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Narrator:
Our galaxy, far in the future.
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A planet shrouded
in turbulence, dense clouds.
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Buried deep below,
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an alien landscape,
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extreme pressures,
and a scorched surface
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with sky-high temperatures.
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But this is not some
distant extraterrestrial world.
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It's Earth's future,
maybe a billion years from now.
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We know this
because Earth has a twin...
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Venus.
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And Venus has already
descended into hell.
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Captions by vitac
www.Vitac.Com
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captions paid for by
discovery communications
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take a look
around the solar system...
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Eight planets orbiting
a central star, the Sun.
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Among them is Earth
and its neighbor, Venus.
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Earth, our home,
is an oasis for life.
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And Venus,
that's the stuff of nightmares.
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Plait: Venus and Earth
couldn't be more different.
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The Earth is
this beautiful planet,
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and there's water everywhere.
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It's ice at the poles.
It's water in the ocean.
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It's in the atmosphere
as water vapor.
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But then you look at Venus.
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It is the worst place
imaginable.
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It is so hot on the surface,
crushing pressures.
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It couldn't be
any less supportive of life.
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Thaller:
To me, the planet Venus
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is sort of a classic definition
of the word hell.
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If you were to transport
to Venus
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and experience
the environment there,
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you'd quickly want
to return back to Earth.
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Narrator:
The conditions on Venus
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are among the most inhospitable
in the solar system.
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It's just a horrible place.
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It's so hot,
and there's no water,
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and the atmosphere is so thick.
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And it rains sulfuric acid.
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It's going to be a competition
between whether or not
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you're gonna be cooked to death
or crushed to death.
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Narrator: Earth and Venus may
seem like very different worlds,
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but they shouldn't.
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They're roughly
the same size, same mass
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and made from the same stuff,
and they started out as twins.
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Early Venus and early Earth
were very similar.
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They were twins,
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probably nearly identical twins,
at their earliest stages.
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Given that Venus is
so Earth-like in so many ways,
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it's really odd that it is
so different than the Earth.
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And this makes it
one of the biggest mysteries
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in the solar system.
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Somewhere
in their two histories,
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the Earth and Venus
took two very different paths.
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Narrator: The result?
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Two totally different worlds.
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Their paths were so different,
you could hardly believe
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that one would have been related
to the other.
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But now, the opposite thing's
going to happen.
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We're gonna catch up
with our twin.
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We're gonna evolve to be a lot
more like Venus in the future.
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Narrator: In the future,
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the two planets' paths
will converge,
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and they will become twin-like
once again.
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There is going to be
hell on Earth.
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The oceans will vaporize.
The land will melt.
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Our hospitable blue planet
will vanish,
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replaced by
a fiery, molten world.
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We are actually on the Earth
at a time
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when there's water and rain,
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and it was so easy
for life to take hold.
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But that's gonna change.
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And take a look in at Venus
and have a look at our future.
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Narrator: And Earth will surpass
the horrors of Venus.
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A billion years from now,
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Earth could be
an unimaginably terrible place.
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Narrator:
How will this happen?
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The roots of
our home world's destruction
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are buried deep
in the past of our twin planet.
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It's very much true that,
in studying the past of Venus,
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we are also studying
the distant future of Earth.
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Narrator: Both planets share
a violent birth,
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scarred by brutal
planet formation,
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giant cosmic impacts,
and rampant volcanism.
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Grinspoon: We're trying
to reconstruct things
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that happened
in the ancient, ancient past.
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It's almost like
forensic planetary geology.
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Narrator: 4.6 billion years ago,
hundreds of infant planets
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begin to form
around the new sun.
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Among them,
the baby Venus and Earth.
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And as they hurtle
around the Sun...
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Collisions are inevitable.
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Planet formation
is like a demolition derby.
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In a derby, the cars are racing
around a track,
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going around in circles
at different speeds.
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Well, it's the same thing
with planets.
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The material
is orbiting the Sun.
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It's going around, and they're
all going at different speeds,
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at different angels,
different trajectories.
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And sometimes, boom.
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Narrator: In this derby,
planet hits planet.
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Two become one.
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Violently.
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You have these large bodies
that are hitting each other
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at really high velocity.
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It's really a very hot,
violent mess.
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Plait:
The amount of energy released
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in these impacts is huge.
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It completely dwarfs
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all of the nuclear weapons
on Earth combined.
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And yet, somehow,
on these scales,
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you wind up forming gigantic
objects that we call planets.
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Narrator: Earth and Venus
become voracious planet eaters.
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But two spectacular collisions
will set the twins
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on very different paths.
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Grinspoon: That was the moment
Venus and Earth went through
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this divergence
to what has now become
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these really
dramatically different worlds.
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Narrator:
The divergence begins
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when a Mars-sized object
hits Earth.
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The impact makes our planet
spin faster.
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The core spins with it,
generating
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a powerful magnetic field
around the planet.
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[ Humming ]
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The field fends off the worst
of the Sun's radiation.
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Around the same time,
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Venus takes a head-on hit
from another infant planet.
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This impact explains something
very weird about Venus.
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Oluseyi:
Venus is actually rotating
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in the wrong direction.
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How could that be?
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Well, what if it got hit
really hard by some object?
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That could do it.
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Narrator: An object so huge,
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Venus stops in its tracks
and begins to spin backwards.
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If you think about
how much energy
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and what size you need
to change a planet's spin,
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that is an incredibly large hit.
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Narrator:
But the backspin is slow,
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243 times slower than Earth.
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Without a fast spin,
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Venus' core can't generate
a strong magnetic field.
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It has no protection
from the deadly stream
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of particles blasted
from the Sun.
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Venus does not have
a strong magnetic field.
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And so it has suffered
the full brunt
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of this wind
blasted out from the Sun.
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Narrator:
The tale of two planets
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now splits radically.
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Venus will roast
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under a violent, suffocating
atmosphere.
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Earth will give birth
to oceans,
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life, and intelligence.
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But ultimately,
these twins' fates
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are one and the same.
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Earth's future is Venus...
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Pure hell.
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Narrator:
Venus is a vision of hell.
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And one day,
we'll meet our twin's fate.
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It turns out
that what Venus went through
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in its distant past is what
Earth is going to go through
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in its distant future.
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Narrator: So, exactly how
will our blue planet
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become a superheated wasteland?
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Only Venus can really tell us.
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Something happened to Venus
long in its past
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to make it
a completely different planet
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with a completely
different personality
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than the Earth
as we know it today.
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Man: Two, three, four.
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Narrator: We Earthlings
sent our first probe
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to our sister planet in 1967.
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And we've been sending them
ever since.
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What they found
blew scientists' minds...
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Rocks that look like granite.
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What makes that interesting
is that, to make granite,
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you need water.
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That means that there
must have been abundant water
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for it to have formed
in the first place.
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Narrator: Abundant water
on a scorched Venus?
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Hard to imagine.
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But Dr. Lewis dartnell
thinks you can get a glimpse
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of a wet Venus
here in Iceland.
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There's the possibility
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that, maybe,
in the early solar system,
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there were not one
but two planets with oceans,
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two water worlds...
Earth and Venus.
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And if Venus did
once have oceans,
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maybe they would've looked
a lot like this here,
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with a raw, volcanic landscape
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descending down into the ocean
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with the waves
lapping against the coastline,
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and maybe a overcast
and a misty, hazy atmosphere,
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not unlike
what we are seeing here today.
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Narrator: But Venus
couldn't hold on to its water.
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Plait:
All of that water is gone.
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It's just gone.
Where did it go?
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Something happened, either
catastrophically or over time,
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to basically dry out
this twin of the Earth.
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Narrator:
The culprit was the young sun.
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Since its birth,
it's grown stronger.
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Krauss: Our sun, when we look
out at it during the day,
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00:12:51,496 --> 00:12:53,397
seems the same today
as it was yesterday.
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00:12:53,398 --> 00:12:55,032
But that's on
a human time scale.
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00:12:55,033 --> 00:12:56,133
On cosmic time scale,
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00:12:56,134 --> 00:12:58,036
the Sun has been getting
hotter and hotter.
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00:12:58,037 --> 00:13:04,408
Narrator: Every billion years,
the Sun gets 10% hotter,
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slowly turning up
the temperature on Venus.
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00:13:09,613 --> 00:13:12,749
Not only that,
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00:13:12,750 --> 00:13:17,220
Venus formed 26 million miles
closer to our star.
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00:13:17,221 --> 00:13:22,625
As it turns out, that distance
to the Sun was critical.
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It's just
an unfortunate circumstance
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of being in the wrong place
at the wrong time.
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Narrator: Earth is far enough
from the Sun
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00:13:31,169 --> 00:13:34,004
to hold on to its water.
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00:13:34,005 --> 00:13:38,775
But Venus can't take the heat.
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Grinspoon: The intensity
of its sunlight got sort of
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00:13:42,514 --> 00:13:44,048
just a little bit too much.
218
00:13:44,049 --> 00:13:46,250
It passed this threshold
where Venus
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00:13:46,251 --> 00:13:48,952
couldn't hold its water
on the surface anymore.
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00:13:48,953 --> 00:13:52,755
Narrator:
As temperatures rise,
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00:13:52,756 --> 00:13:55,726
the oceans start to evaporate.
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00:13:55,727 --> 00:13:58,495
Plait:
All of that water in the oceans,
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00:13:58,496 --> 00:14:00,830
all of those millions
of cubic miles of water,
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00:14:00,831 --> 00:14:02,566
would become water vapor,
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00:14:02,567 --> 00:14:05,402
basically steam clouds
covering the entire planet,
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00:14:05,403 --> 00:14:07,537
hiding the surface
from the outside.
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00:14:07,538 --> 00:14:11,875
Narrator:
Water vapor is a greenhouse gas.
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00:14:11,876 --> 00:14:18,414
The clouds covering Venus
trap the Sun's heat.
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00:14:18,415 --> 00:14:23,421
Temperatures on the surface
rise.
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00:14:23,422 --> 00:14:27,090
But the process
can't go on forever
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00:14:27,091 --> 00:14:31,260
because the clouds
of water vapor in the atmosphere
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00:14:31,261 --> 00:14:35,198
start to disappear,
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00:14:35,199 --> 00:14:38,268
ripped away by the solar wind.
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00:14:38,269 --> 00:14:42,907
Venus does not have
a strong magnetic field.
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00:14:42,908 --> 00:14:45,308
And so the full brunt
of the solar wind
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00:14:45,309 --> 00:14:48,311
has been slamming into Venus
for billions of years.
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00:14:48,312 --> 00:14:50,913
Over time, if a water molecule
was in the upper part
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00:14:50,914 --> 00:14:52,216
of Venus' atmosphere,
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00:14:52,217 --> 00:14:54,650
light from the Sun
could break it apart
240
00:14:54,651 --> 00:14:56,186
into oxygen and hydrogen.
241
00:14:56,187 --> 00:15:00,289
And then the solar wind
could blow that stuff away.
242
00:15:00,290 --> 00:15:02,426
Plait: Over billions of years,
243
00:15:02,427 --> 00:15:04,528
this torrent
of subatomic particles
244
00:15:04,529 --> 00:15:05,894
blasted out from the Sun
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00:15:05,895 --> 00:15:09,231
has stripped the water
out of the atmosphere of Venus
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00:15:09,232 --> 00:15:10,667
and has desiccated it.
247
00:15:10,668 --> 00:15:15,705
Narrator: Our twin,
stripped of its oceans,
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00:15:15,706 --> 00:15:19,442
is a terrifying vision
of our own future.
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00:15:19,443 --> 00:15:24,179
Lanza:
So, if Venus were, in the past,
250
00:15:24,180 --> 00:15:25,515
a lot more Earth-like,
251
00:15:25,516 --> 00:15:29,720
then that tells us
that having a habitable world
252
00:15:29,721 --> 00:15:31,989
is something
that is actually very precious
253
00:15:31,990 --> 00:15:33,222
and maybe is transient.
254
00:15:33,223 --> 00:15:34,559
It's not something
that lasts forever.
255
00:15:36,727 --> 00:15:40,963
Narrator:
But that is just the beginning.
256
00:15:40,964 --> 00:15:42,966
Without its water vapor
to trap heat,
257
00:15:42,967 --> 00:15:46,068
the temperature
stops rising temporarily.
258
00:15:46,069 --> 00:15:48,338
Soon, a new force
259
00:15:48,339 --> 00:15:52,641
will send surface temperatures
rocketing again.
260
00:15:52,642 --> 00:15:56,712
It will become so hot,
261
00:15:56,713 --> 00:15:59,583
metal snow will fall.
262
00:16:06,663 --> 00:16:10,699
Narrator:
Four billion years ago,
263
00:16:10,700 --> 00:16:15,303
Venus and Earth were twins
with oceans.
264
00:16:15,304 --> 00:16:19,674
But soon,
the two planets' paths diverged.
265
00:16:19,675 --> 00:16:22,746
Plait: It's pretty amazing
how different things
266
00:16:22,747 --> 00:16:26,717
must have looked a billion years
after the solar system formed.
267
00:16:28,017 --> 00:16:30,553
The Earth was covered in water,
268
00:16:30,554 --> 00:16:32,889
basically on the path
towards life
269
00:16:32,890 --> 00:16:34,890
and a future as we see it today.
270
00:16:34,891 --> 00:16:39,028
Venus was on a path
away from life,
271
00:16:39,029 --> 00:16:42,664
on a path toward becoming
the hellhole that it is now.
272
00:16:42,665 --> 00:16:48,204
Narrator: The growing sun
burned off Venus' oceans,
273
00:16:48,205 --> 00:16:52,107
for Earth, a terrible omen.
274
00:16:52,108 --> 00:16:53,943
Thaller:
On the planet Venus,
275
00:16:53,944 --> 00:16:56,946
we think there could have been
oceans, lakes, water, and rain.
276
00:16:56,947 --> 00:16:59,616
But all of that came to an end.
277
00:16:59,617 --> 00:17:04,554
That tells you that the Earth's
environment has to change, too.
278
00:17:04,555 --> 00:17:07,923
Nothing is forever.
279
00:17:07,924 --> 00:17:10,292
Plait:
A few billion years ago,
280
00:17:10,293 --> 00:17:11,961
when you looked
in our solar system,
281
00:17:11,962 --> 00:17:13,730
you might have seen two Earths.
282
00:17:13,731 --> 00:17:16,833
Well, a few billion years
from now, in the future,
283
00:17:16,834 --> 00:17:18,535
you might look at
our solar system
284
00:17:18,536 --> 00:17:22,805
and see two venuses.
285
00:17:22,806 --> 00:17:28,144
Narrator: So we can look to
Venus' past and see our future.
286
00:17:28,145 --> 00:17:31,181
We know
that temperatures skyrocketed,
287
00:17:31,182 --> 00:17:35,286
and the scarred surface
hints at why.
288
00:17:39,056 --> 00:17:42,724
In Hawaii, planetary geologist
jani radebaugh
289
00:17:42,725 --> 00:17:45,228
studies the islands' volcanoes.
290
00:17:51,135 --> 00:17:55,173
These volcanoes are
a perfect model for early Venus.
291
00:17:58,075 --> 00:18:02,479
What we're seeing out here
are lava flows
292
00:18:02,480 --> 00:18:05,181
encroaching on
the town of pahoa,
293
00:18:05,182 --> 00:18:08,451
come all the way down
from the pu'u 'o'o vent
294
00:18:08,452 --> 00:18:13,289
which is about 15 miles away.
295
00:18:13,290 --> 00:18:14,757
Oh, there's hot.
You can see that hot stuff.
296
00:18:14,758 --> 00:18:16,494
You can see hot.
Quick, quick, quick, quick.
297
00:18:16,495 --> 00:18:18,827
Right there.
298
00:18:18,828 --> 00:18:21,231
It's really beautiful.
299
00:18:21,232 --> 00:18:24,901
Narrator:
Hawaii's volcanic lava fields
300
00:18:24,902 --> 00:18:27,138
look like Venus in miniature.
301
00:18:30,307 --> 00:18:33,510
Both produce
the same kind of runny lava,
302
00:18:33,511 --> 00:18:37,379
building flat,
shield-like volcanoes.
303
00:18:37,380 --> 00:18:39,316
The big difference
304
00:18:39,317 --> 00:18:45,921
is there are only
five active volcanoes on Hawaii.
305
00:18:45,922 --> 00:18:49,658
Venus is covered in them.
306
00:18:49,659 --> 00:18:53,163
Grinspoon: One thing that really
jumps out all around the planet
307
00:18:53,164 --> 00:18:57,299
is the number and variety
of volcanoes.
308
00:18:57,300 --> 00:18:59,935
I mean, Venus could almost be
nicknamed "volcano world."
309
00:18:59,936 --> 00:19:05,008
Venus has tens of thousands of
volcanoes all over the planet.
310
00:19:07,511 --> 00:19:10,914
Narrator:
But it's not the erupting lava
311
00:19:10,915 --> 00:19:12,781
that turns up the heat.
312
00:19:12,782 --> 00:19:14,951
It's what comes out with it.
313
00:19:14,952 --> 00:19:18,620
Radebaugh: When you think back
to the histories of Venus,
314
00:19:18,621 --> 00:19:20,122
I think we must have seen
a landscape
315
00:19:20,123 --> 00:19:21,991
very similar to this one,
316
00:19:21,992 --> 00:19:24,027
where you have
massive amounts of lava
317
00:19:24,028 --> 00:19:25,429
flowing out of the surface,
318
00:19:25,430 --> 00:19:28,129
dumping huge amounts of gases
into the atmosphere,
319
00:19:28,130 --> 00:19:30,833
carbon dioxide, tons of the gas
into the atmosphere
320
00:19:30,834 --> 00:19:31,868
every single day.
321
00:19:31,869 --> 00:19:35,239
It would have been amazing
to see.
322
00:19:40,376 --> 00:19:42,578
Narrator:
Up close on the surface,
323
00:19:42,579 --> 00:19:45,415
jani can see
the origin of the gases.
324
00:19:47,417 --> 00:19:48,984
Radebaugh:
If we look behind us,
325
00:19:48,985 --> 00:19:52,555
we can see volcanic gases
gushing out of steam vents.
326
00:19:52,556 --> 00:19:55,058
We've got carbon dioxide being
delivered to the atmosphere.
327
00:19:55,059 --> 00:19:57,094
It's exactly like
what has happened on Venus.
328
00:19:59,530 --> 00:20:02,597
Carbon dioxide has been
delivered out of volcanoes
329
00:20:02,598 --> 00:20:05,568
over and over and over again
throughout its history
330
00:20:05,569 --> 00:20:07,903
so that now we have
331
00:20:07,904 --> 00:20:13,108
just a tremendously thick,
dense atmosphere.
332
00:20:13,109 --> 00:20:15,978
The net result
of all of these volcanic gases
333
00:20:15,979 --> 00:20:19,382
pouring out of volcanoes,
major greenhouse gases,
334
00:20:19,383 --> 00:20:21,419
is that they have been
absorbing heat
335
00:20:21,420 --> 00:20:23,818
for billions of years
of the history of Venus.
336
00:20:23,819 --> 00:20:26,256
The temperature
has been gradually creeping up
337
00:20:26,257 --> 00:20:30,628
until, today, the surface
of Venus is 900 degrees.
338
00:20:32,662 --> 00:20:34,265
Plait: It's like if you go
into your kitchen
339
00:20:34,266 --> 00:20:36,298
and set your oven to broil,
340
00:20:36,299 --> 00:20:38,800
wait a couple of minutes
and stick your head in it,
341
00:20:38,801 --> 00:20:41,002
and even that's
not quite hot enough.
342
00:20:41,003 --> 00:20:47,477
It's a crazy, horrible,
hellish spot.
343
00:20:49,980 --> 00:20:53,317
Narrator: It's hard to imagine
such extreme temperatures.
344
00:20:55,886 --> 00:20:58,187
But probes orbiting the planet
345
00:20:58,188 --> 00:21:02,525
revealed just how insanely hot
it is.
346
00:21:03,793 --> 00:21:05,728
Scientists studying the images
347
00:21:05,729 --> 00:21:09,132
noticed something strange
on the planet's mountains.
348
00:21:09,133 --> 00:21:13,234
It looks like, on the mountains,
349
00:21:13,235 --> 00:21:15,105
that there's apparently
snow-like structures.
350
00:21:17,241 --> 00:21:19,808
Narrator: But this is not like
351
00:21:19,809 --> 00:21:22,110
any snow found on Earth.
352
00:21:22,111 --> 00:21:26,315
So, if you look at the
white-peaked mountains of Venus,
353
00:21:26,316 --> 00:21:27,918
you would think
that it was snow,
354
00:21:27,919 --> 00:21:30,051
but it's actually metals
that have rained down
355
00:21:30,052 --> 00:21:32,389
and deposited
on the top of those mountains.
356
00:21:35,192 --> 00:21:39,761
Narrator: Metals like
bismuth and lead melt.
357
00:21:39,762 --> 00:21:43,800
Then they evaporate
into the atmosphere.
358
00:21:46,803 --> 00:21:48,904
As they rise, they cool
359
00:21:48,905 --> 00:21:53,643
until they finally fall
like snow on the mountaintops.
360
00:21:53,644 --> 00:21:57,480
I'm not sure
even the imagination
361
00:21:57,481 --> 00:21:58,981
of science-fiction authors
would have come up
362
00:21:58,982 --> 00:22:00,148
with something
as weird as Venus.
363
00:22:00,149 --> 00:22:01,916
I mean, just think about that.
364
00:22:01,917 --> 00:22:05,087
You have possibly metal frost
on the top of mountains.
365
00:22:05,088 --> 00:22:06,623
I mean, how weird is that?
366
00:22:06,624 --> 00:22:08,856
It's pretty insane.
Raining metals.
367
00:22:08,857 --> 00:22:11,661
Where would you ever think
about that existing?
368
00:22:11,662 --> 00:22:13,197
On Venus.
369
00:22:16,199 --> 00:22:17,533
Narrator: In the future,
370
00:22:17,534 --> 00:22:20,136
metallic snow
is forecast for Earth, too.
371
00:22:20,137 --> 00:22:23,673
And our scorching mountain caps
372
00:22:23,674 --> 00:22:27,743
will glitter like Venus.
373
00:22:27,744 --> 00:22:31,447
But Venus tells us
374
00:22:31,448 --> 00:22:35,518
that things will get even worse.
375
00:22:38,888 --> 00:22:44,160
The atmosphere will grow
heavy enough to crush cars.
376
00:22:54,500 --> 00:22:56,635
Narrator: Earth and Venus
were born twins,
377
00:22:56,636 --> 00:22:59,037
but they took different paths.
378
00:22:59,038 --> 00:23:03,778
Earth slowly evolved
into a habitable world.
379
00:23:07,614 --> 00:23:11,249
Venus was covered
in thick volcanic gases,
380
00:23:11,250 --> 00:23:12,918
trapping the Sun's heat.
381
00:23:12,919 --> 00:23:16,557
Temperatures rose
to 900 degrees.
382
00:23:22,028 --> 00:23:23,595
Extreme temperatures
383
00:23:23,596 --> 00:23:26,866
weren't the only problem
on Venus' surface.
384
00:23:29,303 --> 00:23:32,904
The thick clouds of gas
kept on building up.
385
00:23:32,905 --> 00:23:38,745
A 155-mile-deep
layer of carbon dioxide
386
00:23:38,746 --> 00:23:41,447
piles up around the planet.
387
00:23:41,448 --> 00:23:43,983
We don't think about gases
as weighing anything,
388
00:23:43,984 --> 00:23:45,084
but they actually do.
389
00:23:45,085 --> 00:23:48,086
Narrator:
Trillions and trillions of tons
390
00:23:48,087 --> 00:23:50,456
of gas press downwards.
391
00:23:50,457 --> 00:23:54,693
There is simply
so much air on Venus
392
00:23:54,694 --> 00:23:56,796
that, on the surface,
it's pushing down
393
00:23:56,797 --> 00:23:58,230
with a huge amount of force.
394
00:23:58,231 --> 00:24:00,833
Well, atmospheric pressure
on Venus is a monster.
395
00:24:00,834 --> 00:24:02,236
Think about it this way.
396
00:24:03,803 --> 00:24:06,037
All right, car.
397
00:24:06,038 --> 00:24:07,674
It's time
for you to be crushed, baby.
398
00:24:14,381 --> 00:24:16,316
If you're on Venus,
you're gonna have
399
00:24:16,317 --> 00:24:19,285
155 miles of atmosphere
above your head.
400
00:24:19,286 --> 00:24:20,518
As a result,
401
00:24:20,519 --> 00:24:23,956
atmospheric pressure
is 90 times that on Earth.
402
00:24:23,957 --> 00:24:30,196
So, on Earth, there's about
14.6 pounds per square inch.
403
00:24:30,197 --> 00:24:34,168
On Venus, we're talking about
1,300 pounds per square inch.
404
00:24:34,169 --> 00:24:37,001
So, if you're driving your car
on Venus,
405
00:24:37,002 --> 00:24:40,073
this is what might happen.
406
00:24:42,875 --> 00:24:45,411
Narrator: The crusher delivers
the same force
407
00:24:45,412 --> 00:24:48,447
as the weight
of Venus' atmosphere.
408
00:24:48,448 --> 00:24:51,118
This is pretty serious stuff.
409
00:24:57,223 --> 00:25:00,093
And this is why
it's so hard on Venus.
410
00:25:00,094 --> 00:25:01,594
You get down to the surface,
411
00:25:01,595 --> 00:25:04,131
you have the crushing atmosphere
to deal with.
412
00:25:12,873 --> 00:25:14,539
Narrator:
The extreme pressure and heat
413
00:25:14,540 --> 00:25:19,345
make Venus
nearly impossible to explore.
414
00:25:23,916 --> 00:25:29,188
Only one nation has ever gotten
a probe to the planet's surface.
415
00:25:30,457 --> 00:25:34,427
Truly, one of the engineering
triumphs of the human race
416
00:25:34,428 --> 00:25:36,397
was the Soviet union's
venera program.
417
00:25:36,398 --> 00:25:40,399
The Russians sent over a dozen
probes to the planet Venus.
418
00:25:40,400 --> 00:25:43,402
And only a few of them
were able to survive long enough
419
00:25:43,403 --> 00:25:46,872
to even be able to take pictures
from the surface.
420
00:25:46,873 --> 00:25:49,776
Lanza: The venera missions
were incredible.
421
00:25:49,777 --> 00:25:53,813
It's such a hostile environment
on the surface for electronics.
422
00:25:53,814 --> 00:25:57,384
And they were able to land
on the surface and survive.
423
00:25:59,720 --> 00:26:02,322
Narrator: The probe
that sent back these images
424
00:26:02,323 --> 00:26:05,826
was crushed and burnt out
in 90 minutes.
425
00:26:08,561 --> 00:26:09,929
Some day in the future,
426
00:26:09,930 --> 00:26:12,666
there are going to be
interplanetary tour guides
427
00:26:12,667 --> 00:26:14,967
taking people to every planet
in the solar system.
428
00:26:14,968 --> 00:26:18,037
And you can imagine going
to saturn and seeing the rings
429
00:26:18,038 --> 00:26:19,938
and Jupiter
and it's panoply of moons.
430
00:26:19,939 --> 00:26:21,908
There are all
these great tourist attractions
431
00:26:21,909 --> 00:26:23,642
in the solar system.
432
00:26:23,643 --> 00:26:27,079
At the very bottom of that list
is Venus.
433
00:26:27,080 --> 00:26:29,681
That is the last place
in the solar system
434
00:26:29,682 --> 00:26:31,352
I would ever want to visit.
435
00:26:33,553 --> 00:26:35,688
Narrator: The sun's heat
and volcanic gases
436
00:26:35,689 --> 00:26:39,526
have transformed Venus
into a nightmarish world.
437
00:26:45,499 --> 00:26:49,036
So, why hasn't Earth
followed the same path?
438
00:26:50,804 --> 00:26:54,073
Our volcanoes
also spew out carbon dioxide.
439
00:26:54,074 --> 00:26:57,811
And we orbit around
the same sun.
440
00:27:00,381 --> 00:27:02,182
We're not being
crushed and broiled.
441
00:27:05,751 --> 00:27:09,622
That's because Earth formed
farther away from the Sun,
442
00:27:09,623 --> 00:27:14,058
staying cool enough
to hold on to its oceans.
443
00:27:14,059 --> 00:27:16,428
Grinspoon: Oceans do
a lot of things for us on Earth
444
00:27:16,429 --> 00:27:18,764
because not only, obviously,
are we water creatures,
445
00:27:18,765 --> 00:27:22,434
and we depend on the water cycle
for our existence
446
00:27:22,435 --> 00:27:23,568
in so many ways,
447
00:27:23,569 --> 00:27:25,871
but people don't realize
the oceans also help
448
00:27:25,872 --> 00:27:27,673
to regulate
the climate of Earth.
449
00:27:30,943 --> 00:27:33,344
Narrator: Our oceans
are full of tiny creatures
450
00:27:33,345 --> 00:27:35,481
that eat carbon dioxide.
451
00:27:41,688 --> 00:27:44,957
Richard zeebe
from the university of Hawaii
452
00:27:44,958 --> 00:27:48,961
is diving on
the island's coral reefs.
453
00:27:52,298 --> 00:27:55,401
He's studying
how tiny marine organisms
454
00:27:55,402 --> 00:27:57,671
turn carbon dioxide into rock.
455
00:28:05,178 --> 00:28:08,413
Zeebe: What you see here
as this white stuff,
456
00:28:08,414 --> 00:28:10,582
this is what we call
calcium carbonate.
457
00:28:10,583 --> 00:28:13,085
And on top of this, where
you see these brown layers,
458
00:28:13,086 --> 00:28:15,854
this is essentially
the living organism.
459
00:28:15,855 --> 00:28:17,556
This is the coral itself.
460
00:28:17,557 --> 00:28:19,423
It takes calcium
out of the seawater
461
00:28:19,424 --> 00:28:21,425
and takes carbonate
out of the seawater,
462
00:28:21,426 --> 00:28:25,331
combines them and makes
this piece of calcium carbonate.
463
00:28:29,602 --> 00:28:32,971
Narrator: There's over
70 million billion tons
464
00:28:32,972 --> 00:28:38,643
of carbon
locked up in carbonate rocks.
465
00:28:38,644 --> 00:28:41,681
This helps regulate
carbon dioxide levels
466
00:28:41,682 --> 00:28:45,351
in the atmosphere, keeping
temperatures from rising.
467
00:28:45,352 --> 00:28:49,520
If all the carbon that is being
locked up in carbonate rocks
468
00:28:49,521 --> 00:28:53,424
in these corals would be
put into the atmosphere as co2,
469
00:28:53,425 --> 00:28:55,328
that would be
certainly bad news for us.
470
00:28:58,730 --> 00:29:00,600
Narrator:
Currently, our carbon cycle
471
00:29:00,601 --> 00:29:02,567
helps stabilize our climate.
472
00:29:02,568 --> 00:29:08,474
But in the future,
this won't be able to save us.
473
00:29:12,679 --> 00:29:15,983
Forces far greater
than the ones at work on Earth
474
00:29:15,984 --> 00:29:20,184
will overpower our systems.
475
00:29:20,185 --> 00:29:25,356
Like Venus,
our oceans will burn off.
476
00:29:25,357 --> 00:29:28,125
Temperatures will rocket
477
00:29:28,126 --> 00:29:31,597
as our live-giving sun
becomes a monster.
478
00:29:41,500 --> 00:29:43,035
Narrator:
Venus' hellish landscape
479
00:29:43,036 --> 00:29:46,736
is a glimpse
into Earth's future.
480
00:29:46,737 --> 00:29:48,705
Thaller:
There will be no more rain.
481
00:29:48,706 --> 00:29:50,206
There will be no more oceans.
482
00:29:50,207 --> 00:29:53,109
This wonderful, life-friendly
environment we enjoy now
483
00:29:53,110 --> 00:29:56,146
just won't be here in some
hundreds of millions of years.
484
00:29:56,147 --> 00:30:03,354
Plait: Earth could be
an unimaginably terrible place.
485
00:30:03,355 --> 00:30:05,923
Narrator: Right now,
486
00:30:05,924 --> 00:30:08,460
we live just the right distance
from the Sun,
487
00:30:08,461 --> 00:30:11,395
where it's just
the right temperature
488
00:30:11,396 --> 00:30:14,899
for water to exist as a liquid.
489
00:30:16,701 --> 00:30:20,672
But that's going to change,
just as it did for Venus.
490
00:30:20,673 --> 00:30:24,875
Grinspoon: Venus started off,
probably, in the habitable zone.
491
00:30:24,876 --> 00:30:28,579
And then the inner limit
of the habitable zone crossed
492
00:30:28,580 --> 00:30:30,580
the distance of Venus' orbit.
493
00:30:30,581 --> 00:30:33,350
Well, it's gonna cross the
distance of Earth's orbit, too.
494
00:30:33,351 --> 00:30:35,618
There is an expiration date
to the Earth.
495
00:30:35,619 --> 00:30:37,755
And that's due
to the Sun's evolution.
496
00:30:39,957 --> 00:30:44,360
Narrator: Ever since its birth,
the Sun has been getting hotter.
497
00:30:44,361 --> 00:30:49,067
That increased heat
devastated Venus.
498
00:30:49,068 --> 00:30:54,236
And, in the future,
it will destroy Earth.
499
00:30:54,237 --> 00:30:58,108
In 1.1 billion years,
500
00:30:58,109 --> 00:31:02,513
the Sun is 10% hotter
than it is today.
501
00:31:03,647 --> 00:31:07,050
The oceans start to evaporate
into thick clouds,
502
00:31:07,051 --> 00:31:10,987
which trap
more of the Sun's heat.
503
00:31:10,988 --> 00:31:14,425
Catastrophically, very rapidly
on a geological time scale,
504
00:31:14,426 --> 00:31:17,828
the oceans will put so much
water vapor into the atmosphere
505
00:31:17,829 --> 00:31:20,263
that we will get
a runaway greenhouse effect.
506
00:31:20,264 --> 00:31:21,698
[ Thunder rumbles ]
507
00:31:21,699 --> 00:31:23,600
Narrator: The clouds
forming in the atmosphere
508
00:31:23,601 --> 00:31:25,336
trap more and more heat,
509
00:31:25,337 --> 00:31:27,606
driving temperatures
even higher.
510
00:31:35,312 --> 00:31:38,549
Spiraling temperatures
cause more evaporation,
511
00:31:38,550 --> 00:31:41,518
so the clouds get thicker.
512
00:31:41,519 --> 00:31:46,156
Which led to more heating,
which led to more evaporation.
513
00:31:46,157 --> 00:31:48,224
And you can see
where this is going.
514
00:31:48,225 --> 00:31:50,828
It's a vicious cycle.
It's a positive feedback.
515
00:31:50,829 --> 00:31:54,098
Plait: All of the ocean's water
will boil away,
516
00:31:54,099 --> 00:31:55,966
millions of cubic miles of it.
517
00:31:55,967 --> 00:32:00,204
We have all of this water that
will go into the atmosphere,
518
00:32:00,205 --> 00:32:03,207
covering the Earth and shrouding
it in, basically, steam.
519
00:32:08,478 --> 00:32:11,749
Narrator: Earth has had oceans
for billions of years,
520
00:32:11,750 --> 00:32:16,620
but it could lose them
in just 10,000.
521
00:32:16,621 --> 00:32:19,756
Krauss: All of the water
in the Earth's oceans
522
00:32:19,757 --> 00:32:21,024
will be in the atmosphere.
523
00:32:21,025 --> 00:32:23,961
We'll have an incredibly dense
cloud cover system
524
00:32:23,962 --> 00:32:25,796
where the temperatures on Earth
525
00:32:25,797 --> 00:32:28,066
will be approaching
1,000 degrees.
526
00:32:28,067 --> 00:32:31,569
Narrator:
Like Venus in the past,
527
00:32:31,570 --> 00:32:35,740
Earth will get
hotter and hotter.
528
00:32:35,741 --> 00:32:40,077
But unlike Venus,
which topped out at 900 degrees,
529
00:32:40,078 --> 00:32:43,482
temperatures on Earth
will keep climbing.
530
00:32:46,417 --> 00:32:52,455
Venus lost its water to space,
blasted away by the solar wind.
531
00:32:52,456 --> 00:32:55,993
But Earth holds on to its water.
532
00:32:55,994 --> 00:32:59,996
It's protected
by our magnetic shield.
533
00:32:59,997 --> 00:33:03,768
But that is no longer
a good thing.
534
00:33:03,769 --> 00:33:05,035
[ Humming ]
535
00:33:05,036 --> 00:33:07,104
Unlike Venus, Earth has
a strong magnetic field
536
00:33:07,105 --> 00:33:09,973
which protects it from
the erosion of the solar wind.
537
00:33:09,974 --> 00:33:12,342
That water will stay with us.
538
00:33:12,343 --> 00:33:17,181
The Earth could have a thicker,
hotter greenhouse atmosphere
539
00:33:17,182 --> 00:33:20,983
than Venus does today,
much worse.
540
00:33:20,984 --> 00:33:23,153
[ Thunder rumbles ]
541
00:33:23,154 --> 00:33:25,256
Narrator: This huge volume
of water vapor
542
00:33:25,257 --> 00:33:29,259
all pushes down on the surface,
543
00:33:29,260 --> 00:33:33,030
around 4,000 pounds.
544
00:33:33,031 --> 00:33:36,399
That's the weight
of the average American car
545
00:33:36,400 --> 00:33:41,871
pressing down
on every square inch of Earth.
546
00:33:41,872 --> 00:33:45,509
Surface pressure
goes through the roof,
547
00:33:45,510 --> 00:33:48,912
reaching 270 times higher
than today.
548
00:33:48,913 --> 00:33:53,251
It is ironic to think
that the water on Earth
549
00:33:53,252 --> 00:33:56,153
will one day help contribute
to its demise
550
00:33:56,154 --> 00:33:58,757
after all the water has been
the source of life on Earth.
551
00:33:58,758 --> 00:34:03,995
But, in the far future,
it'll become our enemy.
552
00:34:10,367 --> 00:34:13,369
Narrator: And with no oceans
and their microscopic creatures
553
00:34:13,370 --> 00:34:16,038
to absorb the carbon dioxide,
554
00:34:16,039 --> 00:34:18,709
there's no way back
for the Earth.
555
00:34:27,785 --> 00:34:29,987
In 1.2 billion years,
556
00:34:29,988 --> 00:34:36,259
a probe visiting Earth
would see an alien world,
557
00:34:36,260 --> 00:34:38,996
a scorched, barren landscape.
558
00:34:41,631 --> 00:34:45,668
The pressure is crushing.
559
00:34:45,669 --> 00:34:49,973
Temperatures reach
1,200 degrees.
560
00:34:49,974 --> 00:34:54,878
Molten metals
snow down on the mountaintops.
561
00:34:54,879 --> 00:35:01,750
It's so hot, granite rock melts.
562
00:35:01,751 --> 00:35:06,991
The surface liquefies.
563
00:35:06,992 --> 00:35:09,659
At that point, the Earth
will become a molten ball
564
00:35:09,660 --> 00:35:12,329
very similar to what it was
at the very beginning.
565
00:35:12,330 --> 00:35:17,099
Narrator: Earth and Venus
started as twins.
566
00:35:17,100 --> 00:35:22,239
Venus was destroyed
by rampant global warming.
567
00:35:22,240 --> 00:35:27,911
Earth will follow the same path,
then overtake it.
568
00:35:27,912 --> 00:35:30,848
It is inevitable
that the Earth will someday
569
00:35:30,849 --> 00:35:34,285
not only be like Venus,
but actually put it to shame.
570
00:35:39,490 --> 00:35:44,293
Narrator: In 1.3 billion years,
Earth could hit 3,600 degrees,
571
00:35:44,294 --> 00:35:47,998
four times hotter than Venus.
572
00:35:47,999 --> 00:35:51,735
It will be
the hottest and deadliest planet
573
00:35:51,736 --> 00:35:53,571
in our solar system.
574
00:35:58,809 --> 00:36:02,679
For Earth and its inhabitants,
it's the end of the road.
575
00:36:02,680 --> 00:36:05,681
We could never survive
the extreme temperatures
576
00:36:05,682 --> 00:36:07,618
or the crushing pressure.
577
00:36:07,619 --> 00:36:12,857
Maybe we'll escape to space.
578
00:36:12,858 --> 00:36:19,496
But there's one absolutely
crazy way we could stay here...
579
00:36:19,497 --> 00:36:25,336
Move our planet
further away from the Sun.
580
00:36:34,000 --> 00:36:36,436
Narrator: Earth of the future
will become
581
00:36:36,437 --> 00:36:40,440
the most inhospitable planet
in the solar system.
582
00:36:40,441 --> 00:36:45,211
Its oceans will boil off,
and its surface will melt.
583
00:36:45,212 --> 00:36:47,545
A billion years from now,
584
00:36:47,546 --> 00:36:51,950
Earth could be
an unimaginably terrible place.
585
00:36:51,951 --> 00:36:56,356
Right now, today,
Venus is the evil twin of Earth.
586
00:36:56,357 --> 00:36:57,992
But in the distance future,
587
00:36:57,993 --> 00:37:00,592
Earth could be
the evil twin of Venus.
588
00:37:00,593 --> 00:37:02,827
Narrator:
Earth's surface temperatures
589
00:37:02,828 --> 00:37:05,463
will reach 3,600 degrees
590
00:37:05,464 --> 00:37:10,970
with pressures 270 times greater
than today.
591
00:37:10,971 --> 00:37:12,237
Plait:
At these kind of temperatures,
592
00:37:12,238 --> 00:37:15,775
where rock on the surface
of the Earth is molten,
593
00:37:15,776 --> 00:37:18,613
it's hard to imagine
any place there could be life.
594
00:37:21,381 --> 00:37:24,985
Narrator: But there is hope.
595
00:37:27,955 --> 00:37:30,822
Astrobiologist
Lewis dartnell thinks
596
00:37:30,823 --> 00:37:33,726
that some forms of life
could survive
597
00:37:33,727 --> 00:37:36,329
such terrible conditions.
598
00:37:36,330 --> 00:37:40,967
We're here on top of
a volcanic outcrop in Iceland
599
00:37:40,968 --> 00:37:44,103
with this howling Gale
whistling past our ears,
600
00:37:44,104 --> 00:37:47,438
the stench of hydrogen sulfide,
of sulfurous fumes,
601
00:37:47,439 --> 00:37:49,608
filling our nostrils.
602
00:37:49,609 --> 00:37:52,077
And this is about as close
as you get can on Earth
603
00:37:52,078 --> 00:37:55,113
to high up
in the venusian atmosphere.
604
00:37:55,114 --> 00:37:58,985
About 30, 35 miles above
the surface of the planet Venus,
605
00:37:58,986 --> 00:38:01,519
the air pressure
is about the same
606
00:38:01,520 --> 00:38:03,389
as on the Earth's surface.
607
00:38:03,390 --> 00:38:06,458
The temperature
is pretty similar, as well.
608
00:38:06,459 --> 00:38:10,630
But the cloud droplets are full
of concentrated sulfuric acid,
609
00:38:10,631 --> 00:38:14,934
many, many times more
concentrated than battery acid.
610
00:38:14,935 --> 00:38:18,137
It's a hostile,
horrible environment.
611
00:38:18,138 --> 00:38:19,938
But bizarrely enough,
612
00:38:19,939 --> 00:38:22,441
there's good reasons
to think that there may be life,
613
00:38:22,442 --> 00:38:25,344
venusian life,
high up in the clouds
614
00:38:25,345 --> 00:38:29,049
that are kind of
high-altitude aerial biosphere.
615
00:38:31,651 --> 00:38:34,619
Narrator: High above Venus,
there are nutrients,
616
00:38:34,620 --> 00:38:38,891
solar energy,
and traces of water.
617
00:38:38,892 --> 00:38:44,295
If life can live up there,
then perhaps it might survive
618
00:38:44,296 --> 00:38:48,934
high up in the clouds
of future Earth.
619
00:38:48,935 --> 00:38:52,037
You can easily imagine these
micro-organisms evaporating
620
00:38:52,038 --> 00:38:54,373
in water particles
and being transported
621
00:38:54,374 --> 00:38:55,775
to the upper atmosphere.
622
00:38:55,776 --> 00:39:01,313
Even though it turned into
this toxic greenhouse planet,
623
00:39:01,314 --> 00:39:03,449
life could potentially
still survive
624
00:39:03,450 --> 00:39:06,985
in that upper atmosphere.
625
00:39:06,986 --> 00:39:10,356
Narrator: But what about us?
626
00:39:10,357 --> 00:39:13,159
We couldn't survive
the high temperatures
627
00:39:13,160 --> 00:39:14,594
or pressures at the surface.
628
00:39:14,595 --> 00:39:18,496
And a life in the clouds
doesn't seem likely.
629
00:39:18,497 --> 00:39:21,233
What's our future?
630
00:39:21,234 --> 00:39:24,470
Oluseyi:
If there was this life on Venus,
631
00:39:24,471 --> 00:39:26,706
clearly,
they weren't advanced enough
632
00:39:26,707 --> 00:39:29,041
to stop the changes
in their atmosphere
633
00:39:29,042 --> 00:39:31,110
that led
to Venus' current state.
634
00:39:31,111 --> 00:39:32,546
The question is, are we?
635
00:39:39,886 --> 00:39:42,887
Narrator:
Maybe we'll leave our planet
636
00:39:42,888 --> 00:39:44,524
and find a new home.
637
00:39:51,165 --> 00:39:55,901
But there is
a more outlandish solution...
638
00:39:55,902 --> 00:40:00,106
Stay on Earth and move it
farther from the Sun.
639
00:40:00,107 --> 00:40:05,077
Moving the Earth is at least
imaginable because, in fact,
640
00:40:05,078 --> 00:40:07,246
as objects exchange
gravitational energy,
641
00:40:07,247 --> 00:40:09,382
they move in or out
in the solar system.
642
00:40:09,383 --> 00:40:11,050
It's happened to our planet.
643
00:40:11,051 --> 00:40:13,353
So I could imagine
engineering things
644
00:40:13,354 --> 00:40:16,021
where we directed
large asteroids and comets
645
00:40:16,022 --> 00:40:20,392
close to the Earth,
but not to hit it.
646
00:40:20,393 --> 00:40:23,862
Narrator: The gravity
from these large objects
647
00:40:23,863 --> 00:40:25,999
would slowly alter our orbit.
648
00:40:26,000 --> 00:40:29,568
Krauss: Gravitational energy
would be exchanged,
649
00:40:29,569 --> 00:40:33,371
and the Earth could slowly
move out.
650
00:40:33,372 --> 00:40:36,708
Narrator:
Each gravitational jolt
651
00:40:36,709 --> 00:40:40,545
would only move Earth
a short distance.
652
00:40:40,546 --> 00:40:44,516
But do it thousands
or millions of times,
653
00:40:44,517 --> 00:40:48,820
and we could push the Earth
away from the Sun,
654
00:40:48,821 --> 00:40:50,789
in theory, at least.
655
00:40:50,790 --> 00:40:54,193
Over a billion-year period,
it's possible to imagine.
656
00:40:54,194 --> 00:40:56,764
It would require
incredible technology
657
00:40:56,765 --> 00:40:58,565
and incredible coordination.
658
00:40:58,566 --> 00:41:00,132
The technology is possible.
659
00:41:00,133 --> 00:41:03,235
Whether humanity as a species
could ever coordinate it
660
00:41:03,236 --> 00:41:05,137
is something I'm a little more
skeptical about.
661
00:41:05,138 --> 00:41:10,376
Narrator: It's a crazy option,
but if we don't do something,
662
00:41:10,377 --> 00:41:14,179
Earth and all of us will die,
663
00:41:14,180 --> 00:41:16,917
and we'll become
just like Venus.
664
00:41:21,620 --> 00:41:23,521
Earth and Venus
were probably born together
665
00:41:23,522 --> 00:41:26,291
as identical twins,
but then their paths diverged.
666
00:41:26,292 --> 00:41:29,494
But now, lifetime is gonna send
that cycle all the way back,
667
00:41:29,495 --> 00:41:31,831
and they'll die
as identical twins again.
668
00:41:31,832 --> 00:41:35,633
Narrator:
In the grand scheme of things,
669
00:41:35,634 --> 00:41:38,202
they'll just be
two charred twins
670
00:41:38,203 --> 00:41:44,709
spinning to oblivion in
a backwater of the universe.
671
00:41:44,710 --> 00:41:51,550
On the cosmic scale,
life is short.
672
00:41:51,551 --> 00:41:56,021
When you look at how Earth
evolved and how Venus evolved,
673
00:41:56,022 --> 00:41:57,856
you can see the difference,
674
00:41:57,857 --> 00:42:01,293
even though
it's two almost twin planets,
675
00:42:01,294 --> 00:42:05,030
how life and habitability
could change over time.
676
00:42:05,031 --> 00:42:09,467
So, habitability
isn't always a permanent thing.
677
00:42:09,468 --> 00:42:12,237
Krauss: On human scales,
678
00:42:12,238 --> 00:42:15,374
the universe seems the same
every single day.
679
00:42:15,375 --> 00:42:16,608
But, of course,
680
00:42:16,609 --> 00:42:20,146
that's because human life
and human civilization
681
00:42:20,147 --> 00:42:23,048
is but a brief instant
in cosmic time.
682
00:42:23,049 --> 00:42:28,054
On cosmic scales, the universe
evolves and changes,
683
00:42:28,055 --> 00:42:31,692
and that makes the history
of the universe remarkable.
684
00:42:33,993 --> 00:42:37,630
Narrator: Our tale of two
planets converges in the end,
685
00:42:37,631 --> 00:42:45,170
a cautionary tale
about forces beyond our control.
686
00:42:45,171 --> 00:42:50,742
Maybe a billion years
of learning from Venus
687
00:42:50,743 --> 00:42:56,016
will ultimately save us
from the same terrible fate.
688
00:42:56,066 --> 00:43:00,616
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