Through the Wormhole s02e09 Episode Script

What Do Aliens Look Like?

Across the galaxies lie exotic worlds.
Some made entirely of water.
Others spewing with poisonous gas.
What kinds of creatures thrive in these places? Will they resemble beings on Earth? Or could life take on new, unexpected forms? What do aliens look like? Space, time, life itself.
The secrets of the cosmos lie through the wormhole.
They're out there.
We can see them.
For the first time in human history, we know the Universe is filled with planets stranger than we could ever have imagined -- planets that might be home to extraterrestrial life.
But what will these creatures look like? We're all products of our environment.
If I was born on a planet with carbon dioxide air and gravity three times weaker than the Earth's, I might look likeThis.
On a planet with five times more gravity than Earth, and a star that constantly blasted it with solar storms, I might look like this.
We can't know the face of an alien until we're staring at it.
But like detectives on the hunt for an unknown suspect, biologists and planetary scientists are beginning to piece the puzzle together.
Some of the clues are out there, but a lot of them are right here.
To get home from school every day, I had to cut through the yard of a scary, old house.
I never saw anyone come in or out of it, but someone or something lived there.
I could only imagine who or what it might be.
Harvard Paleontologist Andrew Knoll has spent his life studying creatures beyond our wildest imaginations.
One of the things you learn when you go through a museum like this is that not only is it hard to imagine what life might be on another planet, but it's hard to imagine some of the life that has existed on this planet.
Who would guess that there were things like dinosaurs in the absence of their bones? For the past eight years, Andrew has served as mission biologist on NASA's Mars rovers.
It's a role he's uniquely suited for because of his expertise in the vast array of life on Earth, and his ability to read the history of a planet from its rocks.
There's a tendency for us to think about the Earth in terms of the things we see around us today.
But the one thing that the geologic record tells us is that there have been a series of Earths, and that the Earth that we see around us -- all the plants and the animals and the composition of the atmosphere -- are really an end-member, the end state of a long series of transitions that have happened over 4 billion years.
For example, this rock, which formed about 3½ billion years ago, is full of iron minerals, which means that iron had to be able to be transported through seawater, and it can only do that in seawater that contains no oxygen.
The discovery of rocks like this all over Earth shows that for nearly the first 4 billion years of its existence, our atmosphere had almost no oxygen.
That Earth would have been toxic to us.
Now, there are other things that are sort of unexpected when we actually look at deep-Earth history.
This rock was actually deposited by glacial ice about 635 million years ago.
There are rocks like this that formed literally all over the world at this time, and it shows us that there was glacial ice at sea level at the equator.
In fact, much of the Earth -- perhaps most of the Earth -- was covered with ice, sometimes called a snowball Earth.
These various Earths -- hotter, colder, with more or less oxygen -- were essentially alien worlds.
So, for Andrew, the best place to discover what aliens might look like is in our own fossil records.
These are trilobites.
Now, when you look at this, you'll see things that are familiar.
There is a jointed, segmented body.
There are jointed, segmented legs.
And you might say, "Well, that looks like a shrimp or an insect," and that's right.
Biologists call these repeated similarities of life-forms over Earth's history "convergence.
" One shape that works well gets repeated over and over again.
This giant sea creature looks like a whale, but it is actually an extinct lizard.
Repeatedly over the last 250 million years, vertebrate animals on land have re-invaded the oceans.
And every time they've done so, they've given rise to these giant sea monsters.
there were lizards in the sea.
They were equally large.
In our own lifetimes, there's whales.
If Earth in the past has been as alien as planets orbiting other stars, then aliens you've seen in movies -- lizards with two eyes, two arms, and two legs -- might be pretty close to the mark.
I must admit, I watch a lot of old monster movies from the 1950s specifically looking at the physics and saying, "No, no, no.
That's not gonna work," or "Ooh, that's really good.
" University of Chicago Professor Michael Labarbera is an expert in biomechanics.
He's trying to predict how aliens will walk, fly, and swim by searching for the basic rule of how animals move.
You could call it the lowest common denominator of locomotion.
Things like horseshoe crabs were crawling out on the beach and laying their eggs when pterodactyls were flying in the sky.
One of the features that we share with these animals is a lever-type skeleton.
I have levers in my hands.
That's what allows me to do that.
I have levers in my elbows, in my shoulders.
The basic idea is to use a lever that has a high mechanical advantage, that delivers a lot of the muscle force to the output side of the lever.
Successful designs like jointed limbs and hard skeletons show up again and again in the fossil record.
We see them all around us today, and Michael expects to see them on other worlds, too.
And it doesn't matter whether the skeleton is made out of hydroxyapatite like our bones, made out of chitin like this animal, or carbon nanotubes.
When a principle is easy enough for natural selection to stumble across, then it will evolve over and over again.
On this planet, it has evolved independently at least half a dozen different times.
And there's every reason to believe they will be just as common in any other ecosystem on any other planet.
A torso with jointed limbs acting as levers.
It's a good basic anatomy of an alien, but can we get closer to imagining their true form? In the 19th century, Charles Darwin kept a series of notebooks chronicling how the shapes of animals had evolved to adapt to the environments they lived in.
What would a book of life on other planets look like? What mind-bending, anatomical adaptations might develop in alien surroundings? The environment shapes creatures depending on their ecology.
Density of the atmosphere, whether or not you have a world-covering ocean, is gonna make a big difference in the history and, thus, in the shape of the organisms.
Which is why to know what aliens look like, we must learn more about the planets they live on.
Until very recently, we had no proof other planets existed, let alone any idea what their landscapes or atmospheres might be like.
But now, for the first time in human history, we can see worlds far outside our solar system.
And now that we know where E.
s could live, we're getting closer to revealing their hidden faces.
If we want to know what aliens look like, we first have to know something about the places they live.
Until recently, this was impossible.
Our telescopes could only see stars, not the planets that orbit them.
Today, alien hunters have a dedicated research ship floating 20 million miles from Earth, and it's discovering new worlds by the thousand.
Engines start.
And liftoff of the Delta II rocket with Kepler.
In 2009, NASA launched its latest space telescope -- Kepler.
It's designed not to take pictures, but to detect the tiniest changes in the brightness of distant stars.
Its target area is a patch of our arm of the Milky Way stretching out 3,000 light-years away from us.
Harvard Professor Dimitar Sasselov is one of Kepler's lead scientists.
The beauty of how the Kepler telescope discovers planets as small as the Earth is the method, which we call the transit method.
It's very easy to understand.
So, the planet is passing on its orbit in front of the star.
Its shadow causes that light dip just a little bit, and that's how we know there is a planet there.
By the time Kepler is done with its mission, Dimitar expects it will have found around 100 planets the size of Earth.
But the vast majority of the planets it is finding have almost nothing in common with our world.
Kepler already has a treasure chest of weird planets, if you will -- very interesting, diverse planets.
So, we have Kepler-10, which is as hard as iron.
Then we have two or three planets in the Kepler-11 system of six.
One or two of them are water planets -- endless ocean.
Then we have planets almost the density of a beach ball or styrofoam.
Perhaps the most intriguing of Kepler's discoveries are around 300 super-sized versions of Earth -- planets made of rock, but up to five times as heavy.
If anyone can imagine the landscapes where aliens might jog, swim, or glide, it's Diana Valencia.
Part-time triathlete, she's one of the first geologists to break ground on these super Earths.
I do not have a hammer.
I do not break up rocks.
What I do is I do numerical models to understand how the Earth works and use that to understand how bigger Earths and similar planets work, as well.
To understand whether the super Earths could harbor life, Diana is zeroing in on the basic geological engine that powers rocky planets -- plate tectonics.
The movement of a planet's hard outer crust is driven by a hot and viscous layer of semi-molten rock below it moving much like a jar of bubbling honey.
This experiment here shows us in broad lines what happens.
The mantle is a very viscous fluid, and both fluids are very sensitive to temperature.
So, as we turn this heat up to simulate Earth's engine, you will start seeing motion underneath the surface.
Now you see the overturn.
Now you start seeing things that are moving all sorts of directions.
It's not just moving up.
As heat rises, it forms convective cells in the mantle, which cause the plates on the surface to shift.
These shifts trigger volcanic eruptions and earthquakes -- events we associate more with death than life.
But that's just the short-term view.
From Diana's geological perspective, this cycling of material from the inside of our planet to the atmosphere has been vital to the evolution of life.
Thanks to this process, the surface temperature of the Earth has not swung very much, and it has been around that of liquid water for over billions of years.
Super Earths are bigger and therefore hotter on the inside.
And when you turn up the heat, plate tectonics kicks into a higher gear.
That may mean more volcanoes and more earthquakes.
But also, a planet with a much more stable temperature.
On super Earths, because convection would be much faster, this cycle could respond much quicker -- perhaps an order of magnitude quicker.
And then we can speculate that that has enabled the evolution of complex life.
Think about how a super Earth would have dealt with the impact of the meteorite that wiped out the dinosaurs.
On Earth, this event triggered an extended global winter that spelled the demise of those cold-blooded giants.
But on a bigger planet, better able to control its temperature, dinosaurs might survive and have the chance to evolve bigger brains.
However, there is one major downside to living on a giant version of Earth.
The core of our world is a spinning ball of liquid metal generating a powerful magnetic field.
That field deflects a torrent of dangerous radiation from the sun and forms a protective cocoon for all life here.
Diana's models predict that super Earths may not have these force fields.
It's very possible that these planets do not have a molten core, because their interiors are under so much pressure.
So, if you are a creature in a planet that doesn't have a geomagnetic field, you are being bombarded by high-energy particles, and those are interacting with your cells, causing mutations, probably.
So, you have to be clever, as an organism, to adapt to those conditions.
What kind of alien could survive on a radiation-soaked super Earth? It would need a protective shell, perhaps laced with heavy metals like lead.
It would have powerful limbs and sharp claws to let it burrow under the ground during heavy radiation bursts.
Most important, it would need effective genetic repair mechanisms to fix the inevitable radiation damage to its cells.
Pure fantasy? Maybe not.
Similar life-forms, albeit much smaller, called water bears, survive in boiling-hot, radiation-blasted regions on Earth.
Inhabitants of rocky super Earths might look surprisingly familiar.
But imagine a world where there is no rock, and where creatures living in the ocean also fly through the sky.
On Earth, evolution has produced countless variations on life -- animals that glide through the water and soar through the sky.
Beings that slither, crawl, walk, and run.
If life on other worlds follows the evolutionary pattern of life here, what other mind-bending features might arise? Okay.
So, you got the planet, you've got the atmosphere.
At M.
in Cambridge, astrophysicist Sara Seager and biochemist William Bains are beginning to imagine what these distant worlds will be like.
The atmosphere's gonna come from somewhere, so you're gonna have volcanoes producing atmosphere.
They're trying to predict how a planet's size and composition will shape its biosphere.
Before the discovery of exoplanets, people thought that all planetary systems would be like our solar system.
And since that time, discoveries of exoplanets and exoplanetary systems have surprised us over and over and over again.
So, what has changed? Everything has changed.
Most science fiction assumes that aliens are gonna be walking around, they're gonna be breathing air.
You know, they landed a starship, and they shared dinner with the Captain.
You look at some of the planetary environments out there, and that is not gonna happen.
It's gonna be very different.
Recently, Sara and William have been studying GJ 1214b, a planet about 40 light-years away that's more than twice the size of Earth and shows signs of having an atmosphere.
Together they are working to discover what it might be like to descend beneath the clouds of 1214b.
Now, this planet -- we're not totally sure what it's made of, but it could be a water planet with a steam atmosphere.
And depending on the temperature of the planet, the clean division between liquid water and air with water vapor in it may not exist.
What sort of life could possibly emerge on a boiling-hot, steam world? So, on Earth, an environment like this with boiling water and steam is inimicable to nearly all life.
But we're trying to imagine an alien world in which this is the normal environment, and we can now start to model a planet that has a huge ocean covering it and nevertheless is incredibly hot.
That makes us think about, "could there be life in the ocean? "Can the chemistry work? And if it can, what would it look like?" A molecule like DNA wouldn't survive these conditions, but William believes more heat-tolerant genetic material would likely evolve.
And he's beginning to imagine what entries might fill the pages of a book of life for GJ 1214b.
The atmosphere of this planet would be mostly water.
It would be steam.
It would be very dense and be very hot.
So, as you go down through it, you'll find drifting plants, flying plant life, and a whole range of organisms that eats that plant life.
Organisms would be sort of flying fish or swimming birds, depending on how you look at it.
So, they'll be able to actually fly through or swim through this zone almost as if it was ocean.
Earth's oceans gave rise to creatures of all sizes, but the kings of the deep are the giant filter feeders -- whales.
So, the organism we're imagining here works in a very similar way.
It might have a very different shape.
But it moves through the ocean and then can move up into this interfacial zone.
They can spend much longer in the interfacial zone and move much further up into it than, say, a whale breaching because the density is greater.
This aquatic world is a vision of what Earth might have been like if it were larger and wetter.
Humans couldn't survive here, but could life find a way? We don't knowYet.
There are many important things in science, and one of the most important ones is imagination.
So, what is so fascinating so far -- in exoplanets, anything is possible within the laws of physics and chemistry, and anything we imagine will exist somewhere.
Follow the water.
There, you'll find life.
That's what the astrobiologists like to say.
But what if there is no water? What about planets enveloped in toxic air where the building blocks of life are completely different from our own? Could they also be alive? Life is tenacious.
Everywhere on Earth, from the coldest depths of the sea to the boiling fissures of volcanoes, living things find a way to thrive.
But the conditions on alien planets could be even more extreme.
We're discovering worlds of fire and ice, worlds of permanent night, worlds where hurricanes are constant and global.
What kind of alien could live in these hellish places? Gliese 581d floats in the constellation Libra.
It's one of the small group of planets we have spotted that might harbor alien life.
Its red star burns with only half the heat of our Sun, but because the planet spins very slowly, one side is much hotter than the other.
And its rocky surface is blasted by constant wind -- a great place to fly a kite.
Biomechanics expert Michael Labarbera believes the thick atmosphere on Gliese 581d would shroud the surface in darkness, so life would have to climb up in search of light.
He imagines kite-shaped plants that rise above the storm clouds to get their daily dose of solar energy.
These kite plants have to be able to get up into the higher regions of the atmosphere in order to get enough light, and the way they do that is to utilize the shear in the atmosphere.
Michael's kite requires two forces to stay aloft and stable -- wind to lift the kite, and an anchor to keep it from blowing ever upward.
The alien kite plant works much the same way.
So, what we've posited for this particular plant is a lifting surface on one end of the string, and at the other end of the string, something that functions like a parachute that produces a drag force.
And because the wind changes with altitude, they're moving at different speeds.
You then get a lift force that keeps the kite up and it pulls on the drag chute, but that keeps the tension on the string and the whole system is stable.
Sounds unlikely? Michael doesn't think so.
Years of studying organisms on Earth has convinced him that life would evolve to suit any environment.
Evolution goes through very strange pathways to get to an endpoint.
This particular one, we don't have an example here on Earth, but on the planet posited here with low solar input for the ground level and a high wind shear, it's entirely possible that it could function.
Closer to the surface of Gliese 581d, the once bright sunlight dims as this exoplanet enters a permanent, hazy twilight.
The atmosphere is thick and murky, but warm enough to sustain life.
In fact, Michael Labarbera speculates that it could host a thriving ecosystem of hunters and prey.
What kind of predator would evolve here? An aerial hunter -- thin-winged and bat-like, but able to soar and glide for days like an albatross.
ABat-atross? Now, this animal, because the atmosphere is relatively opaque, has to be able to travel long distances at minimal cost in order to find their prey.
It's got long wings.
It's got relatively narrow wings because they're more efficient.
It has a big wing area relative to its body.
On Earth, albatrosses use a technique called dynamic soaring to travel thousands of miles while barely flapping their wings.
Gliding in long loops, the bat-atross would also conserve energy by letting air currents carry it along.
The animal actually covers many times the distance in these loops that it's covering on the ground, but it doesn't matter.
It doesn't cost it anything.
It's free.
It's energy that's supplied by the environment, not by the organism.
But how, in a world of permanent twilight, does this hunter find its prey? In the absence of light, there's got to be some other way of locating prey.
One way is just to sit and listen and wait for your prey to make noise.
The other way is for you to make noise and listen for echoes -- what we call sonar.
So that you send a sound beam out and you wait for a reflection.
I can get a lot of information from the response of the ball as it comes back.
So, the delay between when I throw and when it returns tells me how far away the object is.
If it comes back faster than I threw it out, then the object is coming towards me.
If it's going in the other direction, it will come back slower.
If you're looking for prey, this is a wonderful idea, unless your prey, of course, can detect the sound.
The bat-atross would be an effective killer, so its prey would need to develop effective defenses.
William Bains imagines an animal similar to the hard-shelled marine life that evolved on Earth hundreds of millions of years ago.
The nautilus is natural prey for the hunters, and they'll have three defense mechanisms.
First is, of course, they have a shell.
The second is if you're being hunted by sonar, then you develop very good ears so you can hear sonar.
When you hear the ping of a sonar, you run for it.
And it has a jet propulsion system that can squirt itself forward in emergencies.
These guys will be able to jet themselves through the atmosphere in short bursts, moving very quickly.
So, at the last minute, they'll jet to one side and escape being eaten.
But even with these defenses, the bat-atross would be a fearsome opponent, and the nautilus won't always get away.
It's life on the edge.
There always is a top predator.
It's the rarest animal, but it's not the guy you want to meet in a dark alley.
Brutal conditions breed brutal life-forms.
Here on Earth, over hundreds of millions of years, billions of different creatures competed for survival, but eventually, a special mutation enabled one animal to become the planet's top predator.
That mutation was the human brain.
Somewhere out in space, alien evolution should have created beings at least as smart as we are.
What do intelligent extraterrestrials look like? This man thinks he knows, and the answer could be bad news for life on Earth.
With each new world we discover, we come one step closer to finding evidence of life beyond Earth and perhaps to fulfilling our dreams of communicating with alien life-forms.
But if that day ever comes, we'd better brace ourselves for a shock, because many scientists think they may not look like living beings at all.
For the past 50 years, the search for extra-terrestrial intelligence, SETI, has attempted to capture any glimmer of communication from alien worlds.
For Seth Shostack, SETI's senior astronomer, it's a search for our distant cosmic image, for a species with a brain at least as smart as ours.
When it comes to intelligent life, we haven't found it.
So, there are people on all sides of the issue.
But the one thing that can convince you -- I think can convince anybody -- is that even if you think the processes that could lead to life, lead to intelligent life, are not going to occur very often, there's so many chances for it to happen in the cosmos, it would be miraculous if we were the only world with intelligent beings.
Humans aren't the largest or the fastest or the most agile animals on Earth, but we are the smartest.
Our brains have put us on top.
There is, however, plenty of room for improvement.
There's an unavoidable tendency to think that we're kind of the crown of creation.
This is it.
You know, 4 billion years of evolution from the beginnings of life to us.
You know, I think if you asked the dinosaurs the same question -- "Do you think you're the crown of creation?" I bet they would have said "yes," if they could have talked.
"This is it.
This is the end of evolution.
" Well, they were wrong.
And it would be wrong for us to think we're the end of evolution, too, obviously.
So, where will evolution take us next? And where is it likely to have taken alien civilizations? Seth thinks we need to look at our computers for the answer.
Since the 1970s, when floppy disks were the gold standard, this speed at which computers process instructions has increased more than 100,000 times.
Today, for $1,000, you can buy a computer that has, if you will, the thinking capability -- or at least the computational capability of a lizard.
Not so interesting.
But by 2020 or 2025, $1,000 will buy you a laptop that has the same computational power as a human Brian.
The I.
s of artificial brains are going from zero to 200 in the historic blink of an eye.
How would a similar trajectory play out on a planet that is a mere 500 years ahead of us? The interesting thing about artificial intelligence, of course, is its pace of evolution.
I mean, we're stuck with Darwinian evolution, but the machines wouldn't be.
What it means is that if you develop a thinking machine, it's going to improve itself very, very quickly.
In 1948, mathematician John von Neumann imagined a machine so intelligent it could make copies of itself.
Each copy would improve on the previous model, much as nature continually improves on its designs.
But this machine's evolution would take place much faster than biological evolution.
Today, von Neumann machines exist in crude form.
On a planet more advanced than our own, could they be the most intelligent life-form, the dominant life-form? Will our first contact be with a race of super-intelligent machines? You're only gonna hear from a species that's at least as clever as we are.
So, what are the odds that they're within 50 or 100 years of our level of development? Pretty slim.
They're likely to be thousands, millions, maybe even more years ahead of us.
So, if you think about that for a moment, you recognize that if we do find a signal, the odds are pretty good that that signal's coming from artificial intelligence, not some soft, squishy, little gray guy with big eyeballs.
On some distant planet, the book of life may no longer contain any biological forms.
And if mechanical life has enough power, there's no limit to how large or complex it can become.
Or maybe they've reorganized themselves so that they can share the thinking load amongst many members of the species, like distributed processing with computers.
I mean, why should the aliens be content to be stuck with a kind of intelligence that can fit inside their heads? Alien evolution could produce a living machine planet throbbing with the combined intelligence of billions of alien minds.
If such advanced life exists, how would we spot it? And should we even want to? Will aliens welcome us as friends or view us as threats? Or perhaps see Earth as a world to conquer? We wonder what aliens look like, but what do we look like to them? This woman has put herself inside their heads, and she believes she has the answer.
As long as humans have looked up at the night sky, we have wondered whether something or someone out there is looking back.
We want to know what aliens look like.
What do we look like to aliens? If there is intelligent life out there, does the Earth look like a place worth visiting? May 29, 2008.
the eyes of a technologically advanced race scan our planet for the signatures of life.
Not aliens, but this was still a close encounter of an extraordinary kind.
It was the NASA space probe EPOXI.
Sent out to get closeups of comets, EPOXI briefly turned its lens back to its mother planet.
And for the first time, we saw the Earth as aliens might see us.
Astrophysicist Sara Seager was part of the EPOXI team.
Sara normally studies exoplanets, looking for clues about alien atmospheres and ecosystems.
The EPOXI probe gave her the chance to find out what Earth might look like to an alien astronomer.
If you pretend you know nothing about Earth, what could you learn about Earth? An alien would be able to pick out Earth's rotation rate.
They would be able to notice that we have surfaces of very different reflectivity -- that's cloud, land, and ocean.
And they could also see that we have weather.
They would see variability that isn't related to the rotation rate of Earth.
The second thing EPOXI did was look at a spectrum of Earth -- that is, take the white light and split it up into the different colors and to check and see if any of those colors were missing.
We call that a spectrum.
The spectrum of Earth's colors are like a flag announcing the presence of life on our planet.
The blue of the oceans, the white of the clouds, the green of the land are all markers of an active ecosystem.
If an alien is looking back at us from far away, the aliens would see that we have oxygen in the atmosphere.
In fact, our atmosphere has 20% oxygen by volume.
What's so fascinating is that, without life, our Earth would have basically So, oxygen would be essentially non-existent on Earth.
And oxygen on Earth is created by life, so those aliens would know that oxygen in such large quantities should not be in our atmosphere unless it is being continually produced by something.
And nothing that we know of in geophysics can produce so much oxygen.
And that's why we attribute it to life.
Aliens might see that our planet supports life, but they might not see that Earth is technologically advanced.
They would have to look carefully to detect things like atmospheric pollution or the heat signatures of our cities.
Reading the colors of our world and the millions of others like it out in the Universe would be easy for an advanced alien civilization.
Unfortunately, it is not yet easy for us.
Spotting exoplanets pushes the limits of current technology.
If we want to see colors, we need a new set of tools.
Astrophysicist Dimitar Sasselov wants to do something about that.
These are little round planets.
I'm gonna just drop a few on to show transiting planets.
I guess there's two transiting.
Dimitar's wife, Sheila, paints scenes of deep space inspired by his research on the Kepler planet-finding probe.
This is the kind of thing we want to discover with Kepler.
A transiting planet, and there is a moon around it.
That would be great.
So, there it is.
That's the planet with life on it -- right here.
We have a big problem.
This challenge relates to our inability to measure the colors of the star or the planets separately to very high precision.
And the challenge is about the factor of 10 to 100 beyond what current technology works.
The biggest barrier we have to seeing the colors of other planets is something every photographer has run into -- camera shake.
If you take a picture in the dark, you need as much light as possible, which means you can't move the camera or you'll get a blurry image.
Earth-like planets are so small and so far away that their images only fill one thousandth of a single pixel of a digital camera.
If that pixel moves even slightly, the camera shake will ruin the picture.
But how can you possibly keep one pixel perfectly still over the days and years it takes to track an object in distant space? Dimitar's solution is the astro-comb.
It uses lasers to keep a telescope's camera sensor precisely calibrated over a period of decades.
The astro-comb that you see here is the technological breakthrough which was needed to bridge that gap.
When we see the true colors of other worlds, we will know where and how life is distributed across the Universe.
And the next phase of our quest for alien life will begin.
Where will it take us? What exciting, new worlds will we see? What new and unexpected creatures might live on them? Biologists think that life out there might look Earth-like, but it won't look human.
With so many planets out there, so many chances at life, we could have human-like relatives on a far-away Earth.
Creatures like us, perhaps as anxious as we are to know if they are alone in the Universe.
As our tools improve, so do our odds of finding them.
It is clear that we're in a new age of exploration and discovery.
It hasn't been for 500 years that people have tried to discover planets around other stars.
Now we have them.
We have much more to explore, and the best is yet to come.
when people look back at our generation and ask, "What are the biggest accomplishments?" I like to think of these people making interstellar journeys and looking back and thinking we were the ones who started it all.
What do aliens look like? What are the limits of our imagination? The true face of an alien will probably defy our scientific speculations.
But our efforts won't be wasted, even if we do get all the details wrong.
Our eternal intrigue about alien life and our persistent fear of it both rise from the same source -- the quest to understand our place in the family of life-forms that populate the cosmos.
Know that, and we'll know the destiny of humankind.