- 16 hours ago
Our search for living organisms outside of Planet Earth is in full swing. This is the question bothering many of us: is there life in space? Scientists've made a list of 29 planets where life could be possible. How did they come to this conclusion and what does it mean for the future of humankind? Find answers to these and other questions about the planets here!
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00:01You're gazing up at the night sky.
00:04Wow!
00:05For much of our history, we've been looking for life among these stars and the planets
00:09near them.
00:11But space has eyes, too.
00:13And there's someone out there looking at us, maybe.
00:18Scientists claim that at least 29 distant planets may be watching us right now.
00:25So comb your hair and smile.
00:27We've so far identified at least 1,715 neighboring star systems in the Milky Way that can detect
00:35our planet with conventional telescopes.
00:38These stars are located in our galaxy.
00:41So if they were to point their telescopes at our Sun, sooner or later, they would see a
00:46small dot that passes between our home star and the observer.
00:50This is called a transit.
00:52It's a method of detecting planets in astronomy.
00:55For example, you can observe transit phenomenon right at home with a telescope.
01:00You have to point it at the Sun and wait.
01:03Then, you'll see Mercury.
01:05That's the closest planet to the Sun.
01:07And now you see it as a small dot.
01:10Mercury transit process can last about 5 hours.
01:13And this phenomenon happens about 14 times in a century.
01:17Mercury.
01:17You'll be able to observe the next transit on November 13, 2032.
01:23Mark your calendar.
01:25Likewise, you can observe Venus, the second planet from the Sun.
01:29But because it's farther away, its transits are less frequent.
01:34The last one was in 2004 and 2012.
01:37The next pair of transits is expected in 2117 and 2125.
01:43Hey, I won't be around then.
01:46So these star systems have the opportunity to observe our planet.
01:50But long-range telescopes work a little differently.
01:54Actually, the observer will not see a black dot with the Sun in the background.
01:59The telescope will measure the brightness of our star.
02:02When Earth begins its transit between the Sun and the observer, the telescope will record
02:07a slight drop in the brightness of the star because our planet is blocking the path of
02:12the Sun's rays.
02:15Those far-away scientists of extraterrestrial civilizations will be able to calculate this drop
02:21in brightness and determine the size of our planet.
02:26But not all 1700-plus star systems may have extraterrestrial life.
02:32Scientists have narrowed it down to 29 planets near some of these stars.
02:36They're potentially habitable.
02:38That means these planets are roughly Earth-like in size and within the habitable zone of their
02:44host star.
02:45That means they're not too close to the star, so it's not too hot for potential life.
02:49The water doesn't evaporate there like in a boiling pot.
02:53And they're not too far away, so it's not too cold and the water doesn't freeze into
02:58thick sheets of ice.
02:59And since water is the basis of life, we can assume that civilization might exist there.
03:05Theoretically, these planets could have seen Earth transits in the last 5000 years.
03:11So while we were building the Pyramids of Giza or Stonehenge, an extraterrestrial civilization
03:17may have been watching us.
03:20One of these planets is only 11 light-years from our home.
03:25Near the Ross 128 star, a red dwarf in the constellation Virgo.
03:30There's an exoplanet about twice the size of Earth and right in the habitable zone of its
03:35host star.
03:37Theoretically, the inhabitants of this planet could see Earth transit the Sun on a regular
03:42basis for 2000 years.
03:44But about 900 years ago, the planet lost its position and can no longer continue observation.
03:51The other planet where Earth can be seen transiting is 12.5 light-years away, near the star called
03:57Teagarden.
03:58The window for observing our planet will open there in about 29 years.
04:03We're betting heavily on the TRAPPIST-1 star system.
04:07It hosts at least 7 exoplanets, almost like our solar system.
04:12And 4 of them are in the habitable zone of the star.
04:15But they won't be able to start observing Earth until 16 centuries from now.
04:21But we can try to make contact with these planets right now.
04:25They're all close enough to us to pick up our radio signals.
04:29Radio waves can travel through space at the speed of light.
04:32And our planet has been emitting radio signals continuously since 1895.
04:38So we're like noisy neighbors in the radio spectrum.
04:41If there's a planet somewhere with an intelligent civilization within 125 light-years of us, our
04:48radio noise would have already reached them.
04:51The only problem is, it would take about the same time to get a response from that civilization.
04:57The other problem with radio is that any civilization uses it for a relatively short period.
05:03Even now on Earth, we use Bluetooth and fiber optics more than radio, except for maybe traffic
05:10reports.
05:10And over time, all the radio noise we create will simply disappear.
05:16Also, radio communication assumes that an extraterrestrial civilization is advanced enough to use this
05:23technology.
05:23technology.
05:24But who knows?
05:26Maybe there are lifeforms in space that are really different from ours.
05:31Our radio signals already could have reached that planet.
05:33But its inhabitants simply aren't capable of receiving them.
05:38And the moment these lifeforms build antennas to receive the signal, we'll no longer emit them.
05:44But we don't lose hope.
05:46And we even send encrypted radio signals into space to communicate with extraterrestrial
05:51civilizations.
05:52In 1974, we sent the Arecibo message into interstellar space.
05:58If some civilization can decipher it, they'll get a rectangle like this.
06:03It has all the information about humanity.
06:06At the top is our number system.
06:08Then the atomic numbers.
06:09And then our DNA.
06:12Which is pictured below.
06:14Then a human being itself, of course.
06:17Below is a diagram of our solar system.
06:19Earth, the third planet from the sun, is slightly elevated.
06:23This is how the extraterrestrial civilization will understand which planet this message came
06:28from.
06:29Below is a diagram of the Arecibo radio telescope itself.
06:34Another option how to deliver a message to a distant planet is to literally send a mail
06:39delivery there.
06:40It could be a space probe.
06:42And we've already done that.
06:44These are Voyagers 1 and 2.
06:47They were launched in 1977 and are still operational.
06:51In 2012, Voyager 1 became the first-ever human-made object in interstellar space.
06:57It travels to distant stars and carries a message written on a golden record.
07:02The disk contains greetings in 55 Earth languages.
07:05A lot of music from different parts of our planet.
07:09Different sounds like ocean noise.
07:11Human voices and animal sounds.
07:15In addition, there are 116 images on the record.
07:19These are pictures of people and earthly landscapes.
07:22In these pictures, there's information about the sun and our DNA.
07:27The record case contains instructions and a needle to play the record.
07:32There's also a map of our galaxy's pulsars so that astronomers from an extraterrestrial
07:37civilization can find our solar system.
07:41The main disadvantage of sending a message this way is time.
07:45Voyager 1 will reach its first stop, the Gliese 445 star, in 40,000 years.
07:52Voyager 2 will reach the Ross 248 star, in 42,000 years.
07:57And in about 296,000 years, it'll pass Sirius, the brightest star in the night sky.
08:03I can't wait.
08:05Also, an extraterrestrial civilization can detect us with calculations and formulas.
08:10All it takes is a little observation of the sun.
08:14In star systems with planets, the host star doesn't stand still.
08:18It rotates around a small orbit.
08:21This is because the heavy star attracts the planet, but the planet also has its own gravity
08:27and resists.
08:28This shifts the star a little and causes it to orbit around.
08:32An extraterrestrial civilization can calculate this shift of the sun and determine the mass
08:38of the planets near the star.
08:40Using such a method, astronomers were able to find 548 exoplanets.
08:47Now suppose we made contact with an extraterrestrial civilization near the closest star, Proxima Centauri.
08:54There's indeed an exoplanet there, but radiation from the host star would destroy any life forms.
09:01But imagine we still got a return signal.
09:04It would be the slowest chat in history, because our message would take 4.2 years to reach the
09:09planet, and we'd have to wait another 4.2 years to get a response.
09:14And so we arranged to meet.
09:18This civilization doesn't know how to fly into space.
09:21So we have to take the first step.
09:24Although Proxima Centauri is the closest star to our solar system, it takes about 73
09:30thousand years to travel there by conventional rocket.
09:33So we have to learn to travel at the speed of light.
09:36But even then, it would take 4.2 years to travel there.
09:41Imagine if we found extraterrestrial life on the other side of the Milky Way.
09:45Our galaxy is 100,000 light-years wide.
09:49So the journey from edge to edge would take 100 millennia.
09:54So, we either have to cheat the laws of physics, or transfer all of human civilization to a giant
10:01spaceship that will travel from star to star for thousands of years.
10:05And when it launches from Earth, only the great-great-great-great and many more greats
10:10of the first crew will be able to see another star system from the spaceship portal.
10:15Hey!
10:16Can you move your head?
10:17I'm trying to see out the window.
10:19Bang!
10:20Another hit on Jupiter.
10:21Hmm.
10:22Let's see.
10:22Gas giant.
10:23The largest planet in the solar system.
10:26318 times bigger than the Earth.
10:28Two and a half times bigger than the rest of the planets in the solar system put together.
10:33One more interesting thing.
10:34If it got any bigger, it would actually become smaller.
10:38You see, with more mass, the planet would be denser.
10:40That would cause Jupiter to start pulling in on itself.
10:44Scientists say Jupiter could have 4 times greater mass, but still keep the same size.
10:49It takes 10 hours to make a full rotation on its axis.
10:52It's the fastest-spinning planet in our solar system and gets hit by so many space objects all the time.
10:59This was discovered by amateur astronomers observing Jupiter and saw some unusual flash at the planet's surface.
11:05Impact events cause flashes like that, and for some reason, Jupiter gets more impacts than other planets.
11:12In 1994, astronomers discovered Shoemaker-Levy 9, a comet that broke apart and collided with the gas giant.
11:20The original comet was approximately the size of one that erased the dinosaurs.
11:24However, this asteroid fell apart into more than 20 fragments.
11:28They darkened the planet's surface, and it remained like that for months.
11:32Fifteen years later, in 2009, astronomers saw a black spot on Jupiter, the size of Earth.
11:38It was the result of an asteroid around 650 to 1650 feet in length.
11:44The biggest asteroid recorded on Earth hit the area of Tunguska, Russia, in 1908.
11:49This caused a massive explosion, even though no one ever found a crater.
11:53So, why is Jupiter the target for so many space objects?
11:58Asteroids and comets that pass by Earth and Jupiter go almost at the same speed.
12:03The number density of the space object that may interact is almost the same, too.
12:07But the cross-section of what they might hit is very different.
12:11Jupiter has 11 times the diameter of our planet, which means it has around 125 times the cross-section.
12:18The more massive some planet is, the stronger its gravitational attraction.
12:22So, it will entice some space objects drifting by.
12:26Our gravitational field is weaker than Jupiter's.
12:29If some object passes near us moving at a speed of 22,300 miles per hour or less, our gravitation
12:35will attract it.
12:37Asteroids and comets usually move at bigger speeds.
12:40Jupiter attracts most of the comets and asteroids passing by.
12:43If our planet was hit by such big objects as frequently as Jupiter, we'd have extinction like with dinosaurs thousands
12:50of times more often.
12:52In 2020, scientists found there was an unusual asteroid in the orbit of Venus, the first one there.
12:58The size of a small mountain and rich in minerals we can find in Earth's deep rocks.
13:04They even think it could be a clue to a bigger set of asteroids created when our solar system was
13:09forming.
13:09That's not the only mystery around Venus.
13:11The planet has insanely violent winds that drive clouds and storms around the planet at speeds greater than 220 miles
13:19per hour.
13:19That's 60 times faster than Venus itself rotates.
13:23Also, scientists are still not sure what happened with its oceans.
13:27They believe since the planet is so close to the sun, the water evaporated and went into the atmosphere as
13:33steam.
13:34It trapped heat coming from the sun, heat that would have vaporized more and more water over time.
13:39Venus probably had an environment like on Earth, but a very long time ago.
13:44The theory says many comets and asteroids were slamming into Venus.
13:48Billions of the planet's pieces were flying all around.
13:51Some may have even crashed into Earth's moon.
13:54Pieces that slammed into our planet are probably buried very deep since we have greater geological activity than the moon.
14:01Uranus also had a collision, but a more serious one than asteroids.
14:05The rest of the planets in our solar system mostly have an axis of rotation that kind of points up
14:10from the elliptical plane.
14:12Uranus is tilted, lying on the side.
14:14So, a season there lasts 42 years, when either its south or the north pole is pointed at the sun.
14:20Most of the planets also rotate counter-clockwise when you see them from above our solar system.
14:26Venus does the opposite, which means maybe it was kicked off axis a long time ago.
14:31Uranus may have collided with the other space body millions of years ago.
14:35When our solar system was still very young, the orbital configuration of Saturn and Jupiter may have crossed.
14:42Their gravitational forces kind of created orbital momentum and transferred it to Uranus.
14:47That knocked it off axis.
14:50Millions of asteroids orbit the sun, and not so many pass by Earth from time to time.
14:54So, we don't have some dangerous space bodies coming toward us.
14:58The plan is to visit Mars in the 2030s.
15:01And scientists hope Mars won't be a target of some bigger space bodies.
15:05New craters are formed on the red planet every one to two days.
15:09They can be 13 feet across, which means they could have been formed by objects that are the size of
15:14a soccer ball.
15:15Since the atmosphere there is thinner than ours, smaller bodies can enter easier.
15:19Most of the Martian north is smooth lowlands.
15:22The south is higher, full of craters.
15:25And the planet's interior has a surprising amount of rare metals.
15:29The theory says this is because a big celestial body collided with Mars and tore away a part of its
15:35northern half.
15:36Debris from that asteroid circled the planet and then mixed into two small moons that orbit Mars.
15:41We also have some Mars rocks on Earth, found in the Sahara Desert, Antarctica, and some other places across the
15:48globe.
15:49Some of these rocks have gas that's chemically the same as the atmosphere on Mars.
15:54Rocks probably came due to a big explosion that happened when some larger asteroid or meteor that was ejected from
16:00Mars and landed on our planet.
16:02Mercury also has a thin atmosphere, so there are many smaller strikes there.
16:07Imagine waking up, going to your window, and see there are micrometeor showers every morning, which is something that happens
16:14on Mercury.
16:15This strange weather pattern shapes its atmosphere, called an exosphere.
16:19Mercury is so dense, its heavy iron core accounts for two-thirds of its total mass.
16:24Scientists think it could have been bigger in the past, but many collisions got the surface sort of scraped off.
16:30It's been constantly bombarded by rocks from space that left marks with craters.
16:36Planes on its surface seem to have been created because of volcanic lava spilling over the surface and then dried
16:42smooth.
16:43Many craters are filled with such a material, which means there's one more thing that rocked Mercury's world – volcanoes.
16:50There's an unusual group of asteroids discovered near Neptune – wide range in sizes, from big metropolitan areas to tiny
16:58pebbles.
16:58They are thought to come from an asteroid group called the Kuiper Belt.
17:02It makes a ring well beyond Neptune.
17:05But these new asteroids have different colors than the Kuiper Belt.
17:08They're so far away from the Sun, their surface was supposed to stay almost pristine.
17:13But they have a similar color to those sun-baked asteroids around Jupiter.
17:17Like the rest of the planets, Neptune gets heat from the Sun.
17:21But there's something mysterious inside the planet that makes it generate more heat than it gets.
17:26This affects its weather.
17:28And Neptune has the weirdest weather in the whole solar system.
17:31Massive storms, insanely high winds, cirrus-like clouds that rapidly change all the time.
17:37There are dark spots in its atmosphere.
17:40They come and gall.
17:41We receive a thousand times more sunlight than Neptune.
17:44Gas giants like Saturn and Jupiter can protect our planet from asteroids.
17:49Without them, the big impacts that created enough debris to form both moons and other planets would happen more often.
17:56There's a huge asteroid going around Saturn, which could be a potential flyby by 2031, more than ten times bigger
18:03than the asteroid that erased the dinosaurs.
18:05Titan, one of the moons orbiting Saturn, 80% more massive than our moon, is actually the only moon in
18:13our solar system that has an atmosphere.
18:15It's one and a half times thicker than ours and consists mainly of nitrogen, like our atmosphere.
18:20No one knows where all that nitrogen came from.
18:23However, unlike Saturn and most of the other places in our solar system, its moon has a real potential to
18:29host life.
18:33More than one million Earths can fit in our sun.
18:37New research shows that between 20% to 35% of suns eat their own planets.
18:43And a quarter of planetary systems orbiting stars like the sun had a chaotic past.
18:49The very thing that gives life can also take it away.
18:53All the planets in our solar system revolve around the sun, and they all do it in a somewhat consistent
18:59way.
19:00It's most likely that they stayed that way ever since they first came into the picture.
19:05But not all of them.
19:06This chaotic existence means that a solar system had a lot of planets in the litter until the host sun
19:13decided to melt them away.
19:15Our solar system has panned out perfectly so that no planet's gravity interferes with each other.
19:21The gravitational force on Jupiter is a lot tougher than Earth's.
19:25Which means that if Earth gets close to Jupiter, we'd be another moon for Jupiter.
19:30The planet is so big that if Earth were the size of a grape, Jupiter would be the size of
19:36a basketball compared to it.
19:38Even with the best technology in the world, it's difficult to tell if stars do, in fact, eat their planets.
19:45The best way to study this is to observe binary systems.
19:49That's just a science-y way of saying a system with two stars orbiting each other.
19:54Usually, the two stars were formed around the same time from the same gases and the same conditions.
20:00It means they should contain the same elements, more or less.
20:04When you open your eyes in the morning, the sunlight that's been traveling for millions of miles greets you.
20:10The closer we get to it, the hotter it is.
20:13But the rays traveling from the sun also contain certain chemicals that make it unique.
20:18The chemicals that are associated with the sun are light materials like oxygen, carbon, hydrogen, and helium.
20:26You can find some other stuff in it too, but these are the main ones.
20:30By studying these elements, you can learn the history of a solar system with enough detail to determine if it
20:37was chaotic or smooth.
20:38Scientists studied 107 binary systems composed of suns like ours by analyzing the light.
20:45Since each system contains two suns, they compared and contrasted them to see the differences.
20:51They observed the stars with a thin outer layer having different elements than their companion.
20:56All suns contain light elements, but there are some that have rocky elements like iron, silicon, and titanium near the
21:04sun.
21:04These elements are associated with rough terrains that you'd find on the surface, but they're out there floating in the
21:11middle of space.
21:12The thinnest outer layer is especially rich in iron compared to the other layers.
21:18Many stars are twins at birth.
21:21Even most of the Milky Way stars have a buddy in a binary system.
21:24It means our sun is pretty unique for not having a partner.
21:29But there are some theories out there that suggest that the sun may have lost its twin in the past.
21:35It's around 184 light-years away and is called HD 186302.
21:41And this might be our lucky star.
21:44A stellar nursery is where thousands of stars are born.
21:48They're made up of gas and dust that gradually collapse under their own weight.
21:52Our sun may have started in such a way 4.6 billion years ago.
21:57And when they're mature enough, they go out into the open, usually with their travel buddy.
22:02Actually, scientists claim that up to 85% of all stars could be in binary pairs or have more buddies.
22:09But over 50% are dual pairs.
22:12The only problem is that we can't really see it since it strayed from its original orbit an eternity ago.
22:19But traces of it can be found in the Oort cloud.
22:22That's the vast cluster of space consisting of comets, space rocks, and ice in the outer edges of our sun's
22:29reach.
22:29They float around quite a lot since they're far off the sun's gravity and can easily be knocked out of
22:36their orbit into open space.
22:38Flying through such a space is no different than flying through any random void of space.
22:43The reason why some of these light elements in space contain rock elements you'd find on the surface of a
22:48planet is because the sun knocked them off their orbit and devoured them as they got closer.
22:55It also happens when a star becomes too big in its place and starts eating everything around it.
23:00According to scientists, if a star eats a planet, it can make it go chaotic and spin so quickly that
23:07it eventually rips apart.
23:09But don't worry, there's a very low chance of the sun devouring the planet in the near future.
23:15Stars are formed when a huge cloud of hydrogen and helium grows until it collapses under its own weight.
23:22The pressure increases and reaches extreme heat levels we can't even measure.
23:26Eventually, the hydrogen atoms lose their electrons, causing the hydrogen to fuse together and release energy, countering the gravity collapsing.
23:34But when the gravitational force overpowers the hydrogen fusion, the star begins to expand and becomes a red giant.
23:43And then, after around a billion years, the hydrogen in the outer core will go away, leaving plenty of helium
23:50hanging around, which will fuse with the rest of the elements around.
23:54And once all the helium disappears, gravity will shrink the red giant into a white dwarf.
24:00And when it's completely gone, the remains of the star release tons of gas and dust into space.
24:06Scientists claim that our sun has between seven to eight billion years left before it reaches that stage.
24:13But even if that becomes a reality, it wouldn't happen overnight.
24:17Something like this takes millions of years to take place.
24:20But what if the sun decided to devour us overnight as we speak?
24:25The planet would start feeling hot in seconds.
24:28Every slight degree change can lead to some catastrophic events.
24:32Ice caps can melt in a matter of seconds and flood the coastal lands.
24:37Even little islands in remote areas of the world will be submerged.
24:41And as it gets hotter, every snow-capped area will melt instantly and turn into desert-like climates.
24:48Some places will burn and your everyday objects will melt on the spot.
24:52The Earth's interior will also get hotter, allowing volcanic eruptions to happen across the world.
24:58Antarctica will melt from the heat, as well as the volcanoes erupting inside.
25:03And just in a matter of minutes, the whole planet will turn into fire and ash before it explodes into
25:10tiny bits floating in space,
25:12reaching areas we've never even heard of.
25:15But no worries. Something like this won't really happen.
25:18In case the sun knocks us off our rotation, the results would be different.
25:23It'll also get hot, because the magnetic field around us protects us from the sun's radiation.
25:29And once we get knocked out of place, the magnetic field gets tarnished.
25:33And the extreme heat from the sun will boil us.
25:36The gravitational force will be unstable, so the physics of our everyday life will be chaotic.
25:42We'll have to wait five billion years from now, when the sun turns into a red giant.
25:47It'll grow in size, eventually eating up Mercury and Venus.
25:51Chances are, Earth will also be on the menu.
25:55If Earth were to move only 900,000 miles closer to the sun, then it would be uninhabitable.
26:01It may seem like a lot, but it's only four times the distance between the moon and Earth.
26:07Detecting the chemical composition of the sun rays in solar systems that are further away
26:12could help scientists find other Earth-like planets.
26:15Since the atmosphere around these planet-eating stars changes the chemical composition,
26:20we can detect which solar systems out there have had a calm past.
26:24The main thing we have to observe is if the planets have a healthy orbit cycle.
26:28With nothing else getting in the way, we can assume that the planet could follow the same steps as Earth
26:34did for humans to be here.
26:36But this process will take ages, since there are millions of nearby stars similar to our sun.
26:42The odds of finding a planet similar to ours are near impossible at this rate.
26:47But if so, then there might be life on those planets.
26:50There will be no way of knowing if it's intelligent life, but they might have had the same evolutionary fate
26:56as us.
26:57There is something you are words that Alsaka has proven,
26:57I feel at some time that will combine and turn around.
26:57Takes for sure and poet and 활 —
26:57It is a long term and of nice and வ.