Is Oumuamua Artificial? + 40 Intriguing Space Facts

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Transcript

00:00:00In 2017, a strange object was spotted in our Solar System.

00:00:06It had the shape of a long tube, similar to a pancake.

00:00:10No known asteroid or comet we've seen looks like that.

00:00:13Its exterior was also peculiar.

00:00:16It was at least 10 times more reflective than the average stuff that flies through space,

00:00:20with some saying it had a surface similar to polished metal.

00:00:24When it went past the Sun and left our reach, it accelerated faster than what our gravity

00:00:29could account for.

00:00:31At first glance, it was like this thing had a rocket strapped to its back.

00:00:35This unusual visitor even got a special name – Amuamua.

00:00:39It comes from Hawaiian and translates to scout or visitor from a faraway land.

00:00:45And because of its characteristics, scientists soon began to wonder if this was, at last,

00:00:50a visit from otherworldly creatures.

00:00:55So they went full-on with the science fiction suppositions.

00:00:59Astronomers gathered the information they were sure about.

00:01:02Starting with the fact that Amuamua must've come from another Solar System.

00:01:06There must've been some unfortunate event in its home system that led to its ejection.

00:01:11What they didn't know was that this was a comet or asteroid.

00:01:15They're both celestial objects orbiting the Sun, but they have distinct compositions

00:01:19and behaviors.

00:01:21Comets are composed primarily of ice, dust, and rocky material, often referred to as dirty

00:01:26snowballs.

00:01:28When a comet approaches the Sun, the heat causes the ice to vaporize, releasing gas

00:01:32and dust particles into space.

00:01:35This creates a bright glowing tail that can extend for millions of miles.

00:01:40Comets generally have elliptical orbits, often taking them from the distant reaches of our

00:01:44Solar System closer to the Sun.

00:01:49Comets, however, are mostly made of rock and metal.

00:01:52In our neighborhood, they are remnants of the early formation of the Solar System and

00:01:57are typically found in the asteroid belt between Mars and Jupiter.

00:02:01Unlike comets, asteroids do not develop tails when they approach the Sun, as they have no

00:02:06ice.

00:02:07Their orbits generally follow more circular paths compared to comets.

00:02:12By all accounts, Amuamua should be a comet, because it seems to come from a different

00:02:17location in the Universe.

00:02:20But it doesn't exhibit the typical signs of cometary activity.

00:02:24Amuamua lacks a tail and does not spew out gas as it passes by, not like me.

00:02:30Even though it behaves like a comet, it looks more like an asteroid.

00:02:36Another big question is how scientists even managed to spot Amuamua in the first place.

00:02:42Considering the vastness of space and time in the galaxy, it's remarkable.

00:02:46Stars have lifetimes spanning millions or billions of years.

00:02:50And the formation of a solar system takes hundreds of millions of years.

00:02:54Even the fastest objects take tens of thousands of years to travel from one star to another.

00:03:00In contrast, humans have only been observing the skies with telescopes for around 400 years,

00:03:06a tiny fraction of cosmic time.

00:03:09And it's only in recent decades, even years, that we've had the technology to detect

00:03:14and track fast-moving, dim objects.

00:03:17Either rocks like these are abundant, or we've been incredibly lucky with our detections.

00:03:22Or it simply wanted to be seen.

00:03:27Another question that was asked was where such objects could come from.

00:03:31It's highly unlikely that Amuamua came from a mature, stable solar system.

00:03:37That's because such systems don't eject enough material to fill up the galaxy.

00:03:41Occasionally, a random rock might get flung out, but it can rarely travel so far.

00:03:47Young systems, however, act differently.

00:03:50In these chaotic environments, collisions, mergers, and migrations are happening everywhere.

00:03:56Plenty of tiny rocks roam around, perfect candidates for ejection.

00:04:00The solar system that kicked Amuamua out must've had a planet similar to Jupiter.

00:04:06Its massive size and gravity could influence other objects in the system, causing potentially

00:04:11ejections.

00:04:12But not all solar systems develop Jupiter-sized planets.

00:04:16Often massive planets end up close to their stars, becoming hotter versions of Jupiter.

00:04:22These planets, snugly orbiting the Sun, are less likely to eject debris.

00:04:27Now Neptune-like planets may play a role too.

00:04:30While not as massive as Jupiter, they tend to call the outer regions of solar systems

00:04:34their home.

00:04:36Our solar system has the Kuiper Belt, a reservoir of comets in its outer reaches.

00:04:41During a solar system's early stages, interactions between Neptune-like planets and debris are

00:04:47common.

00:04:48Finding Neptune-like planets in other systems has been challenging though.

00:04:52Our methods for detecting exoplanets work better for massive objects close to their

00:04:56stars, making it difficult to spot Neptune counterparts farther out.

00:05:04Amuamua was also linked to a peculiar theory about how life came to be in the universe

00:05:09– panspermia.

00:05:11Now that's a hypothesis that suggests that life exists throughout the universe and can

00:05:16be distributed between planets by various means, such as asteroids, comets, or even

00:05:22spacecraft.

00:05:23It says that life must have originated in one location in the universe and then spread

00:05:28to other celestial bodies.

00:05:30Fans of the panspermia theory have suggested that such interstellar objects could potentially

00:05:35carry tiny microbes.

00:05:37Those building blocks of life between star systems.

00:05:41If such objects were to impact a planet or a moon, they could transfer these materials

00:05:46and seed the celestial body with life.

00:05:49For now, there is no evidence to support the theory that this comet in particular has transported

00:05:54life between star systems.

00:05:59After years of research, the overall consensus became that Amuamua was indeed a comet.

00:06:05The reason why it moved so strangely is because it might have frozen hydrogen on its surface

00:06:10that reacts when touched by sunlight.

00:06:13The closer it got to our Sun, the faster it became, releasing that hydrogen and also changing

00:06:18its path through our solar system.

00:06:21Its color also supports this theory – it's red, which might mean it's been hit by cosmic

00:06:26rays for a long time.

00:06:28The longer it was touched by those rays, the more hydrogen it gathered in the process.

00:06:34But since they can't be completely sure, astronomers have a plan to follow this visitor.

00:06:39One idea is to send a mission to check it out.

00:06:42It's already far away from us, but it may not be too late just yet.

00:06:47We may be able to send a probe fast enough to catch up with the comet.

00:06:51The plan was named Project Lyra, and aims to use the Earth's orbit and that of Jupiter

00:06:56to bounce out a probe far enough to reach Amuamua.

00:07:00If it works, it will be the fastest space device we've sent out in the Universe.

00:07:05One potential trajectory of the space probe involves the gravitational pull of our planet

00:07:10and that of Jupiter as a lasso effect, but not Ted Lasso.

00:07:15The probe will leave our planet and re-enter Earth's orbit before sending it to meet

00:07:19with Jupiter's pull.

00:07:20It will be sent back near our planet a second time, where it will be ejected with enough

00:07:25force to reach the comet.

00:07:30Project Lyra also aims to follow a second far-away visitor, named Borisov.

00:07:35This one was discovered by an amateur astronomer and now bears his name.

00:07:39What's interesting about it is that it's, well, spotless.

00:07:44Similar to our experience with Amuamua, we haven't seen anything like Borisov before

00:07:48either.

00:07:49Studies of the light coming from its cloud of dust and gas show it's very clean compared

00:07:54to other space objects.

00:07:56After it was first noticed in August 2019, astronomers studied its path through our solar

00:08:02system and concluded it came from another star too.

00:08:06But Borisov gave us more time to study it because we spotted it earlier in its journey

00:08:11through our neighborhood.

00:08:13Researchers used advanced telescopes to look at the dust coming off Borisov.

00:08:17They found it's throwing off over 400 pounds of dust every second.

00:08:22They also found Borisov has more carbon monoxide than comets from our solar system usually

00:08:27do.

00:08:28But the amount isn't the same everywhere on the comet.

00:08:31This tells us the space object probably started forming near its home star before moving away,

00:08:37maybe because of larger planets in its system.

00:08:40The light from Borisov is way more polarized than light from other comets we've seen,

00:08:45and its cloud is super smooth.

00:08:47This tells us Borisov has never interacted with another star.

00:08:57Back in the day, from 774 to 775, Earth got hit with a mega blast of radiation.

00:09:05This crazy burst of energy left its mark.

00:09:08Three rings from that year show way too high levels of radioactive stuff.

00:09:13But what exactly caused it?

00:09:16Astronomers are inclined to think that the reason was a solar flare.

00:09:20Some folks think maybe a massive supernova caused the radiation blast.

00:09:25But astronomer Phil Plait says that if that had been the case, it would have had to be

00:09:30less than a thousand light years away and would have been crazy bright.

00:09:34But there's no record of that happening.

00:09:36No bright shiny death star in sight.

00:09:40After looking at the radioactive carbon and beryllium in tree rings, scientists ruled

00:09:44out a bunch of other possibilities.

00:09:47At first, they considered that it was a smash-up between neutron stars or a neutron star and

00:09:52a black hole.

00:09:54These types of crashes produce a super-quick blast of gamma rays without any light show,

00:10:00which lines up best with the evidence.

00:10:03But these kinds of collisions are super rare.

00:10:06Plait thinks it's kinda unlikely that this is the answer.

00:10:10He figures we should only see one of these events in our galaxy about once every million

00:10:14years.

00:10:15So having one just 1,200 years ago seems pretty wild.

00:10:20Scientists are seriously worried about these rare events.

00:10:23If one happened closer to Earth, it could seriously mess up life on our planet.

00:10:28Even if it was thousands of light years away, a similar event today could cause chaos with

00:10:33all the fancy electronic systems we've come to rely on.

00:10:37So it's a good thing those gamma ray bursts are so rare, because if they were more common,

00:10:43Earth might be in for a rough ride!

00:10:46You may think that if our planet could withstand mega-radiation blasts, it can easily withstand

00:10:51something less frightening.

00:10:53Let's say grasshoppers.

00:10:55Sorry to say that, but it's not exactly true.

00:10:58Back in 1874, during a hot summer in Kansas, things took a strange turn.

00:11:05Grasshoppers, or should I say locusts, invaded the Great Plains like nobody's business.

00:11:11They came down like a storm, blanketing houses, trees, and even poor trains passing by.

00:11:18These bugs were on a mission to cause chaos.

00:11:22Farmers had to scramble to protect their wells and just about anything else worth saving.

00:11:28Locusts landed everywhere, wreaking havoc on everything in sight.

00:11:32Even poor sheep lost their wool.

00:11:35Locusts even stripped paint off wagons and handles off pitchforks.

00:11:39This is how destructive they were.

00:11:42Livestock tried to fight back by eating them, but there were just too many of these insects.

00:11:47That year, those critters caused about $200 million in crop damage.

00:11:52The locust invasion was so tough, even the U.S. Army stepped in to help.

00:11:57In the end, locusts began to disappear, sparing the plains from further devastation.

00:12:04Natural disasters can be even more unexpected than radiation blasts from space and locust

00:12:09invasions.

00:12:11Check this out.

00:12:12Back in June 2017, a reindeer herder up in northwest Siberia was minding their own business

00:12:18when they suddenly heard a crazy loud blast and saw smoke shooting up from the ground.

00:12:24If that happened to me, I'd need to change my pants.

00:12:28Sorry.

00:12:29Later on, they found this huge hole that was like 23 feet wide and nearly 65 feet deep

00:12:34and was surrounded by chunks of ice and dirt.

00:12:38It turned out that there were over 17 such black holes in the area.

00:12:43They were filled with peaty water and shrouded in mystery.

00:12:47Some folks thought those were sinkholes.

00:12:49Others were sure they were left by top-secret device tests or even a bunch of meteorites.

00:12:55Now, the latest idea is that these holes are actually craters caused by the Arctic

00:13:00warming up and melting the frozen ground.

00:13:03The theory states that as the ground thaws, gas pockets trapped beneath the surface burst

00:13:08through, creating such dramatic holes.

00:13:12Apparently, these eerie craters have been showing up in specific spots in Siberia where

00:13:18ancient geological faults have been leaking out hot natural gas for ages.

00:13:23Combine that with some leftover methane from old lake sediments, and you've got a recipe

00:13:28for some explosive surprises as the planet heats up!

00:13:33Not scared yet?

00:13:34All right, maybe you're afraid of darkness, huh?

00:13:37If so, you wouldn't like it back in 536.

00:13:41It's the year when the world went through a crazy 18-month period of darkness.

00:13:47A mysterious fog covered Europe, the Middle East and parts of Asia, blocking out the sun

00:13:53and causing chaos.

00:13:55It was like the Dark Ages, but for real.

00:13:58It turns out that the main culprit behind this fog was a volcanic eruption in Iceland.

00:14:04This eruption spread ash across the northern hemisphere, causing temperatures to drop and

00:14:09crops to fail.

00:14:11People were freezing and starving.

00:14:13It was a mess.

00:14:15Historians from back in the day even talked about how weird it was.

00:14:19The sun looked like the moon, summers were freezing cold, and even China had summer snow.

00:14:26It was all because of the volcanic ash blocking out the sun.

00:14:30And to make things even worse, this period of darkness sparked the beginning of the bubonic

00:14:36plague in 541.

00:14:39Talk about a rough time to be alive!

00:14:43Let's go back to Siberia real quick.

00:14:46Back in 1908, way out in the wilds of Siberia, an asteroid dropped for an unexpected visit.

00:14:53Today, we know it as the Tunguska asteroid, but it didn't get its name instantly.

00:14:59Local folks only caught a glimpse of the show.

00:15:02A bright fireball streaking across the sky, followed by a massive boom.

00:15:08Trees went flying, fires blazed, and animals weren't too happy about it either.

00:15:14But since the area was so remote, not many folks took notice.

00:15:19For almost two decades, nobody bothered to check out the Tunguska site.

00:15:24People had too much on their plates back then.

00:15:26But then, scientists finally made it out there and found evidence of the asteroid's shenanigans.

00:15:33Later in expeditions, they found some spacey microparticles.

00:15:37Fast forward to now, and NASA has a whole planetary defense thing going on.

00:15:42They even sent a mission to test out asteroid-deflecting tech.

00:15:46Because who knows when the next cosmic rock will come knocking on our door, right?

00:15:51In the middle of the 19th century, there was one more epic solar storm called the Carrington

00:15:57Event.

00:15:58It may not sound like a big deal to you, but it had pretty rough consequences.

00:16:03The next day after the storm, Earth was hit with this insane geomagnetic storm that threw

00:16:09telegraphs off the rails and brought auroras to the tropics.

00:16:13And it's the place where they normally never show up.

00:16:18Turns out, all this space weather madness started with weird stuff happening on the

00:16:22sun's surface, like sunspots.

00:16:25From these spots, solar flares and other crazy electromagnetic stuff can pop out and mess

00:16:30with our technology.

00:16:33Massive solar storms like this one can shoot out from the sun at speeds of up to 1800 miles

00:16:38per second.

00:16:39They can contain billions of tons of solar material, complete with a sassy little magnetic

00:16:44field that loves to mess with Earth's magnetic field when they meet.

00:16:49Now, listen closely.

00:16:51We're getting close to the next solar maximum in 2025, so it's a good time to check out

00:16:56the history of the worst solar storms like the Carrington Event and take notice.

00:17:02Imagine if a similar storm hit today.

00:17:05An internet apocalypse, anyone?

00:17:07Businesses would be sent offline and we'd be facing some serious damages.

00:17:11Luckily, these mega solar storms don't happen very often.

00:17:16But hey, space weather is tricky to predict, so who knows when the next one will hit?

00:17:23You may think the Earth is pretty big, but the sun makes up almost 99.9% of the mass

00:17:28of the whole solar system.

00:17:31The rest of the mass is made up by the planets and their satellites, asteroids, comets, gas

00:17:37and dust.

00:17:38It's around 93 million miles away from our planet, but it keeps us warm every day.

00:17:44Its temperature is about 10,000 degrees Fahrenheit, but the space surrounding it is still cold

00:17:50as ice.

00:17:51To understand this, we need to distinguish between heat and temperature.

00:17:55Heat is the energy inside some object.

00:17:59Temperature is something that tells us if that object is hot or cold.

00:18:03When the heat is transferred to that object, it makes its temperature go up.

00:18:08When the object is losing heat, the temperature goes down.

00:18:11Heat can be transferred in three different ways.

00:18:14The sun does it through radiation.

00:18:16That means it's releasing heat in the form of light.

00:18:20Your body radiates heat too, as infrared waves.

00:18:24That's why thermal imaging cameras will detect that you're in the room even at night.

00:18:28The hotter the object, the more heat it will radiate.

00:18:31The temperature only affects matter.

00:18:34Since space is mostly a vacuum, it doesn't have enough particles for heat to transfer

00:18:38in any other way than through radiation.

00:18:41When the heat from the sun gets to an object, the atoms start absorbing energy, but the

00:18:46heat can't transfer since there is no matter in space.

00:18:50Those rare atoms and molecules in space will absorb the heat, and they'll simply stay

00:18:56that way, while the cold vacuum will stay cold.

00:19:00There's a lot of matter inside Earth's atmosphere, so the energy of the sun can transfer

00:19:04easily.

00:19:05But if you put an object outside of the Earth's atmosphere in direct sunlight, it would end

00:19:10up heated to 250 degrees Fahrenheit because it's matter made of atoms and molecules.

00:19:17The temperature of the vacuum is negative 454 degrees Fahrenheit.

00:19:22That means, depending on where you are, space can either burn or freeze you.

00:19:28The sun isn't actually yellow.

00:19:30It emits light over a wide range of wavelengths.

00:19:33We can tell both its temperature and color by the peak in its spectrum.

00:19:38For instance, cooler stars will appear red, and hotter stars will be blue with yellow,

00:19:44orange and white stars in between.

00:19:47When it comes to the sun, the spectrum peaks at a wavelength we'd usually call green,

00:19:52but our eye perceives it differently.

00:19:54So the shade of green in combination with other wavelengths from the spectrum is going

00:19:59to look white to the human eye.

00:20:01We generally see the sun as yellow because our atmosphere scatters blue light more efficiently

00:20:06than the red one.

00:20:08During sunrise and sunset, there's more red light in the spectrum of the sun, which gives

00:20:13us amazing sceneries.

00:20:15Sunspots are part of the sun's visible surface that are on average way cooler than the sun

00:20:20itself.

00:20:22They overlap with parts that have an increased magnetic field.

00:20:26These parts don't allow the release of heat to the sun's visible surface.

00:20:30That way, the rest of the sun's surface is three times brighter than those sunspots.

00:20:36That contrast makes them appear almost black.

00:20:39If we could take a sunspot apart from the sun and place it somewhere in the night sky,

00:20:44it would be different, as bright as the moon when we see it from the Earth.

00:20:48All the planets in our solar system spin in the same direction because they were formed

00:20:52from one protoplanetary cloud, except for Uranus and Venus.

00:20:57They have probably had some strong impact on them that made them spin in the opposite

00:21:02direction.

00:21:04But it's different with galaxies.

00:21:05They don't usually form the same cloud of dust and particles.

00:21:09Also, they're not randomly distributed across space.

00:21:13They come in filaments, dense, slender strands of dark matter and galaxies, with voids in

00:21:19between.

00:21:21Proto-galaxies are linked by gravitational forces in small areas of space.

00:21:26This is probably because of the distribution of dark matter throughout the universe.

00:21:31The matter in the filaments moves in a corkscrew motion and goes towards the densest area.

00:21:37So, there might be a common direction galaxies tend to spin, but it's mostly random.

00:21:43There's a possibility we'll see a lunar elevator one day.

00:21:46Yep, a cable anchored to the surface of the moon.

00:21:49It would stretch 250,000 miles.

00:21:53We wouldn't be able to directly attach it to our planet because both Earth and the moon

00:21:57are moving.

00:21:59But we could keep it terminated high in our planet's orbit.

00:22:04Some researchers believe we could build such an elevator for a few billion dollars.

00:22:08The moon has resources we could definitely use.

00:22:12A rare form of helium found there could be of use in fusion power stations on our planet.

00:22:18Also, we could take some other rare elements and use them in smartphones and the rest of

00:22:23electronics.

00:22:24So, after around 53 trips up and down, the elevator could pay for itself.

00:22:30The cable would be as thick as a pencil, but its weight would be around 40 tons.

00:22:36It could even be made of materials we already have here on Earth, with no need to invent

00:22:40something.

00:22:41There could even be a combination of two elevators.

00:22:45A spacecraft would winch up an elevator from the surface of our planet to a space station.

00:22:51Then it would be flung towards the moon.

00:22:53There would be another elevator to finally lower it down to the surface of the moon.

00:22:59Planets in our solar system have predictable and stable orbits.

00:23:03But gas giant collisions could have happened at an early stage when a planetary system

00:23:08was still forming.

00:23:10In case of a head-on collision, two gas giants would merge.

00:23:14They wouldn't end up losing their mass, the materials in their gaseous envelopes,

00:23:18or the ones in their solid cores.

00:23:21Such a collision at a higher speed would cause the loss of the major part of the envelope

00:23:25gas, and at very high speeds, boom, both planets are gone.

00:23:31It's different if it's not a head-on collision.

00:23:33If two cores manage to completely avoid each other, gas giants won't merge, but they'll

00:23:38lose some of the mass.

00:23:40Gas giants might even change their shape due to such collisions.

00:23:45Astronomers found out there's a galaxy extremely far away from us that looks similar to our

00:23:50Milky Way.

00:23:52We now see it as it was when the universe was only 1.4 billion years old, and now it's

00:23:5813.8 billion years old.

00:24:01It took over 12 billion years for the light to come from this faraway galaxy and reach

00:24:06our planet.

00:24:08This galaxy is peaceful, stable, and surprisingly non-chaotic, unlike all other galaxies that

00:24:14were quite turbulent in their early stages.

00:24:17To leave the Milky Way, we'd have to travel around 25,000 light-years away from the center

00:24:22of the galaxy, or 500 light-years vertically.

00:24:27Our galaxy is a disk of stars that spreads around 100,000 light-years across and is 1,000

00:24:33light-years thick.

00:24:35The Sun, its central star, is located halfway from the center of the galaxy and close to

00:24:40the middle of the disk in the vertical direction.

00:24:43We'd have to go further than its edge to get away from the halo that surrounds the

00:24:48Milky Way, old stars, diffuse gas, and globular clusters.

00:24:54If you wanted to go even further to see the Milky Way in all its glory, you'd have to

00:24:58travel 48,000 light-years vertically.

00:25:01At this moment, we don't even have a telescope we can send there.

00:25:06There are central stars that eat planets.

00:25:09Our solar system is stable, unlike many other planetary systems, so we don't have to be

00:25:14afraid the Earth or some other planet will change its orbit and go towards the Sun.

00:25:18But, at least a quarter of other planetary systems with orbiting stars similar to the

00:25:23Sun have a pretty chaotic past.

00:25:26In some of them, there are planets that used to move around, and their unpredictable migrations

00:25:31have disrupted the paths of some other planets, or even pushed them outside of their orbit.

00:25:37That means some planets probably have fallen into the central star.

00:25:41When that happens, the planet gets dissolved in the outer layer of the star, which means

00:25:46it gets eaten.

00:25:50It's September 1977.

00:25:52You're playing one of the first video game consoles released in North America.

00:25:56You step outside and see the whole neighborhood waiting for Voyager 1 to launch.

00:26:01It's a super sunny day, so you squint a little, trying to see what's happening.

00:26:05You live in the neighborhood right outside the launching station.

00:26:09You get yourself some food and watch the Voyager take off into space.

00:26:14You're so impressed, you decide to dedicate your career to working with NASA.

00:26:1935 years later, you're now a senior official in NASA, specializing in Voyager 1.

00:26:26It's 2012, and you're sitting in the control room with your colleagues.

00:26:31Everyone is staring at their computer screens as they work on the Voyager.

00:26:35You're sitting on the top, overlooking everything, and making sure all systems are in check.

00:26:41This day is special, as Voyager 1 is about to exit the heliosphere, which is a science

00:26:47word for the outer shell of our solar system.

00:26:50It's a bubble of space affected by the solar wind, which comes from the sun.

00:26:55By 2021, it got 14 billion miles away from Earth, which is equivalent to 153 astronomical

00:27:03units from the sun.

00:27:05One astronomical unit is the distance between the sun and the earth.

00:27:09The craft was originally meant to fly by Uranus, Saturn, and Jupiter, and toss itself from one

00:27:15planet to another with the use of their gravitational pull.

00:27:19Everyone is impatiently waiting for it to exit the heliosphere.

00:27:233, 2, 1, and it's officially out!

00:27:28All systems are normal and functioning.

00:27:30You praise your team for doing an excellent job.

00:27:33With Voyager 1 reaching this far, there's still tons to explore in outer space.

00:27:39You were once a young adult, watching the craft launch outside your neighborhood, and

00:27:44now, you're the main person in charge of the operation.

00:27:48Nine years later, since Voyager 1 left the heliosphere, you've been checking up on it

00:27:54every now and then, making sure all systems and functions are in order.

00:27:58It's been sending back measurements of the interstellar medium.

00:28:02It's the area between the stars of our galaxy, consisting of ionized materials.

00:28:08Ionized is basically a simple version of a molecule or substance.

00:28:12The interstellar medium is an electrically charged state of plasma, or ionized plasma,

00:28:17and is very unstable.

00:28:19It's like going from lightning in a thunderstorm back to calm rain in a matter of seconds.

00:28:25The plasma up there is different than the plasma on Earth, in that it's difficult to

00:28:30filter out.

00:28:31There are around 0.06 atoms for every cubic inch in the interstellar medium.

00:28:37The air we breathe on Earth has billions of atoms.

00:28:41By measuring the plasma in the interstellar medium, we can further understand the behavior

00:28:46and structure of chemicals and gases.

00:28:49It's possible that the oxygen we know and love on Earth is different than the ones out

00:28:54there.

00:28:55One of your main tasks is to learn more about how the solar wind from the sun and interstellar

00:29:00medium interact with each other to create the heliosphere.

00:29:04So, after doing some routine checkups and other maintenance work on Voyager 1 from the

00:29:09control room, you notice something strange coming from the screen.

00:29:14You sit in front of the computer, crunching the numbers of the plasma vibrations and convert

00:29:18them into an audio file of about 3 kilohertz.

00:29:22You click on it and listen to an eerie, subtle hum.

00:29:26You and your team are surprised that these vibrations occurred in such a small frequency.

00:29:31Given that space is massive, something like this might mean life on other planets.

00:29:37Everyone else at the station rushes to the control room to listen to that sound from

00:29:42outer space.

00:29:43It's monotonous and faint, but it's definitely coming from outside the heliosphere.

00:29:50You run the numbers over and over to make sure it's not a fluke, but it's on point.

00:29:55You make sure your team doesn't spill the beans to anyone outside until everything is

00:30:00known and clear.

00:30:01You get into beast mode with work and try to catch the sound again, and it remains.

00:30:07You can't sleep trying to think of something that could be producing this hum.

00:30:11A few days pass by, and the sound is pretty consistent.

00:30:16If there was some life out there trying to communicate with you, then surely it would

00:30:20have said something that can be deciphered.

00:30:22You analyze the audio files once again, trying to see if it's some phonetic language you

00:30:28don't know.

00:30:29You call in a linguist to see if she can make something out of it.

00:30:33You and the squad gather around, waiting impatiently for some answers.

00:30:37After a while, she believes that it might be someone out there communicating with us,

00:30:42but the only way to find out is by sending something back to them.

00:30:46You arrange a meeting with your team and try to figure out what message you can send.

00:30:52After much thinking, and lots of coffee, you decide to send them one phrase in English.

00:30:57Who are you?

00:30:59You send out the signal through Voyager 1 and wait for any changes in the hum, but you

00:31:04don't get anything straight away.

00:31:07It may take some time for a response.

00:31:09You wait all night, and still, there's nothing.

00:31:13It's starting to look like there isn't anything out there.

00:31:17For the next couple of days, you keep sending out phrases for anything to pick up.

00:31:22Since space is a vacuum, sound waves can't travel, so sending out voice messages on a

00:31:27large speaker won't work.

00:31:29You locate the source of the humming and aim for it when sending the audio file.

00:31:35Every day, you send something different, but still, you don't hear anything from them for

00:31:39a week.

00:31:41It seems that intelligent life in the distant world isn't real.

00:31:45The areas between the star systems and a galaxy aren't necessarily a complete vacuum.

00:31:51That's where the interstellar medium is.

00:31:53It contains gases, dust, and cosmic rays, which are energy particles.

00:31:59After many months of this constant humming being produced, you still try to figure out

00:32:03what's going on.

00:32:05You sit there, remembering the time when the Voyager was first launched.

00:32:09You remember running outside after playing some video games.

00:32:12You couldn't see properly because of the sun, and you freeze in your spot and have a eureka

00:32:18moment.

00:32:19You go through some notes taken in the past.

00:32:21The answer was in front of you all this time!

00:32:25Every now and then, the sun sends a burst of energy that causes the plasma of interstellar

00:32:30space to vibrate.

00:32:32Scientists can measure the frequency of waves when the plasma vibrates to show how close

00:32:37they are to each other, and on the day when the hum was delivered, there were some irregular

00:32:42frequencies coming from the sun.

00:32:44So that hum might have been the plasma vibrating in a weird way because of the sun flares.

00:32:52But these low-level vibrations last longer than quick jumps and spikes.

00:32:56They're fainter.

00:32:57You run the tests again, and find out that it's not some intelligent lifeforms out there

00:33:01trying to talk to you.

00:33:03It's the little vibrations caused by sun flares.

00:33:07You notify your team about this breakthrough, and everyone's celebrating.

00:33:11But after all these tests and research, you still don't know why plasma in the interstellar

00:33:16medium vibrates in such a way.

00:33:19Those answers will have to wait.

00:33:222027.

00:33:23It's been 50 years since the launch of Voyager 1.

00:33:27You're way into your senior years, and just retired from NASA.

00:33:31You have many scholarships in your name, and programs for young people who want to learn

00:33:35about space and science.

00:33:38You go back to the control room once more, where you thought you had discovered intelligent

00:33:42life on a distant world.

00:33:45Then you remember all the good times you had.

00:33:47You say goodbye to everything, knowing that this is Voyager's final moments.

00:33:53It was built to last up to 50 years.

00:33:56After that, it'll just be a floating object in the vastness of space.

00:34:01It's already surprising to know that this is Earth's most distant object from us.

00:34:06But it's time to let others take your place.

00:34:09You shut off the lights and close the door.

00:34:11The Voyager makes one last beep before eternal silence.

00:34:18Hey MythBusters, today we're debunking some classic space myths.

00:34:23Hop on the next space shuttle and let's get to the bottom of these tales once and for

00:34:27all.

00:34:30Picture this.

00:34:31You're floating weightlessly in space, sipping on a cup of delicious hot chocolate, when

00:34:36a peculiar thought pops into your head.

00:34:39Can you scream in outer space?

00:34:41And if yes, would anyone hear that scream?

00:34:47If you've watched the movie Alien, then you know the answer to this one.

00:34:51You can't hear sounds in outer space.

00:34:53It's not that sounds don't exist.

00:34:55It's just that you can't hear them.

00:34:58There's no one better to clarify this myth than Chris Hadfield.

00:35:02He's been on a couple of spacewalks during his life as an astronaut.

00:35:07And once you're out there in the darkness of space, you can't hear anything.

00:35:11All you hear is silence.

00:35:14Complete silence.

00:35:16But hey, just around the corner is a massive ball of explosion, aka the sun.

00:35:22We just can't hear the explosions happening because there's no medium for sound to travel

00:35:26through.

00:35:27It would be quite uncomfortable for an astronaut though, if they could hear all the noises

00:35:31going on in outer space.

00:35:34Now, imagine you're zipping through space, feeling like a futuristic superhero, when

00:35:39a shooting star passes by your side.

00:35:41But wait, is it really a star?

00:35:44Unfortunately, shooting stars are not stars at all.

00:35:48They are small space rocks known as meteoroids, entering Earth's atmosphere and creating

00:35:54a stunning light show.

00:35:56Oh, and since we're debunking myths, let's head straight for another one.

00:36:01You've probably heard that meteors only crash into Earth on extremely rare occasions,

00:36:07like once every dinosaur extinguishing apocalypse.

00:36:10That's not true.

00:36:12Scientists estimate that about 48 tons of meteoritic material fall on Earth each day.

00:36:19But almost all of this material is vaporized in Earth's atmosphere.

00:36:23The bright trail we see in the night sky is what we popularly call a shooting star.

00:36:28Next time you make a wish upon a shooting star, remember you're actually hoping on

00:36:32a tiny piece of space debris.

00:36:34It's not so romantic after all.

00:36:39Can we or can we not fly into the stratosphere on air balloons?

00:36:43Apparently, we can.

00:36:45The Earth's stratosphere starts relatively close to the ground, about 7 or 8 miles up

00:36:50from the Earth's surface, but it continues a long way up.

00:36:55If you were to fly yourself all the way into the stratosphere with some type of air balloon,

00:37:00just make sure you have really good equipment at hand.

00:37:03You'll need a special suit and some breathing devices because air starts to get pretty thin

00:37:08the higher you get.

00:37:10Of course, if you do go all the way up, you need to get a picture of the Earth's curvature.

00:37:15So take a chest harness with you where you can put a special camera or something like that.

00:37:20And how about you live stream the whole thing?

00:37:22That would be a first!

00:37:26Imagine it's been 102 days since you left Earth.

00:37:29You've adapted well to life in outer space, but something weird is happening to your body.

00:37:35You're getting taller.

00:37:36How is that even possible?

00:37:38Don't stress about it, it's completely normal.

00:37:41The truth of the matter is, you're not getting taller.

00:37:44This is what happens to your body when it's not under the effect of gravity.

00:37:49Our body has natural space between vertebrae and joints.

00:37:53On Earth, this space is almost completely squeezed due to the force of gravity.

00:37:58But in space, your body gets some time off of the pushing force of gravity

00:38:02and begins to stretch more and more.

00:38:05So yes, astronauts can grow up to 3% taller when they're on long missions.

00:38:10And here's a curiosity.

00:38:12NASA has that all covered when they're tailor-making spacesuits, of course.

00:38:16This way, astronauts will always have extra space in their suits.

00:38:20Once astronauts are back on Earth, the anti-gravity effect will wear off.

00:38:25So maybe they'll spend a few days wearing capri pants before it fits perfectly on their bodies again.

00:38:32Never have I ever pictured an airplane door bursting open mid-flight

00:38:36and a bunch of passengers being sucked into the atmosphere like flying feathers.

00:38:40Well, I'm betting most of you have had similar thoughts when getting inside a plane.

00:38:45Now imagine if this were to happen in outer space.

00:38:48Common knowledge says that if an astronaut is sucked out of an airlock,

00:38:52this person would be burnt to a crisp.

00:38:55Brace yourselves, because this is not only true, but the reality of it is way worse.

00:39:00According to astronaut Chris Hadfield, this is what would happen.

00:39:04The part of your body in the shade of the sun would experience temperatures of negative 418 degrees Fahrenheit,

00:39:12while the part of you getting sunlight would burn at around 480 degrees Fahrenheit.

00:39:18Your lungs would collapse, and your blood would start to boil like tea water.

00:39:22So you would burn, freeze, lose your ability to breathe, and boil. Yikes!

00:39:30How many times have you heard that astronauts have to work out every second of every day,

00:39:35otherwise they'll pass out?

00:39:37This is a complete myth.

00:39:39Remember we talked about gravity earlier?

00:39:42Due to the lack of gravity in outer space, our bodies don't have to do any heavy work.

00:39:47Our torsos don't have to sustain the weight of our heads,

00:39:50and we don't have to make any effort to move our legs because, essentially, there's no walking in outer space.

00:39:57Now imagine living like that for six months, or even a year of your life.

00:40:03Your muscles could turn into jello.

00:40:06That's why astronauts work out.

00:40:08They'll strap themselves and run on a treadmill,

00:40:11or they'll do some weightlifting in a special machine.

00:40:14This way their muscles won't feel the lack of gravity too much.

00:40:18They do need to keep hydrated though.

00:40:22You know what?

00:40:23If I was an astronaut, I'd ask NASA if I could take my super soft water flask up into space with me.

00:40:30You've probably heard that space smells like burnt steak or barbecue sauce.

00:40:35Now as much as this sounds absurd, this myth is more true than it is false.

00:40:41Astronauts obviously can't smell space when they're in it because they can't take off their helmets.

00:40:46They usually smell it once a space vehicle docks and they open up a hatch.

00:40:51Apparently, what causes this smell is the presence of hydrocarbons that float around in space.

00:40:57Who would have thought, huh?

00:40:59Hey smart people, let me ask you a question.

00:41:02Do you really think that if astronauts fly at the speed of light, they won't age a single second?

00:41:08I knew you'd say no!

00:41:10Let's get a few things straight.

00:41:12First of all, we haven't figured out how to operate vehicles at the speed of light.

00:41:17This would require an immense amount of energy and we don't have the technology to do that.

00:41:22Second, even if we managed to send a human inside a spacecraft that travelled at the speed of light,

00:41:28this person would still age.

00:41:30They would age differently than the people who remained on Earth, that's a fact.

00:41:34But they would still age.

00:41:36Do you lot really think there's such a thing as immortality?

00:41:39Nah.

00:41:41If you've seen the first Avatar, then you certainly remember that humans only managed to get to Pandora

00:41:46because they travelled in cryosleep.

00:41:49In other words, they froze their bodies, put them in a cryo bed and travelled for years without aging.

00:41:55Yes, this sounds amazing, but we still don't have the technology to do that.

00:41:59Our bodies are mainly made out of water, right?

00:42:02And when you freeze water, it expands.

00:42:05That's why you should never leave soda cans unattended in your freezer.

00:42:09Right now, if we froze a person's body, the water inside of it would expand, harming tissues and organs.

00:42:16So no, we can't cryosleep our way into interstellar travel.

00:42:20Not yet at least.

00:42:23Here's a crazy thought.

00:42:24Here's a crazy thought.

00:42:25What would happen if an astronaut took a drone with him on one of their spacewalks?

00:42:30Unless it's a NASA-designed drone, maybe the thing would freeze and burn like humans would

00:42:35if they went into space without a suit.

00:42:37But hey, a person can dream, can't they?

00:42:41Asteroids flying around is sometimes like a fierce game of dodgeball,

00:42:45where you never know when some of them can go in your direction.

00:42:48So we can just track the situation and hope for the best.

00:42:51To figure out the risk, scientists from different organizations

00:42:54have to study the positions and paths of the asteroids that come close to our planet,

00:42:58especially those that are at least 0.6 miles wide.

00:43:02And the good news is that none of these asteroids will probably hit us for at least the next 1,000 years.

00:43:07Phew!

00:43:08To give us an idea of their power,

00:43:10scientists did an experiment to simulate the impact of such a gigantic asteroid.

00:43:16The energy released from the collision would be a mind-blowing 100,000 megatons.

00:43:21That's like detonating 15,000 tons of dynamite.

00:43:25Also, if such a big asteroid hit us, Earth would cool down significantly

00:43:29because of all that debris that would go into the atmosphere and block sunlight.

00:43:34Plants wouldn't be able to get their fuel in this case,

00:43:36so we'd all be in trouble, both humans and animals.

00:43:39Thankfully, such mammoth asteroid impacts are quite rare.

00:43:42The larger an asteroid, the longer it takes it to collide with Earth.

00:43:45For example, it's estimated that asteroids with diameters of at least 0.6 miles

00:43:50strike our planet about once every 700,000 years.

00:43:54And if we're talking about even bigger ones that are 3 miles wide,

00:43:57well, those are predicted to come crashing down only once every 30 million years.

00:44:01Yay!

00:44:02But hold on.

00:44:03Don't get too relaxed just yet.

00:44:05Astronomers focus on really large asteroids

00:44:07because those are the ones that can kind of doom our planet if they hit us.

00:44:12Yep, you got it right.

00:44:14In a dinosaur kind of way.

00:44:16Even if one of them didn't erase us completely,

00:44:19the damage would still be enormous.

00:44:21So, there are still some asteroids wandering around

00:44:24that we need to keep an eye on to see how they might evolve over time.

00:44:28Scientists have a model of tracking them

00:44:30where they focus on the parts of an asteroid's path that come close to our planet

00:44:34to see if the space rock poses a risk to us.

00:44:37And it seems there might be one asteroid,

00:44:397482, 1994 PC1,

00:44:433,600 feet in diameter that might pose some danger.

00:44:47It's supposed to come closer to our planet in the next 1,000 years.

00:44:51And when I say risky,

00:44:52it means there's a 0.0151% chance of it coming within one Earth-Moon distance.

00:44:58It already passed by us in 2022,

00:45:00but we were lucky because it was far enough 1.2 million miles.

00:45:04I'd say we can relax when it comes to asteroid scenarios.

00:45:07For now.

00:45:08Asteroids slamming into Earth would be new for humankind,

00:45:11but not for the planet itself.

00:45:13As I said, there weren't many of those big ones,

00:45:15but they still had enormous consequences.

00:45:17The first one that comes to most people's minds is, of course,

00:45:20the dinosaur asteroid as big as a mountain

00:45:23that struck our home planet around 66 million years ago

00:45:27near Mexico's Yucatan Peninsula.

00:45:29It was chaotic.

00:45:31Global firestorms and tsunamis were all over the place.

00:45:34Dust was blocking out the sun,

00:45:36and vaporized rock released sulfur,

00:45:38which then led to acid rain and the acidification of the oceans.

00:45:41But there was an even bigger fella that came before that one.

00:45:44Around 2 billion years ago,

00:45:46a gigantic asteroid crashed into our planet

00:45:48and left a massive crater in South Africa.

00:45:51The one we know today as the Redifort Crater.

00:45:54And it seems this asteroid might have been even bigger

00:45:56than we all originally thought,

00:45:58twice as wide as the space rock that erased dinosaurs.

00:46:01The Redifort Crater is confirmed to be the biggest visible crater on Earth,

00:46:05with a diameter of about 99 miles.

00:46:08It used to be even bigger when it first formed, though,

00:46:11maybe even 155 to 174 miles across.

00:46:15It's hard to figure out its true size

00:46:17because the crater has been eroding for the past 2 billion years.

00:46:20Think of it like slicing off layers from the rim of a bowl.

00:46:23The diameter gets smaller with each slice.

00:46:26When the asteroid, 7 to 5 miles wide,

00:46:29that wiped away dinosaurs hit Earth about 66 million years ago,

00:46:33it caused massive destruction.

00:46:35Forest fires, acid rain, tsunamis,

00:46:37and so much ash and dust that it changed Earth's climate.

00:46:41This all made about 75% of life on our planet extinct.

00:46:45The asteroid that created the Redifort Crater was not only bigger,

00:46:49but it also traveled at a higher speed,

00:46:52which means the consequences there would have been even worse.

00:46:55But it happened a long time ago,

00:46:57and living beings were different back then.

00:47:00Maybe it was some bacteria that didn't even notice that something unusual was happening.

00:47:04Earth is not the only one.

00:47:06Lots of impacts have happened across our solar system, too.

00:47:09For example, in our close neighborhood.

00:47:11Yup, moving to Mercury and its massive crater called the Caloris Basin.

00:47:16It measures about 950 miles across, which is more than the state of Texas.

00:47:21There's a ring of towering mountains around the crater

00:47:23which makes it look even more impressive.

00:47:25You can see different colors in the mosaic image of the Caloris Basin.

00:47:29They tell us more about the geology of the basin.

00:47:32The orange parts represent lava that once flooded the basin.

00:47:36These lava flows covered the original surface and added this specific orange hue.

00:47:41And after the lava flooded the basin on Mercury,

00:47:44smaller craters formed on top of the lava surface.

00:47:47These craters dug into the ground and uncovered the material hidden beneath the lava.

00:47:51Some of this material is blue in color.

00:47:53And this blue stuff could be a clue about what the original floor of the basin had looked like

00:47:57before the lava covered it.

00:47:59Venus, the hottest planet in our solar system,

00:48:02has a thick atmosphere that comes with a pretty good defense system against space rocks.

00:48:06It's so dense that it burns up most meteors before they even reach its surface.

00:48:11As a result, you won't see as many visible craters on Venus

00:48:14as on other rocky planets in our solar system.

00:48:17But Venus still has some scars that can tell us about some serious impacts that happened there.

00:48:22And one of the biggest scars we know about is Mead Crater.

00:48:26It's enormous.

00:48:28About 170 miles in diameter.

00:48:31The inner floor of this crater is relatively flat and kind of brighter than its surroundings.

00:48:35It's possible that the crater ended up filled with a mixture of melted rock after the impact

00:48:40and maybe even lava from volcanic activity on Venus.

00:48:44Want to get an idea of what Earth might look like without its protective layer called atmosphere?

00:48:50Just take a look at the moon.

00:48:52Its surface is littered with impact craters.

00:48:54This tycho is one of the craters you'll easily notice on the moon.

00:48:58When you look at the full moon, you can spot it as a distinct circle

00:49:01with bright rays that radiate outward, slightly off-center, on the lower left side of the moon.

00:49:06This crater, 53 miles wide, has a beautiful central peak in the middle

00:49:10that's topped with an intriguing boulder.

00:49:12The size of this boulder is impressive.

00:49:14It would fill about half of a typical city block here on Earth.

00:49:18When talking about craters, we definitely can't leave out Mars.

00:49:21The red planet has a much thinner atmosphere than Earth.

00:49:24When spacecraft approach Mars, they rely on the planet's atmosphere to slow them down as they enter it.

00:49:29And indeed, the atmosphere helps slow spacecraft down during landing.

00:49:33But it's still not thick enough to completely protect Mars from all those space rocks that are coming all the time.

00:49:39From July to September 2018, a dark spot appeared on the southern pole of Mars.

00:49:44It consists of two distinct patterns.

00:49:46A theory says that the bigger, lighter-colored blast pattern

00:49:50can be the result of an impact shock wave scouring the ice surface.

00:49:54The impact generated winds that spread out and scoured the ice.

00:49:58The inner blast pattern, which is darker in color,

00:50:01occurred because the impacting object managed to penetrate the thin ice layer.

00:50:05As it hit the surface, it sent dark sand and debris flying in all directions.

00:50:10If an asteroid like Apophis hits Earth, we will be destroyed.

00:50:16Massive earthquakes will strike.

00:50:19And tsunamis will flood everything.

00:50:22Apophis is a billion-year-old celestial body that has been in the solar system since its inception.

00:50:29So, you might be thinking, well, how likely is it that this giant space stone will collide with our planet in 2029?

00:50:37Well, let's find out, shall we?

00:50:40Apophis is a big, bad asteroid discovered in 2004 by the Kitt Peak National Observatory in Arizona.

00:50:48Since then, it has proudly held the title of one of the most dangerous asteroids ever located.

00:50:54It's around 1,100 feet wide, which is a bit bigger than the Empire State Building and the Eiffel Tower.

00:51:01Because of how scary it is, it was named Apophis,

00:51:04like the Egyptian immortal creature that was considered to bring eternal darkness and destruction to Earth.

00:51:10Oh, boy!

00:51:12In 2021, researchers had a once-in-a-lifetime opportunity to study this floating rock when it passed near our planet.

00:51:19And we'll come back to that in a minute.

00:51:22Now, some scientists say that there is a small chance of Apophis hitting the Earth on Friday, April 13, 2029.

00:51:31The Yarkovsky effect is to blame for this since it can slightly nudge this space rock towards Earth.

00:51:38This effect originates from the uneven emission of thermal photons from a rotating celestial object,

00:51:44resulting in a fascinating force exerted upon it in space.

00:51:48These emitted photons possess momentum and play a pivotal role in shaping the dynamics of the body.

00:51:55The asteroid has two sides, light and dark, just like the Moon.

00:51:59The light side faces the Sun and is warmer than the dark side.

00:52:03But the thing also turns, so the sides constantly change direction and temperature.

00:52:08This change could be detrimental because it slightly pushes Apophis toward Earth.

00:52:15Unfortunately, nobody knows how the Yarkovsky effect will influence the asteroid's path.

00:52:21On the other hand, on the asteroid's last flyby of Earth in 2021,

00:52:26astronomers used radar to take accurate measurements of its trajectory

00:52:30and confidently concluded Apophis will safely miss Earth in 2029 by about 20,000 miles

00:52:37and won't bother us again for at least 100 years.

00:52:41Now, generally speaking, every 8,000 years our planet is hit by a falling star

00:52:47that has similar dimensions to those of Apophis.

00:52:50The last time we were hit by a slightly smaller meteor was in 2013.

00:52:58A new spacecraft developed by NASA called the OSIRIS-REx was launched in 2016

00:53:04to collect samples from another slightly less terrifying celestial body called Bennu.

00:53:09Four years later, it finally arrived at the thing, got some samples,

00:53:14quickly said goodbye to Bennu and started traveling back towards Earth.

00:53:19The samples were safely stored in a capsule dropped in Utah.

00:53:23So far, this has been the most significant sample ever taken from an asteroid.

00:53:28After the delivery, the spacecraft didn't waste any time and started chasing Apophis.

00:53:34Now, OSIRIS-REx has been renamed to OSIRIS-APEX and is currently playing tag with Apophis.

00:53:42With some luck, on the 2nd of April, 2029, when the asteroid zips close by Earth,

00:53:48the spacecraft will reach Apophis and land on it.

00:53:52It will stay on Apophis for 18 months, collecting valuable information and taking thousands of pictures.

00:53:59The asteroid will be monitored with the help of powerful telescopes.

00:54:03At some point, Apophis will get too close to the Sun,

00:54:06and then all the monitoring work will be on OSIRIS-APEX back.

00:54:12If you live in Europe, West Asia, or Africa,

00:54:15you're one of those lucky people who will have a once-in-a-lifetime opportunity to see Apophis with the unaided eye.

00:54:22It'll be visible in the sky in these regions in 2029,

00:54:26and those who have telescopes will be able to spot it once again in 2036.

00:54:32OSIRIS-APEX will experience some problems because the asteroid has a thick crust,

00:54:37and the spacecraft won't be able to collect data as easily as it did with Bennu.

00:54:42OSIRIS-APEX has a unique thruster that will blow all the dust from Apophis while landing.

00:54:48This will be a perfect chance to analyze the surface of the asteroid to see what it's made of.

00:54:54The craft will spend one and a half years mapping the asteroid, trying to detect changes in its shape.

00:55:00All this research will show how the celestial body is likely to move,

00:55:04so we can better design plans to protect Earth from such things.

00:55:09In 2025, NASA is also going to launch the mission Apophis Pathfinder,

00:55:14and it will be the first spaceship to ever touch this asteroid.

00:55:18It will land approximately a year after its launch.

00:55:21Also, NASA has proposed sending a swarm of tiny craft into space

00:55:26to help humanity develop effective protective tactics against asteroid strikes.

00:55:31We know that Apophis originated in the primary asteroid belt between Mars and Jupiter.

00:55:37In the past million years, this celestial body has changed its path

00:55:42because of the considerable influence of Jupiter's gravitation.

00:55:45Now it seems like it favors the Sun more, meaning this asteroid will come very close to Earth.

00:55:51That's why it's classified as a near-Earth celestial body.

00:55:55A lot of tests and research have been done to find a way to deal with asteroids.

00:56:00Some solutions include drilling and detonating the space body from inside,

00:56:04or testing new technologies, like attaching rockets to it and trying to steer it away from Earth.

00:56:10We can also hit it with something moving at high speeds to make it change its course.

00:56:16Apophis is an S-type asteroid made of rocks and minerals, like iron and nickel,

00:56:22and is shaped like a peanut.

00:56:24It can tell us a lot about the past and possibly the future.

00:56:28Sampling this space object could reveal how life on Earth began and how plants appeared.

00:56:34There are many theories that suggest that water arrived on our planet on an asteroid or a comet.

00:56:41Asteroids are like priceless time capsules.

00:56:44Unlike rocks on Earth, which have undergone thousands of changes, like erosion,

00:56:49most celestial bodies are still intact and much easier to study.

00:56:53When meteors fall on Earth, they get covered in debris that's impossible to clean.

00:56:58That's why studying Apophis while it's still in space is so important.

00:57:03Also, some asteroids are made of precious metals, like platinum.

00:57:08Right now, we have a high demand for metals that we use in production,

00:57:12and mining metals on Earth is quite tricky.

00:57:15Just one large meteor might have iron, nickel, gold, and platinum that could last us millions of years.

00:57:22If Apophis has this amount of metals, well, we'd want to break it down and bring it back to Earth.

00:57:28One space rock could be worth quadrillions of dollars, making space mining highly profitable.

00:57:34And still, it would cost us more to get it back to Earth than to dig up these materials here.

00:57:40As technology progresses, and new kinds of rockets are developed, this might become possible at some point.

00:57:48So, even though we're safe for the next hundred years from Apophis,

00:57:52you probably still want to see what would happen if something like it did impact.

00:57:57Come on, sure you do.

00:57:59Well, first let me tell you, you'll hear the sound of the collision and know what's happened even if you're miles away.

00:58:06You should leave your house or apartment immediately.

00:58:09Shortly after the impact, massive earthquakes will strike, and many tall buildings will fall.

00:58:15So, staying away from cities might be your best option if you have a choice.

00:58:20But don't escape by car, there will be massive traffic jams, and everyone will panic.

00:58:27Going on foot or by bike is your best option in this scenario.

00:58:31A prime way of transportation will be traveling by plane,

00:58:35so if you've always wanted to get that pilot license, now you've got a good excuse.

00:58:41If you have time, take along extra snacks and water, and an extra pair of socks.

00:58:47It's nice to live by the ocean or the sea, but in this scenario, it's the worst place to be,

00:58:53because giant tsunami waves will hit coastlines after the impact.

00:58:57If you live far away from the impact area, the tsunami might take 30 hours to arrive.

00:59:03You'll have a bit of time to prepare.

00:59:08No one will hear your cry in space, or something like that.

00:59:12We've all heard this famous chilling phrase, and it's actually true.

00:59:16Space, for the most part, consists of a giant nothingness.

00:59:20There's a lot of, you know, space in space.

00:59:23But this doesn't mean there are no sounds in space.

00:59:26In fact, there are plenty of them, and some of them can even make you shiver.

00:59:30Let's take a look at the scariest space sounds.

00:59:33First of all, how are cosmic sounds even recorded?

00:59:36Sound is just the vibration of molecules.

00:59:39When you scream, you make the molecules push each other furiously

00:59:43until they reach the ear of the person you're yelling at.

00:59:46Then these vibrations get transmitted to the brain,

00:59:49and we recognize them as something that you might need to apologize for.

00:59:53In other words, to hear something, we need molecules.

00:59:57And that's where things get complicated.

00:59:59There aren't any of them in space.

01:00:01The entire universe, almost completely, consists of a vacuum.

01:00:04No, not a Hoover. Absolute nothingness.

01:00:07However, the wizards from NASA still record space sounds somehow.

01:00:11So how do they do it?

01:00:13The thing is, there are some types of waves that don't care about molecules.

01:00:17We regular folk can't perceive them without some special devices.

01:00:21These waves include, for example, radio waves.

01:00:25We'll need a radio or something like that to recognize them.

01:00:28And that's exactly what NASA's satellites do.

01:00:31They catch random radio waves.

01:00:33Thanks to their heroism, we can find out how different cosmic bodies sound.

01:00:38These satellites record a variety of waves, fluctuations of plasmas,

01:00:42magnetic fields, and other, you know, stuff.

01:00:45And then scientists from NASA transform all this into normal soundtracks.

01:00:50And some of them sound quite frightening, to put it mildly.

01:00:54Let's take our magnetic field, for example.

01:00:57It surrounds our planet like an invisible shield,

01:01:00protecting us from all sorts of nasties, like radiation and solar winds.

01:01:05At the same time, we can neither see it, feel it, nor hear.

01:01:08Oops! Well, the last one is outdated.

01:01:11Scientists from the Technical University of Denmark

01:01:14took magnetic waves recorded by the ESSA swarm satellite,

01:01:18they converted them into an audio track, and got a pretty creepy result.

01:01:24Now, to be honest, it sounds more like an eerie entity stalking you in the middle of the night.

01:01:30And if you remember the maps of Earth's magnetic field,

01:01:34it starts to feel like a spider crawling nearby.

01:01:37And this isn't the first strange sound that we caught on Earth.

01:01:41Recently, we caught another weird radio emission from space.

01:01:45Scientists found out that the repeating signal came from somewhere very far away,

01:01:49like billions of light-years away from us.

01:01:52Such fast radio bursts usually lasted no longer than a few milliseconds,

01:01:56but this one was unique.

01:01:58It lasted about 3 seconds, basically thousands of times longer than usual.

01:02:03And at the same time, the signal was very precise,

01:02:07so much so that scientists even compared it to a heartbeat.

01:02:11Scientists believe that this signal is caused by pulsars, or neutron stars.

01:02:16One time, Nikola Tesla caught something similar.

01:02:19But unfortunately, at that time, we didn't know about such things as pulsars,

01:02:24so Tesla was sure that he had caught a message from some extraterrestrial life.

01:02:29It's a pity that the truth turned out to be much more boring.

01:02:32But let's move on from the Earth to the Moon.

01:02:35In 1969, the astronauts of the Apollo 10 mission,

01:02:39the spacecraft that made the final test flight to the Moon,

01:02:42flew past its surface.

01:02:44And then they caught some strange signals coming from the dark side of the Moon,

01:02:49the side that we never see because the Moon is tidally locked to us.

01:02:53The sound was so weird that the astronauts weren't even sure whether to report it to NASA.

01:02:58They were afraid they wouldn't be taken seriously,

01:03:01and maybe even not allowed to participate in the next space missions.

01:03:05Here's what it sounded like.

01:03:08But according to NASA, it's not some creepy extraterrestrial music at all.

01:03:14These may just be some radio waves that affected each other because of their proximity.

01:03:20Although the astronauts who heard it for the first time probably felt a little creeped out.

01:03:25Let's move to the other planets.

01:03:27Now, 40 years ago, scientists actively explored the surface of Venus.

01:03:31They sent as many as 10 probes there,

01:03:34and were supposed to capture audio and video shooting from the surface.

01:03:37Now we know what Venus, which could easily destroy us at any attempt to even get close to it, sounds like.

01:03:47Horrifying.

01:03:48And you wouldn't expect anything else from the most dangerous planet in the Solar System.

01:03:53Unfortunately, Venus is even more toxic than the average Twitter user.

01:03:57Ha!

01:03:58So, these probes didn't last too long.

01:04:00They heroically arrived on a planet and soon broke down.

01:04:04Next one is Jupiter.

01:04:06This space giant, which is 11 times larger than the Earth, never fails to scare us.

01:04:11One of NASA's probes, Juno, flies around Jupiter every few weeks.

01:04:16The probe is moving at a tremendous speed, 130,000 miles per hour.

01:04:21One day, Juno caught one of the strongest invisible signals it had ever encountered.

01:04:27This was the point at which the mad solar wind came into conflict with the magnetic field of Jupiter.

01:04:33It kind of sounded like a cosmic boom.

01:04:36The original sound lasted 2 hours, but it was compressed to a few seconds.

01:04:41It actually sounds more like a collision of a sea wave and a rock.

01:04:45But here, in terms of horror, Jupiter surprisingly loses to one of its small moons, Ganymede.

01:04:52In 2021, the Galileo space probe flew past Ganymede.

01:04:57And during its flight, it received a rather strange recording.

01:05:05These sounds are satellite radiation.

01:05:08And it's unclear whether it sounds like a cozy sunny day in the jungle,

01:05:12or like thousands of bats waiting for you in the night.

01:05:16Next one is Saturn.

01:05:18Juno was caught by the Cassini-Huygens Automatic Interplanetary Station,

01:05:22which was launched into space in 1997.

01:05:25When flying past Saturn, Cassini recorded a pretty scary sound.

01:05:32This terrifying cry of thousands of souls is actually just some radio waves.

01:05:37They aren't too different from what the auroras emit on Earth.

01:05:40A little later, Cassini received another recording.

01:05:43The sounds made by lightning and thunderstorms on Saturn.

01:05:46They sound pretty interesting too.

01:05:51More like popping corn or a Geiger counter, right?

01:05:54But that's just because these lightning strikes have a crazy frequency.

01:05:58Moving on from the Solar System to outer space.

01:06:01The famous Voyager 1 was launched back in 1977,

01:06:05and continues to send us data even 40 years after its launch.

01:06:10In 2012, it left the Solar System and entered interstellar space.

01:06:15And then, while abandoning its home, Voyager 1 detected the sound of plasma waves.

01:06:21The original recording lasted 7 months.

01:06:24But fortunately, scientists felt sorry for us and reduced it to 12 seconds.

01:06:30It isn't really eerie, but it's still kind of unsettling.

01:06:34And although it feels like nothing can beat Saturn's horrors,

01:06:37let's end this tournament with one of the scariest objects in the Universe.

01:06:41A black hole.

01:06:43This sound was recorded by the Chandra Space Telescope.

01:06:46While studying a cluster of galaxies in the constellation Perseus,

01:06:50they discovered something strange.

01:06:53Some undulating movements appear from the center of the cluster.

01:06:57They spread out in all directions, like circles on the water.

01:07:01Scientists have suggested that this was caused by a supermassive black hole.

01:07:06The thing is, black holes don't always devour space objects entirely.

01:07:10Sometimes, they kind of spit them out.

01:07:13This causes vibrations of gases, which we can convert into soundtracks.

01:07:18What's interesting is that the oscillation of each such wave actually lasts about 10 million years.

01:07:24You're just listening to a very accelerated recording.

01:07:28Scientists have reduced the delay between oscillations by about 144 quadrillion times.

01:07:34So, let's check it out.

01:07:37This is probably the eeriest sound from the whole list.

01:07:40Nothing too loud or wild, but there's something dark and disturbing about it.

01:07:45Now, those were the scariest space sounds captured by NASA.

01:07:49To be fair, most of them sounded creepy simply because they're radio waves.

01:07:53But it's still fun to get spooked sometimes.

01:07:58Uh-oh, something is nearing the surface of the planet.

01:08:02It looks like a fireball hurtling closer and closer at a truly incredible speed.

01:08:07Soon, it becomes obvious that the collision is inevitable.

01:08:11Bam!

01:08:12The impact leaves a huge crater.

01:08:14It evaporates thousands of cubic miles of solid rock,

01:08:17and it also sets off a series of terrible natural disasters.

01:08:21Yeah, I know what you're thinking.

01:08:23You believe I'm talking about the catastrophic collision that occurred around 66 million years ago on Earth.

01:08:29You know, the one that's responsible for the extinction of non-avian dinosaurs

01:08:33and three-quarters of other life forms on our planet?

01:08:36But no, the disaster I'm talking about happened on a different planet.

01:08:41Scientists think that our close neighbor, Mars, once experienced the same catastrophe that struck Earth.

01:08:47It happened around 3.4 billion years ago.

01:08:50An asteroid collision might've caused a mega-tsunami on the Red Planet,

01:08:55similar to the one that caused the Chicxulub impact on Earth.

01:08:59Scientists have identified an impact crater on Mars

01:09:02that was probably left by a comet or asteroid collision with the surface of the planet.

01:09:07Most likely, the space body landed in an ocean in the Martian northern lowlands.

01:09:12And the impact was so powerful that it caused a mega-tsunami.

01:09:18Before the latest studies, the exact location of the impact crater wasn't verified.

01:09:23It was just a theory.

01:09:25To confirm it, a team of astronomers simulated a comet and asteroid collision

01:09:30in the area where they supposed the impact crater was.

01:09:33They even named this crater Paul.

01:09:36Paul is 68 miles across and lies in a region that is almost 400 feet below the supposed sea level.

01:09:43Anyway, the simulations formed several craters of the same size as Paul.

01:09:48One of the simulations claimed that these craters had been left by a 5-mile-wide asteroid

01:09:54that had encountered strong ground resistance.

01:09:57The other simulation showed that the craters had been caused by a bit smaller asteroid

01:10:02that met a weaker ground resistance.

01:10:04But, according to both simulations, the impact crater was almost 70 miles in diameter,

01:10:10and the collisions produced mega-tsunamis up to 900 miles away from the center of the impact site.

01:10:16The simulations also helped scientists estimate the height of the tsunami.

01:10:20It was about 820 feet tall, almost as tall as the Eiffel Tower.

01:10:25The authors of the study also suggest that the Paul crater might be similar to the Chicxulub impact crater on our planet.

01:10:35The Chicxulub asteroid, as we now know it, is believed to come from the outer reaches of the Solar System.

01:10:41This space body was at least 6 miles across.

01:10:44It crashed into the shallow seawaters near the Yucatan Peninsula.

01:10:48This splashdown was so powerful that it left its signature on the entire face of the planet.

01:10:56In 2021, researchers found out that the collision had carved mega-ripples into Earth's crust

01:11:02in the region of modern-day central Louisiana.

01:11:05An even newer study suggests that the asteroid also triggered a tsunami so devastating

01:11:11it eroded seafloor sediments half a world away.

01:11:15The team of scientists remodeled the events of the first 10 minutes after the impact,

01:11:20and the models showed that the asteroid had produced waves up to 30,000 times greater

01:11:25than one of the largest tsunamis people have ever recorded,

01:11:29the Indian Ocean tsunami that hit Indonesia in 2004.

01:11:33The collision displaced so much water that it created a wave almost a mile high

01:11:39that's like two Burj Khalifas, which is the tallest construction in the world,

01:11:43stacked one on top of the other.

01:11:45And, of course, all that empty space didn't stay empty for long.

01:11:49The ocean gushed back to fill the crater, but in the process,

01:11:53it only ricocheted off the crater's rim, which produced even more waves.

01:11:58After that, tsunami waves that were more than 33 feet tall

01:12:02traveled around the world at a speed of 3 feet per second,

01:12:06lashing at all coastlines on their way.

01:12:08Imagine a three-story building rushing up to you.

01:12:11No wonder the largest and fastest-moving waves occurred near the impact area

01:12:16in the open waters of the Gulf of Mexico.

01:12:19Those rose more than 330 feet tall, which is taller than the Statue of Liberty,

01:12:24and moved at a speed 10 times greater than more distant tsunami waves.

01:12:29But back to the Red Planet.

01:12:31Some experts think that not one but two megatsunamis could happen on Mars.

01:12:36They could be triggered by a pair of meteor impacts

01:12:39that were several millions of years apart.

01:12:42Between these two collisions, Mars went through a period of climate changes.

01:12:46As a result, liquid water on its surface turned into ice.

01:12:50In other words, the first asteroid impact most likely produced waves composed of liquid water,

01:12:57and the second tsunami was probably formed by rounded chunks of ice water.

01:13:02By the way, the largest asteroid to have ever crashed into Earth

01:13:06might not actually be the one that ended dinosaurs.

01:13:10A much more catastrophic collision likely happened about 3.5 billion years ago.

01:13:15New evidence scientists found in northwestern Australia

01:13:19suggests that the asteroid I'm talking about was 12 to 18 miles across.

01:13:25It struck Earth at an immense speed, releasing an unimaginable amount of energy.

01:13:30Now this made me think, what if something like that happened these days?

01:13:34More than 30,000 objects that are circling Earth these days could potentially crash into our planet.

01:13:40NASA considers around 1,500 of them to be potentially hazardous.

01:13:45These space rocks are the remains left after the solar system was formed some 4.6 billion years ago.

01:13:52For example, in 2004, astronomers discovered a huge asteroid nearing Earth.

01:13:58The first observations showed that the chance of the space rock hitting our planet was less than 3%.

01:14:05The asteroid was named Apophis.

01:14:07It's more than 1,200 feet across and weighs about 20 million tons.

01:14:11It's supposed to streak across the sky on April 13, 2029.

01:14:16Apophis will pass at a distance of 19,000 miles away from Earth's surface.

01:14:21But even though the space rock might miss our planet in 2029,

01:14:25it doesn't mean it won't return 15 years later in 2036.

01:14:31If such an object hits our planet, the consequences will be unpredictable.

01:14:36They can vary from shattered glass and broken windows

01:14:39to most life forms getting wiped off the face of the Earth.

01:14:42And it'll probably affect the Internet.

01:14:45Now that last thought is truly scary.

01:14:48But luckily, modern technologies are likely to help us avoid any catastrophic consequences.

01:14:54Experts have developed several ways to prevent a real-life disaster movie from happening.

01:14:59For one thing, we could use a spacecraft to knock this visitor from outer space off its course.

01:15:05Or it could somehow be blasted into pieces.

01:15:08Scientists could also slow the thing down with the help of concentrated sunlight.

01:15:13Or people could tug it away with a gravity tractor.

01:15:17It's a theoretical spacecraft that can influence objects in space without touching them.

01:15:22In sci-fi movies, a huge asteroid often sneaks up on Earth

01:15:27and turns out to be a nasty surprise to astronomers.

01:15:30It hurdles toward our planet at breakneck speed

01:15:33and gets discovered just weeks or even days before the collision.

01:15:37In reality, scientists are constantly watching all large objects in Earth's neighborhood.

01:15:43This means there would be plenty of time to do something before the inevitable happened.

01:15:48There are three kinds of missions scientists could prepare at short notice.

01:15:52Type 0, when a heavy spacecraft hurdles toward the intruder with one single goal

01:15:57to knock it off its course.

01:15:59In this case, astronomers would have to rely on the already available information.

01:16:04The Type 1 mission would involve a scout.

01:16:07It would be launched first to get more close-up information about the space rock.

01:16:12Only after that, the main spacecraft would be launched.

01:16:15With more precise information, its journey would be way more productive.

01:16:20And if scientists chose the Type 2 mission,

01:16:23they would send a scout and a small spacecraft at the same time.

01:16:27The spacecraft would knock the asteroid a bit off its course.

01:16:30Then the scout would collect all the necessary information.

01:16:34Based on this data, the spacecraft would finish its job with a more fine-tuned second push.

01:16:41If none of these methods worked, people could try going deep underground

01:16:45or even build a shelter on the ocean floor.

01:16:48But in this case, we'd need to find sources of energy

01:16:51that could help us survive for at least several decades.

01:16:54Plus, people would have to create a life-support system

01:16:57that could somehow keep air and water fresh.

01:17:02More than 20 years ago, back in 1999,

01:17:05we discovered an interesting diamond-shaped space rock.

01:17:09It was an asteroid called Ryugu.

01:17:11Its name is the Japanese term for Dragon Palace.

01:17:15There's a Japanese folktale behind that name.

01:17:18Basically, it's about a magical palace hidden deep underwater.

01:17:22In this story, there's a fisherman who visits the castle traveling on the back of a turtle.

01:17:28He returns back to the surface with a mysterious box.

01:17:32About two years ago, a similar thing happened in reality

01:17:36when the Japanese spacecraft Hayabusa 2 visited Ryugu

01:17:40and came back with mysterious samples it picked up there.

01:17:43And the fairy tale doesn't just stop there.

01:17:46There are so many craters and rocks on Ryugu,

01:17:49so it probably had quite a rough past.

01:17:52And the craters all share a theme.

01:17:54They're named after something from the world of fairy tales.

01:17:59For example, the name of the princess who lived in this magical Ryugu castle

01:18:03together with her dad, a dragon deity.

01:18:06Some got names after the fisherman who saved a turtle.

01:18:09And the turtle itself, of course.

01:18:12But back to the science now.

01:18:14So this spacecraft took a sample from the surface of Ryugu,

01:18:18got back to Earth, and teams of researchers discovered something really cool.

01:18:23The asteroid is even older than our solar system!

01:18:28The spacecraft took the sample to help researchers

01:18:31to understand the origins of our solar system better.

01:18:34But this is not the first time scientists came across such ancient grains.

01:18:38They previously found them in multiple meteorites.

01:18:41Meteorites are generally space rocks

01:18:44that survived the fall through the atmosphere to land on Earth.

01:18:47They're usually rich in carbon, just like the asteroid Ryugu.

01:18:51But the material on Ryugu is even more specific

01:18:55and something you can't stumble upon on our planet.

01:18:58Silicon carbide, a combination of pure silicon and pure carbon.

01:19:04The material Ryugu is made of is so unusual,

01:19:08it even tells us the asteroid was formed in the outer solar system.

01:19:12It's one of the three asteroids that are orbiting the sun

01:19:15but are moving relatively close to Earth.

01:19:18Each of them is just a loose pile of rubble,

01:19:21and their collective gravity is something that holds them together.

01:19:24They probably formed after their parent bodies collided

01:19:27and shattered into smaller pieces.

01:19:30Ryugu's individual rocks are probably 4.6 billion years old, or even more.

01:19:36So it's most likely made up of material from its parent body.

01:19:40But some theories claim its surface could be 158 million years old.

01:19:47Ryugu sneaked into the inner part of our solar system,

01:19:50so we got a better chance to study it a little bit.

01:19:53It's circling around the sun somewhere between our home planet and Mars.

01:19:57It crosses Earth's orbit from time to time,

01:20:00which is why it ended up in a category of potentially dangerous things for us,

01:20:05even though it's peaceful at the moment and it really doesn't harm us in any way.

01:20:11It's one of the darkest space bodies in our solar system,

01:20:14and surprisingly dry.

01:20:17Strange, its parent body probably consists of lots of water ice.

01:20:22Maybe Ryugu is dry because it has flown too close to the sun sometime in the past.

01:20:27That heated up its surface and dried it out.

01:20:30Or some of its radioactive materials heated the asteroid and removed most of its water.

01:20:38How do we even know how old our solar system is?

01:20:41Once upon a time, which is billions of years ago,

01:20:44in some faraway, almost forgotten corner of the Milky Way,

01:20:48there was a molecular cloud.

01:20:50It fell apart and collapsed like many others across the universe did.

01:20:55That's how new stars form.

01:20:58This one formed new stars too,

01:21:00and one of them was a little bit isolated from the others.

01:21:04It collected material around it and turned it into something we call a protoplanetary disk.

01:21:10That's a disk of gas and dust that rotates

01:21:13and goes around the core of what will later become a solar system.

01:21:17That disk can develop into celestial bodies too,

01:21:21like asteroids and planets.

01:21:24But this disk formed the central star we know today as our sun,

01:21:28eight planets, and the rest of the objects that make our solar system.

01:21:32It's about 4.6 billion years old.

01:21:36All stars come from this pretty cool thing called a presolar nebula.

01:21:41It's, once again, a cloud of dust and gas that pulls material in.

01:21:46Later, a star forms out of it.

01:21:48A big outer region that surrounds a nebula is cold.

01:21:52A presolar nebula creates a protostar.

01:21:55It's a young star that is still not on its own

01:21:58but needs to gather mass from its parent cloud.

01:22:01Then the star becomes independent.

01:22:04The material from the outer, cold region then starts forming bigger clumps.

01:22:09As time goes by, these large clumps grow and fall in.

01:22:13They move around, interact with each other,

01:22:16and sometimes even merge or eject one another.

01:22:19After hundreds of thousands to even millions of years,

01:22:22once there's a star, the planets start forming.

01:22:25There were probably many objects that are gone by now,

01:22:28but our solar system doesn't look very different

01:22:31from what it was back when it was formed.

01:22:35Some things may have been different though.

01:22:37We have four gas giants now, Jupiter, Saturn, Uranus, and Neptune.

01:22:42Maybe there might have been a fifth one too.

01:22:45It's possible our four gas giants were closer to the Sun,

01:22:49but they migrated outwards.

01:22:51And what was between Venus and Mars?

01:22:54One theory says Theia, a smaller Mars-sized world that later,

01:22:59BAM, collided with Earth and we got the Moon.

01:23:04Checking the materials of these objects,

01:23:07scientists have found out many interesting things

01:23:10when they study all kinds of minerals, rocks, and solid bodies.

01:23:14The composition of different elements

01:23:16tells them about how old some object is.

01:23:19They have studied meteorites that have landed on our planet.

01:23:22They assumed these meteorites and the Earth

01:23:25are part of the same system,

01:23:27so they calculated their potential age

01:23:29and got around 4.54 billion years.

01:23:32Rocks from the Moon haven't gone through the same processes as Earth rocks,

01:23:37and they're younger by a couple of million years.

01:23:41And the Sun, the central star of our solar system,

01:23:44could be a bit older,

01:23:46maybe tens of millions of years older than the oldest rocks.

01:23:50That's how formation in most cases goes, remember?

01:23:53Stars first, then planets and other solid objects next.

01:23:57So yes, it could be close to 4.6 billion years old.

01:24:03Jupiter's satellite Callisto is, as far as we know,

01:24:07the oldest Moon both in our solar system and the Universe.

01:24:11It's not that glamorous,

01:24:13just a rocky world with ice covering its surface and many craters.

01:24:17These craters tell us that many random flying objects

01:24:21have been hitting it over the past 4 billion years.

01:24:24That's how long we believe it's been around.

01:24:27Callisto and the rest of the Moons around Jupiter

01:24:30have probably been born out of debris that was left after Jupiter formed.

01:24:35This all seems so old,

01:24:38but the Universe is 13.7 billion years old.

01:24:42So imagine how many things out there are even older than our solar system.

01:24:47But now, scientists have confirmed that they have found

01:24:50one of the oldest but also most distant objects we've ever known in the Universe.

01:24:55It's a galaxy 12.8 billion light-years away from us.

01:24:59It started forming within the first billion years of the Universe,

01:25:03which also means it was that long after the Big Bang started everything.

01:25:08During the first 400 million years after the Big Bang,

01:25:12it was most likely way too hot for anything to form.

01:25:16So first galaxies, black holes, and stars

01:25:19started forming maybe within the first half a billion to billion years.

01:25:24So this old galaxy could be one of the first things that ever appeared in the Universe,

01:25:29and we get to see it.

01:25:32It's hard to observe it, though.

01:25:34Scientists use a telescope to explore it,

01:25:36but the picture's still very blurry.

01:25:39It's hard to see such objects

01:25:41because of all those thick gigantic clouds of dust that surround them.

01:25:44The Hubble Space Telescope is usually best to view distant galaxies,

01:25:48but there's another telescope with a better position to look at such objects,

01:25:53and we can't wait for it to be fully operational to see what else it'll discover.

01:25:58Two pictures are rapidly changing in front of your eyes.

01:26:02Our huge planet and a black void.

01:26:05The picture of Earth is getting smaller by the second.

01:26:08You're flying away from the spaceship into an endless vacuum

01:26:11and don't know what to do next.

01:26:14The International Space Station flies 250 miles above Earth's surface.

01:26:19A spacewalk is routine for astronauts who work there.

01:26:22Astronauts have spent more than 11,000 hours in the black abyss to this day.

01:26:27Fortunately, during all this time,

01:26:30no one has ever flown away into outer space without coming back,

01:26:34as we've seen in the movies.

01:26:36But unfortunately, astronauts face other, no less terrible, dangers during spacewalks.

01:26:43One such accident happened in 1966.

01:26:47Eugene Cernan put on a jetpack and went into outer space to carry out some repair work.

01:26:53The jetpack, which helps an astronaut control flight in zero gravity, heated up a lot.

01:26:59Eugene put on special protective pants made of metal to protect himself from this heat.

01:27:04The pants protection didn't work when he went into outer space.

01:27:09Instead of directing the heat away from his body, the pants began to heat up.

01:27:13The suit was heavy and uncomfortable, like a knight's armor.

01:27:17It rubbed his skin and restricted movement.

01:27:21Working in zero gravity is physically very hard,

01:27:25but Eugene also had to deal with his whole suit heating up that day.

01:27:29Inside the spacesuit, he felt like he was in a hot bath.

01:27:33High temperatures and hard work caused overexertion,

01:27:37dehydration, and severe weight loss.

01:27:40His face was sweating, and drops of sweat blinded him.

01:27:44During this spacewalk, the astronaut lost about 13 pounds of weight.

01:27:49Other astronauts came to the rescue and took him back to his spacecraft.

01:27:54To reduce overheating, they sprayed him with cold water from a hose.

01:27:59In a sense, to go out into an infinitely huge open space,

01:28:03an astronaut must put on a suit resembling a body cage.

01:28:11Another dangerous incident happened in 1973.

01:28:15Two astronauts, Pete Conrad and Joe Kirwan,

01:28:18went into outer space to repair a solar wing on the Skylab space station.

01:28:24The wing didn't turn around, and the astronauts tried moving it manually.

01:28:29Using force, they turned the stuck wing,

01:28:32but it pushed them.

01:28:33The push was so strong that it threw both astronauts aside.

01:28:37They didn't have time to grab onto a nearby surface

01:28:40and began to fly away into outer space.

01:28:43Fortunately, they had safety cables that didn't let the astronauts go away for good.

01:28:48By grasping them, the astronauts returned to safety.

01:28:53In an ordinary modern spacesuit, there are more than 10 protective layers.

01:28:58Such a suit protects against extreme cold and hot temperatures.

01:29:02It's tear-resistant and doesn't leak moisture from the outside.

01:29:07This protection is necessary to prevent depressurization.

01:29:11If a small passage appears between your body and space,

01:29:15then all the oxygen will start coming out of the spacesuit.

01:29:18The more oxygen the suit loses, the more vacuum it gets.

01:29:22This leads to terrible consequences, such as suffocation and increased body volume.

01:29:28It looks as if you start to inflate from the inside.

01:29:33In 2007, Rick Mastracchio went into outer space to do some repair work.

01:29:38For some reason, there was a hole in his left glove next to his thumb.

01:29:42It was on the outer layer of the glove.

01:29:45But the worst thing was that the astronaut hadn't noticed it.

01:29:48He continued to work as if nothing had happened.

01:29:51But one damaged layer could destroy the second.

01:29:54The second one could tear the third one.

01:29:56And so on, until the vacuum reached the astronaut's skin.

01:30:02Rick was supposed to work six hours in outer space.

01:30:05But during the fourth hour, he noticed the damage in his spacesuit.

01:30:09The astronaut reported this to command and received an urgent order to return to the ship.

01:30:15He never found out how the hole had appeared.

01:30:21Inside the ISS, there are many chemicals necessary for working in space.

01:30:26For example, ammonia has the property of freezing almost any surface.

01:30:31This chemical frost is used to cool some components of the station during overheating.

01:30:36The leakage of this substance on the ISS is practically impossible.

01:30:40This is exactly what astronaut Robert Kirby heard from experts during the training before his first flight to space.

01:30:47But this accident occurred to him on his first spacewalk in 2001.

01:30:53Robert was working outside the space station when an ammonia leak started.

01:30:58The liquid splattered all over his spacesuit.

01:31:01A thick layer of ice quickly covered the glass.

01:31:04Robert didn't see anything.

01:31:06He feared that he had broken something.

01:31:08But the accident was not his fault.

01:31:12The protective layers of the spacesuit didn't allow Robert to freeze.

01:31:16But the ammonia severely restricted his movements.

01:31:19The main problem was that he couldn't return to the ship.

01:31:23Ammonia could get into the station, and this could lead to an emergency.

01:31:27Robert had to stand in outer space for one and a half hours and wait for the leak to end.

01:31:33After that, he successfully returned to the station.

01:31:38To realize how difficult work is in outer space, we need to understand what a spacesuit is.

01:31:44It weighs 280 pounds, which is as much as a scooter.

01:31:48You won't feel its weight in zero gravity, but it will still make you sweat.

01:31:53Astronaut Chris Hadfield had described it by saying that every movement inside your spacesuit meets resistance.

01:32:01The suit scratches your skin, squeezes your bones and joints, and forces you to spend twice as much energy on simple movements.

01:32:09In such conditions, you start sweating and your eyes get wet.

01:32:13This moisture flies inside the helmet and blinds you until it evaporates.

01:32:17But if there's too much moisture, it can threaten the life of an astronaut.

01:32:23Such a case happened in 2013 with astronaut Luca Parmitano.

01:32:28He went into space to measure something outside the station.

01:32:32At one point, he felt that the back of his head was wet.

01:32:35He informed the others about it and got an order to return to the station.

01:32:41When Luca was coming back, he had to turn upside down.

01:32:44As soon as he did this, water gushed into his helmet.

01:32:48It covered most of his face.

01:32:50Luca couldn't see or hear.

01:32:52He tried to report the trouble to base, but the water covered his mouth.

01:32:56Fortunately, his partners rescued him and helped him return to the station.

01:33:01When they opened the helmet, almost half a gallon of water poured out.

01:33:09Astronauts' cables are some of the most reliable defenses against floating away into space.

01:33:14But what if one broke from a strong push?

01:33:17Or because the astronaut didn't fix it well?

01:33:20For additional protection, there's a backpack called SAFER, Simplified Aid for EVA Rescue.

01:33:26It's like a jetpack.

01:33:28It releases gas from small tubes and changes the direction of your flight.

01:33:33If you're spinning in space, SAFER stops and aligns your movements.

01:33:37You can take manual control and fly using a special joystick.

01:33:43SAFER was first used in 1994.

01:33:46But before engineers created it, there was the MMU, the Manned Maneuvering Unit.

01:33:52In 1984, astronaut Bruce McCandless used it for the first time.

01:33:57You may have seen this famous photo where he floats in outer space without a cable.

01:34:03The problem was that Bruce was the first tester of such a jetpack.

01:34:07He wasn't 100% sure if it would work.

01:34:10He went into outer space and unhooked the cable from himself.

01:34:14There was nothing else to keep him from flying into the infinite black abyss.

01:34:18And his team wouldn't be able to save him.

01:34:21Imagine how scary it must have been.

01:34:24Fortunately, the jetpack worked.

01:34:26However, after three missions, NASA decided to stop using the MMU as it was unsafe.

01:34:33After that, engineers invented SAFER.

01:34:38Jetpacks and cables are reliable safety systems.

01:34:41But the best protection for an astronaut in space is their skills.

01:34:45Each astronaut has six years of higher education and several more years of training.

01:34:50They spend many hours training in virtual reality with spacewalk simulations.

01:34:55They train their body, endurance, and mind,

01:34:58since the main thing in a dangerous situation in space is not to panic and stay calm.

01:35:11Woosh! Debris runs through outer space all the time, often heading towards our planet.

01:35:17We're mostly not aware of it.

01:35:19Most of that debris burns up when it enters our atmosphere anyway.

01:35:24We do get to enjoy the bright blaze in the clear night sky because, from time to time,

01:35:30we see it as fleeting meteor showers.

01:35:33But sometimes, a meteorite is tough enough to survive the atmosphere

01:35:37and large enough to leave a remarkable spot on our planet.

01:35:40We're talking about what often looks like nearly circular excavated holes.

01:35:47Nestled in the Colorado Plateau in northern Arizona,

01:35:50Beringer Crater is a rimmed pit in the shape of a bowl we also call Meteor Crater.

01:35:56It's relatively young since it formed only 50,000 years ago.

01:36:00There was this enormous iron meteor that hit at eye-watering speeds of up to 26,000 mph.

01:36:08It exploded so hard that the meteorite excavated an amazing 175 million tons of rock.

01:36:17Daniel M. Beringer first identified this crater.

01:36:20He strongly believed the pit was a result of a meteor hitting our planet,

01:36:24but not many scientists believed him.

01:36:27Beringer spent a couple of years investigating this crater to prove his theory.

01:36:32Not just that, he also hoped to find some of the valuable metal content.

01:36:37But a major part of this once pretty large meteorite would have been destroyed during the collision.

01:36:46At first, it seems like you're looking at a nice swimming pool.

01:36:49But 7,500 years ago, another meteorite headed towards the Earth.

01:36:55While passing by through our planet's atmosphere, it fell apart and hit our planet in fragments.

01:37:01That's how Kali Meteorite Crater Field formed.

01:37:05A group of nine meteorite craters in the Estonian village of Kali.

01:37:09That's located on one of the country's islands.

01:37:13The largest crater ended up being 360 feet wide and 72 feet deep.

01:37:19The rest of the eight smaller holes are located right around the main one.

01:37:23It's a tourist attraction today.

01:37:25But imagine how panicked our prehistoric ancestors that lived there

01:37:29must have felt while watching these gigantic rocks fall from the sky.

01:37:34Also, there's a chance the surface of this island was covered in forest.

01:37:39But it all probably burned down during the impact.

01:37:43South Africa has its own gem too, Fridafort Crater.

01:37:47The largest and the oldest one in the world.

01:37:50More than two billion years ago, a meteorite with a diameter of six miles

01:37:54struck our planet close to today's Johannesburg, South Africa.

01:37:58This impact was nearly twice as powerful as the one that made the dinosaurs go extinct.

01:38:04Almost right after the meteorite hit the ground, the crater formed.

01:38:08The hole shallowed and widened as the rock below began to rebound.

01:38:12Plus, its walls collapsed.

01:38:15The meteorite that hit this spot was probably six to nine miles in diameter.

01:38:20If a celestial object that hit the Earth is bigger than 0.6 miles,

01:38:25it could have effects on the global level.

01:38:28So this one probably caused fires across the world.

01:38:31Also, enormous amounts of dust probably ended up in the atmosphere,

01:38:36which changed the climate for months, maybe even years.

01:38:40Lonar Crater is an astonishing spot in southern India,

01:38:44discovered almost 200 years ago.

01:38:47The pit lies within a large plain of basaltic rock

01:38:50left over from violent volcanic eruptions in this area,

01:38:53which happened 65 million years ago.

01:38:57Scientists even thought it was a volcanic crater at first.

01:39:00But soon, they realized it was the result of a strong meteor impact

01:39:05up to 50,000 years ago.

01:39:08Look how specific basaltic rock is.

01:39:11And Lonar Crater is the only one formed in such a type of rock.

01:39:15There are trees all across the lower crater hills.

01:39:18And you can find a couple of interesting species over there,

01:39:22such as chinkra, peafowl and gazelles.

01:39:25Plus, you can see many migratory birds

01:39:28flocking to the lake in the cold winter months.

01:39:32Yup, there's a lake there, and it's both alkaline and saline.

01:39:36In 2020, it surprised the local people

01:39:38because it changed its color to a rosy pink.

01:39:42It seemed unusual at first,

01:39:44but then scientists discovered such a specific color

01:39:47was the result of a growing population

01:39:49of a specific type of salt-loving microscopic organisms

01:39:53that produce such a pink pigment.

01:39:56This place is important for Indian mythology too,

01:39:59which is why there are multiple temples around the edge of the crater.

01:40:04Here's something really remarkable.

01:40:06The Ries Crater contains an entire town within its inner ring.

01:40:10It's a small town in Germany.

01:40:13You can see the full result of this impact only from the air.

01:40:17The town walls highlight the inner ring of this crater

01:40:20that's about 0.6 miles, one kilometer, in diameter.

01:40:25Those are probably the dimensions

01:40:27of the meteorite that formed the crater.

01:40:30You can't distinguish the rest of it so easily

01:40:32since the crater has been eroded away.

01:40:35That means natural forces such as rain and winds have changed it.

01:40:41In the heart of the Ungava Plateau

01:40:43lies the amazing Pingualuit Crater.

01:40:47The crater has its own pristine rainwater,

01:40:50some of the purest water you could find.

01:40:53It's not in any way linked to other lakes in that area,

01:40:56nor does it receive water from them.

01:40:59The water there accumulates from snow and rain.

01:41:03It's only lost when it evaporates.

01:41:06The depth of almost 900 feet

01:41:08is like a window to the crater's rich geological past.

01:41:13Scientists found different elements such as cobalt,

01:41:16nickel and iron that helped them determine

01:41:19it was a specific type of meteorite

01:41:21where its parent body hadn't modified it in any way.

01:41:25The parent body is the celestial body

01:41:27from which a single meteorite

01:41:29or an entire class of them originate.

01:41:32Pingualuit Crater formed over a million years ago.

01:41:36There are even traces of stone

01:41:38set in a circular arrangement and rock shelters.

01:41:42People that used to live in this area

01:41:44would set up camps on the ridges of the crater.

01:41:47It was a good position for them to catch animals

01:41:49and stay safe at the same time.

01:41:54Australia is home to some of the world's

01:41:56most fascinating impact craters.

01:42:00In its western part,

01:42:01you can find the massive Wolf Creek Crater.

01:42:04It's the world's second largest crater

01:42:06that lies on the edge of the Great Sandy Desert.

01:42:10More than 100,000 years ago,

01:42:12one meteor was most likely travelling

01:42:14at crazy speeds of 10 miles per second

01:42:17before finally slamming into the desert.

01:42:21Scientists discovered it in the middle of the 20th century,

01:42:24but local people had known about it long before that.

01:42:28They had many cultural stories about that crater.

01:42:32One was about two ancestral snakes

01:42:34who were so incredibly big

01:42:36they managed to form both Wolf

01:42:38and the nearby Sturt Creeks

01:42:40as they were making their way across the desert.

01:42:43One of those giants emerged from the ground

01:42:46and that's where the big crater is today.

01:42:48It's dangerous to climb there

01:42:50since rocks are pretty loose,

01:42:52but that's where you can see some interesting animals

01:42:55like brown ring-tailed dragon lizards

01:42:57catching insects for lunch

01:42:59or Major Mitchell's cockatoo

01:43:01harvesting seeds from the plants

01:43:03that grow on the crater floor.

01:43:07Another must-see crater in Australia

01:43:09is Goss's Bluff.

01:43:11It lies in the heart of the continent,

01:43:13sandwiched between the James Range

01:43:15and the MacDonald Range.

01:43:17It's a place of great cultural importance,

01:43:20so if you're visiting, respect signs

01:43:22stating which areas you're not allowed to access.

01:43:26A giant meteor slammed into our planet

01:43:28more than 140 million years ago.

01:43:31It was a really long time ago,

01:43:33so the original crater has been eroded through time.

01:43:36But even today, you can still see its core,

01:43:39a central ring of hills

01:43:41nearly three miles in diameter.

01:43:44This looks like you're on Mars, doesn't it?

01:43:47It's actually southwestern Algeria

01:43:49and its famous Amguid crater.

01:43:52This one is relatively young

01:43:54considering it's a result of a meteor impact

01:43:57that happened 100,000 years ago.

01:43:59This crater has an almost perfectly circular shape.

01:44:03Its center is unusually flat

01:44:05because of the type of soil at the bottom

01:44:08and the fact it's tightly compacted.

01:44:11Asteroids aren't as rare on our planet as we may think.

01:44:15About 17,000 of them visit us every year.

01:44:18You've probably seen at least one in your life,

01:44:20for example, if you've seen a shooting star.

01:44:23They leave these bright tails behind them

01:44:25as they pass through Earth's atmosphere.

01:44:27Of course, they only look beautiful in the sky.

01:44:29If they reach the ground,

01:44:31the consequences would be catastrophic.

01:44:33Luckily for us, most of them explode

01:44:3530 to 50 miles above the surface.

01:44:39Their mass is too small for them

01:44:41to withstand such a journey to the end,

01:44:43so most of them remain harmless to us.

01:44:45But we shouldn't underestimate them.

01:44:47Let's start with the smallest ones.

01:44:491 to 3-foot-high asteroids are about the size of a person.

01:44:53They're too small to cause any real damage.

01:44:55Most often, they explode in the atmosphere

01:44:57without even reaching its lower layers.

01:44:59But at the same time,

01:45:01they splash up tons of energy over the surface every time.

01:45:08The height of giraffes and mammoths.

01:45:10These larger meteorites come to us less often,

01:45:13once a year and a half.

01:45:15Like the previous ones, they, fortunately,

01:45:17don't pose a serious threat,

01:45:19but they splash out much more energy.

01:45:25The height of a 3- to 4-story building.

01:45:28They visit us once every 10 years,

01:45:30and now we're talking seriously.

01:45:32It throws out a wave that could demolish an entire city.

01:45:35I think you understand how catastrophic

01:45:37the consequences would be if this asteroid touched Earth.

01:45:44They like to visit Earth once every 60 to 70 years.

01:45:48Good news, it explodes at 12 miles above the ground.

01:45:51Its released energy could destroy an entire region

01:45:54if it touched the ground.

01:45:56Bad news, such an asteroid has already visited us recently,

01:45:59and the consequences were pretty rough.

01:46:02It all happened in a city called Chelyabinsk.

01:46:04On February 15th, 2013,

01:46:06at about 9.20am local time,

01:46:09the giant slowed down in the Earth's atmosphere

01:46:11and then broke up into small pieces

01:46:13at 14.5 miles above the Earth.

01:46:16These pieces then flew in different directions.

01:46:19It shattered the windows all over the city

01:46:21and damaged many buildings,

01:46:23including people's houses, schools, and others.

01:46:26It took a while to repair everything,

01:46:28and the scale of this destruction was quite serious.

01:46:31As a result, there were 1,615 injured,

01:46:35but, fortunately, no casualties.

01:46:38At least we're safe for the time being.

01:46:40The next such asteroid may come to us

01:46:42only in the 2070s or 80s,

01:46:44and no one knows where exactly it wants to land.

01:46:47Now let's move on.

01:46:51300 feet.

01:46:52This is the height of the Statue of Liberty

01:46:54together with the pedestal.

01:46:55Such a giant can be seen every 4,500 years,

01:46:58and this is the first asteroid on our list

01:47:00that may literally crash into Earth.

01:47:03The consequences are disastrous.

01:47:05Not only may it demolish an entire city,

01:47:07but it can also set fire to neighboring areas.

01:47:10Well, some people even witnessed

01:47:12such a meteorite land on our planet.

01:47:14The notorious Tunguska meteorite

01:47:16is the biggest asteroid disaster

01:47:18that people have ever seen.

01:47:20It all happened on June 30, 1908,

01:47:22in eastern Siberia.

01:47:24The meteorite was bright, like a second sun,

01:47:27and people felt the heat wave

01:47:29when it just approached the Earth.

01:47:31It exploded near the river.

01:47:32Fortunately, the whole area was surrounded by taiga,

01:47:35and there were no big cities nearby.

01:47:37But even there,

01:47:38it immediately destroyed a lot of trees.

01:47:41Serious forest fires broke out.

01:47:43The sound of the explosion was heard

01:47:45by people hundreds of miles around.

01:47:47At tens of miles around,

01:47:48all the houses' windows broke.

01:47:50The magnetic storm that resulted from this collision

01:47:53lasted five hours.

01:47:55The consequences were truly disastrous.

01:47:58But perhaps this is not the worst thing

01:48:00that awaits humankind.

01:48:0299942 Apophis

01:48:051,215 feet.

01:48:07It's slightly bigger than the Eiffel Tower.

01:48:10This meteorite,

01:48:11as scientists discovered in 2013,

01:48:13will be our next guest.

01:48:15Collisions of such force

01:48:17occur in about 100,000 years,

01:48:19and this one is gradually approaching.

01:48:21The force of such an explosion

01:48:23is equal to the force of the catastrophic eruption

01:48:26of the Krakatoa volcano in 1883.

01:48:29This eruption is considered

01:48:31one of the most destructive in history.

01:48:33It caused a terrible tsunami.

01:48:35165 cities and settlements

01:48:37were completely destroyed,

01:48:39and another 132 were seriously damaged.

01:48:42People all around the globe

01:48:44could feel the consequences of this eruption,

01:48:46at least to some degree.

01:48:48Such an asteroid could leave a 3.5-mile crater,

01:48:51and this is one we'll face in the distant future.

01:48:54But calm down.

01:48:55No need to panic yet.

01:48:56By 2070,

01:48:58the meteorite will be almost 174 million miles away from us.

01:49:02It still has a very long journey ahead of it,

01:49:05so we're safe for at least 100 years,

01:49:07or even more.

01:49:08Besides,

01:49:09our planet has survived something even worse.

01:49:153,280 feet.

01:49:18This is higher than the tallest tower in the world,

01:49:20the Dubai Burj Khalifa Tower.

01:49:23Such collisions occur once every 500,000 years.

01:49:27We're not sure when such a collision occurred the last time.

01:49:3070% of our planet is covered with water.

01:49:33If such meteorites fell into the ocean,

01:49:35it would be extremely difficult to find their traces.

01:49:38But we can assume the possible consequences.

01:49:41The wave would have swept across the entire hemisphere.

01:49:44The crater would be about 9 miles in diameter,

01:49:47and that would be a complete disaster.

01:49:49The last event of such a force happened 26 to 28 million years ago.

01:49:54It was an eruption of the supervolcano La Garita,

01:49:57which is located in the southwest of Colorado, USA.

01:50:00It was one of the most powerful known supervolcanic phenomena in history.

01:50:05During this monstrous eruption,

01:50:07a significant part of the current state of Colorado was destroyed.

01:50:10Scientists are still not sure how far the ashes have spread.

01:50:14But there was an even bigger meteorite in the history of mankind.

01:50:18The consequences of that impact were irreversible for an entire species of animals.

01:50:23I think you know what I'm talking about.

01:50:27Chichilub meteorite, the thing that wipes the dinosaurs off the face of the Earth.

01:50:31This happened about 66 million years ago.

01:50:34These collisions in general happen about every 500 million years.

01:50:39The height of the Chichilub meteorite was 12.4 miles.

01:50:43It's so high that when it touched the ground, it could reach the stratosphere.

01:50:47Even looking at the 124-mile diameter crater left by this meteorite,

01:50:52you can understand how huge it was.

01:50:55When it collided with the Earth, millions of tons of energy were released.

01:51:00This is an unimaginable disaster.

01:51:03It fell at a very steep angle,

01:51:05creating a giant cloud of dust and chemicals that spread around the world.

01:51:09This dust had a very thin layer, but also a mass of 50 trillion tons.

01:51:15The shockwave swept across the entire planet.

01:51:18It caused several earthquakes.

01:51:20Volcanoes began to erupt actively.

01:51:22Forest fires broke out everywhere, all over the world.

01:51:26The amount of soot and carbon dioxide released into the atmosphere is invaluable.

01:51:31The Earth was closed from the sun for several days.

01:51:34Darkness reigned all over the planet.

01:51:37Planets couldn't produce enough oxygen, so there was nothing to breathe.

01:51:41Temperature on the continents and in the oceans dropped by an average of 50 to 90 degrees Fahrenheit.

01:51:47Sounds horrific, doesn't it?

01:51:49And, of course, it caused one of the greatest extinctions in the history of the Earth's biosphere.

01:51:54Amazingly, the Earth was able to recover after such a catastrophe.

01:51:58This event became the boundary between the Mesozoic and the Cenozoic eras.

01:52:02So now, those who wondered,

01:52:04how could a small meteorite destroy all the dinosaurs,

01:52:07probably understand the answer.

01:52:11Perhaps the largest collision in the history of our entire planet

01:52:14was not a collision with a meteorite, but with an entire planet.

01:52:18This happened many, many billions of years ago.

01:52:22Theia, as this hypothetical dwarf planet was called,

01:52:25crashed into our Earth, releasing an incommensurable amount of energy,

01:52:29just quadrillions of fuel.

01:52:32The Earth then instantly turned into a giant fire,

01:52:35and it was this collision that led to the creation of the Moon.

01:52:39All that sounds terrifying, I know.

01:52:41So let's just hope that you and I will never see anything like this.

01:52:47Imagine flying in a spacecraft in a cloud of asteroids at high speed.

01:52:51You dodge one, one more, and then hit the gas pedal to the floor,

01:52:56and crash into an asteroid at full speed, on purpose.

01:53:00This is exactly what NASA is going to do in the near future.

01:53:03The entire mission will begin at Vandenberg Air Force Base in California

01:53:07on November 24th.

01:53:09Let's follow it step by step.

01:53:11So, the Falcon 9 booster rocket is already on the launch pad.

01:53:14It's as tall as a 22-story building, or 11 giraffes.

01:53:19And it can get about 8 tons of cargo into orbit.

01:53:22So you could send a big elephant into space,

01:53:25and a supply of food for it.

01:53:27Countdown, 3, 2, 1, ignition!

01:53:31Smoke clouds everywhere, and the rocket begins to gain altitude.

01:53:35Nine engines are working at full power to accelerate the rocket.

01:53:39At its peak, it reaches speeds 10 times faster than the speed of sound.

01:53:43And then, the rocket engines shut down,

01:53:46and the rocket's first stage undocks to return to Earth.

01:53:49A couple of seconds later, the second stage receives the ignition command.

01:53:53It turns on its one engine, and climbs even higher to orbit.

01:53:57The cargo capsule then opens, and releases the DART spacecraft.

01:54:02DART stands for Double Asteroid Redirection Test.

01:54:05Once released, the spaceship deploys two large solar panels.

01:54:09It'll convert solar energy into electrical energy

01:54:12to power a revolutionary ion engine.

01:54:15Conventional engines create thrust by burning tons of fuel,

01:54:18and ejecting it outward.

01:54:20The rocket itself is essentially pushing off the emitted gases.

01:54:23The ion engine will not burn fuel.

01:54:26It'll use a strong electric field to accelerate the ionized gas.

01:54:30Like conventional rockets, it'll eject this gas,

01:54:33and create thrust by repelling it.

01:54:35And though the ion engine produces less thrust,

01:54:38it can accelerate the spacecraft to higher speeds.

01:54:41So regular rocket engines have an excellent performance on the road.

01:54:45They push the pedal to the metal, burning a bunch of fuel,

01:54:48while the ion engine slowly accelerates.

01:54:51But when a conventional rocket needs to make a refueling stop,

01:54:54the ion spacecraft will whiz past the regular one at insane speeds.

01:54:59So the DART spacecraft begins its year-long journey.

01:55:02By comparison, a flight to Mars would take about seven months.

01:55:06Fast forward one year ahead, and we've arrived.

01:55:10This is the asteroid Didymos.

01:55:12The far point of its orbit is two astronomical units from our star.

01:55:16That's two Earth-Sun distances.

01:55:18At this point, the Sun begins to pull the asteroid back,

01:55:22and then it approaches the closest point to the star,

01:55:25one Earth-Sun distance.

01:55:27That is, its orbit lies very close to the orbit of our planet.

01:55:31Didymos made its closest approach to Earth at a distance of about 4.8 million miles.

01:55:36That's 20 times farther than the Moon's orbit.

01:55:39It takes 770 days to complete one such revolution around the Sun.

01:55:43So Didymos is not considered a hazardous asteroid,

01:55:47but in the future, it'll approach the Earth even closer.

01:55:50And the consequences of a collision with it could be catastrophic, given its size.

01:55:55It's bigger than two Empire State Buildings,

01:55:58and it rotates at a rate of one revolution in 2 hours and 15 minutes.

01:56:02So it has a tremendous amount of energy.

01:56:05Plus, it has an asteroid companion.

01:56:07It's a small pebble 520 feet wide.

01:56:10It's like 12 school buses or 10 train cars.

01:56:13Its orbital period, that is, the time it takes the pebble to make a complete circle around the asteroid,

01:56:18is about 11.9 hours.

01:56:21NASA believes that asteroids up to 80 feet wide are likely to burn up completely in our atmosphere

01:56:26due to friction with the air.

01:56:28So they're not hazardous.

01:56:30Asteroids between 80 feet and half a mile in size will not burn completely

01:56:34and could cause severe damage.

01:56:37And asteroids over half a mile have the potential to wipe out large cities or even entire states.

01:56:43In that sense, we can consider Didymos potentially hazardous.

01:56:47So we're going to test one way of defending against asteroids on it.

01:56:51Kinetic impact.

01:56:53That's why we sent DART here.

01:56:55So our spacecraft is going to hit an asteroid.

01:56:58Only not its main body, but its little companion.

01:57:01DART is already moving toward it at about 4 miles per second.

01:57:05At that speed, a trip from New York to Washington, D.C. would take less than a minute.

01:57:10And a trip across the United States from coast to coast would take about 10 minutes.

01:57:15It's getting close.

01:57:16Three seconds to impact.

01:57:17Two.

01:57:18One.

01:57:19Bam!

01:57:20The spacecraft crashes into the asteroid at full speed.

01:57:24What are your predictions?

01:57:25Asteroid explodes and is blown to pieces?

01:57:28Or asteroid flies off the main body into space like a billiard ball?

01:57:32Well, scientists predict that this collision will reduce the speed of this small asteroid by a fraction of a percent.

01:57:38But it'll still be enough to reduce its orbital period by a few minutes.

01:57:42Then our telescopes on Earth will be able to study the effects of the collision in more detail.

01:57:47And to learn even more, we'll send another spacecraft to Didymos on another mission.

01:57:52This is HERA.

01:57:54It'll be launched in 2024 and is scheduled to arrive at Didymos around 2027.

01:58:00This spacecraft will carry a bunch of research equipment to assess the collision damage done by DART.

01:58:05When it arrives, HERA will take many pictures of the small asteroid, including a fresh impact crater.

01:58:11HERA will also be carrying two CubeSats.

01:58:14These are miniature space probes, smaller than a shoebox.

01:58:18It'll launch these mini-satellites, and they will make an even closer approach to the asteroid.

01:58:23They will study this space rock for three to six months.

01:58:26At the end of the mission, one of them will attempt to land on the asteroid's surface

01:58:30to learn even more about its composition and internal structure.

01:58:34It's also possible HERA will carry a mini-impactor.

01:58:38This thing will have to make another impact on the asteroid.

01:58:41Then scientists will be able to evaluate the difference in impacts with a large spacecraft and a small one,

01:58:47and understand how we can defend against asteroids in the future.

01:58:51In theory, we don't need to send a giant rocket to a dangerous asteroid to destroy it.

01:58:56A single strike might be enough to shift the trajectory of the asteroid slightly.

01:59:01On a cosmic scale, changing the trajectory even by a fraction

01:59:05will dramatically change the asteroid's finish point.

01:59:08But kinetic impact is not the only way to deal with hazardous asteroids.

01:59:12Check out the gravity tractor.

01:59:14For this technique, we need to send a spacecraft toward the asteroid, too.

01:59:18Only, it won't crash into it. It'll have to go into its orbit.

01:59:22Any asteroid has a force of attraction, and it'll pull the spacecraft toward it.

01:59:27But the spacecraft's engines will keep it at the same altitude,

01:59:30so the asteroid itself will start attracting to the spacecraft.

01:59:34This method is reliable enough, but it takes a long time.

01:59:38And it'll only work if we detect a potentially hazardous asteroid

01:59:42many years before it arrives at Earth.

01:59:44We should have enough time to send a spacecraft to the asteroid,

01:59:48and then carry out an asteroid tractor technique.

01:59:51The other option is a laser.

01:59:53When an asteroid is found, we need to aim a powerful laser beam at it.

01:59:57It'll heat up a certain point on the asteroid, causing the material there to evaporate.

02:00:02This is where physics comes into play.

02:00:04The material on the asteroid evaporates upwards.

02:00:07It makes the asteroid itself move downward.

02:00:10Just like our rocket engines work, the burning fuel is ejected one way,

02:00:14and the spacecraft moves the other.

02:00:16We can also use solar power instead of lasers.

02:00:20To do that, we need to build a big space station,

02:00:23which would be equipped with a lot of magnifying glasses.

02:00:26Have you ever tried to burn letters on a wooden surface with a magnifying glass?

02:00:30Well, we'd be doing the same thing, but with an asteroid.

02:00:33The space station will have to focus lots of the sun's rays into one point on the asteroid.

02:00:38Again, the material evaporates because of the high temperature,

02:00:42and this causes the asteroid to change its trajectory slightly,

02:00:45so that it flies past our planet.

02:00:47How about foil?

02:00:49That's right, we can avoid a collision with an asteroid by using ordinary foil.

02:00:54We would have to wrap the asteroid in the same reflective material.

02:00:57Then the asteroid won't absorb the sun's rays, but will instead reflect them.

02:01:02This creates a little pressure on the surface of the asteroid.

02:01:05It's as if the sun's rays are pushing the asteroid,

02:01:08and it'll be able to change its trajectory.

02:01:11And not the most obvious, but reliable option is conventional rocket engines.

02:01:16We can put several powerful engines on the asteroid.

02:01:19This would create thrust and change the trajectory of the asteroid.

02:01:23And if there are enough engines, we can even take control of the asteroid.

02:01:27So when a bigger space rock appears on the horizon,

02:01:30we'll turn on our engines and point the asteroid straight at it.

02:01:34Such a collision can completely destroy even a very large asteroid.

02:01:38And it would make for one epic light show.

02:01:43That's it for today.

02:01:44So hey, if you pacified your curiosity, then give the video a like and share it with your friends.

02:01:49Or if you want more, just click on these videos and stay on the Bright Side.

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