The new discovery of seven alien Earth-like planets in a faraway planetary system is a major milestone in the hunt for extraterrestrial life. Experts investigate the secrets of TRAPPIST-1's mysterious worlds to reveal if Earthlings are alone in the universe.
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LearningTranscript
00:06We're living in a new golden age of exploration.
00:11Planet hunters are searching far beyond our solar system for exoplanets.
00:17We're not only finding different continents,
00:21we're actually finding new worlds orbiting other suns.
00:26Thousands of these alien worlds have already been found,
00:30but this is the story of perhaps the greatest discovery yet.
00:35A star 40 light years away, with seven Earth-sized planets, Trappist-1.
00:44When we saw this, that was a very happy morning when we made this plot.
00:49I really liked winning the lottery. It's a cosmic lottery.
00:55Now, these modern day explorers are racing to learn more about these extraordinary worlds.
01:02They want to know what the planet's surfaces and climates are like.
01:06And could any of them win the ultimate battle to host life itself?
01:12You'd see this planet light up with a glow,
01:15and that gives us a strong indication that something is living there on that planet.
01:19Finding life on an alien world is the ultimate prize for planet hunters.
01:25And it may soon be within reach.
01:42The story begins high in the Atacama Desert in Chile.
01:47With some of the clearest skies on Earth,
01:49it's arguably the best place to spot alien worlds orbiting distant stars.
01:57And sure enough, the aptly named Very Large Telescope is hunting for exoplanets.
02:05It's actually made up of four massive telescopes,
02:09each of which is one of the biggest ever built.
02:12Together, they form the most advanced visible light observatory in the world.
02:17So already with individual telescopes, we can see very sharp details.
02:21But when we combine the light of the four of them,
02:23we can actually distinguish the two lights of a car,
02:27of the headlight of a car, on the surface of the moon.
02:30So that's pretty impressive.
02:33The telescopes are used to study everything,
02:36from near-Earth asteroids to far-away galaxies.
02:40Dr. Julien Mili is one of their top planet hunters.
02:44We have here the primary mirror,
02:47the secondary mirror, the tertiary mirror,
02:49and then it sends the light.
02:51It's a high-contrast imager.
02:52So the goal is to make images of planets around the stars.
02:55With four 26-foot-wide mirrors,
02:59this is one of the only places in the world
03:01where astronomers can actually see exoplanets.
03:05But even in ideal conditions,
03:08Julien and his colleague face a huge challenge.
03:12Planet hunting can be like finding a needle in a haystack,
03:15because the image is full of other spots that can look like planets,
03:19such as bad pixels and light speckles.
03:25All these elongated features here,
03:28or in the center you have some little dots close to the star,
03:31these are speckles.
03:33So this is residual starlights
03:36that are created because of the imperfect optics within the system.
03:41Their task is to rule out all the dots that are bad pixels,
03:46in the hope that they will be left with what's called a companion,
03:49a real planet or other object orbiting the star.
03:56Tonight, they've captured a rare direct image of an alien world orbiting a distant star,
04:03almost 100 light years away.
04:05But this so-called companion is nothing like Earth.
04:09In fact, it's not even strictly a planet.
04:13It's a brown dwarf, an object slightly bigger than a planet.
04:17This one is about 50 Jupiter masses.
04:23We think that the lightest object that we're able to see is one to two Jupiter masses.
04:28We can't go below that, unfortunately, so we wouldn't be able to detect an Earth, for instance.
04:34Even with the most advanced optical telescope ever built,
04:38viewing these remote worlds directly is incredibly challenging.
04:43And seeing exoplanets the size of Earth remains impossible.
04:48Luckily, there's a clever way to find exoplanets without ever actually seeing them.
05:02The most successful planet-hunting technique so far has bagged thousands of discoveries.
05:09But as NASA astronomer Natasha Batalla knows well, you need patience.
05:16Finding planets is a lot like a stakeout.
05:19You're sitting around waiting for a very long time before something actually happens.
05:24It can take months or even years for a planet to orbit its star.
05:30During most of this time, they're virtually impossible to detect,
05:34unless they happen to pass in front of their star.
05:40So if you can imagine a moth flying in front of a car's headlamp,
05:45the headlamp would be so bright that the moth might be washed out.
05:48But if you looked hard enough, you'd get a very, very small dip in brightness.
05:53And so we can detect that brightness, and that's how we find planets.
05:59It's very hard to see a distant planet directly.
06:02But if you see the light from its star dim a little,
06:05you know a planet must be passing in front of it.
06:09An event known as a transit.
06:13But this transit technique doesn't work as well for small planets as big ones.
06:18Now imagine a small fly in front of a car's headlamp.
06:22That fly would be so small compared to the big light of the headlamp
06:26that the dip in brightness that you see is very difficult to detect.
06:31An Earth-sized planet blocks a hundred times less light from its star
06:35than a Jupiter-sized planet.
06:38So although hundreds of gas giants have been found this way,
06:42smaller worlds have proved more elusive.
06:46Until one astronomer had the idea of looking in a different place,
06:51small red dwarf stars.
06:54And that changed everything.
06:59Red dwarfs are many times smaller than stars like our Sun.
07:04So Earth-sized planets will cause a bigger dip in their light.
07:09Allowing astronomers to spot small, rocky worlds like our own.
07:13So if you're looking for a true Earth-like planet,
07:16it's actually easier around smaller stars.
07:22This simple but revolutionary approach meant planet hunters
07:26didn't need a giant telescope to search for Earth-sized alien worlds.
07:32And just 500 miles south of the very large telescope
07:36sits a pioneering device that's over ten times smaller.
07:41The brainchild of Belgian planet hunter, Michael Gillon.
07:45My goal was to detect new planets with a special focus on small planets
07:50that would be potentially habitable,
07:52so that could harbor liquid water on the surface,
07:55possibly, maybe life, who knows.
07:59To search for these new worlds,
08:02Michael began stalking out red dwarf stars in 2011
08:05using his small telescope which he named Trappist
08:09after the beer which is famously brewed by hand in Belgium.
08:13But unlike Trappist beer,
08:16this robotic telescope can be operated from anywhere in the world
08:19with an internet connection.
08:21The telescope itself is a remote control device,
08:25so we just press a button and launch a telescope
08:28and it start observing.
08:30And during the whole night,
08:31it will observe without any human intervention.
08:35For four years,
08:36the Trappist telescope steadily recorded the brightness
08:39of individual stars, one by one,
08:42waiting for the characteristic dip that reveals a planet.
08:46And it was remarkably successful.
08:49So, in 2015, we had around 100 giant exoplanets
08:53that we contributed to the discovery.
08:56And so, it was very encouraging,
08:59but of course, the dream was still Earth-sized planets.
09:04The Trappist telescope was working perfectly,
09:07but 7,000 miles away,
09:09Michael was still hoping for an historic breakthrough.
09:12Then, on September 16th, 2015,
09:16a dramatic sequence of events ended in a huge discovery.
09:26UNITELO
09:34UNITELO
09:35UNITELO
09:35UNITELO
09:35UNITELO
09:36UNITELO
09:36UNITELO
09:37UNITELO
09:37UNITELO
09:37On September 16th, 2015,
09:41Trappist was scheduled to watch a very faint red dwarf star
09:45just 40 light years away.
09:46But that night, a powerful earthquake struck northern Chile.
09:53The Trappist telescope was in one of the worst affected areas,
09:57but it was built to withstand seismic events.
10:01UNITELO
10:02When there is a certain level of earthquake,
10:04the first thing that happens is that the telescope is going to stop functioning.
10:09The observation stopped, and the dome was closed in safe mode.
10:14And then, in the morning, my student noticed the situation,
10:18and she relaunched the observation of the star.
10:22The telescope wasn't damaged, but by the time it was working again,
10:26the night was nearly over,
10:28and there were only three hours left to observe the target star before dawn.
10:34Back in Europe, Michael was analyzing the data when something caught his eye.
10:39I was at home in my sofa with my laptop,
10:43and I saw a very clear transit-like signal.
10:46And so I was super, super excited.
10:48And furthermore, I knew that the star was small,
10:50so the planet should have been more or less the size of the Earth.
10:56Forty light years away, an Earth-sized planet had passed in front of its dwarf star,
11:01and the earthquake almost caused Michael and his team to miss it.
11:10The TRAPPIST telescope had made its first discovery of an Earth-sized planet a huge achievement.
11:23The system was named TRAPPIST-1 in its honor,
11:26but as they continued to watch,
11:29it soon became clear that this was not the regular signal you'd expect from a single planet.
11:36One planet should lead to one frequency, one period.
11:40It should be something like...
11:42You looked at the data, and it's...
11:47Something like this. So it's totally different.
11:51That could mean only one thing.
11:54More planets.
11:56But to find out how many,
11:58Michael needed more observations.
12:02Observatories all over the world,
12:04including the very large telescope,
12:06swung their gaze towards the TRAPPIST-1 star.
12:09And the results were groundbreaking.
12:14And we observed plenty and plenty of nights,
12:17with plenty and plenty of transit.
12:19And at some point we are sure there were four planets and five planets,
12:22and maybe six, maybe seven.
12:24In fact, it was really too complex for us to decipher,
12:28because we were observing from the ground, from Earth,
12:31and we knew we needed very precise observation,
12:34and continuous observation.
12:39The only way to get a clear enough picture of the Red Dwarf Star
12:42would be to view it from space.
12:47Telescopes beyond Earth are few and far between,
12:50so time on them is limited.
12:54But as news spread of this extraordinary discovery,
12:57every resource was soon put at their disposal,
13:02including one of NASA's four great observatories,
13:05the Spitzer Space Telescope.
13:08Astronomer Sean Carey runs NASA's Spitzer Science Center in California.
13:16So this is a model of the Spitzer Space Telescope.
13:18It's a one-third scale model,
13:20so add two more of these on top,
13:22then you get a sense of how big the telescope is in space.
13:26Spitzer was the perfect instrument
13:28to gather more information about TRAPPIST-1.
13:33First, it's an infrared telescope,
13:35so the TRAPPIST-1 star is 4,000 times brighter in the infrared
13:39than it is in visible light.
13:41The second thing is Spitzer's orbit,
13:43because Spitzer isn't on the Earth,
13:44so it doesn't have day-night.
13:46You know, we don't have to stop observing when the sun comes up,
13:48and that allows us to look at objects for a much longer time.
13:52The Space Telescope watched the TRAPPIST star
13:55for over 20 continuous days and nights.
13:59So these are images from Spitzer of TRAPPIST-1,
14:04and believe it or not, what you're looking at is the data that we're used
14:07to determine the number of planets around TRAPPIST-1
14:10and help us determine their properties.
14:13So if you measure the amount of light from the star
14:15and then plot that as a function of time,
14:18this is what astronomers do,
14:19you see these dips, because that's when a planet passes in front of the star.
14:23When we saw this, that was a very happy morning when we made this plot.
14:29Scientists around the world raced to decipher the signal.
14:33We analyzed the data as soon as they came from space,
14:37and the conclusion that there were seven planets was inescapable.
14:42My best hope would have been to detect one planet.
14:45So this system of seven planets came out of the blue as a total surprise
14:49and really, like, winning the lottery.
14:51It's a cosmic lottery.
14:56Planet hunter extraordinaire, Michael Gion,
14:59had made an historic discovery,
15:02armed with a remarkably small telescope.
15:06But this was just the beginning of the story.
15:27Since the historic discovery of the seven Earth-sized planets that surround the TRAPPIST star,
15:33scientists have been piecing together the data,
15:35learning more about these alien worlds
15:38and giving a glimpse of how they might look from a neighboring planet.
15:43The system is unique not only by the sheer number of Earth-sized planets,
15:47but also because of its very compact configuration.
15:50The planets are very close to each other.
15:53So you can imagine the views that you should have from the surface of one of these planets.
15:57You would see the other planets like we see the Moon.
15:59So you would see all the details, not just the dot of light, but you would really see,
16:05I don't know, the clouds, the continents, whatever is there.
16:10As well as the planets being near each other,
16:13they are also much closer to their star known as TRAPPIST-1A.
16:19The inner two planets, TRAPPIST-1b and 1c, are in a danger zone,
16:24over 60 times closer to the red dwarf star than the Earth is to the Sun.
16:31From the surface of its nearest planet, TRAPPIST-1 would appear ten times bigger than the Sun looks to us
16:38here on Earth.
16:39It would be red and heating the surface to a temperature that is well above the boiling temperature of water.
16:49So it would be extremely hot on a sunny day out there.
16:55Harvard professor Avi Loeb has studied how stars can affect nearby planets.
17:01The inner two TRAPPIST worlds are so close to the red dwarf that one side of each planet is thought
17:08to be gravitationally locked to always face its Sun.
17:12Meaning one hemisphere would be continuously blasted by intense radiation, while the other is trapped in perpetual darkness.
17:22One side of the planet that is facing the star would be so hot that liquid water would boil off
17:29the surface.
17:30The other side would be extremely cold, such that if there is any water there, it would become ice.
17:37In between the two regions, there is a permanent sunset strip from which one can always see the sunset.
17:49The average temperature on planet TRAPPIST-1b could be around 270 degrees Fahrenheit.
17:57But on the day side, it could get much hotter than that.
18:01The extreme heat from the star might even create a thick haze covering the surface.
18:11But as well as scorching the inner planets from above, the red dwarf star also generates incredibly powerful magnetic fields.
18:21Dr. Christina Kislyakova has studied how this invisible force can actually cause the planets closest to the star to heat
18:29up from the inside.
18:32She's come to a foundry that melts steel inside furnaces by generating a powerful magnetic field.
18:40So here we are looking at a few induction furnaces, which are used to melt materials, especially metal, using induction
18:48heating effect.
18:49And the same very effect can be at work in the TRAPPIST-1 planetary system.
18:54The magnetic field changes direction 200 times every second, triggering intense electrical currents deep inside the metal.
19:03As electrons swarm through the steel, they crash into its atoms, heating it to over 2500 degrees Fahrenheit.
19:13As the planets hurtle around the star, they pass through a rapidly changing magnetic field, which heats metals deep within
19:21them.
19:25This phenomenon is far more powerful than it is in our own solar system.
19:30Because the TRAPPIST-1 star has a magnetic field hundreds of times stronger than our sun.
19:37And its planets are much nearer.
19:41The closer you go to the star, the stronger the effect will be, simply because the magnetic field will be
19:47stronger closer to the star.
19:48So in TRAPPIST-1 system, planets B and C have the most significant effect.
19:53If the magnetic field is strong enough, it will basically create currents of such strength that it will melt the
19:59planetary mantle.
20:03Christina's study predicts that molten rock could be flowing under the surface of the inner planets.
20:09And, just like on Earth, when planets have molten rock inside, it will sometimes force its way to the surface,
20:18creating volcanoes.
20:23The closest worlds to the star could be covered in volcanoes all over their surface.
20:28Maybe one can imagine that it can look something similar to this furnace, when one can see the molten metal
20:35with fumes coming out of it.
20:40Although not as volcanic as the innermost planet, TRAPPIST-1c is less likely to be shrouded in a hot gassy
20:47haze, revealing a pockmarked desolate surface.
20:52It may look like a much hotter version of the most volcanic body in our own solar system, Jupiter's moon
20:59Io.
21:04Beyond the fiery danger zone, the next two planets are in a cooler, more temperate zone.
21:10In fact, scientists have calculated that TRAPPIST-1d and 1e get a similar amount of heat from their star as
21:18the Earth does from the Sun.
21:21But to find out how similar they really are to our world, scientists are striving to discover more about these
21:28planets.
21:28And they're making good progress.
21:45At NASA's Spitzer Science Center, astronomer Sean Carey is part of a team of scientists making great strides in the
21:53race to find out more about the extraordinary worlds of TRAPPIST-1.
21:58We know an amazing amount about the TRAPPIST-1 planets compared to other exoplanets.
22:03In fact, we know more about this particular system than any other planetary system except for our own solar system.
22:10Scientists were able to work out the mass and size of each planet from the Spitzer data and could then
22:16use these results to calculate how dense they are.
22:19Like all kinds of rocks, some are much denser than others.
22:25So here are a selection of meteorites.
22:28Most of these are from asteroids in our solar system.
22:30And this one here is from Mars.
22:32This one here is very dark.
22:34It's rather heavy.
22:35It's made mostly of iron.
22:38This one is much rockier.
22:40It's a mixture of iron rock but more rock than iron.
22:43It's much wider than, much less dense than this.
22:48As with meteorites, the density of a planet can give you a clue as to what it's made of.
22:53And the most tantalizing substances defined on the TRAPPIST world would be the least dense, like water and a gassy
23:01atmosphere.
23:04When the density of the planets was finally calculated, the team gained a fascinating glimpse of what these worlds might
23:11be like.
23:13The densities tell us that they're lighter than a pure ball of rock, that there has to be lighter material
23:19like water, like carbon dioxide.
23:22TRAPPIST-1D and E, which have temperatures which are kind of similar to the Earth, would potentially have liquids on
23:29their surface, potentially liquid water.
23:31But then, you know, if you start talking about water, you can talk about the potential for life.
23:35So everybody's excited about that.
23:38Scientists think both the TRAPPIST planets and the temperate zone have water on them.
23:43TRAPPIST-1D is actually the least dense of all the planets, which means it could have 250 times more water
23:51than Earth.
23:53With a warm climate, it could be a water world, covered by a deep ocean over the entire surface.
24:05The fourth planet, however, TRAPPIST-1E, has almost the same density as Earth,
24:10suggesting it could have a mix of oceans and land, which would make it look eerily like our home.
24:25Beyond this temperate zone, the last three planets receive much less heat from their star.
24:31In its frigid zone, these outermost worlds also have a low enough density to have water in some form.
24:39To find out if they're all just frozen ice balls, scientists need to know another crucial detail.
24:47Dr. Alexandria Johnson creates alien skies in her lab.
24:52We're trying to simulate exoplanet atmospheres.
24:55In particular, we're trying to look at how exoplanet clouds scatter light,
24:58because it tells us a little bit about the atmosphere and the climate on that system.
25:02By firing a laser at cloud particles in a chamber,
25:05Alexandria can see if the light gets absorbed by the atmosphere or reflected back out to space.
25:12She can then multiply the effect by the millions of particles in a cloud
25:17to simulate the overall impact on an exoplanet.
25:20We don't quite know if there are clouds on the TRAPPIST-1E yet,
25:24but if we study them in this manner, we can get an idea of how much starlight is actually making
25:29into the atmosphere,
25:30and that's how warm the atmospheres could be and what sort of climates might be on these planets.
25:34The clouds around a planet can change its climate, and so can the gases in its atmosphere.
25:42To study that, there's no better lab than the Earth itself.
25:46Fortunately, Alexandria's lab is in the tallest building in Cambridge, Massachusetts,
25:51the perfect spot for a weather station.
25:56So, in Boston and Massachusetts, we've been recording the temperature since the early 1900s,
26:01and what we've seen is that over the 20th century, there's an average temperature.
26:05But over the past 25 years, the average temperature for the year has always been higher than that.
26:10So what we're seeing is continual warming of the atmosphere.
26:13It's pretty much the same trend we see all over the world.
26:18It's now well known this warming is caused by more greenhouse gases in the atmosphere.
26:23The main ones are carbon dioxide and methane,
26:26and they collect the infrared radiation that's given off by the surface,
26:30and then they in turn heat the atmosphere.
26:32Just like on Earth, these gases can trap heat on exoplanets.
26:38Astronomers have calculated that without an atmosphere,
26:41the outer TRAPPIST planets would be frozen solid.
26:45But with the right kind of atmosphere and clouds, these giant snowballs could warm up.
26:51If you put into those systems greenhouse gases, create a substantial atmosphere,
26:56you can begin to trap the radiation from that star,
26:58and you can have warming, and you could actually potentially have liquid at the surface.
27:05With help from an atmosphere,
27:08calculations show that planet TRAPPIST-1f receives just enough heat
27:13to melt water at its warmest region,
27:16an ice-rimmed ocean forming the pupil of a frozen eyeball staring at its sun.
27:23But the last two planets have less hope of liquid water on their surface.
27:28TRAPPIST-1g and 1h are further from their stars, so they receive less radiation,
27:33which means it's actually considered to be past the ice line,
27:35which is a temperature regime where volatiles such as water would be locked up in solids like ice.
27:42Planet TRAPPIST-1g receives so little heat from the star
27:46that even with an atmosphere, its surface is likely covered in solid ice.
27:51without one, it could be as bitterly cold as night on Mars, minus 112 degrees Fahrenheit.
27:59Finally, the frigid outermost world of the TRAPPIST-1 system is the coldest of all.
28:06With the surface temperature predicted to be no more than 150 degrees below freezing,
28:11it could be almost as cold as Jupiter's largest moon, icy Ganymede.
28:23The unremarkable TRAPPIST-1 star has seven extraordinary worlds,
28:30of which at least three may have thick atmospheres and liquid water on their surfaces,
28:37features that would make the planets potentially habitable.
28:42And that raises an enticing question.
28:45Could these worlds also harbor life?
29:03As scientists learn more about the extraordinary worlds that surround the TRAPPIST-1 star,
29:10they're finding that at least three of them have the potential for life.
29:14But there's a problem.
29:16To give evolution enough time to get started, you also need stability.
29:23Something the TRAPPIST planets at first seemed to lack.
29:31From planet TRAPPIST-1 age, the other six worlds would hang clearly in the sky,
29:37a stunning display of just how compact the system is.
29:42But if planets get too near each other, it can spell doom.
29:47The planets are all very close together, and so they each feel each other's gravity,
29:51and they give each other little tugs over and over again, and that can be a very dangerous situation.
29:56When he heard about the compact system, astrophysicist Matt Russo was fascinated by these interactions and the fate of the
30:04planets.
30:05When the TRAPPIST-1 planets were first discovered, astronomers tried to simulate their orbits,
30:09and they found that after a very short amount of time, the system went unstable.
30:13Planets started crashing into each other or getting ejected.
30:15It was just a complete mess, very, very fast.
30:17So that means that either we're catching the system just before everything goes haywire,
30:21or there was something mysterious keeping this system stable.
30:26The seven worlds appear on the verge of catastrophe, but appearances can be deceptive.
30:32As well as being a scientist, Matt is an accomplished musician,
30:36and this TRAPPIST mystery got him thinking about an unusual connection.
30:44With the help of an orchestra, he set out to translate the movements of the planets into actual music.
30:51If you speed up the motion of these planets by millions of times,
30:55their motion would actually produce musical notes.
30:59If the orchestra represents the TRAPPIST system, then tuning up is a bit like how the planets formed.
31:06And that could be the key to the system's survival.
31:11So when planets form, the planets are orbiting inside a disk of gas and dust.
31:16And while they're inside that disk, they can slide around and tune themselves to their neighbors.
31:23And as these planets slide around, sometimes they can get locked into a very stable configuration.
31:37The different sections of the orchestra are now in harmony with each other,
31:42playing the music of the perfectly synchronized TRAPPIST-1 system.
31:48The unprecedented symmetry that allows Matt to turn the TRAPPIST-1 orbits into music,
31:54also causes all the planetary tugs to cancel each other out, keeping the planets in balance.
32:03We now know that the TRAPPIST-1 system is about 7 billion years old.
32:07That's much older than our own solar system.
32:10And so if these planets weren't finely tuned in this musical configuration,
32:13there's no way they could have lasted that long.
32:16If it turns out that any of the TRAPPIST-1 planets do have the right conditions for life,
32:227 billion years is certainly long enough for evolution to get going.
32:27An exhilarating possibility.
32:31But not everyone is optimistic.
32:35Like our Sun, the TRAPPIST-1 produces explosive destructive outbursts called stellar flares.
32:47The biggest solar flares of our Sun can release the energy of a billion hydrogen bombs.
32:53Yet the Sun's activity is relatively tame compared to that of other stars,
32:58including red dwarves like TRAPPIST-1, that are much smaller in size.
33:05These stars are fainter than the Sun by 10,000 times,
33:09but the frequency of flares on red dwarves is much higher,
33:13and the flares are much more powerful than they are for the Sun.
33:20Whenever the TRAPPIST star flares, the nearby planets are bathed in intense ultraviolet or UV light.
33:27And this kind of radiation can have a devastating effect on life.
33:34With the TRAPPIST planet so close to such a volatile star,
33:39Avi Loeb doubts whether living organisms could survive.
33:44I believe that the planets around TRAPPIST-1 do not have life as we know it on them,
33:51due to the many risks that this environment poses for life.
33:55Yet other scientists believe there may be reason for hope.
34:09Astrobiologist Jack O'Malley James wants to know if there's a way for life to survive these stellar super flares.
34:17To find out, he's been investigating how life on Earth copes with UV.
34:23He's come to the London Aquarium to see how sea creatures respond to the radiation.
34:30So most of the Sun's UV is filtered out by the ozone layer in the atmosphere,
34:34and the rest that makes it down to the surface is low enough that animals can cope with it by
34:39moving away into the shade,
34:40like this sea turtle here, which is hiding under a rock.
34:43Anything that puts a small barrier between you and that radiation is enough.
34:47But not all creatures can escape into the shade during the heat of a midday sun.
34:54Coral polyps are small animals that create hard skeletons around their bodies,
34:59which, together, anchor coral reefs to the sea floor.
35:03Corals, like in this reef here, are stuck in place.
35:06So when they're exposed to high levels of UV radiation, such as when the tide goes out,
35:11they can't move away from it, they can't hide, so they need to do something else to deal with that
35:16radiation.
35:17Somehow corals manage to survive, even thrive, in shallow tropical waters, where ultraviolet is at its strongest.
35:26Behind the scenes of the London Aquarium, some newly grown coral may provide a clue as to how they do
35:32it.
35:33One theory suggests the marine creatures may have evolved a mechanism to cope with the high energy radiation.
35:41They have these fluorescent pigments inside them.
35:44So as the UV from the lamp hits the fluorescent proteins on the outside of the coral,
35:48they're acting like a sort of shield.
35:50And they're absorbing the high energy UV light and almost instantly converting that into a lower energy, harmless form of
35:58light.
35:58So it is like a glowing form of sunscreen.
36:02By converting the UV light into visible light, the coral polyps are protecting themselves from harm.
36:09And Jack believes this process could be happening elsewhere in the universe.
36:14So it could in theory be happening anywhere where there's high levels of UV radiation,
36:20such as the planets in the TRAPPIST-1 system or planets around similar stars they're starting to find now.
36:25This mechanism could actually make those worlds a lot more habitable for life rather than less habitable.
36:32Many scientists think it's possible that life does exist on the TRAPPIST planets.
36:37In particular, the planet right in the middle, TRAPPIST-1e.
36:42And if biofluorescent organisms are thriving there, it could have an extraordinary effect on the Earth-like world.
36:51As a flare hit, you'd see this planet light up with a glow of whatever color it was fluorescing.
36:57So you can imagine this planet that has a vague outline that suddenly becomes bright green in the sky.
37:05A beautiful sight, but if Jack O'Malley James is right, the glowing planet could have a significance beyond its beauty.
37:13Like a great astronomical beacon, it could one day betray the presence of alien life.
37:39Today, detecting signs of life on an Earth-sized exoplanet is not yet possible even with the world's biggest telescopes.
37:48But in the Atacama Desert in Chile, that is about to change.
37:53Dr. Julian Mealy is preparing for a project that will transform the search for life elsewhere in the galaxy.
38:03We are looking for life, or to find hints that there is life on other planets.
38:08And it's much more likely to find life on rocky planets than on gas giants.
38:13So this is why we want to go for those faint, rocky planets that are much difficult to catch,
38:18but also much more rewarding, potentially.
38:22To find those rocky planets, astronomers need bigger telescopes.
38:27Just down the road from the Very Large Telescope, construction has begun on the Extremely Large Telescope, or ELT.
38:37So the new telescope will be five times bigger, so it means it will be the biggest optical telescope on
38:43Earth.
38:43And with that, we'll be able to search for planets that are much fainter,
38:47and we'll be able to go from the regime of giant planets to smaller planets and maybe rocky planets.
38:55Once complete, the ELT will be the biggest optical telescope in the world.
39:01Its 128-foot mirror will collect 100 million times more light than the human eye,
39:09allowing it to detect crucial details about Earth-sized planets.
39:13We could find some signature of life.
39:17So to do that, we would need to analyze the atmosphere of those planets.
39:21So we're looking for a combination that could only be produced if there is a biological process.
39:28As well as new ground-based telescopes,
39:31the James Webb Space Telescope should reveal unprecedented new details
39:36about alien planets after its launch, planned for 2021.
39:41These massive new telescopes will give astronomers the best chance of finding evidence of alien life.
39:48I would feel extremely rewarded, of course, to detect signs of life,
39:53and it would be an amazing discovery.
39:55And it's actually one of the goals of this big telescope is to look for life.
40:00Answering the question of whether we're alone in the universe could be a few short years away.
40:06In the meantime, astronomers are lining up as many Earth-sized planets as possible,
40:12so they can be scanned for signs of life as soon as the new telescopes are ready.
40:2550 miles across the Chilean desert,
40:28Micael Gion is also building a new observatory,
40:31this time with four telescopes, which he has named SPECULOS.
40:38TRAPPIST-1 has proved beyond any doubt that red dwarves really are good targets for planet hunting,
40:45so Micael plans to stake out a lot more of them.
40:49There are 1,000 of them that are nearby enough to make possible,
40:53if we detect Earth-sized planets, to search for traces of life in the atmosphere of these planets.
41:00If the tell-tale signs of life are one day found in a system like TRAPPIST-1,
41:05it would confirm that organisms can and do thrive around red dwarf stars,
41:10and that matters because there are more of them out there than you might think.
41:19Not a single red dwarf star is visible to the naked eye.
41:24But if you could see red dwarves as clearly as other stars,
41:28the sky would look very different.
41:31In fact, there are more red dwarves than any other kind of star,
41:36with around 200 billion of them in our galaxy alone.
41:40And recent studies suggest they're usually accompanied by small planets.
41:45It seems that these kind of planets are very common around these small stars.
41:50And if you sum up all the red dwarves in our galaxy,
41:53you could end up with, I don't know, thousands of billions of planets over there.
42:01One day, the seven worlds of TRAPPIST-1 may not seem so unique after all,
42:06with the galaxy brimming with Earth-sized planets orbiting red dwarf stars.
42:13And if someone does find traces of life on one of these worlds,
42:18it would have profound implications about the nature of the universe.
42:23If we would detect life on a nearby red dwarf,
42:27it would probably mean that life is everywhere in the universe,
42:30that life is a cosmic phenomenon.
42:34Within a decade, we may discover that far from being alone,
42:38we are surrounded by life,
42:42that the universe is teeming with it.
42:45We'll see you next time.
42:46Bye.
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