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It`s Okay To Be Smart, Is There Life on Earth?

Is There Life on Earth?

Hey Smart People, Joe here.

Yes.

The answer to the question in the title of this video… is YES.

There is life on Earth.

We know that because, well we live here.

But what would we think if we were looking at Earth from 6 million km away?

That's the distance from which Voyager 1 captured this image on February 14, 1990;

all the complexity of our living planet summed up in a single pixel of bluish light.

Now, if one day some extraterrestrials download that image off of Voyager, how would they

be able to tell there's life on Earth, based on… that?

This is the question we face as we get ready to aim the most powerful telescopes ever built

at distant worlds outside our solar system.

If we're gonna search for signs of life… what exactly are we searching for?

Since the discovery of the first exoplanet–a planet orbiting a star outside our own solar

system–in 1992, we've confirmed the existence of almost 4,000 distant worlds.

Scientists think every star in the sky may host at least one planet of its own.

More than 2,000 exoplanets were discovered by the Kepler Space Telescope–moment of

silence.

Never going to forget you.

Looking at artistic renditions of these alien worlds, if you didn't know better, you might

think we can just point a big telescope at an exoplanet and snap an image of it.

But Kepler's raw data looks less like this, and more like this.

Kepler would stare at one spot in the sky, looking for stars that dimmed as an exoplanet

crossed in front of them, blocking some of their light.

By putting together a bunch of data like the size of the star, how much light is blocked,

how often the planet passes in front, then we can estimate the size and mass of the exoplanet.

And if you know how big something is and you know its mass, you know its density, like

if it's a gassy planet or a rocky one.

And because we've studied how orbits work in our own solar system, that same data can

tell us how far an exoplanet orbits from its star.

Finally, if we measure how hot a star is (by looking at the color of its light), we can

tell if a planet has the right conditions where liquid water, or as I call it… “life

juice”… *could* exist on its surface.

Based on all this, we've learned some exoplanets are tiny ice-Earths, some are these big warm

Neptunes, even hot Jupiters… and only some are potentially habitable.

But there's a big difference between could have life and does have life… to tell the

difference, we need to see something that could only be made by life.

I'm not talking intelligent life, or even complex life.

The tiniest puddle of replicating pond scum on an exoplanet would still be the biggest

discovery we've ever made, ever, about anything.

We need to find… biosignatures.

So, a “biosignature” is like a chemical fossil.

Something we can see that must be produced by life, and–this is important–it can't

be made by some natural process.

So what the heck counts as a biosignature?

Voyager 1's “Pale Blue Dot” is the Earth-selfie Carl Sagan is famous for, but he had a different

one taken a few years later that not many people know about.

In 1993, as the Galileo spacecraft passed by Earth on its way to Jupiter, it turned

its sensors towards our home planet, to ask “if we had no previous knowledge of whether

Earth was home to life, would we actually be able to detect any of our own biosignatures?”

So, life on Earth has been around for at least three and a half billion years, and biology

has changed the atmosphere in some pretttty BIG ways during that time.

Take these chemicals.

Here's what their levels would be on a dead Earth, versus what they actually are.

Sagan was looking for a kind of “chemical disequilibrium”– basically you look for

chemicals that shouldn't be there, and if you find them, there must be something on

the planet consistently making them.

And when he looked at Earth… he found… water.

Which actually wasn't very hard.

H2O turns out to be one of the most abundant molecules in the universe.

Liquid water is a necessary ingredient for life, but it's not a sign of life.

Galileo also found methane.

Methane breaks down really fast in a planet's atmosphere, so if you find it that means something

is making it.

Here on Earth it's made by microbes and by burping cows–we have a lot of both.

But, there are natural processes that can make methane too, so it doesn't necessarily

mean “life”.

We've also detected methane on Mars, and Saturn's moon Titan has lakes of the stuff.

No sign of life on either of those.

Well how about carbon dioxide?

I'm alive, and I make it… but so do volcanoes.

Not a perfect biosignature.

Ok, what about oxygen?

O2 was incredibly toxic to Earth's earliest life forms, and for the first billion years

of life there wasn't much of it around… until photosynthesis showed up and started

just throwing it away.

Today this previously poisonous photosynthetic trash gives us life.

But not so fast.

You guessed it, there are natural processes that can make O2… too.

Like on super-hot planets, ultraviolet light can break down water, kick out the hydrogen,

and leave oxygen behind.

But the levels of oxygen and methane that the Galileo measured on Earth were way higher

than those natural processes would predict.

This was the “chemical disequilibrium” Sagan was looking for.

But it still wasn't a smoking gun, just suggested life as a possibility.

A maybe.

Sagan did find one other biosignature on Earth that was especially weird.

On lighter areas of the planet's surface–dry land–there were massive areas that absorbed

red light, and just beyond that, into the infrared part of the spectrum, a whole bunch

of light that wasn't absorbed.

Since no rock or mineral that we know of absorbs red light quite like this, the best explanation

was a pigment covering the planet's surface, one that absorbs red light, and hates near-infrared

light.

That pigment?

Well, we know it as chlorophyll.

It absorbs red and blue light, but not other colors, and that's why so much of Earth

is green.

This biosignature is known as the “vegetation red edge”

Since Sagan's little Galileo experiment, scientists have added to the list of possible

biosignatures and they've learned a lot about how we might tell them apart from natural

processes.

In general, we know different chemicals absorb different colors of light.

So if we can somehow measure how an exoplanet's atmosphere filters light from its star, we

can get a fingerprint of all the chemicals in that atmosphere.

Now that we know what to look for, how do we detect these signatures from light years

away?

The best study of Earth-like planets will come from looking at light from the host star

reflected off the planet and filtered by the atmosphere.

Basically the same way we take pictures of Earth today, only much, much, MUCH farther

away.

Thing is, Earth-sized planets are about ten billion times dimmer than their stars, and

exoplanets are separated from their star by *extremely* small angles.

Directly imaging an exoplanet is like trying to see a moth buzzing around a searchlight,

on top of the Eiffel Tower, from New York City.

To do this, astronomers have designed starshades, which can be placed tens of thousands of kilometers

in front of orbiting space telescopes, to precisely block out the star's light and

make the exoplanets visible, the way blocking out a car's headlights with our hand helps

us see at night.

Of course we only know the signs of life as it exists here, the only place we've found

it.

Somewhere else, life may use completely different chemistry, giving off completely different

biosignatures.

And even here on Earth, life hasn't always looked the same.

Back in the ancient Archaean Era, early life forms lived under a cloudy methane haze.

And the first photosynthesizers may have been purple microbes, not green.

This would all be SO much easier if we could just sense some convenient radio signal coming

from an exoplanet, sent by an intelligent technological life form.

But when you consider human technological civilization only covers 0.000002% of our

planet's history, our chances of listening in the right place at the right time are not

great.

We're looking at the very edge of what is technologically possible, so best not to hold

your breath on finding alien life just yet.

Stay curious.

Notice anything different?

Oh yeah, I got a haircut.

Is There Life on Earth? Gibt es Leben auf der Erde? ¿Hay vida en la Tierra? Is er leven op aarde? Existe vida na Terra? Есть ли жизнь на Земле? Dünya'da Yaşam Var mı? 地球上有生命吗? 地球上有生命嗎?

Hey Smart People, Joe here. Olá pessoal inteligente, fala o Joe.

Yes.

The answer to the question in the title of this video… is YES. A resposta à pergunta no título deste vídeo... é SIM.

There is life on Earth. Existe vida na Terra.

We know that because, well we live here. Sabemos isso porque, bem, nós vivemos aqui.

But what would we think if we were looking at Earth from 6 million km away? Mas o que pensaríamos se estivéssemos a olhar para a Terra a 6 milhões de quilómetros de distância?

That's the distance from which Voyager 1 captured this image on February 14, 1990; Foi a essa distância que a Voyager 1 captou esta imagem em 14 de fevereiro de 1990;

all the complexity of our living planet summed up in a single pixel of bluish light. toda a complexidade do nosso planeta vivo resumida num único pixel de luz azulada.

Now, if one day some extraterrestrials download that image off of Voyager, how would they |||||extraterrestrial beings|||||||||

be able to tell there's life on Earth, based on… that?

This is the question we face as we get ready to aim the most powerful telescopes ever built

at distant worlds outside our solar system.

If we're gonna search for signs of life… what exactly are we searching for?

Since the discovery of the first exoplanet–a planet orbiting a star outside our own solar

system–in 1992, we've confirmed the existence of almost 4,000 distant worlds.

Scientists think every star in the sky may host at least one planet of its own.

More than 2,000 exoplanets were discovered by the Kepler Space Telescope–moment of

silence.

Never going to forget you.

Looking at artistic renditions of these alien worlds, if you didn't know better, you might |||interpretations|||||||||||

think we can just point a big telescope at an exoplanet and snap an image of it.

But Kepler's raw data looks less like this, and more like this.

Kepler would stare at one spot in the sky, looking for stars that dimmed as an exoplanet

crossed in front of them, blocking some of their light.

By putting together a bunch of data like the size of the star, how much light is blocked,

how often the planet passes in front, then we can estimate the size and mass of the exoplanet.

And if you know how big something is and you know its mass, you know its density, like

if it's a gassy planet or a rocky one.

And because we've studied how orbits work in our own solar system, that same data can

tell us how far an exoplanet orbits from its star.

Finally, if we measure how hot a star is (by looking at the color of its light), we can

tell if a planet has the right conditions where liquid water, or as I call it… “life

juice”… *could* exist on its surface.

Based on all this, we've learned some exoplanets are tiny ice-Earths, some are these big warm

Neptunes, even hot Jupiters… and only some are potentially habitable. Neptunus, zelfs hete Jupiters... en slechts enkele zijn potentieel bewoonbaar.

But there's a big difference between could have life and does have life… to tell the

difference, we need to see something that could only be made by life.

I'm not talking intelligent life, or even complex life.

The tiniest puddle of replicating pond scum on an exoplanet would still be the biggest Найменша калюжа з реплікованого ставкового мулу на екзопланеті все одно буде найбільшою

discovery we've ever made, ever, about anything.

We need to find… biosignatures. We moeten... biohandtekeningen vinden.

So, a “biosignature” is like a chemical fossil.

Something we can see that must be produced by life, and–this is important–it can't

be made by some natural process.

So what the heck counts as a biosignature?

Voyager 1's “Pale Blue Dot” is the Earth-selfie Carl Sagan is famous for, but he had a different

one taken a few years later that not many people know about.

In 1993, as the Galileo spacecraft passed by Earth on its way to Jupiter, it turned

its sensors towards our home planet, to ask “if we had no previous knowledge of whether

Earth was home to life, would we actually be able to detect any of our own biosignatures?”

So, life on Earth has been around for at least three and a half billion years, and biology

has changed the atmosphere in some pretttty BIG ways during that time. heeft de sfeer in die tijd op een aantal mooie GROTE manieren veranderd.

Take these chemicals.

Here's what their levels would be on a dead Earth, versus what they actually are.

Sagan was looking for a kind of “chemical disequilibrium”– basically you look for ||||||||chemical imbalance|||| Sagan was op zoek naar een soort "chemisch onevenwicht" - eigenlijk zoek je naar

chemicals that shouldn't be there, and if you find them, there must be something on

the planet consistently making them.

And when he looked at Earth… he found… water.

Which actually wasn't very hard.

H2O turns out to be one of the most abundant molecules in the universe.

Liquid water is a necessary ingredient for life, but it's not a sign of life.

Galileo also found methane.

Methane breaks down really fast in a planet's atmosphere, so if you find it that means something

is making it.

Here on Earth it's made by microbes and by burping cows–we have a lot of both.

But, there are natural processes that can make methane too, so it doesn't necessarily

mean “life”.

We've also detected methane on Mars, and Saturn's moon Titan has lakes of the stuff.

No sign of life on either of those.

Well how about carbon dioxide?

I'm alive, and I make it… but so do volcanoes.

Not a perfect biosignature.

Ok, what about oxygen?

O2 was incredibly toxic to Earth's earliest life forms, and for the first billion years

of life there wasn't much of it around… until photosynthesis showed up and started

just throwing it away.

Today this previously poisonous photosynthetic trash gives us life.

But not so fast.

You guessed it, there are natural processes that can make O2… too.

Like on super-hot planets, ultraviolet light can break down water, kick out the hydrogen,

and leave oxygen behind.

But the levels of oxygen and methane that the Galileo measured on Earth were way higher

than those natural processes would predict.

This was the “chemical disequilibrium” Sagan was looking for.

But it still wasn't a smoking gun, just suggested life as a possibility.

A maybe.

Sagan did find one other biosignature on Earth that was especially weird.

On lighter areas of the planet's surface–dry land–there were massive areas that absorbed

red light, and just beyond that, into the infrared part of the spectrum, a whole bunch

of light that wasn't absorbed.

Since no rock or mineral that we know of absorbs red light quite like this, the best explanation

was a pigment covering the planet's surface, one that absorbs red light, and hates near-infrared |||||||||||||dislikes strongly||

light.

That pigment?

Well, we know it as chlorophyll.

It absorbs red and blue light, but not other colors, and that's why so much of Earth

is green.

This biosignature is known as the “vegetation red edge”

Since Sagan's little Galileo experiment, scientists have added to the list of possible

biosignatures and they've learned a lot about how we might tell them apart from natural

processes.

In general, we know different chemicals absorb different colors of light.

So if we can somehow measure how an exoplanet's atmosphere filters light from its star, we Dus als we op de een of andere manier kunnen meten hoe de atmosfeer van een exoplaneet het licht van zijn ster filtert,

can get a fingerprint of all the chemicals in that atmosphere.

Now that we know what to look for, how do we detect these signatures from light years

away?

The best study of Earth-like planets will come from looking at light from the host star

reflected off the planet and filtered by the atmosphere.

Basically the same way we take pictures of Earth today, only much, much, MUCH farther

away.

Thing is, Earth-sized planets are about ten billion times dimmer than their stars, and

exoplanets are separated from their star by *extremely* small angles.

Directly imaging an exoplanet is like trying to see a moth buzzing around a searchlight,

on top of the Eiffel Tower, from New York City.

To do this, astronomers have designed starshades, which can be placed tens of thousands of kilometers

in front of orbiting space telescopes, to precisely block out the star's light and voor ruimtetelescopen in een baan om de aarde, om het licht van de ster nauwkeurig te blokkeren en

make the exoplanets visible, the way blocking out a car's headlights with our hand helps

us see at night.

Of course we only know the signs of life as it exists here, the only place we've found

it.

Somewhere else, life may use completely different chemistry, giving off completely different

biosignatures.

And even here on Earth, life hasn't always looked the same.

Back in the ancient Archaean Era, early life forms lived under a cloudy methane haze.

And the first photosynthesizers may have been purple microbes, not green.

This would all be SO much easier if we could just sense some convenient radio signal coming

from an exoplanet, sent by an intelligent technological life form.

But when you consider human technological civilization only covers 0.000002% of our

planet's history, our chances of listening in the right place at the right time are not

great.

We're looking at the very edge of what is technologically possible, so best not to hold

your breath on finding alien life just yet.

Stay curious.

Notice anything different?

Oh yeah, I got a haircut.