Astronomers are on the hunt for the groundbreaking discovery that confirms extraterrestrial life. Using state-of-the-art technology like the Kepler space telescope, scientists examine thousands of exoplanets in search of another Earth.
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LearningTranscript
00:02Life, an unbelievably perfect combination of elements, that is able to create living matter.
00:10Maybe the biggest mystery of nature.
00:17Is life an amazing phenomenon, exclusive to our planet?
00:25So where might this second Earth be?
00:31The second genesis within the same solar system implies that life, the origin of life, is a likely event.
00:37If it happens twice in the same solar system, it's likely happening everywhere in the universe.
00:42Now, scientists are searching for planets far beyond the boundaries of our solar system,
00:48where we might detect life in the near future.
00:53Thanks to NASA's Kepler Space Telescope, launched in 2009, we know that in our galaxy alone, there are billions of
01:02Earth-like exoplanets orbiting their stars.
01:08Given the vastness of the universe, with more than a hundred billion galaxies, it is hard to conceive that somewhere,
01:16there is no Earth-like planet that can harbor life.
01:23Unless something very unusual happened here on Earth, then life is developed on thousands of millions of planets just in
01:31our galaxy, right?
01:32If it's not a miracle, then it's all over the place. That's the bottom line.
01:37When we take a look at what we know about the origins of life on this planet, it leads us
01:45to think that the same things that happened here might well have happened elsewhere.
01:52And so, life beyond this planet is quite plausible in terms of the science that we know today.
02:02Could there be life beyond our solar system?
02:20Is there life beyond Earth?
02:24Humankind has always asked itself this question, but no answer has yet been found.
02:32However, thanks to the latest advances in space technology, it appears that we are closer to solving this mystery.
02:41Recent discoveries have uncovered planets beyond our solar system that are believed to be similar in many ways to Earth.
02:50If I got to ride on a spaceship to one planet that we found with Kepler, the one that I
02:56would go to is Kepler 186f.
02:57It's one of the smallest ones. It's at the right temperature that liquid water could exist on its surface.
03:08Kepler 186f is the first validated Earth-sized planet to orbit a distant star in the habitable zone,
03:15where liquid water might pool on the planet's surface.
03:22The discovery of Kepler 186f confirms that Earth-sized planets exist in the habitable zones of other stars,
03:31and signals a significant step closer to finding a world similar to Earth.
03:39Kepler 186f orbits its star once every 130 days and receives one-third the energy that Earth does from the
03:47Sun,
03:47placing it near the outer edge of the habitable zone.
03:53If you could stand on the surface of Kepler 186f, the brightness of its star at high noon would appear
04:00as bright as our Sun is about an hour before sunset on Earth.
04:07Before Kepler was launched, there was hundreds of planets that we knew of in systems around other stars, and now
04:15we know of thousands.
04:17And that's why Kepler was so revolutionary.
04:21Kepler is a space telescope specifically designed to survey our region of the Milky Way galaxy to discover Earth-sized
04:29and smaller planets
04:30in or near the habitable zone of their respective stars, and determine the fraction of the hundreds of billions of
04:37stars in our galaxy that might have such planets.
04:41It works very simply. I mean, anybody can understand this. It's just staring at one spot on the sky all
04:47the time, never blinks.
04:48And it's looking at 150,000 stars, and it just monitors how bright they are, kind of like a camera
04:54light meter, really.
04:55And occasionally, they'll see this star over here, for example. It'll get a little bit dimmer, a very fraction of
05:01a percent dimmer for a few hours, and then it'll get bright again.
05:05Well, that happens if a planet passes in front of that star.
05:09We've gone from finding 100 planets to over 1,000 planets with Kepler, those that have been confirmed.
05:15And there's about 3,000 or 4,000 more, which we have strong evidence for, but we wouldn't consider confirmed
05:20planets just yet.
05:23Kepler is on the hunt for planets.
05:26Kepler has found literally thousands of planets or planetary candidates.
05:30It's a planet-finding machine.
05:35In 2011, for the first time ever, Kepler provided scientists with an astonishing calculation of the number of stars in
05:44our galaxy that could have a planet like ours.
05:50Around a billion.
05:53Maybe there are a million, maybe there are a billion, maybe there are 100 billion planets in the Milky Way
05:58galaxy that could support life, the kind of planets that earthly life could survive on.
06:03How many of them have cooked up their own life?
06:06And we don't know the answer to that, okay?
06:08Because that depends on how hard it is to get life started.
06:11Just because I give you all these, you know, these worlds, doesn't mean that life will get started.
06:15But, on the other hand, those planets are all made out of the same stuff that Earth is.
06:21So, again, unless something very unusual happened here and nowhere else, there's going to be biology all over the place.
06:35On April 2013, just four years after its launch, the Kepler team reported one of their first great triumphs.
06:43The discovery, for the first time ever, of two exoplanets very similar to the Earth.
06:50Kepler 62E and Kepler 62F.
06:55This discovery created great enthusiasm as it implied the confirmation of Earth-like planets where life might be possible.
07:06These planets have a radius 1.6 and 1.4 times that of Earth and orbit Kepler 62, an orange
07:14dwarf star, in its circumstellar habitable zone.
07:20A modeling study also concluded that Kepler 62E and Kepler 62F are likely covered, perhaps completely, in water.
07:31Kepler 62E probably has a very cloudy sky and is warm and humid all the way to the polar regions.
07:40Kepler 62F would be cooler, but still potentially life-friendly.
07:48Unfortunately, they are at a huge distance of 1,200 light-years away in the constellation of Lyra.
07:57Thanks to the Kepler mission, we now know that there are tens of billions of planets orbiting stars in our
08:04galaxy alone.
08:05And we know that there are billions of galaxies across the universe.
08:11So, if in just one planetary system like ours, life arose on one planet, and there are at least four
08:18more candidates, the likelihood of finding a planet in outer space that could harbor life should be very high.
08:31But Kepler has discovered for us not only the existence of Earth-like planets, but also has provided amazing data
08:40about the universe, such as the confirmation of the existence of planets that orbit around not only one, but two
08:48stars, like Kepler 16b.
08:50This planet was Kepler's first discovery of a planet that orbits two stars, what is known as a circumbinary planet.
09:00So, one of the most exciting discoveries from Kepler was that we were actually able to find planets around binary
09:08stars, and the first one that was found was Kepler 16b.
09:14Kepler 16b is many people's favorite planet that was discovered with Kepler.
09:18It orbits around not one, but two stars at the same time.
09:24This was something which was predicted not to exist. Two stars setting at the same time was just a piece
09:30of science fiction.
09:31But the universe is stranger than what scientists can imagine, and it turns out that this sort of thing is
09:35true.
09:40Since 1992, over 2,000 exoplanets have been discovered.
09:47Thanks to future space telescope missions planned for launch, the number of observed exoplanets is expected to increase greatly in
09:56the coming years.
10:00Despite having discovered just a tiny fraction of all those billions of exoplanets we think exist, how could we know
10:09how many of them could harbor life?
10:14In astronomy and astrobiology, the region around a star, where a planet with sufficient atmospheric pressure can maintain liquid water
10:24on its surface, is known as the Circumstellar Habitable Zone.
10:28The habitable zone is a place, it's kind of a way of thinking about the right way to go look
10:33for planets like our own.
10:36The Earth is obviously in the Circumstellar Habitable Zone of our solar system.
10:42A potentially habitable planet implies a terrestrial planet with conditions roughly comparable to those of Earth, and thus potentially favorable
10:52to life.
10:53There's a sweet spot, an area where it's not too hot and not too cold, and we call that the
10:59Habitable Zone, or some people call that the Goldilocks Zone.
11:03If you've got a planet in that region, and if it's small and it's rocky enough, and it had water,
11:08that water would be in a liquid state, more than likely.
11:10So that would be a good place to go looking.
11:28On November 4th, 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40
11:37billion Earth-sized planets orbiting in the habitable zones of sun-like stars.
11:41And red dwarfs just in our galaxy, 11 billion of which may be orbiting sun-like stars.
11:55However, now we know that stars very different from our sun may also be a good place to look for
12:03life.
12:05In May 2016, a team of astronomers announced, for the first time ever, the finding of three habitable planets orbiting
12:13a star completely different from ours, an ultra-cool dwarf star.
12:22It's the first planetary system found around a star like this.
12:27The star, named Trappist-1, is just 40 light-years away, and is much cooler and redder than the sun,
12:35and barely larger than Jupiter.
12:40Stars like this are very common in the Milky Way, and they are very long-lived.
12:47The three planets are very similar in size to the Earth, and might have habitable regions on their surfaces.
12:54So, the answer as to what place in the universe is best-defined life has radically changed.
13:05To date, among all of the more than 1,000 confirmed exoplanets, there are around 50 that are in the
13:13circumstellar habitable zone of the star they orbit.
13:17And therefore, they could be potentially considered Earth-like planets, which does not imply these distant worlds may harbor life.
13:26However, could life be possible outside those habitable zones?
13:35The discovery of hydrocarbon lakes on Saturn's moon Titan has begun to call into question the carbon chauvinism that underpins
13:43circumstellar habitable zone theory.
13:48Liquid water environments have been found to exist in the absence of atmospheric pressure, and to temperatures outside the circumstellar
13:57habitable zone temperature range.
14:00Just because a planet is outside the habitable zone doesn't mean that it couldn't have life.
14:05For example, Saturn's moon Enceladus and Jupiter's Europa, both outside the habitable zone of our solar system, may hold large
14:15volumes of liquid water in subsurface oceans.
14:21If we are considering the possibility that life could arise in such harsh environments that are not in the circumstellar
14:28habitable zone,
14:29that implies that we should look for exoplanets far beyond those zones.
14:35Therefore, the chances of finding an exoplanet with conditions to support life are much higher.
14:47Just analyzing the planets and moons of our own solar system is not an easy task, since they are millions
14:53of miles away from Earth.
14:59However, exoplanets are not just millions of miles away, but many light-years away from Earth.
15:06How can astronomers manage to study exoplanets if they are trillions of miles away?
15:15There are several methods used by astronomers and astrobiologists to discover and to study these extremely distant, mysterious worlds.
15:28Before the launching of the Kepler mission in 2009, the most successful technique for detecting exoplanets was Doppler spectroscopy, also
15:38known as the radial velocity method.
15:41The radial velocity method relies on the fact that a star does not remain completely stationary when it's orbited by
15:49a planet.
15:49A planet is much smaller than its star, but it still exerts a tiny gravitational pull, or tug, on the
15:57star as it orbits.
15:59When a planet is behind the star, from our point of view, it pulls the star slightly away from us.
16:06When it's in front, it pulls the star slightly towards us.
16:10This causes the star to wobble back and forth.
16:15Astronomers look for this wobbling to find planets.
16:19They use something called a spectrograph and powerful telescopes to examine the light coming from a star.
16:26A spectrograph, like a prism, splits the light from the star into its component colors, producing a spectrum.
16:33Some of the starlight gets absorbed as it passes through the star's atmosphere, and this produces small, dark gaps, or
16:42lines in the spectrum.
16:44As the star moves closer to us, these lines shift toward the blue end of the spectrum.
16:50As the star moves away, the lines shift back toward the red end of the spectrum.
16:55So the spectrum appears first slightly blue shifted, and then slightly red shifted.
17:03Therefore, astronomers can look for orbiting planets by looking for these back and forth motions of the lines in a
17:10star's spectrum.
17:12And you can work out from the speed that's being pulled toward you and how long it takes to go
17:15around in that circle,
17:16you can work out the mass of the planet, or the companion thing which is pulling it around.
17:20If that mass is very small, they think it's a planet.
17:23That method has been very successful. It found most of the planets which were discovered early on.
17:28However, Kepler's observations were based on something entirely different.
17:45The Kepler telescope used the transit method to detect planets.
17:50It's based on the observation of a star's small drop in brightness that occurs when the orbit of one of
17:56the star's planets passes,
17:58or transits in front of the star.
18:01The amount of light lost depends on the size of the star and the planet,
18:05and the duration of the transit depends on the planet's distance from the star and the star's mass.
18:12With the Kepler Space Telescope, when we look at a star, we don't see the planet directly.
18:17All we see is a tiny dip in the brightness of the star when the planet passes in front of
18:21us.
18:22From the size of the dip, we can work out the relative size of the planet.
18:25Is it a big planet? Is it a small planet? Is it a small planet?
18:40Is it a small planet as an Earth-like candidate, and thus able to harbor life?
18:48Once you know the distance away from the star, and you know how hot the star is,
18:51you can estimate what the temperature on the surface of the planet would be like.
18:57Another of the main parameters to analyze the Earth-like potential of an exoplanet is its atmospheric composition.
19:05Atmospheric studies of exoplanets might be performed with spectroscopy during planetary transits.
19:13During the transit, the stellar light passes through the atmospheric limb of the planet.
19:19Spectral analysis of this filtered light reveals the structure and composition of the atmosphere.
19:28Astronomers could identify the most Earth-like exoplanets by detecting the biomarkers,
19:34which are the imprints that life forms have on their host planet atmosphere.
19:39For example, the molecular oxygen that we are breathing results from the presence of life on Earth.
19:47Unfortunately, with present-day technology, it's extremely hard to study the atmosphere composition of those remote planets.
19:56The main thing that's keeping us from being able to do that now, of course, is technology.
19:59We don't have the technology, you know, in functioning instruments at the moment to be able to do that effectively.
20:06But that's something that will change with other missions in the pipeline, like Jack Webb Space Telescope and other missions
20:13that are happening.
20:15Kepler continuously monitors over 100,000 stars similar to our sun for brightness changes produced by planetary transits.
20:24Thanks to this ingenious technique, Kepler has confirmed to date more than 1,000 exoplanets.
20:33Scientists think that a few dozen of them can be labeled as Earth-like.
20:43Considering the possibilities of finding an Earth-like exoplanet are much higher in the circumstellar habitable zone of its planetary
20:50system,
20:51planet hunting then started to focus on those areas.
20:59One of the first discoveries was 70 Virginus B, an exoplanet located approximately 60 light-years away in the constellation
21:09of Virgo.
21:1070 Virginus B was located exactly in the middle of the circumstellar habitable zone of its planetary system.
21:18So it was supposed to not be too hot or too cold.
21:24Unfortunately, further studies reported that this remote world was a gas giant with very high temperatures,
21:32which ruled out any potential for liquid water, and therefore, life.
21:41The early findings were discouraging in terms of detecting an Earth analog.
21:47But this was just the beginning.
21:53In 1998, a discovery made in the star Gliese 876, a red dwarf located in the constellation of Aquarius,
22:02at a distance of 15 light-years away from Earth, really encouraged astronomers.
22:13A gas giant was detected in its habitable zone, Gliese 876-B.
22:25Three years later, another gas giant closer to this one was found, Gliese 876-C.
22:35We know that life as we know it is not possible on gas giant planets, such as Jupiter or Saturn.
22:43But the big surprise was that both exoplanets may have habitable moons orbiting around them, as Jupiter and Saturn have.
22:52This was one of the first planets to be discovered in the habitable zone,
22:55and people theorized that if it had a moon around it, the moon would be rocky,
22:59and the moon would be at the right temperature to have liquid water.
23:03Why couldn't any of these hypothetical moons around Gliese 876-B and C harbor life?
23:10As we hoped Jupiter's moon Europa, or Saturn's moons Titan and Enceladus might.
23:18So it's an exciting place to think about, and maybe an exciting place to look for in the future.
23:23After the discovery of these exoplanets with potential Earth-like moons,
23:27several similar exoplanets with moons orbiting around them were discovered.
23:32Maybe on any of those remote moons, life arose in the past, or exists in the present, or might appear
23:41in the future.
23:43After all these early discoveries, we started to approach the main goal, to find the most Earth-like world.
24:05An Earth analog, also referred to as a twin Earth, or Earth-like planet, is a planet or moon with
24:11environmental conditions similar to those found on the planet Earth.
24:19If life could arise on Earth millions of years ago, and if we look for exoplanets similar to our planet,
24:26the chances of finding habitable planets skyrocket.
24:33Recent discoveries have uncovered planets that are believed to be similar in many ways to Earth, with relatively high Earth
24:40-similarity indexes.
24:45The size is often thought to be a significant factor, as planets of Earth's size are thought more likely to
24:52be terrestrial in nature, and be capable of retaining an Earth-like atmosphere.
25:07From the point of view of Kepler, a planet is Earth-like. If it's small enough that it's probably rocky,
25:12it's not a gas giant like Jupiter or Saturn.
25:15But size alone is a poor measure, particularly in terms of habitability.
25:21Because next to us, there is a planet with a very similar size and mass, Venus, where it's almost impossible
25:28for life to arise.
25:35There are other criteria to be considered, like the surface gravity, or the star's size and type.
25:42Our planet is Earth-like. If it's the right distance away from its star, that it's in the habitable zone.
25:47That it's not too close, that it's too hot, and all the water that it would have would boil away.
25:51And not so cold, that if there was any water, it would all freeze to ice.
25:55If we were able to examine all of these parameters of an exoplanet, we would be able to know if
26:02it is, or isn't, a real twin Earth.
26:05So when we say Earth-like, for Kepler, we usually just mean that it's small enough that we think that
26:11it's solid enough that you could stand on it.
26:13But that doesn't mean that it has an atmosphere, or that it has an ocean.
26:19It's also cited that an Earth analog must be terrestrial. That is, it should possess a planetary surface composed of
26:28materials similar to Earth's.
26:31The conclusion would be that extrasolar planets, or moons, with substantial atmospheres, may possess oceans and water clouds like those
26:40on Earth.
26:43In addition to surface water, a true Earth analog would require a mix of oceans or lakes, and areas not
26:51covered by water.
26:53We believe that water is essential, but just about everything else you can think about, which is important for life,
27:00there seems to be life on the Earth that doesn't need it.
27:03There is life that survives without sunlight, there is life that survives without oxygen,
27:07there is life that survives deep down underneath the ice in Antarctica.
27:11Unfortunately, with present technology, we can't properly evaluate most of the parameters like the temperature, the atmosphere composition, or the
27:20surface of the exoplanets.
27:26Nevertheless, considering we have already discovered hundreds of exoplanets, we can't help but wonder if a real Earth analog has
27:35already been discovered.
27:45On April 18th, 2013, astronomers from the Kepler team announced a discovery that created great expectation.
27:56For the first time ever, two very Earth-like exoplanets were found.
28:04They were the Kepler-62e and the Kepler-62f, which orbit Kepler-62, an orange dwarf star in its circumstellar
28:20habitable zone.
28:23They immediately became prime candidates to host alien life.
28:31A modeling study also concluded that Kepler-62e and Kepler-62f are likely covered mostly, perhaps completely, in water.
28:41Kepler.
28:43Kepler-62e probably has a very cloudy sky and is warm and humid all the way to the polar regions.
28:52Kepler-62f would be cooler but still potentially life-friendly.
28:57Unfortunately, they are at a huge distance of 1,200 light-years away in the constellation of Lyra.
29:10Soon after, an exoplanet even more similar to the Earth was discovered.
29:16Kepler-186f.
29:19This finding was a milestone, as it was the first rocky planet found in the habitable zone of its system.
29:26It is 492 light-years away from the Earth.
29:33Kepler-186f is possibly my favorite planet to come out of the Kepler mission.
29:37It's a small planet. It's maybe 10 to 20 percent bigger than the Earth.
29:42Based on everything we know about planets, it's almost certainly to be rocky.
29:45And it's the right distance away from its parent star that if the atmosphere is right, if the greenhouse effect
29:50is right,
29:50it could have liquid water on the surface.
29:53After that discovery, several more Earth-like candidates started to arise.
29:58Like Kepler-438b, Kepler-442b, or Kepler-440b.
30:07All of them were very similar to our planet, but none of them was a real twin Earth.
30:15But everything changed on July 23rd, 2015.
30:19That day, NASA's Kepler Space Telescope science team shocked the scientific community with an amazing finding.
30:42Scientists announced an amazing finding.
30:46They had discovered the most Earth-like planet ever.
30:50Its name, Kepler-452b.
30:53What made this one different to the other previous Earth analog candidates?
30:59Kepler-452b is the very first apparently rocky planet that orbits a G-type star like our Sun.
31:09It's a planet in the habitable zone around the star which is almost a clone of our own Sun.
31:15After this discovery, the Earth is a little less lonely in the Universe.
31:24Kepler-452b circles its star, which is about as hot as our Sun, 10% brighter and 20% larger,
31:32at an orbital radius just 5% larger than that of the Earth.
31:37A year on this planet is 385 Earth days long, just 20 days longer than Earth's.
31:48What makes this slightly less exciting from the point of view is could it be habitable is its size.
31:53Our best guess at the size is that it's about 60% bigger than our own Earth.
31:59It is the smallest Earth analog planet ever found in the habitable zone of a G-type star like our
32:06Sun.
32:07Previous research on super-Earth-sized planets like 452b suggests this one has a good chance of being rocky.
32:17If it is a rocky world, it would weigh in at about 5 Earth masses, giving it a surface gravity
32:24of roughly 2g, which would mean that our weight would be double on its surface.
32:31Kepler-452b could have a thick, cloudy atmosphere and volcanic activity.
32:39Even more exciting than Kepler-452b's Earth-like demeanor is the fact that this world has spent around 6 billion
32:47years in the habitable zone of its star.
32:51That's considerable time for life to arise somewhere on its surface, or in its oceans, should the conditions for life
32:58exist.
33:00Kepler-452b is about 1.5 billion years older than the Earth.
33:05If it was Earth-sized, the planet and its aging, brightening star might be at a point in their evolution
33:12where liquid water would be rapidly evaporating from the surface.
33:18But because of its higher mass, astronomers believe Kepler-452b could continue to hold liquid water for the next 500
33:27million years.
33:33So far, it's the only known world in its system which lies some 1400 light-years away in the Cygnus
33:40constellation.
33:43Obviously, we're not going to get there any time soon, but it's fascinating to imagine that far off from the
33:50distant reaches of space, a world very much like our own might already exist.
33:57If this Twin Earth exists, why couldn't thousands more like it also exist?
34:20Less than a year after the amazing finding of Kepler-452b in May 2016, a new discovery shocked the scientific
34:29community.
34:34Astronomers using telescopes at European Southern Observatory in Chile discovered three planets around a dim dwarf star just 40 light
34:43-years from Earth and the constellation of Aquarius.
34:48These worlds may be the best targets so far found in the hunt for life elsewhere in the universe.
34:56They used the TRAPPIST telescope to monitor the brightness of an ultra-cool dwarf star in the constellation of Aquarius,
35:04which has been named TRAPPIST-1.
35:09TRAPPIST-1 is much cooler and redder than the Sun and barely larger than Jupiter.
35:17Stars like this are very common in the Milky Way, and they are very long-lived.
35:24This was the first time that planets have been found around one of them.
35:28The three planets are very similar in size to the Earth and might have habitable regions on their surfaces.
35:38But the really exciting result is that these are the first Earth-like planets that are well-suited for the
35:45detection of life.
35:46The ultra-cool dwarf stars are the only places where life could be detected on an Earth-sized exoplanet using
35:54our current technology.
35:55The light from much brighter stars like the Sun, for example, would swamp vital measurements of the atmospheres of any
36:03candidate planets.
36:06The next step is to make more detailed observations using the next generation of telescopes, such as ESO's European Extremely
36:16Large Telescope and the James Webb Space Telescope.
36:19That will allow astronomers to study the atmospheres of planets like this and to search for molecules related to biological
36:28activity like ozone, methane, or water.
36:34Although there is not yet any proof of the existence of life on all of those exoplanets that we have
36:40already found, even in the most Earth-like of them like Kepler-452b, we can't help but wonder if any
36:47of those potential forms of life that might have arisen there were or will be able to evolve into intelligent
36:55life.
36:58If any of those extremely remote worlds were formed billions of years ago, as Earth was, and it became a
37:05habitable planet, then the organic compounds had time enough to be mixed up and organized into living forms.
37:12Perhaps any of those living forms might have evolved into complex forms of life, and some of those complex forms
37:21of life might evolve into intelligent beings with consciousness.
37:26Thanks to Kepler mission research, it's known that just in our galaxy, the Milky Way, there might be millions of
37:33Earth analogues, and there are billions of galaxies across the universe.
37:40So the chances are much higher than we could have ever imagined.
37:46For that reason, science is carrying out an intense search for intelligent life.
37:53The SETI Institute in California is the main world institution devoted to the search for extraterrestrial intelligence.
38:01Its name, SETI, stands for Search for Extraterrestrial Intelligence.
38:08This search is based on the use of radio telescopes.
38:12Radio telescopes receive radio waves.
38:15As we can't go to space aboard spacecrafts to find that intelligent life, what we look for are radio signals.
38:23What we're looking for is a signal that's at one spot on the radio dial.
38:28Just like when you're listening to the radio in your car.
38:31You know, you tune across the dial, you hear static everywhere, and then at one spot you're...
38:35And there's a station.
38:38That's the signal that's produced by a transmitter somewhere.
38:42It's not natural static.
38:44It's not like a quasar or a pulsar or galaxies or hot gas, cold gas.
38:48All those things in space make radio noise.
38:51But it's all over the dial.
38:53So we look for signals that are at one spot on the dial.
38:55And, of course, the source of the signal has to be up in the sky.
38:58Those are the kinds of criteria we use to know that even if we don't know what it means,
39:04we at least know they're there.
39:06They're on the air.
39:09Unfortunately, till now, we haven't received a signal that can be really attributed to extraterrestrial intelligence.
39:22In the coming years, NASA and ESA, the European Space Agency, have planned to launch several space telescopes
39:30that will surely help to unveil the mystery of life beyond the boundaries of our solar system.
39:39The most ambitious one is the James Webb Space Telescope.
39:43This project is an international collaboration between NASA, ESA, and the Canadian Space Agency, CSA.
39:53It will be the premier observatory of the next decade, serving thousands of astronomers worldwide.
40:00It will study every phase in the history of our universe, ranging from the first luminous glows after the Big
40:07Bang,
40:08to the formation of solar systems capable of supporting life on planets like Earth,
40:13to the evolution of our own solar system.
40:17This new telescope, three times more powerful than Hubble, will be able to analyze starlight passing through the atmosphere of
40:25the closest Earth-like worlds,
40:27looking for the telltale signs of life itself.
40:30Like, for instance, detecting gases in its atmosphere, usually linked to life processes such as oxygen, methane, carbon dioxide, or
40:41nitrogen.
40:43JWS2 is really going to help us understand what atmospheres of planets are like under different conditions,
40:47and that's going to be a really exciting result.
40:49There is another mission, the CHEOPS mission.
40:53The CHEOPS comes from characterizing exoplanet satellite.
41:01This is an ESA mission dedicated to searching for exoplanet transits,
41:06by performing ultra-high precision photometry on bright stars already known to host planets.
41:18With all of these new space telescopes programmed to be launched in the coming years,
41:23we are sure that finding a habitable exoplanet, and any consistent biosignature, will be just a matter of time.
41:41If we are ever able to find evidence of the existence of any form of life among one of those
41:48billions of exoplanets we know are across the observable universe,
41:52it would be undoubtedly shocking.
41:57If we did find life somewhere else in the solar system, and we were able to do, for example, a
42:02genetic analysis to determine that it was distinct from life on Earth,
42:06that would be a really Earth-shaking discovery.
42:11Living generations might be witness to a finding that would undoubtedly be a turning point in the history of humankind.
42:22The discovery of life in outer space.
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