.

Maybe being a second-generation planet

is one of the advantages we need to look for.

If this is true, the incredible birth story

of our planet could offer a reason

why we don't see other worlds

out there teeming with intelligent life.

Perhaps the earth is the planet

that broke the rules.

What we're seeing is that our own solar system

may be the exception.

And when you look at our solar system,

what's the weirdest planet?

Well, the weirdest planet would have to be earth.

Right now, earth seems to be

the oddball in the universe

because we haven't found life in the universe.

But we continue to search.

And hopefully, we'll prove ourselves wrong.

Eventually,

amongst the billions of worlds out there,

we might find another planet

that beat the odds,

gave birth to life,

nurtured intelligence

and created a civilization smart enough

not to extinguish itself.

Only then will we know

whether the earth is truly unique.