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00:00:00Black holes, the most terrifying, mysterious and fascinating objects in the universe.
00:00:09Eternally hungry, they eat everything in their path and are constantly expanding.
00:00:15But how small and how big can a black hole be? Let's find out.
00:00:22It's not very easy for a black hole to be born.
00:00:25Most often they're just a result of a massive star ending its life cycle.
00:00:30If you take a star and squeeze it very, very hard, at some point it cannot withstand the pressure anymore.
00:00:37So it collapses and turns into a black hole.
00:00:41For example, we can create a black hole by shrinking the Sun to about 1.8 miles,
00:00:47or squeezing the Earth into the size of a pea.
00:00:51Either way, in the end, we get a mysterious, dark object with incredible mass and gravity.
00:00:59Unlike stars and planets, black holes have no size restrictions.
00:01:04They grow when they eat the matter around them. But how much does their size vary?
00:01:09For example, can they be very small?
00:01:13Theoretically, yes. There may be black holes with a diameter of one atom or even less.
00:01:19They're called primordial black holes. They may or may not exist.
00:01:24And if they do, they're probably the oldest objects in the universe, older than the atoms themselves.
00:01:32They would have formed right after the Big Bang, a long time ago, when the universe still had an incredible density.
00:01:39A huge amount of energy and in general was like a boiling broth.
00:01:44Any particle that was slightly denser than its neighbors could form a black hole.
00:01:50And the smallest of them would still weigh trillions of pounds.
00:01:55Those that were the size of atoms would weigh as much as a big mountain,
00:01:59and those that would weigh as much as the Earth could be a little bigger than a coin.
00:02:04But even if they exist, they're pretty harmless.
00:02:08The temperature in them would be so many times hotter than in our Sun,
00:02:11so they would evaporate pretty quickly after their birth.
00:02:15Now let's check out the black holes we know and saw.
00:02:19The first ones are called stellar black holes.
00:02:22Usually, they weigh tens of solar masses, which doesn't seem like much
00:02:27until you remember that the Sun weighs nonillions of pounds.
00:02:31Don't even try to imagine this number. It has 30 zeros.
00:02:35The smallest black hole known to us is about 2 to 4 times heavier than the Sun.
00:02:40It's a lonely hole that wanders through space in search of prey.
00:02:45The one that's closest to us is called Gaia BH1.
00:02:49It weighs about 10 times more than the Sun and can reach many miles in size.
00:02:55And the farthest one is called M33X7.
00:02:58It's somewhere around 3 million light years away from us,
00:03:02and right now it's eating a blue giant that's several times bigger than our Sun.
00:03:08Now let's move to the so-called intermediate-mass black holes.
00:03:12You see, just eating a few stars isn't enough.
00:03:15To become larger in size, black holes must either absorb a lot of stars
00:03:20or, more often, merge with another black hole.
00:03:25One of the first intermediate-mass black holes that we found was born this way.
00:03:30It weighs 142 times more than the Sun.
00:03:33It's even larger than some counties on Earth.
00:03:37Recently, we discovered two black holes in a galaxy 17 billion light years away from us.
00:03:43One day, they'll merge, but right now these guys are spinning around each other in a crazy dance.
00:03:50And while doing that, they release a crazy amount of energy.
00:03:56It may seem scary, but it's nothing compared to what comes next.
00:04:00Let's move to some serious stuff.
00:04:02Supermassive black holes.
00:04:05Giant, inexplicable monsters that are millions of billions of times bigger and heavier than our Sun.
00:04:12But how did they become so huge?
00:04:15The universe is about 14 billion years old.
00:04:18The black holes grew very slowly,
00:04:21so they couldn't have time to eat so much matter or merge with each other so quickly.
00:04:25So maybe they were also born from the stars,
00:04:29but very, very big ones.
00:04:32Quasi-stars.
00:04:34To imagine their scale, let's take, for example, the red supergiant Stevenson 218.
00:04:40Compared to this star, our Sun is just a grain of sand, even smaller.
00:04:46And Stevenson 218 would be a grain of sand next to a quasi-star.
00:04:51We don't know if they really existed, though.
00:04:54They could have formed after the birth of the universe.
00:04:57They could be so big that their core collapsed under their own weight before they even formed.
00:05:02And if that's the case, a small black hole would have appeared in the center of this quasi-star.
00:05:09Now, the frenzied gravity of the black hole held the star together and ate it at the same time.
00:05:16The temperatures were huge, so the star remained stable.
00:05:19And they would live like this for millions of years,
00:05:23until the black hole would grow to enormous sizes.
00:05:28Most supermassive black holes are located in the centers of galaxies.
00:05:33You might think that our galaxies orbit around them as we do around the Sun,
00:05:37and that one day we will inevitably all be dragged inside it.
00:05:41But don't worry, that's not the case.
00:05:45Although these guys are incredibly massive, they're not very large in diameter.
00:05:50They can't swallow entire galaxies.
00:05:53For example, in the center of our Milky Way, there's a black hole called Sagittarius A.
00:05:58It has 4 million solar masses, but it's still quite small in size, only 17 times larger than the Sun.
00:06:06And yes, it's still considered small.
00:06:09If we had replaced the Sun with this black hole, it wouldn't even have reached the orbit of Mercury.
00:06:15Sagittarius A is actually pretty nice and calm.
00:06:19Yes, it still swallows giant stars, but it's definitely not a threat to us.
00:06:24But not all of them are like that.
00:06:27For example, a black hole in the galaxy BL Le Certe devours a huge amount of gas and dust.
00:06:33If we were somewhere near it, it would look 115 times larger than the Sun.
00:06:39And we would have burned up just getting close to it.
00:06:44Do you remember that first black hole we ever captured in a photograph?
00:06:48It's located in the Messier 87 galaxy, and it may look small and cute in the photo,
00:06:54but in reality, it's capable of absorbing our entire solar system up to the Orion belt, and even further.
00:07:02Well, now that we've discussed the terrifying size of supermassive black holes,
00:07:07it's time to move on to the real titans of the universe.
00:07:11Ultramassive black holes.
00:07:13Terrifying, unimaginable giants.
00:07:16The largest objects that have ever existed, and probably will exist in our world.
00:07:22Their masses exceed the mass of the Sun by tens of billions of times.
00:07:26Their gravity becomes so strong that they create quasars around them.
00:07:31Discs that shine brighter than thousands of galaxies combined.
00:07:35Remember we talked about the fact that supermassive black holes aren't able to eat galaxies?
00:07:41Well, these guys devour not only their host galaxies, but literally everything on their path.
00:07:48The ultramassive black hole at the center of the galaxy OJ287 has 18 billion solar masses.
00:07:56It's so gigantic that it has another black hole orbiting it.
00:08:01It would also easily fit not one, but three solar systems inside of it.
00:08:09And now, finally, we've come to the largest object in the entire universe.
00:08:14TON618, the almighty destroyer of worlds.
00:08:20A black hole that has eaten far more than one galaxy.
00:08:24Its mass exceeds 66 billion solar masses, and it could fit 11 solar systems inside of it.
00:08:32The quasar around TON618 shines brighter than 100 trillion stars.
00:08:38Its light is so powerful that it has even reached us, even though we're at a distance of 18 billion light years from it.
00:08:46And the creepiest part is, this isn't even its true size.
00:08:51This is what it looked like around 10 billion years ago.
00:08:55Since TON618 is so far away, its light reaches us for a very long time.
00:09:01That means what we see is how this black hole looked after the universe was born.
00:09:07But what does it look like now? We have no idea.
00:09:11But it's probably millions, billions of times bigger.
00:09:16Millions of people around the world go out on the streets and rooftops to look at the amazing cosmic phenomenon.
00:09:24Another planet, right next to the Moon, a big red one.
00:09:29At first, everyone's excited. Mars showing up out of nowhere is having a strange effect on humanity.
00:09:36Just as the Moon can affect the psychological and physical state of some people,
00:09:41Mars' unexpected visit is causing people to behave pretty strangely.
00:09:46Every night, the sky is lit up by the white light of the Moon and the red glow of Mars.
00:09:52Many people get a sort of instant insomnia.
00:09:55Some even stop drinking coffee because they no longer feel sleepy.
00:10:00Mars brings out energy and a little wildness in people, making them laugh more, and even drives a few poor people crazy.
00:10:08They begin to go out of their houses more often and enjoy the unusual night sky.
00:10:13A few days later, everybody can see what's happening. Mars is getting bigger.
00:10:19Scientists announced that the red planet is slowly moving towards Earth.
00:10:24A collision is inevitable. Earthlings only have a few years left.
00:10:29A few months ago, a huge asteroid crashed into the red planet with such force that Mars simply flew out of its own orbit and went rogue.
00:10:38The chance that Mars would fly close to Earth was always going to be pretty high.
00:10:43After about three seconds of being announced, the news went viral and panic set in.
00:10:49The situation's getting worse and worse. The closer Mars gets, the more it affects people on a physical level.
00:10:56Hundreds of videos pop up showing collision simulations of Mars and Earth.
00:11:01And there's no happy ending.
00:11:03Want to see what happens? One famous blogger asked her followers.
00:11:07The Earth's almost completely covered with water, and Mars is all dust, sand, and rocks.
00:11:13Then she puts a huge watermelon in the middle of her room.
00:11:17From the far end, she launches a bowling ball at it. Strike!
00:11:22Mars looks almost the same size as the Moon now.
00:11:25It's about to come into the Moon's orbit, and it's affecting the Earth's magnetic field.
00:11:30Floods, hurricanes, tsunamis, powerful thunderstorms. They go from bad to worse.
00:11:37Animals go crazy. Birds no longer migrate south.
00:11:42The polar northern lights appear in the Caribbean.
00:11:46The economy isn't handling the news that well.
00:11:49If people stopped showing up to work, why wouldn't they?
00:11:52They just want to have fun and be with loved ones.
00:11:55There are enough resources on the planet to last until the catastrophe, so no one's even trying to fix the Earth's problems.
00:12:02Clothing, food, cars, yachts, whatever. Everything loses its value and becomes free.
00:12:09Every day, huge street parties pop up all over the world.
00:12:13People decide to live their last months in peace and harmony.
00:12:17The global catastrophe is uniting humanity like never before.
00:12:21To go out with a bang, Earthlings team up to organize a huge rock concert.
00:12:26The Red Giant destroying our beautiful blue planet.
00:12:30Yeah, rock and roll's the perfect soundtrack.
00:12:33There's just enough time to eat, dance, party, and listen to good music.
00:12:38Huge stages are built all over the planet.
00:12:41It's every musician's last concert.
00:12:44During all that preparation, hope suddenly appears.
00:12:47Scientists have calculated all the events that'll occur when Mars crashes into Earth, and they have a simple plan.
00:12:54Luckily, humans had already planned on moving to Mars, so they already have been building spaceships for years.
00:13:01There's no time to get to another planet before the collision.
00:13:04But the good news is that people can wait out the disaster just outside Earth's orbit.
00:13:10You get to sit in a space station, munch some popcorn, relax, and enjoy the show.
00:13:16When the dust settles, it might just be possible to return to Earth, or what's left of it.
00:13:22After learning about this plan, people start working on finishing the ship's night and day.
00:13:27Everyone in the world pitches in.
00:13:29There are still two years left before the big day.
00:13:32The huge concert stages are converted into more space stations.
00:13:36Mars is now giving people more energy, and with epic teamwork, people manage to create thousands of stations in just a few months.
00:13:44That's what happens when 7 billion people work together.
00:13:48Farmers, physical therapists, chefs, engineers, athletes, accountants – all on the same team.
00:13:55Mars is now closer to us than the Moon.
00:13:58The red giant blocks out the Sun, and our planet is plunged into darkness.
00:14:03There are only a few days left.
00:14:05People are working like ants in a massive colony, putting the finishing touches on several hundred thousand space stations.
00:14:12It takes four whole days for everyone to get on board.
00:14:16Plus, there's the loading of supplies – animals, fish, seeds, plants, vegetables, fruits, video games, fruit roll-ups.
00:14:25The red giant is scheduled to enter Earth's orbit in a couple of days.
00:14:29That's when it will really pick up speed.
00:14:32Mars is only a little more than half the size of Earth, but up in the sky, it looks infinitely huge.
00:14:38The ships start taking off.
00:14:41People take a last look around, memorizing every inch.
00:14:45In a few hours, it'll all change forever.
00:14:49The stations fly up far enough away to clear any orbits.
00:14:53Two worlds colliding together should still have a soundtrack, though.
00:14:57Rock stars on every ship organize an outer space music festival.
00:15:02To the awesome sound of rock, Mars enters Earth's atmosphere and burns a thin layer of its own surface.
00:15:10This releases an incredible amount of energy.
00:15:13It gets faster and faster and smashes into the Pacific Ocean.
00:15:17A huge blast wave sweeps across the entire planet.
00:15:21Everything is lit up by flames, and everyone on the ships has to put on sunglasses to avoid being blinded.
00:15:28Our blue planet is turning into a fiery one.
00:15:32The dust of Mars mixes with the water of Earth.
00:15:35The force of the impact goes through the Earth's crust into the liquid hot magma.
00:15:40Hundreds of pieces of Mars, some the size of entire countries, are somehow floating in the atmosphere.
00:15:47Collision generates so much energy that all oceans boil and evaporate.
00:15:52Seas and rivers of molten metal are now spreading all over Earth.
00:15:57Days, weeks, months pass.
00:16:00A belt made up of bits of Mars forms around the Earth.
00:16:03It's like a fiery version of Saturn.
00:16:06It'll take a long time before it's safe to land back down.
00:16:10But humanity can't stay alive on the ships all that time.
00:16:13Food, water, and oxygen will run out after a few years.
00:16:17But scientists already have a plan.
00:16:20The ships flip a switch and become huge cryo-chambers.
00:16:24The ships are equipped with energy panels, and the roasting hot Earth's giving off a lot of energy.
00:16:30Totally enough to keep the ships working while everyone on board takes a few thousand year nap.
00:16:36As soon as the planet cools down, humans will wake up.
00:16:40Hundreds of thousands of years pass.
00:16:43One day, alarms go off simultaneously on all the ships.
00:16:47People wake up, slowly.
00:16:49Their bodies are exhausted, but after a few billion cups of coffee, everyone's ready to go.
00:16:55Down on Earth, new continents should have formed, and the atmosphere is most likely way different.
00:17:01The planet might have lost its original orbit, so it might be spinning at a different angle.
00:17:06The seasons as we know them, gone.
00:17:09All the water on Earth evaporated in the first few hours.
00:17:12But there were huge glaciers on Mars, which might have melted on impact.
00:17:17Mars may have shared its water with our planet.
00:17:20The clouds of dust and dirt should have settled by now, and the ground should be pretty good for growing stuff on.
00:17:27All that magma probably spewed up a bunch of useful minerals and chemicals.
00:17:31It's going to be difficult, but humanity somehow must adapt to the new Earth.
00:17:36People are ready for anything.
00:17:39All the Earthlings run to the nearest windows to see what their beloved planet looks like after all these centuries.
00:17:46Um, where is it?
00:17:48People are craning their necks, looking out at the empty spot where the Earth used to be.
00:17:53The impact of Mars was so strong that it pushed the Earth out of its orbit around the Sun.
00:17:59It's gone.
00:18:01Great, what are we going to do now?
00:18:04Some bearded guy grabs a guitar and says, let's play!
00:18:09Dust storms on Mars can really go crazy.
00:18:12They hurtle through the red planet's southern hemisphere, especially during the summer.
00:18:16These storms can grow and encompass large areas of the planet, as happened in January 2022.
00:18:22Then, a dust storm covered almost twice the area of the United States.
00:18:27Could it be something like this that caused one of the robots we sent to Mars to go missing?
00:18:32The atmosphere and climate are harsh on Mars.
00:18:35It's mostly a desert with strong winds and average temperatures of minus 81 degrees Fahrenheit.
00:18:41It drops down to minus 220 at the poles during the winter.
00:18:45A lander needs to be specifically equipped and very sturdy to withstand such conditions.
00:18:50But researchers thought the Beagle 2 could handle the difficult trip to the red planet.
00:18:56June 3rd, 2003.
00:18:58A team of researchers got one of their pioneering robots they were about to send to space ready.
00:19:03It was a small and compact lander called the Beagle 2.
00:19:07Its mission was to touch down on Mars and search for what the world has been actively looking for for decades now.
00:19:13Life on the red planet.
00:19:15Now, the touchdown was due on December 25th, but the signal never came.
00:19:21The team tried to contact the spaceship, but at one point, they had to accept they wouldn't be able to reach it.
00:19:27Some thought the landing was too difficult and complex after all, so the lander crashed.
00:19:32But they couldn't find any technical errors.
00:19:35Others had a theory that the lander may have become entangled in its own parachute and fell down to the surface of Mars.
00:19:42Either way, the Beagle 2 was considered missing.
00:19:45Until 2015, when NASA took pictures of what could be the remains of the lost lander.
00:19:51They weren't just smashed debris.
00:19:53The components actually looked to be intact.
00:19:56The lander's remains were lying with its solar panels partially deployed around 3 miles away from the site where it was supposed to land.
00:20:04Apparently, the Beagle 2 managed to land successfully, but its radio antenna got blocked.
00:20:10That's why researchers couldn't control it from Earth or communicate with it.
00:20:14But no one knows exactly why it happened.
00:20:17Have you heard of a face on Mars?
00:20:20In the 1970s, one of NASA's spaceships took the iconic images of the Martian surface that showed a face-like formation, as you can see in the upper part of the picture.
00:20:30If you have a rich imagination, you can easily see a nose, two eyes, a mouth, and an unusual hairdo.
00:20:38Some even thought it was a monument built on the Red Planet by another civilization.
00:20:43How about some other unusual things people have found on Mars?
00:20:47Like Happy Face Crater.
00:20:49You can easily see why it has this nickname.
00:20:52Or rocks in different shapes.
00:20:54A pancake, brachiosaurus, or a fish.
00:20:57Mars also has a waffle-shaped island on its surface.
00:21:01It's a 1.2 mile wide feature you can see in the area of lava flows.
00:21:06It might be the result of lava pushing this formation from below.
00:21:10It seems astronomers have also got some images of blue dunes.
00:21:14It's a sea of stunning dark dunes that strong winds sculpted into long lines.
00:21:19They surround the planet's northern polar cap and cover a region as large as Texas.
00:21:24The Red Planet is usually known for its brown sandy dunes, so these ones certainly came as a surprise.
00:21:30In reality, though, they're not really blue.
00:21:33If you could visit Mars right now just to take a look,
00:21:36you'd see that these dunes appear brown and orange like the rest.
00:21:40And the picture is a false color image.
00:21:43Scientists often use false colors to highlight differences in something.
00:21:47For example, here it's the difference in depth.
00:21:50Also, the biggest valley on Mars is so large it could eat our Grand Canyon for breakfast.
00:21:56It's a fascinating system of canyons 2,500 miles long called Valles Marineris.
00:22:03And it's over 10 times as long as the Grand Canyon.
00:22:06Now, if you could stretch this Martian canyon, it would go from coast to coast of the entire United States.
00:22:13Since Mars doesn't have any active plate tectonics, no one knows for sure how this canyon formed.
00:22:20One theory says a chain of volcanoes located on the other side of Mars,
00:22:24the one that includes Olympus Mons, bent the crust from the opposite side of the planet.
00:22:29This powerful force caused cracks in the Martian crust as well as activated enormous amounts of water lying under the surface.
00:22:37This water then emerged and carved the rock away.
00:22:40The force activated glaciers too, and they possibly created new pathways in this gigantic canyon system.
00:22:47Volcanoes on the Martian surface could have erupted about 50,000 years ago.
00:22:52Although the most powerful eruptions happened 2 to 3 billion years ago.
00:22:57But the planet doesn't have active volcanoes today.
00:23:00Most of the heat stored in its interior during the planet's formation has been lost.
00:23:05So now, Mars' outer crust is way too thick for the molten rock to reach the surface.
00:23:11But a long time ago, eruptions formed giant volcanoes.
00:23:17And these volcanoes most likely had an important role in melting ice deposits, which released floods of water onto the Martian surface.
00:23:25Now Mars has a thin atmosphere with a volume of gas, mostly carbon dioxide, less than 1% of Earth's.
00:23:32But 4 billion years ago, it was way warmer and wetter than now.
00:23:37Its atmosphere must have been thicker back then too.
00:23:40That's why it could create a powerful greenhouse effect and trap sunlight.
00:23:44Mars also has a powerful magnetic field.
00:23:47Similar to Earth's, it formed because of the currents of molten metals in the planet's core.
00:23:52But unlike our home planet, Mars lost its magnetic field after its core had cooled down.
00:23:58And without it, the planet didn't have any protection from the solar wind, which is a stream of charged particles flowing from the Sun.
00:24:06The solar wind pulled away most of Mars' atmosphere in just a couple of hundred million years, give or take.
00:24:12This is what makes those powerful Martian dust storms even more intense.
00:24:16Mars has a fascinating history.
00:24:19Judging by the planet's glaciers, Mars has probably gone through multiple ice ages, just like Earth.
00:24:25A team of researchers got images of about 60,000 Martian rocks.
00:24:29Rocks were different in size and distributed randomly, which means they probably formed during different ice ages.
00:24:36Glaciers hide their own stories too.
00:24:38Who knows what kinds of gases, rocks, or even microbes could be trapped inside?
00:24:43Now, if you could get into a time machine and stop it 4 billion years ago, on Mars, of course,
00:24:49the chances are you'd see spectacular scenes of flooding.
00:24:53Maybe there would even be some form of life on the planet's surface.
00:24:57A strong meteorite impact that formed the red planet's Gale Crater could be something that triggered that mega-flood.
00:25:04After that collision, the temperatures on the planet got insanely high.
00:25:09This caused the melting of all that ice that was stored on the Martian surface at that time.
00:25:14The flooding was so massive, it changed the geological structure of the planet's surface.
00:25:19It carved out big ripples as well as waves in the sedimentary rock.
00:25:23Now, speaking of water, vapor has been noticed escaping the atmosphere of Mars.
00:25:28Also, researchers have found some evidence of water flowing on the planet's surface.
00:25:33There are dark streaks in the soil. They seem to get bigger in the summer and shrink over the winter.
00:25:39There are numerous dried-out valleys and river channels on the planet.
00:25:43It's possible that liquid water once flowed there.
00:25:46Now, most of it could be locked up in ice caps or even hidden under the surface.
00:25:51Our Sun is an average-sized star, and still, it could fit 1,300,000 Earths.
00:25:59The star is also 333,000 times as heavy as our planet.
00:26:04NASA has translated radio waves created by planets' atmospheres into audible sounds.
00:26:10That's how astronomers found out that Neptune sounds like ocean waves,
00:26:15Jupiter like being underwater,
00:26:18and Saturn's voice resembles background music to a horror movie.
00:26:22Here on Earth, it's bebop jazz. Now I made that up.
00:26:27The Sun's surface is scorching hot, but a bolt of lightning is five times hotter.
00:26:33Earth gets struck by 100 lightning bolts every second,
00:26:37which results in 8 million lightning strikes a day and around 3 billion a year.
00:26:43Ooh, shocking!
00:26:45If you manage to go to the Moon one day and see fresh footprints,
00:26:49that doesn't mean there's someone else there with you.
00:26:52Footprints or similar marks can last for a million years over there.
00:26:56Because the Moon doesn't have an atmosphere.
00:26:59There are no winds, not even a breeze, that can slowly erase those footprints.
00:27:04Astronomers have found the largest hole we've ever seen in the Universe.
00:27:09It's the giant void that spreads a billion light-years across.
00:27:14They found it accidentally.
00:27:16One of the research team members was a little bored
00:27:19and wanted to check how things are going in the direction of the cold spot.
00:27:23That's an anomaly in the Cosmic Microwave Background Map, or CMB for short.
00:27:29It's a faint glow of light that falls on our planet from different directions and fills the Universe.
00:27:34It's been streaming through space for almost 14 billion years
00:27:38as the afterglow that occurred after the Big Bang.
00:27:42So you fall right into the heart of the black hole and prepare for a sad end.
00:27:48Well, you don't have to.
00:27:50Falling into a black hole won't necessarily destroy you or your spaceship.
00:27:55You have to choose a bigger black hole to survive.
00:27:59If you fall into a small black hole, its event horizon is too narrow,
00:28:03and the gravity increases every inch down.
00:28:06So if you extend your arm forward, the gravity on your fingers is much stronger than on your elbow.
00:28:12This will make your hand lengthen, and you'll feel some discomfort.
00:28:16Rather significant, to be honest.
00:28:18Things change if you fall into a supermassive black hole, like the ones in the center of galaxies.
00:28:24They can be millions of times heavier than the Sun.
00:28:27Their event horizon is wide, and the gravity doesn't change as quickly.
00:28:31So the force you'll feel at your heels and at the top of your head will be about the same,
00:28:37and you can go all the way to the heart of the black hole.
00:28:40This myth is busted.
00:28:43If you watch a very touching movie in space and start crying, your tears won't run down.
00:28:49They will gather around the eyeballs.
00:28:52Your eyes will get too dry, so you'll feel like they're burning.
00:28:56Any exposed liquid on your body will vaporize, including the surfaces of your tongue.
00:29:01Speaking of burning, that's one thing fire can't do in space.
00:29:05Fire can spread when there's a flow of oxygen.
00:29:08And since there's not any in space, well…
00:29:12Once they explode, stars aren't supposed to come back to life.
00:29:16But some of the stars somehow have survived the great supernova explosion.
00:29:21Such zombie stars are pretty rare.
00:29:24Scientists found a really big one called LP40365.
00:29:29It's a partially burnt white dwarf.
00:29:32A white dwarf is a star that burned up all of the hydrogen,
00:29:35and that hydrogen was previously its nuclear fuel.
00:29:39In this case, the final explosion was maybe weaker than it usually is,
00:29:44not powerful enough to destroy the entire star.
00:29:47It's like a star wanted to explode but didn't make it,
00:29:51which is why part of the matter still survived.
00:29:54If you ever go into space, don't take off your spacesuit unless you're on a spaceship.
00:29:59Air in your lungs would expand, as well as the oxygen in the rest of your body.
00:30:04You'd be like a balloon, twice your regular size.
00:30:08Good news, the skin is elastic enough to hold you together,
00:30:12which means you wouldn't explode.
00:30:14Small comfort.
00:30:16When something goes into a black hole,
00:30:18it changes shape and gets stretched out just like spaghetti.
00:30:22This happens because gravitational force is trying to stretch an object in one direction
00:30:27but at the same time squeeze it into another, like a pasta paradox.
00:30:32Speaking of, a black hole that's as big as a single atom
00:30:36has the mass of a really big mountain.
00:30:39There's one at the center of the Milky Way called Sagittarius A.
00:30:43It has a mass like for a billion suns, but luckily it's far away from us.
00:30:51If you made a big boom on an asteroid, you'd never be able to hear its loud sound.
00:30:56Yes, we often hear the sound of spaceships and battles in space in the movies,
00:31:00but that's just a myth.
00:31:03Sound is a wave that spreads because of the vibrations of molecules.
00:31:07A person claps a few feet away from you,
00:31:10the sound wave begins to push the first air molecule next to the clap,
00:31:14then the second, third, and so on, until the wave reaches your ear.
00:31:18So, to spread sound, we need molecules like air or water.
00:31:23In our atmosphere, sound waves spread out just fine,
00:31:26but space is a vacuum, so it's nothing here.
00:31:30You can clap your hands loudly there,
00:31:32but there just won't be any molecules that can vibrate and carry that sound.
00:31:36So, to carry on a conversation,
00:31:38you'd either need a radio or really good lip-reading skills.
00:31:44Meteoroids orbit the Sun,
00:31:46while the majority of human-made debris orbits our planet.
00:31:50For example, we launched almost 9,000 spacecraft around the world
00:31:54from satellites to rocket ships.
00:31:57Even the tiniest pieces can damage a spacecraft at such high speeds.
00:32:02Galaxies, planets, comets, asteroids, stars, space bodies
00:32:07are things we can actually see in space,
00:32:09but they make up less than 5% of the total universe.
00:32:13Dark matter, one of the biggest mysteries in space,
00:32:16is the name we use for all the mass in the universe that's still invisible to us.
00:32:21And there's a lot of it.
00:32:23It may even make 25% of the universe.
00:32:26Dark energy makes the other 70% of the universe.
00:32:29Hmm, that adds up to 100, right?
00:32:33Now, let's look at the Moon.
00:32:35It always looks at us with one side.
00:32:38This means the Moon has a dark side,
00:32:40and the Sun's rays never get there.
00:32:42Well, that's a myth.
00:32:44The whole point is that the Moon is gravitationally locked to the Earth.
00:32:48There are days and nights there, too.
00:32:50It's just that this rotation is perfectly aligned with the rotation of the Earth.
00:32:55So, whenever you look at the Moon, you only see one side.
00:32:59Although there are days when the Sun shines there, too,
00:33:02so it's not the dark side, it's the far side.
00:33:05And we even have pictures of this place.
00:33:08And there's one of the biggest craters in our entire solar system,
00:33:12the South Pole-Aitken Basin.
00:33:14It's as wide as two states of Texas.
00:33:17Yeehaw!
00:33:19One myth that turned out to be untrue
00:33:21is that people have never actually been on the Moon.
00:33:25This is the original space suit of the first astronauts who were there.
00:33:29Look at the sole of the shoe.
00:33:31Some people claim there's no way they could've left footprints like this there.
00:33:35Actually, they could.
00:33:37On the Moon, the astronauts wore extra boots over their suits,
00:33:40and their soles matched the footprints on the Moon perfectly.
00:33:44Now, the astronauts didn't need them when they left the Moon,
00:33:47and tossed them when the Moonwalk was over.
00:33:50They left a lot of stuff there, too.
00:33:52They even tossed the armrests of the seats in the lunar module to reduce the weight.
00:33:57Now, counting all the Apollo lunar missions,
00:34:00the total weight of rubbish on the Moon is approximately 187 tons,
00:34:04including several lunar rovers, spacecraft debris,
00:34:08six lunar modules, and all the experiments left behind.
00:34:12That's like three Boeing 737s.
00:34:15Another myth about the Sun is that it's yellow.
00:34:18Let's send you into space for this one.
00:34:20You look out the window, and… it's white!
00:34:23The Sun only appears yellow to us through the filter of our atmosphere.
00:34:27The composition of the air and its thickness just distorts the light of the star.
00:34:32But stars do come in different colors.
00:34:35Cooler stars have bright orange and red colors.
00:34:38You're sitting at a coffee shop on Mars,
00:34:41keeping your head down, trying not to draw any attention to yourself.
00:34:44It's crowded, and many people are singing, dancing,
00:34:47and talking loudly about life on Mars.
00:34:50Your drink arrives, and you sip on it.
00:34:52So far, no one recognizes you.
00:34:55You're wearing a cloak with a large hoodie to cover your face
00:34:58and disguise yourself from everyone.
00:35:00Someone accidentally bumps into you and sees your face.
00:35:03The music stops, and now everyone is staring at you.
00:35:07You have nowhere to hide or run.
00:35:09You ignore the leering eyes and keep sipping on your beverage.
00:35:12An old bearded man sits in front of you, amazed to be in your presence.
00:35:17So, it's true. No one believed you'd make it, he says.
00:35:22You don't reply and continue with your drink.
00:35:25Everyone else gathers around you.
00:35:27Another man speaks.
00:35:29Well, are you not going to tell us how you escaped from the clutches of the Space Kraken?
00:35:35Everyone gasps in shock.
00:35:37No one has ever made it to tell the tale of the Kraken, except you.
00:35:42Your plan was to find your messenger to take you to a spaceship far away from this planet.
00:35:47But it's too late, now that everyone knows you're here.
00:35:51And the messenger fled, knowing all the attention was on you.
00:35:55You lay back your hoodie and explain what happened.
00:36:01You're in your full gear, ready to make the voyage into deep space.
00:36:05You have a solo ship that's designed to maneuver through all the obstacles in space.
00:36:10You prepare the rest of the gear and fuel up.
00:36:13Everyone is watching you, knowing that you might not make it back.
00:36:17But the Kraken has been floating in space for too long, disrupting shipping containers bringing in goods.
00:36:23A small ship like yours can sneak past its acute sense of smell and vision.
00:36:28But larger ships will get destroyed.
00:36:31You made it your mission to find this Kraken and study it.
00:36:35If you learn its ways and patterns, you can figure out how to get rid of it.
00:36:40Everyone says their goodbyes, and you lift off.
00:36:43You know that it'll be a very long way to get there.
00:36:47Possibly three days in the emptiness of space.
00:36:50You saw some quick footage of it, but no one knows exactly where it sleeps.
00:36:55Or if it even does sleep.
00:36:58You put on some tunes and set your ship for cruise control.
00:37:02You make some notes and set the camera to document yourself while you prepare everything you need.
00:37:07You also have some cameras outside recording everything that moves.
00:37:11Even thermal sensors to catch living creatures floating in space.
00:37:16After a few hours, you exit the safe quarters of Mars and enter into the hostile territory.
00:37:22There is no place to hide or anyone to help you.
00:37:26A few little ships like yours pass by now and then.
00:37:29They watch you going further to the Kraken.
00:37:32You notice many floating signs powered by machines warning you about the Kraken.
00:37:37The cameras start recording, and you begin your video journal which is transmitting to your network at home.
00:37:43So far, nothing.
00:37:45It's quiet and dark.
00:37:47Hours pass, and you're just floating in the middle of nowhere.
00:37:50You almost feel like you want to turn around.
00:37:53Then, you pick up something in the sensors.
00:37:56You see a large live object nearby.
00:37:59You turn off the lights and slow down your ship.
00:38:02You resume recording and start talking to yourself, explaining everything.
00:38:07The object is getting closer and closer.
00:38:10You move aside to avoid it and latch on to a floating rock.
00:38:14But you still don't see anything.
00:38:16Out of nowhere, you see some glowing jellyfish-like creatures flowing together in a cluster.
00:38:22Like thermal sensors, they appear to be large objects.
00:38:25But in fact, they are just little creatures.
00:38:28According to your studies, these creatures are some of the main foods for the Kraken.
00:38:33So, they're probably running away from it.
00:38:36After a few minutes, the creatures float away, and you launch yourself out and turn the lights back on.
00:38:43A few more hours pass, and you still see no Kraken.
00:38:47Suddenly, a whoosh shakes your ship, and you're thrown slightly off course.
00:38:52You notice that a large object has spiked your thermal sensors and left.
00:38:56You keep going and check the playback settings to see if your cameras manage to catch something.
00:39:02You try to look carefully, but it seems like a gust of wind blew past you.
00:39:06Which is weird, because there is no wind in space.
00:39:10You check the thermal sensors and notice that a large object shaped like the Kraken has zipped past you.
00:39:17It's still around, and it has probably caught your scent.
00:39:20Your system's got some DNA particles and are studying them.
00:39:24After a while, they show that the Kraken's skin can change colors according to its surrounding.
00:39:30Its skin is thick and made up of some cosmic fluorescent material that is new to any creature you've ever come across.
00:39:37The system continues studying it.
00:39:40After a while, the Kraken goes off your radar and disappears.
00:39:44You circle back, trying to find it.
00:39:47People back on Mars can see the data and already have information about its size and skin quality.
00:39:53They even see some footage you've managed to catch.
00:39:56As you continue driving towards it, you open your floodlights, trying to see anything.
00:40:01Your cameras are still rolling.
00:40:03Suddenly, the Kraken changes skin color and appears right in front of you!
00:40:08Its large tentacles flash around, whipping nearby space debris.
00:40:12Its large eye that's as big as a bus looks right at you.
00:40:17It opens its mouth, and you see layers of sharp teeth circling like a grinder.
00:40:22It has a large beak that can break your ship easily.
00:40:26It starts flashing its colors rapidly as a way to warn you.
00:40:30It shoots out some liquid to move in a no-gravity space environment.
00:40:34It's moving towards you until it launches itself.
00:40:37Your ship has an auto-force field for protection, but it can't sustain the powerful bite of the Kraken.
00:40:43After only a few seconds, the shield breaks, and your ship spirals down to another planet.
00:40:49You crash-landed in a swampy land.
00:40:52Your ship has survived, but it can't take off.
00:40:55The analysis of the Kraken is ready.
00:40:58It shows that it doesn't need oxygen to breathe, and its DNA is evolving.
00:41:03Now that it got a bite of your force field, it can adapt itself to create a bio-force field of a similar nature.
00:41:10But you crashed on a planet that is foreign to you.
00:41:13You put on your safety suit and observe the environment.
00:41:16The atmosphere is filled with nitrogen and sulfur.
00:41:19You get out and walk around. It has similar gravity to that of Earth.
00:41:24As you venture through the swamp, you start seeing little skin particles similar to those your ship has caught.
00:41:31The liquid below you is some foreign substance that seems to be deteriorating your suit, so you opt to hover.
00:41:38The trees are strange and seem to be living off the atmosphere, but there is no sign of life anywhere.
00:41:45Suddenly, you see a huge crater that leads to the center of the planet.
00:41:50You enter it and see some ships similar to yours.
00:41:53It seems that the Kraken knocked them off course, and they all crash-landed on this planet.
00:41:59Many of them seem to be intact, while others are completely obliterated.
00:42:04Your sensors pick up another reading. It senses another creature dwelling in the center.
00:42:09You try to get closer. You're doing your best to be as gentle as possible, but you feel the ground shaking below you.
00:42:16You duck down and try to avoid the rocks falling overhead.
00:42:20A large tentacle pops out of nowhere, and then another, and another. It swings itself out and crawls in the open.
00:42:27You know, back in the 1970s, scientists discovered a mysterious gravitational anomaly called the Great Attractor.
00:42:35Wait a minute, I had that nickname in high school.
00:42:38Anyway, it's a place in the sky that draws hundreds of galaxies, including our Milky Way.
00:42:43You won't be able to see it because it's on the other side of the Milky Way, 150 million light-years away.
00:42:49The Great Attractor actually lies in the direction scientists usually call the Zone of Avoidance.
00:42:56I have one of those too. It's my closet.
00:42:59Now, there's so much dust and gas in this region that we can't see what's happening there.
00:43:04That area blocks most of the visible light from beyond.
00:43:07But all that dust and gas don't block X-rays and infrared light.
00:43:11So, as X-ray astronomy developed, researchers could finally start to observe all the objects within that area,
00:43:18including the mysterious force attracting everything.
00:43:21But so far, no one has figured out why it's happening.
00:43:25Our Moon may be 200 million years younger than we previously thought.
00:43:30Many scientists believe that the Moon formed during a powerful collision between our planet and an unknown Mars-sized body.
00:43:37The molten dust and debris got together and formed a new object we know as the Moon.
00:43:43The lunar crust was probably going through a process of solidifying over a couple of hundred million years.
00:43:49Did you know about an early magma ocean on the Moon?
00:43:53Scientists realized it was a real thing after they had discovered big amounts of the lightweight mineral called plagioclase.
00:44:00This material usually crystallizes and floats to the surface of magma.
00:44:04Anyway, this mineral was 4.36 billion years old,
00:44:08which means it formed 200 million years after the first solid materials had appeared in our solar system.
00:44:14Thus, the theory that the Moon formed during this giant chaotic collision might be true.
00:44:20Now, if you stand on the Moon one day and leave your footprint on its surface, it can stay there for a million years.
00:44:26You'd also see the footprints of other astronauts, even though no one has landed on the lunar surface for decades now.
00:44:33The Moon doesn't have a full-fledged atmosphere.
00:44:36There's no breeze or anything else that can sweep up the dust and erase the footprints.
00:44:41We see it as a small dot somewhere in the distance.
00:44:44But in reality, the Sun is so big that if it were an empty ball, you could fill it with more than a million Earths.
00:44:51The Sun makes up 99.86% of the mass of our entire solar system.
00:44:57Another enormous object in our solar system is Jupiter.
00:45:00It's 11 times wider than our planet.
00:45:03For example, Earth isn't even the size of the Great Red Spot.
00:45:07This enormous storm has been raging on Jupiter for more than a century.
00:45:11And no, it's not anchored to anything solid since Jupiter is a gas giant.
00:45:16It's like a massive hurricane, oval in shape, reddish in color, and wide enough to engulf our home planet.
00:45:23Once upon a time, it was three times as wide as our planet.
00:45:27But over the last few centuries, it's been shrinking as well as growing taller.
00:45:32As for Jupiter, this gas giant is some sort of vacuum cleaner that keeps our solar system safe.
00:45:38Jupiter has incredibly strong gravity that eats up comets or asteroids that might potentially harm our home planet.
00:45:45In some other planetary systems, gas giants similar to Jupiter migrate from the position where they formed.
00:45:52They spiral inward and come closer to their parent stars.
00:45:55And as they travel, they swallow up small rocky planets.
00:46:00Therefore, their strong gravitational force flings these planets out of their star systems.
00:46:05Luckily for us, Jupiter's gravitational force doesn't work that way.
00:46:09If Jupiter-like planets stay away from their stars, they keep their planetary systems safe,
00:46:14protecting those small planets in their inner orbit.
00:46:17Jupiter, for instance, can change the orbits of small space bodies that come too close to the inner planets of our solar system.
00:46:25That's why this gas giant is a good guardian of our solar system.
00:46:29Now, there's a supermassive black hole that roams through space at a speed of 3 million miles per hour and leaves a trail of debris behind.
00:46:38Hey, I had a little brother who once did that.
00:46:41It's about a million times as heavy as our Sun and, at the moment, 2 billion light-years away from Earth.
00:46:47This black hole started like any other in its own elliptical galaxy with many stars surrounding it.
00:46:53Supermassive black holes often form and remain in the center of galaxies.
00:46:57But this one got away.
00:47:00One theory claims that this black hole is different because the galaxy where it formed may have bumped into another galaxy at one point in the past.
00:47:08Sometimes, galaxies merge into a new one if this happens.
00:47:12But not this time.
00:47:14Instead of merging, the black hole's galaxy passed through a way bigger one millions of years ago.
00:47:19That giant galaxy already swallowed up some other galaxies along the way.
00:47:24And since it was so large, the galaxy surrounding our supermassive black hole ended up ripped apart.
00:47:30The black hole at its center managed to run away with some of the nearby stars.
00:47:35That's what left a burning trail stretching across the surrounding space.
00:47:40Solar superstorms are so powerful that they can cause blackouts all over the world.
00:47:45Random flares coming from the Sun cause solar storms.
00:47:49And they can really happen at any time.
00:47:52Back in 2012, we were lucky because the strongest solar storm in over 150 years passed very close to us.
00:48:00It just tore through Earth's orbit.
00:48:02If it had happened only a week earlier, our planet would have had to deal with tons of terrible consequences, including power outages all over the globe.
00:48:11Gamma-ray bursts are strong enough to destroy planets.
00:48:14We're talking about extremely strong bursts that mostly occur in galaxies very, very far away.
00:48:20If these rays are pointed directly at some space object, they can completely wreck it, even if we're talking about an entire planet.
00:48:28So, Earth is safe for now, and we have nothing to be afraid of.
00:48:32A gamma-ray burst happens in our galaxy approximately once every 5 million years.
00:48:37Luckily, it occurs too far away and doesn't affect life on Earth.
00:48:41That's what I call irrelevant but still scary.
00:48:45A burning ice is a thing.
00:48:47It may be hard to picture it here on Earth, but one strange planet called Gliese 436 b is literally a burning ball of ice.
00:48:55It's covered with ice, but at the same time, it has temperatures of 822 degrees Fahrenheit.
00:49:01You can't actually see the planet burn since there's too much water on the planet.
00:49:06It's because of the strong gravitational force that pulls the water molecules to the core of the planet and packs them together incredibly densely.
00:49:14That way, water molecules can't evaporate, which is why the ice on the planet's surface doesn't melt.
00:49:20There are stars that can munch on other stars.
00:49:23These space objects are mostly smaller stars with a lower mass.
00:49:27They target the closest stars and begin to absorb their hydrogen fuel to boost their own mass and generally live longer.
00:49:35A vampire star becomes strikingly blue.
00:49:38It also gets hotter.
00:49:40This way, it seems that it's way younger than it actually is.
00:49:44If a star or basically any other object falls into a black hole, it gets stretched like spaghetti.
00:49:51This process is even called spaghettification.
00:49:54In space, no one can hear you scream.
00:49:57Or is that in space, no one can hear ice cream?
00:50:00Well, either way, we know that no supernovas, crashing asteroids, and burning planets make a sound in space.
00:50:07Or do they?
00:50:09What if you actually can hear something out there?
00:50:12Well, let's see.
00:50:14Okie dokie, back to middle school.
00:50:16Ahem.
00:50:17Sound is a mechanical wave originating from vibration.
00:50:20Uh, what exactly does that mean?
00:50:22Well, the simplest example is guitar strings.
00:50:25Let's pluck one of them.
00:50:27It starts to vibrate.
00:50:28The atoms inside the metal string begin to push and beat the atoms of the air around them.
00:50:33So now, atoms are constantly pushing each other until they reach our ears.
00:50:38It's like a wave from a pebble thrown into a pond.
00:50:41And it happens very quickly, at a speed of about 761 miles per hour.
00:50:47Then our eardrums begin to vibrate at the same frequency.
00:50:51And the little bones inside our ears transmit this vibration to the brain.
00:50:56The brain then does its magic, recognizes the pattern, and turns it into sounds.
00:51:02Great!
00:51:04Now we know that we need some particles to create sound.
00:51:07We can find these particles in gases, liquids, and solid substances.
00:51:12And what about space?
00:51:13Nope, it's almost a perfect vacuum.
00:51:16And you've probably already heard that there's no sound in space because it's a vacuum.
00:51:21But what does it actually mean?
00:51:24Well, a vacuum is a perfect void.
00:51:27It's an area completely devoid of matter.
00:51:29It means there's nothing there.
00:51:31Yeah.
00:51:32Despite all those celestial bodies in space, there's actually no air in between them.
00:51:37No atoms, no particles, nothing.
00:51:39Nada.
00:51:40Zippo.
00:51:41Well, almost.
00:51:42To be honest, the perfect vacuum doesn't really exist.
00:51:46We can't get rid of atoms for good.
00:51:48But space is very close to this notion.
00:51:51On average, there are 15 to 80 atoms per one cubic inch.
00:51:55This may sound like a big number, but keep in mind that these atoms are tiny.
00:52:00And the void distance between them is huge.
00:52:03For comparison, one cubic inch of air contains about 16,000 atoms.
00:52:08So, of course, with such a low density, these atoms can't push each other.
00:52:13Even if the vibration is very strong, like, I don't know, a supernova,
00:52:17they still won't be able to do that.
00:52:20So, movies have been lying to us.
00:52:23All these epic space scenes actually take place in an awkward silence.
00:52:28Who would've guessed?
00:52:30But don't get upset.
00:52:32What if I tell you there are, in fact, some ways to hear sound in space?
00:52:38First of all, there's still sound on other planets.
00:52:41If there's an atmosphere on a space body, or at least something like gas, water, or a solid surface,
00:52:47there will be sound.
00:52:49In our case, the atmosphere becomes completely silent at about 60 miles above the Earth's surface.
00:52:56That's where the sky stops being blue, and a black starry veil begins.
00:53:02In any case, we'd have to land on another planet,
00:53:05or at least get close to its atmosphere to hear something.
00:53:09But whatever it is, it would sound very different.
00:53:12Let's take our favorite Venus as an example.
00:53:15The atmosphere there is very dense.
00:53:18Scientists jokingly call it a thick chemical soup.
00:53:21No thanks.
00:53:22So, if you somehow manage to stay alive and speak there,
00:53:26your voice would be very different.
00:53:28It would become much louder, and it would sound deeper.
00:53:33So, if you want a pleasant baritone, you know what to do.
00:53:38I wonder what would happen if Earth had a denser atmosphere.
00:53:41What would we hear then?
00:53:43Well, you can vaguely imagine that if you've ever been in the water.
00:53:48Water is very dense.
00:53:50Sound moves there much faster and better compared to the air,
00:53:54at a speed of almost a mile per second, depending on the water temperature.
00:53:59So, if you sit in an empty room with no sound sources, you won't hear much, right?
00:54:04Now, dip your head in the water and check out how the same silence sounds here.
00:54:09It's not quiet at all.
00:54:11Even if you ignore the ever-present sounds of the water itself,
00:54:14you'll immediately notice how well you can hear your own body,
00:54:18how your blood pulsates in the veins, how your heart works,
00:54:21the slightest movement of your fingers.
00:54:23Kind of creepy, isn't it?
00:54:26This gives us an idea of what would happen to us on a planet with a denser atmosphere.
00:54:30And that's just crazy.
00:54:32We would hear everything.
00:54:34From scurrying animals to the movement of tectonic plates.
00:54:38Ah, come on, you'd probably say.
00:54:40It's obvious that there's sound on other planets.
00:54:43But didn't you say we can hear something in open space?
00:54:46Actually, yes.
00:54:48For example, in a cloud of dust.
00:54:50You can find space dust almost everywhere in space.
00:54:53It may be the remains of a star or something else.
00:54:57And in these places, everything is a bit denser than usual.
00:55:01This means there are probably dust clouds where particles are very close to each other,
00:55:05which means they can produce sounds.
00:55:08Of course, those will be very quiet and transmitted over a very short distance.
00:55:13But it's better than nothing, right?
00:55:17Plus, we already have one real space sound recorded.
00:55:21It came from the Perseus galaxy, which is located 250 million light-years away from us.
00:55:27NASA recorded it in 2003.
00:55:30Those of us music geeks will want to know that it's a B-flat,
00:55:3457 octaves below middle C on the piano.
00:55:38You'd have to add another 660 keys to the left on the keyboard.
00:55:42But its frequency is so low that the human ear unfortunately can't hear it.
00:55:47But besides that, we can only hear something inside spaceships.
00:55:52These are small pockets of air, after all.
00:55:55In a spacesuit, you would hear sounds very well too,
00:55:59including your breathing or blood circulation in a spacesuit.
00:56:03But two astronauts flying side by side wouldn't hear each other,
00:56:07even if they got very close and shouted very loudly.
00:56:10It's quite funny.
00:56:11If you, being an astronaut, bumped into something,
00:56:14it would be very loud for you, but your friend wouldn't hear anything.
00:56:18That's why astronauts use radio devices.
00:56:24Now, purely theoretically, if you could somehow crawl out of your spacesuit and survive,
00:56:31you'd be able to hear the chatter and noises going on inside the spaceship.
00:56:35But how?
00:56:36So, look, we have some air inside the spaceship, and it transmits sound.
00:56:41It reaches the metal casing and gets through it.
00:56:44And then, if you leaned against the ship, preferably touching it with your elbow or knee,
00:56:49the sound would be transmitted to the brain directly through your bones, ignoring the ears.
00:56:55Yes, our bones conduct sound.
00:56:58That's how, for example, deaf people listen to music.
00:57:01It's called bone conduction.
00:57:03It's used in some headphones and some other technologies.
00:57:07You can do a little experiment.
00:57:09Hold your fingers over your ears.
00:57:11Shut them properly so that you really don't hear much.
00:57:14Then try to touch a sound source.
00:57:16It can be anything vibrating.
00:57:18For example, a speaker playing music with some part of your body where the bone is close to the skin.
00:57:24Now watch the miracle happen.
00:57:26You can hear the sound not through your ears, but directly in your brain.
00:57:30But please, don't repeat this experiment in open space.
00:57:34You know, ice cream.
00:57:36Now, you've probably heard about things like the sounds of space,
00:57:40where you can listen, for example, to the sounds made by the Sun or different planets.
00:57:45How do we record these ones?
00:57:47Easily.
00:57:48There is another way to hear sound in space.
00:57:51Electromagnetic waves.
00:57:53Venus most likely used to be covered with oceans from 30 to 1,000 feet deep.
00:57:59Also, some water was locked in the soil of the planet.
00:58:02On top of that, Venus had stable temperatures of 68 to 122 degrees Fahrenheit,
00:58:08which, you have to admit, was quite pleasant and not that different from the temperatures on Earth nowadays.
00:58:14So, what I'm getting at is that for 3 billion years,
00:58:17right until something irrevocable happened 700 million years ago,
00:58:21Venus could've been habitable.
00:58:23But now, it's not.
00:58:25The Moon is the second brightest object in our sky.
00:58:29At the same time, among other astronomical bodies, it's one of the dimmest and least reflective.
00:58:35Our natural satellite only seems bright because it's so close to Earth.
00:58:39For comparison, our planet looks much brighter when you look at it from space.
00:58:44It's because clouds, ice, and snow reflect way more light than most types of rock.
00:58:49Triton, Neptune's moon, has all its surface covered with several layers of ice.
00:58:54If this satellite replaced our current moon, the night sky would get 7 times brighter.
00:59:01Neutron stars are some of the smallest, yet most massive objects in space.
00:59:06They're usually about 12 miles in diameter, but are several times heavier than the Sun.
00:59:11Oh, and they also spin about 600 times per second, far faster than your average figure skater.
00:59:19Saturn is the least dense planet in the Solar System.
00:59:22It has one-eighth the average Earth's density.
00:59:25And still, because of its large volume, the planet is 95 times more massive than Earth.
00:59:32A transient lunar phenomenon is one of the most enigmatic things happening on the Moon.
00:59:37It's a short-lived light, color, or some other change on the satellite's surface.
00:59:42Most commonly, it's random flashes of light.
00:59:45Astronomers have been observing this phenomenon since the 1950s.
00:59:49They've noticed that the flashes occur randomly.
00:59:52Sometimes they can happen several times a week.
00:59:54After that, they disappear for several months.
00:59:57Some of them don't last longer than a couple of minutes.
01:00:00But there have been those that continued for hours.
01:00:04The year was 1969, one day before Apollo 11 landed on the Moon.
01:00:09One of the mission participants noticed that one part of the lunar surface was more illuminated than the surrounding landscape.
01:00:16It looked as if that area had a kind of fluorescence to it.
01:00:19Unfortunately, it's still unclear if this phenomenon was connected with the mysterious lunar flashes.
01:00:26Trash isn't just a problem in Earth's oceans, cities, and forests.
01:00:29There is a thing called space junk, which is any human-made object that's been left in space and now serves no purpose.
01:00:37There's also natural debris from meteoroids and other cosmic objects.
01:00:41There are currently over 500,000 pieces of space debris orbiting the Earth at speeds high enough to cause significant damage if they were to collide with a spacecraft or satellite.
01:00:52NASA does its best to track every single object to ensure that missions outside Earth can reach their destination safely.
01:00:59Our Sun is insanely massive.
01:01:02Want some proof?
01:01:0399.86% of all the mass in the Solar System is the mass of the Sun.
01:01:09In particular, the hydrogen and helium it's made of.
01:01:12The remaining 0.14% is mostly the mass of the Solar System's 8 planets.
01:01:18The Sun's temperature is hotter than the surface of a star.
01:01:22The surface temperature reaches 10,000 degrees Fahrenheit, but the upper atmosphere heats up to millions of degrees.
01:01:30If someone could dig a tunnel straight into the center of the planet and out the opposite side, and you were adventurous enough to jump into it, it would take you 42 minutes to fall to the other side.
01:01:41You'd speed up as you fell, reaching maximum speed by the time you reached Earth's core.
01:01:47After the halfway point, you would then fall upwards, getting slower and slower.
01:01:52By the time you reached the opposite surface, your speed would be back to zero.
01:01:56Unless you managed to climb out of the hole, you'd immediately start falling again, back down, or up, to the other side of the planet.
01:02:04This trip would go on forever, all thanks to the weird effects of gravity.
01:02:08Hey, might be a fun way to spend an afternoon!
01:02:13There might be more metals, for example, titanium or iron, in lunar craters than astronomers used to think.
01:02:20The main problem with this finding? It contradicts the main theory about how the Moon was formed.
01:02:26That theory says that Earth's natural satellite was spun off from our planet after a collision with a massive space object.
01:02:33But then, why does Earth's metal-poor crust have much less iron oxide than the Moon's?
01:02:39It might mean the Moon was formed from the material lying much deeper inside our planet.
01:02:45Or these metals could have appeared when the molten lunar surface was slowly cooling down.
01:02:50Or maybe, as they've been saying for centuries, it's made of green cheese.
01:02:56Earth could have been purple before it turned blue and green.
01:03:00One scientist has a theory that a substance existed in ancient microbes before chlorophyll, that thing that makes plants green, evolved on Earth.
01:03:08This substance reflected sunlight in red and violet colors, which combined to make purple.
01:03:14If true, the young Earth may have been teeming with strange purple-colored critters before all the green stuff appeared.
01:03:21The highest mountain in the Solar System is Olympus Mons on Mars.
01:03:26It's three times as high as Mount Everest, the Earth's highest mountain above sea level.
01:03:31If you were standing on top of Olympus Mons, you wouldn't understand you were standing on a mountain.
01:03:36Its slopes would be hidden by the planet's curvature.
01:03:40Astronomers have found a massive reservoir of water in space, the largest ever detected.
01:03:46Too bad it's also the farthest, 12 billion light-years away from us.
01:03:50The water vapor cloud holds 140 trillion times as much water as all the Earth's oceans combined.
01:03:57What are we supposed to do with that information?
01:04:00Venus spins at its own unhurried pace.
01:04:03A full rotation takes 243 Earth days, and it takes the planet a bit less than 225 Earth days to go all the way around the Sun.
01:04:12It means a day on Venus is longer than a year.
01:04:15There's very little seismic activity going on inside the moon.
01:04:20Yet many moonquakes, caused by our planet's gravitational pull, sometimes happen several miles below the surface.
01:04:27After that, tiny cracks and fissures appear in the satellite's surface, and gases escape through them.
01:04:33Hey, they sometimes escape from me, too.
01:04:37Mars is the last of the inner planets, which are also called terrestrial since they're made up of rocks and metals.
01:04:44The red planet has a core made mostly of iron, nickel, and sulfur.
01:04:48It's between 900 and 1200 miles across.
01:04:52The core doesn't move.
01:04:53That's why Mars lacks a planet-wide magnetic field.
01:04:56The weak magnetic field it has is just 1,100% of the Earth's.
01:05:02When the planets in the Solar System were just starting to form, Earth didn't have a moon for the longest time.
01:05:09It took 100 million years for our natural satellite to appear.
01:05:13There are several theories as to how the moon came into existence, but the prevailing one is the fission theory.
01:05:21Somebody went fishing and caught the moon?
01:05:24Actually, no.
01:05:26The fission theory proposes that the moon was formed when an object collided with Earth, sending particles flying about.
01:05:33Gravity pulled the particles together, and the moon was created.
01:05:37It eventually settled down on the Earth's ecliptic plane, which is the path that the moon orbits.
01:05:42So, looks like the green cheese is off the table now.
01:05:47The largest single living thing on Earth turns out to be a mushroom in Oregon.
01:05:52This enormous honey mushroom lives in Malheur National Forest and covers an area of 3.7 square miles.
01:05:59It could be as much as 8,500 years old.
01:06:02You could be forgiven for missing it, though, since most of it's hidden underground.
01:06:08When the roots of individual honey mushrooms meet, they can fuse together to become a single fungus,
01:06:14which explains how this one got so big.
01:06:17If you could gather all that mushroomy stuff into one big ball, it could weigh as much as 35,000 tons.
01:06:24That's about as heavy as 200 grey whales.
01:06:27Hey, that's a whale of a mushroom.
01:06:31The largest asteroid in the Solar System is called Vesta, and it's so big that it's sometimes even called a dwarf planet.
01:06:38No one will hear your cry in space, or something like that.
01:06:42We've all heard this famous chilling phrase, and it's actually true.
01:06:46Space, for the most part, consists of a giant nothingness.
01:06:50There's a lot of, you know, space in space.
01:06:53But this doesn't mean there are no sounds in space.
01:06:56In fact, there are plenty of them.
01:06:58And some of them can even make you shiver.
01:07:00Let's take a look at the scariest space sounds.
01:07:03First of all, how are cosmic sounds even recorded?
01:07:06Sound is just the vibration of molecules.
01:07:09When you scream, you make the molecules push each other furiously until they reach the ear of the person you're yelling at.
01:07:16Then these vibrations get transmitted to the brain, and we recognize them as something that you might need to apologize for.
01:07:24In other words, to hear something, we need molecules.
01:07:27And that's where things get complicated.
01:07:29There aren't any of them in space.
01:07:31The entire universe almost completely consists of a vacuum.
01:07:35No, not a hoover.
01:07:36Absolute nothingness.
01:07:38However, the wizards from NASA still record space sounds somehow.
01:07:42So how do they do it?
01:07:44The thing is, there are some types of waves that don't care about molecules.
01:07:48We regular folk can't perceive them without some special devices.
01:07:52These waves include, for example, radio waves.
01:07:55We'll need a radio or something like that to recognize them.
01:07:59And that's exactly what NASA's satellites do.
01:08:01They catch random radio waves.
01:08:04Thanks to their heroism, we can find out how different cosmic bodies sound.
01:08:09These satellites record a variety of waves, fluctuations of plasmas, magnetic fields, and other, you know, stuff.
01:08:16And then scientists from NASA transform all this into normal soundtracks.
01:08:21And some of them sound quite frightening, to put it mildly.
01:08:25Let's take our magnetic field, for example.
01:08:28It surrounds our planet like an invisible shield, protecting us from all sorts of nasties, like radiation and solar winds.
01:08:35At the same time, we can neither see it, feel it, nor hear.
01:08:39Oops.
01:08:40Well, the last one is outdated.
01:08:42Scientists from the Technical University of Denmark took magnetic waves recorded by the ESSA swarm satellite.
01:08:48They converted them into an audio track.
01:08:51And got a pretty creepy result.
01:08:55Now, to be honest, it sounds more like an eerie entity stalking you in the middle of the night.
01:09:01And if you remember the maps of Earth's magnetic field, it starts to feel like a spider crawling nearby.
01:09:08And this isn't the first strange sound that we caught on Earth.
01:09:12Recently, we caught another weird radio emission from space.
01:09:15Scientists found out that the repeating signal came from somewhere very far away, like billions of light-years away from us.
01:09:23Such fast radio bursts usually lasted no longer than a few milliseconds.
01:09:27But this one was unique.
01:09:29It lasted about 3 seconds.
01:09:31Basically, thousands of times longer than usual.
01:09:34And at the same time, the signal was very precise.
01:09:37So much so, that scientists even compared it to a heartbeat.
01:09:42Scientists believe that this signal is caused by pulsars, or neutron stars.
01:09:47One time, Nikola Tesla caught something similar.
01:09:50But unfortunately, at that time, we didn't know about such things as pulsars.
01:09:55So, Tesla was sure that he had caught a message from some extraterrestrial life.
01:10:00It's a pity that the truth turned out to be much more boring.
01:10:03But let's move on from the Earth to the Moon.
01:10:06In 1969, the astronauts of the Apollo 10 mission, the spacecraft that made the final test flight to the Moon, flew past its surface.
01:10:14And then they caught some strange signals coming from the dark side of the Moon.
01:10:19The side that we never see because the Moon is tidally locked to us.
01:10:23The sound was so weird that the astronauts weren't even sure whether to report it to NASA.
01:10:28They were afraid they wouldn't be taken seriously.
01:10:31And maybe even not allowed to participate in the next space missions.
01:10:35Here's what it sounded like.
01:10:40But, according to NASA, it's not some creepy extraterrestrial music at all.
01:10:45These may just be some radio waves that affected each other because of their proximity.
01:10:50Although the astronauts who heard it for the first time probably felt a little creeped out.
01:10:55Let's move to the other planets.
01:10:57Now, 40 years ago, scientists actively explored the surface of Venus.
01:11:01They sent as many as 10 probes there, which were supposed to capture audio and video shooting from the surface.
01:11:08Now we know what Venus, which could easily destroy us at any attempt to even get close to it, sounds like.
01:11:15Horrifying.
01:11:17And you wouldn't expect anything else from the most dangerous planet in the Solar System.
01:11:22Unfortunately, Venus is even more toxic than the average Twitter user.
01:11:26Ha!
01:11:27So, these probes didn't last too long.
01:11:29They heroically arrived on a planet and soon broke down.
01:11:33Next one is Jupiter.
01:11:35This space giant, which is 11 times larger than the Earth, never fails to scare us.
01:11:42One of NASA's probes, Juno, flies around Jupiter every few weeks.
01:11:46The probe is moving at a tremendous speed, 130,000 miles per hour.
01:11:51One day, Juno caught one of the strongest invisible signals it had ever encountered.
01:11:57This was the point at which the mad solar wind came into conflict with the magnetic field of Jupiter.
01:12:03It kind of sounded like a cosmic boom.
01:12:07The original sound lasted two hours, but it was compressed to a few seconds.
01:12:12It actually sounds more like a collision of a sea wave and a rock.
01:12:16But here, in terms of horror, Jupiter surprisingly loses to one of its small moons, Ganymede.
01:12:23In 2021, the Galileo space probe flew past Ganymede.
01:12:27And during its flight, it received a rather strange recording.
01:12:36These sounds are satellite radiation.
01:12:38And it's unclear whether it sounds like a cozy sunny day in the jungle,
01:12:42or like thousands of bats waiting for you in the night.
01:12:46Next one is Saturn.
01:12:48This signal was caught by the Cassini-Huygens Automatic Interplanetary Station,
01:12:52which was launched into space in 1997.
01:12:55When flying past Saturn, Cassini recorded a pretty scary sound.
01:13:01This terrifying cry of thousands of souls is actually just some radio waves.
01:13:07They aren't too different from what the auroras emit on Earth.
01:13:10A little later, Cassini received another recording.
01:13:13The sound's made by lightning and thunderstorms on Saturn.
01:13:16They sound pretty interesting, too.
01:13:21More like popping corn or a Geiger counter, right?
01:13:24But that's just because these lightning strikes have a crazy frequency.
01:13:29Moving on from the Solar System to outer space.
01:13:32The famous Voyager 1 was launched back in 1977,
01:13:36and continues to send us data even 40 years after its launch.
01:13:40In 2012, it left the Solar System and entered interstellar space.
01:13:45And then, while abandoning its home, Voyager 1 detected the sound of plasma waves.
01:13:51The original recording lasted 7 months.
01:13:54But fortunately, scientists felt sorry for us and reduced it to 12 seconds.
01:14:00It isn't really eerie, but it's still kind of unsettling.
01:14:04And although it feels like nothing can beat Saturn's horrors,
01:14:08let's end this tournament with one of the scariest objects in the Universe – a black hole.
01:14:13This sound was recorded by the Chandra Space Telescope.
01:14:16While studying a cluster of galaxies in the constellation Perseus,
01:14:20they discovered something strange.
01:14:23Some undulating movements appear from the center of the cluster.
01:14:27They spread out in all directions, like circles on the water.
01:14:31Scientists have suggested that this was caused by a supermassive black hole.
01:14:36The thing is, black holes don't always devour space objects entirely.
01:14:40Sometimes, they kind of spit them out.
01:14:43This causes vibrations of gases, which we can convert into soundtracks.
01:14:48What's interesting is that the oscillation of each such wave actually lasts about 10 million years.
01:14:54You're just listening to a very accelerated recording.
01:14:58Scientists have reduced the delay between oscillations by about 144 quadrillion times.
01:15:04So, let's check it out.
01:15:07This is probably the eeriest sound from the whole list.
01:15:10Nothing too loud or wild, but there's something dark and disturbing about it.
01:15:16Now, those were the scariest space sounds captured by NASA.
01:15:19To be fair, most of them sounded creepy simply because they're radio waves.
01:15:24But it's still fun to get spooked sometimes.
01:15:27It's staring at you, and you're staring at it.
01:15:30A giant eye that seems to be pulling you into an abyss.
01:15:34You're hovering over it in your space copter.
01:15:37But, however scared you might be, you still need to do your job.
01:15:41So, you send your copter down to the surface of the Red Planet.
01:15:44Right, that's where you are, on Mars.
01:15:47But, first things first, you take a moment to remember everything you know about the 4th planet from the Sun.
01:15:53It's the last of the inner planets.
01:15:55Those are the planets that lie within the asteroid belt.
01:15:58They're also called terrestrial, since they're made up of rocks and metals.
01:16:02The atmosphere of Mars is much thinner than Earth's.
01:16:05It contains 95% carbon dioxide and a mere 1% of oxygen.
01:16:10In other words, don't even think about pulling off your helmet.
01:16:14Anyway, there's no time to waste.
01:16:16You land on the surface of the planet and find yourself in a brownish-red world.
01:16:21That's a good thing you're wearing a space suit.
01:16:23This place is freezing cold.
01:16:25The thermometer sewn into the sleeve of your suit shows minus 80 degrees Fahrenheit.
01:16:31Time to take your first step on the Martian surface.
01:16:34The planet looks quite colorful.
01:16:36And the hue of a particular area depends on the minerals that make up the soil.
01:16:41The ground under your feet is covered in fine dust.
01:16:44It looks like rust.
01:16:46The same orange dust is in the air.
01:16:48Good thing you have your own supply of oxygen and don't need to breathe Martian air.
01:16:53The layer of this dust covering the surface of Mars can be from 6 to 40 feet thick.
01:16:58You hope you'll avoid getting swallowed by some Martian quicksand.
01:17:02You start walking, feeling very light.
01:17:05Mars is just 15% of our planet's volume and a mere 11% of Earth's mass.
01:17:10It means that gravity here is much weaker.
01:17:13Its pull is 38% as strong as the pull of gravity on the surface of Earth.
01:17:18You jump up and down and then try to run several hundred feet.
01:17:22You haven't even broken a sweat.
01:17:24What makes it harder for you to explore the place on foot is that the planet's surface is rocky,
01:17:30covered with craters and volcanoes, old dry lake beds, and canyons.
01:17:35You see something huge towering on the horizon, but you try to suppress your curiosity.
01:17:41You'll have enough time to figure out what it is later.
01:17:44Suddenly, a massive cloud appears in the distance.
01:17:47It looks as if a huge herd of horses is approaching you.
01:17:51In reality, you better get back into your copter and fly away as fast as you can.
01:17:56That's one of Mars' infamous dust storms.
01:17:59They mostly occur during the summer in the southern hemisphere of the Red Planet.
01:18:03They can sometimes cover the entire planet.
01:18:06And you see the largest ones from Earth.
01:18:08You hop into your copter and set a course for the eye that scared you so much.
01:18:13Winding channels that look like veins run through the eyeball.
01:18:17But the closer you get, the less it looks like an actual eye.
01:18:21Soon you realize it's a crater.
01:18:24It's giant, almost 19 miles across.
01:18:27Around the crater, which looks as if it has a pupil, there are other even bigger craters.
01:18:33They likely formed billions of years ago.
01:18:35That's when Mars had to withstand multiple attacks of space rocks.
01:18:39But why is the eye crater darker than the surrounding landscape?
01:18:43Scientists think that once there was Martian water in the enormous pit.
01:18:48Remember those channels? They were likely carrying that water.
01:18:52And since the crater was filled with water, it stopped some substances and minerals from eroding away.
01:18:58Now, remember that towering something on the horizon?
01:19:02It's time to go and explore it.
01:19:04When you come close, you realize it's the largest shield volcano in the entire solar system.
01:19:10Olympus Mons.
01:19:12It's more than 370 miles in diameter, which is almost the same size as the state of Arizona.
01:19:18You tilt your head.
01:19:20Wow, the mountain is 16 miles high.
01:19:23It's also rimmed by 4-mile-high cliffs.
01:19:26To picture the sheer size of the volcano, let's make some comparisons.
01:19:30The largest volcano on Earth is Mauna Loa, towering around 2.5 miles above sea level and stretching 75 miles across.
01:19:39Sounds impressive, but the volume of Olympus Mons is around 100 times larger than that of Mauna Loa.
01:19:46The Martian giant could swallow the whole chain of Hawaiian islands from Kauai to Hawaii.
01:19:52But why is this volcano so large?
01:19:55It might be the result of lower surface gravity and higher eruption rates.
01:19:59Or the reason might be the Red Planet's crust, which is very different from Earth's.
01:20:04It's static.
01:20:05You see, on our planet, the crust is made of 15 to 20 moving tectonic plates.
01:20:11As plates move over hotspots producing lava, new volcanoes form, and the already existing ones become extinct.
01:20:19That's why lava can get to the surface through many vents.
01:20:22But on Mars, the crust isn't broken into the same tectonic plates as on Earth,
01:20:27and the lava has nothing to do but pile in one very, very large volcano.
01:20:34So how about getting closer to the enormous mountain?
01:20:37But once you step out of your copter on Martian soil, the ground under your feet starts shaking.
01:20:43Well, that's a marsquake.
01:20:45But how can it happen if Mars doesn't have any actively shifting tectonic plates?
01:20:50Specialists from NASA are sure marsquakes occur when energy inside the planet gets suddenly released.
01:20:57It leads to rock fractures and cracks in the planet's crust.
01:21:01Another powerful jolt, and one of such cracks opens right next to you.
01:21:06You fall to the ground, afraid to move.
01:21:08But soon, everything calms down.
01:21:11You wait for a couple of minutes, just to be sure, and get up.
01:21:15Oh, look! Here's a perfect opportunity to explore the insides of the Red Planet.
01:21:20The crack is large enough to send a special research robot.
01:21:24The planet's crust is thin and consists of volcanic basalt rock.
01:21:29The mantle that surrounds the core of the planet is made up of thick silicates, oxygen, and some minerals.
01:21:35You can probably compare it with soft, rocky toothpaste.
01:21:39Mars' mantle is also much thinner than Earth's.
01:21:42It's just 800 to 1100 miles thick.
01:21:45As for the planet's core, it's made mostly of iron, nickel, and sulfur, and is between 900 and 1200 miles wide.
01:21:53This core doesn't move.
01:21:55That's why Mars doesn't have a planet-wide magnetic field.
01:21:59Unfortunately, your drone is now lost in the depths of the Red Planet.
01:22:03You leave it there and continue your exploration.
01:22:06Your next destination is Valles Marineris.
01:22:09It sounds more like an Italian red sauce.
01:22:12But it's actually an enormous canyon, or rather a canyon system, that runs along Mars' equator.
01:22:18It's as awe-inspiring as Olympus Mons, more than 2,600 miles long and over 4 miles deep.
01:22:25The thing is so huge, it could span the entire continental United States from the Pacific to the Atlantic Ocean.
01:22:32Now let's make another comparison.
01:22:34One of the most famous canyons on Earth is the Grand Canyon in Arizona.
01:22:38But it's 10 times shorter and around 4 times less deep than this canyon on Mars.
01:22:44Some scientists think that Valles Marineris is the edge of an enormous tectonic plate.
01:22:49It moves so slowly that almost nothing has happened in that region over millions of years.
01:22:55And the movement of this plate probably began 3.5 billion years ago.
01:23:00Anyway, the only thing left on your today's to-do list is to visit Mars' moons.
01:23:06The center of the Milky Way is a story of intense radiation, gravity, and mystery.
01:23:12A place where the forces of nature are pushed to their limits.
01:23:16But what if our own planet were to find itself in this cosmic theater?
01:23:21What would happen if the Earth were located there and somehow managed to survive?
01:23:26Let's start this journey to the heart of our galaxy and find out.
01:23:32Picture this. You're floating in space, surrounded by billions and billions of stars.
01:23:38Suddenly, you see a bright, swirling mass of gas and dust in the distance.
01:23:43That, my friend, is the Milky Way Galaxy, our home in the vast expanse of the universe.
01:23:50The Milky Way is estimated to contain over 100 billion stars.
01:23:55And is about 100,000 light years across.
01:23:59In other words, if you were traveling at the speed of light,
01:24:02it would take you 100,000 years to cross the Milky Way from one end to the other.
01:24:07It's a couple trillions of miles.
01:24:10And it isn't just a static collection of stars and gas.
01:24:14It's a dynamic, evolving system.
01:24:17In fact, the Milky Way is currently hurtling through space at a speed of about 1.3 million miles per hour.
01:24:25One of the most fascinating things about our galaxy is its shape.
01:24:29The Milky Way is a spiral galaxy, which means that it kind of looks like a disc,
01:24:34with a central bulge and spiral arms.
01:24:37The spiral arms are the areas where new stars are born.
01:24:41It's where the most stars, gas and dust are concentrated.
01:24:45And this is where the solar system is located.
01:24:49Our system is like a tiny speck in the grand cosmic tapestry of the Milky Way.
01:24:55It's about 26,000 light years away from the center of the galaxy.
01:24:59A pretty long distance, isn't it?
01:25:02The solar system is also moving through the Milky Way as it orbits around the galactic center.
01:25:09It takes about 230 million years for our system to make one complete orbit around the galaxy.
01:25:16Just imagine that.
01:25:18Since the time of the dinosaurs, we've traveled just a quarter of this way.
01:25:23The position of the solar system in the galaxy affects our life in many ways.
01:25:29For example, things like the amount of radiation and cosmic rays we're exposed to,
01:25:34and even the likelihood of asteroid impacts, and so on.
01:25:40Also, thanks to our location, we can enjoy some pretty amazing views of the universe around us.
01:25:46From our vantage point in the Milky Way,
01:25:49we're able to see other galaxies, nebulae and star clusters in breathtaking detail.
01:25:55We're also a part of a pretty happening neighborhood,
01:25:58with lots of other stars and planets nearby.
01:26:01So we're lucky fellas!
01:26:03But what would happen if we weren't so lucky?
01:26:07What if the Earth was located in the center of the Milky Way instead?
01:26:12The center of the Milky Way is home to a region of space called the central bulge,
01:26:17and it's just packed with stars.
01:26:20It's like a disco ball, but instead of shiny mirrors, it's covered in stars.
01:26:25Only this disco ball is really huge, about 10,000 light years in diameter.
01:26:32The center of the Milky Way is also home to some extreme environments
01:26:36that would make even the bravest astronauts shiver.
01:26:39High energy particles and intense magnetic fields can wreak havoc on electronics and spacecraft.
01:26:46Intense radiation fields can fry anything in their path,
01:26:50so it's not exactly a friendly place for life as we know it.
01:26:55So if the Earth were located somewhere closer to the center of the Milky Way galaxy,
01:27:00it would be a very different place.
01:27:03Let's take a look at some of the potential effects.
01:27:07First of all, radiation.
01:27:10As we mentioned earlier, the center of the Milky Way is one of the most radiation-dense regions in the galaxy.
01:27:17It would make life on Earth very challenging, if not impossible.
01:27:22Sure, we have the Earth's magnetic field.
01:27:25It's like a giant shield that protects us from harmful radiation from outer space.
01:27:29But could it protect us if we were located in the center of the Milky Way?
01:27:34Unfortunately, the answer is no.
01:27:36It's kind of like trying to use a tiny umbrella to protect yourself from a massive storm.
01:27:42So it would be an easy win for the galaxy.
01:27:46But it's not all doom and gloom.
01:27:48There are some brave organisms that are able to adapt to high levels of radiation.
01:27:54We've seen that life on Earth has evolved to survive anywhere,
01:27:58from the depths of the ocean to the icy poles of the planet.
01:28:03So let's imagine what would happen if we somehow evolved to survive in these harsh conditions.
01:28:10Like, picture humans with tough, scaly skin that protects them from radiation,
01:28:15and plants with unique structures that allow them to thrive in this bright environment.
01:28:21In that case, radiation could still have some seriously spooky effects on us.
01:28:27For example, it could damage DNA molecules and cause mutations.
01:28:32Imagine a world where plants grow with five leaves instead of four.
01:28:36Animals have strangely colored fur.
01:28:39Or people have unusual eye colors or other unique features.
01:28:43And these are just some of the best examples.
01:28:46Let's not dive into the bad ones.
01:28:49Also, it could cause us to undergo some metabolic changes.
01:28:53Maybe our bodies could process food and other resources more quickly,
01:28:57which could lead to faster growth rates and larger sizes.
01:29:01Plants could grow tall and thick, and animals would be much larger than usual.
01:29:08There are also some organisms on Earth that are able to bioluminesce.
01:29:13Thanks to high levels of radiation, these organisms could potentially glow even brighter than usual.
01:29:19Imagine walking through a forest at night and seeing trees, mushrooms,
01:29:24and even insects glowing with an eerie blue or green light.
01:29:28Frightening and amazing, isn't it?
01:29:31But let's move on to the next big change, gravity.
01:29:35The gravity in the center of the Milky Way is incredibly strong,
01:29:39all thanks to a supermassive black hole.
01:29:42Which is about 4 million times the mass of the Sun.
01:29:46This black hole is called Sagittarius A.
01:29:49And yep, it's our neighbor now. Great.
01:29:53And assuming we don't get swallowed by this black hole or crushed by this incredibly strong gravity,
01:29:59it still could trigger lots of earthquakes and volcanic eruptions.
01:30:03This black hole would be like the gravitational bully,
01:30:07pulling and tugging at everything in its path.
01:30:11Basically, if we survived this, we'd have an epic surfing competition every single day.
01:30:17Just add a bit of the thrill of risking your life,
01:30:20and forget about running away from the planet.
01:30:22No easy rocket launches anymore.
01:30:25And physical objects won't be the only ones affected by gravity.
01:30:29Time would flow very differently for us.
01:30:32According to Einstein's theory of relativity, time passes more slowly in areas of high gravity.
01:30:39In other words, earthlings would age more slowly than someone far from the center of our galaxy.
01:30:46Also, the center of the Milky Way is a very busy place.
01:30:50Stars, planets, and other celestial objects moving around at incredibly high speeds there every day.
01:30:57The positions of stars and other objects would be constantly changing.
01:31:01In other words, say goodbye to normal navigation.
01:31:05The GPS system would likely be unreliable due to the strong gravitational forces and high radiation.
01:31:12So, if you accidentally got lost in a glow-in-the-dark forest with some creepy animals, good luck!
01:31:19But it's not all bad.
01:31:21The center is also home to molecular clouds.
01:31:24These are the regions of space where new stars are born.
01:31:28And the Milky Way in general has some pretty amazing sights to offer.
01:31:33For example, stunning nebulae like the Orion Nebula and the Eagle Nebula,
01:31:38which are visible with telescopes or even just a good pair of binoculars.
01:31:43So, if earth were located in the center of the Milky Way,
01:31:46we would have a front row seat to some of the most spectacular cosmic events.
01:31:51Wouldn't that be awesome?
01:31:54Overall, if earth were located in the center of the Milky Way, it would be a very different place.
01:32:00Of course, we all understand that our planet wouldn't have survived such a change.
01:32:05But it's still pretty interesting to imagine how our life would flow if we were there.
01:32:10And judging by what we just discussed, it wouldn't be pretty.
01:32:14So, let's treasure and appreciate our small, quiet solar system.
01:32:19The infinite vasts of the universe hold endless possibilities and secrets.
01:32:24And here's one of the intriguing questions.
01:32:27How life and we as humans would look like on other planets.
01:32:31Imagine a world where the laws of physics, the environment and the conditions are vastly different from what we're used to.
01:32:39How would we adapt and evolve to survive in these strange new lands?
01:32:44Let's see.
01:32:45Mercury is the closest planet to the sun and has a thin atmosphere.
01:32:50The temperatures there are extreme,
01:32:52with the day side reaching over 800 degrees Fahrenheit and the night side dropping to negative 290 degrees Fahrenheit.
01:33:00So, what can we do to survive these crazy temperatures and constant solar radiation?
01:33:06Maybe we can magically turn into metal.
01:33:09For example, titanium and platinum can perfectly tolerate high temperatures.
01:33:14But seriously though, there is an option.
01:33:17We could settle underground where the temperatures aren't so frenzied.
01:33:21If we lived underground, we might evolve with large eyes to better capture light.
01:33:26We might also evolve thicker skin to protect ourselves from the intense radiation.
01:33:31Basically, we have two options.
01:33:33Become metal or become moles.
01:33:36Let's move on to Venus.
01:33:38This planet is extremely hostile.
01:33:41First of all, Venus is known for its thick, more toxic than your ex type of atmosphere.
01:33:47The whole planet is covered with carbon dioxide and its surface is absolutely dry, making it incredibly hot.
01:33:54The average temperature is around 847 degrees Fahrenheit, making it one of the hottest planets in our solar system.
01:34:02Also, don't forget about the crazy pressure.
01:34:05Standing on Venus would be like standing 3000 feet underwater.
01:34:09Only particular hardy microbes from Earth could survive in such conditions.
01:34:14So, if you want to live on Venus, you might have to become a microbe.
01:34:18But unfortunately, since we're not microbes, we have to wear special gear and equipment to survive there.
01:34:25Maybe we'd have to develop a heat-resistant exoskeleton to protect ourselves,
01:34:30as well as get some new lungs that can filter out the toxic elements in the atmosphere.
01:34:35Let's talk about our favorite red sibling, Mars.
01:34:39The first noticeable change after a few hundred years would be your new skeleton.
01:34:43The gravity on Mars is much weaker than on Earth, so your muscles and bones would shrink.
01:34:49To make up for this difference, you'd have to eat more and probably start going to the gym.
01:34:54Also, you'd have to adapt to the low atmospheric pressure and colder temperatures.
01:34:59You need to retain heat, right?
01:35:01That means you'd need a thicker layer of body fat.
01:35:04Sorry folks, but on Mars, we might become fatter.
01:35:08Another reason to start working out.
01:35:11Another big change would occur in your skin.
01:35:13Your skin is like a big barrier that protects you from harmful things such as bacteria, UV light, looking totally creepy, and so on.
01:35:22So what would happen to it?
01:35:24Most likely, you would turn orange, due to the carotenoids.
01:35:28Carotenoids are a type of nutrient that you'd get from foods such as carrots, potatoes, tomatoes, and so on.
01:35:35They protect very well against ultraviolet radiation on Mars.
01:35:39They only have one downside.
01:35:41By eating a lot of pumpkins from the Martian farmer's market, you'll gradually start to turn orange.
01:35:46But maybe it's not so bad.
01:35:48Maybe life on Jupiter would be easier.
01:35:51Yeah, no, it has no solid land.
01:35:54This planet is made up of hydrogen and helium and is referred to as a gas giant.
01:36:00You would simply float there, like in a huge cloud.
01:36:03And even if you manage to land and try to walk, it would be like moving through a super thick fog.
01:36:08So how would we evolve there?
01:36:10Firstly, we might become much larger in size to withstand the immense pressures.
01:36:15Secondly, the temperature fluctuations on Jupiter are enormous.
01:36:20The surface is terrifyingly cold and the temperature rises significantly under the outer layers of the atmosphere.
01:36:27Thirdly, if you lived on Jupiter, there would be no verbal language.
01:36:31This gas giant absorbs radio waves, so even if you were speaking, no one would hear you.
01:36:36There would be no music either, so no parties.
01:36:39And what's the point then?
01:36:41Hey, maybe we could communicate with sign language, but that's not so simple either.
01:36:46Jupiter is full of wild winds and storm clouds, so it's unlikely you would be able to see anything.
01:36:52So even if we evolved there in some way, our lives would still not be easy.
01:36:57Before landing on Saturn, you would probably want to check out its iconic rings.
01:37:02But you wouldn't be able to do that because Saturn's rings consist of a bunch of ice particles flying in space,
01:37:08so it would be extremely hard to land.
01:37:11So let's go straight to Saturn itself.
01:37:14At first, it may seem that Saturn is not bad for us.
01:37:17Some layers of this gas giant have quite pleasant temperatures.
01:37:21If we dive deeper into Saturn, it gets surprisingly warm, up to 26 degrees Fahrenheit in its second layer.
01:37:28This is an average temperature in countries like Sweden and Canada.
01:37:32But unfortunately, this is only one such layer.
01:37:36The rest of the planet is incredibly cold, so in order to survive on Saturn, we'd have to do a lot of work.
01:37:43In addition to the cold, we'd have to deal with the planet's harsh environment,
01:37:47including its intense storms, strong winds, and radiation.
01:37:51To protect ourselves from these conditions, we'd need to evolve tough skin, again.
01:37:56Find some insulation, and so on.
01:37:59Next planet is Uranus.
01:38:01Uranus has a very different environment from Earth, with much colder temperatures,
01:38:06a lack of a solid surface, and a much different atmosphere.
01:38:09It's like another Jupiter, but with blue vibes.
01:38:12It's not that bad, though. There's even water on Uranus.
01:38:15The only problem is, the planet is full of ammonia, that nasty stuff we use for cleaning.
01:38:20So don't be surprised if you feel the gross smell.
01:38:23Also, it's incredibly cold out there, almost like a never-ending winter.
01:38:27So what would it be like to survive in such a dark and harsh environment?
01:38:31We'd need thicker skin, again, to cope with extreme temperatures.
01:38:35And again, we'd need larger eyes to see better in all this darkness.
01:38:39We might even have to develop a new hearing system, like that of dolphins.
01:38:43Wouldn't that be fun?
01:38:45Let's move on to Neptune.
01:38:47If human beings were to evolve on Neptune, they would need to adapt to its harsh conditions.
01:38:53Neptune, the 8th and farthest planet from our Sun, is another gas giant.
01:38:58The only difference is, this planet may have a solid core.
01:39:02If we were to live on Neptune, we'd need to float or swim in its methane-rich atmosphere.
01:39:07We'd also need to develop gills or something like that in order to breathe.
01:39:12Basically, we'd turn into space reptiles or cosmic fishes.
01:39:16The gravity on Neptune is slightly stronger than Earth's,
01:39:19but strong winds make it difficult to stand in one place.
01:39:22To withstand the wind, we'd need to be much heavier.
01:39:26Once again, you'd need to eat a lot and pump up some muscles.
01:39:30Yeah, yeah, technically it's not a planet, but we still love it and can't forget it.
01:39:35A small, distant, and incredibly cold world, Pluto's even smaller than our Moon.
01:39:40And because of that, there's almost no gravity there.
01:39:44It will be extremely difficult to stand on it.
01:39:46To avoid accidentally flying into outer space while playing football,
01:39:50we'd need to create a fake gravity machine.
01:39:53And if we don't want to feel dizzy, we'd need to evolve a brand new nervous system.
01:39:57But Pluto isn't all that bad.
01:39:59For example, there's liquid water under the surface, and even some icy mountains.
01:40:04Maybe it would be possible to survive there if we had some serious equipment.
01:40:08Clothes, supplies, and… nah, too much hassle.
01:40:12Anyway, from the scorching heat of Mercury to the freezing temperatures of Neptune,
01:40:17each planet has a unique set of environmental challenges and opportunities for evolution.
01:40:22While we may never truly know what humans would look like on these other worlds,
01:40:27it's exciting to consider the endless possibilities.
01:40:30Never stop looking at the stars and asking these questions.
01:40:34It was January 7th in 1610,
01:40:37when Italian astronomer Galileo Galilei made an astonishing discovery
01:40:42using his homemade telescope.
01:40:45Four moons orbiting the planet Jupiter.
01:40:48By the way, these days you can make your own version of his telescope
01:40:51using cardboard tubes, lenses, and some superglue.
01:40:55The main point of this DIY telescope is to place two lenses at the correct distance from each other.
01:41:01You'll need two lenses.
01:41:03One lens should be concave, the other one convex.
01:41:07So one lens is curved out and the other one is curved in.
01:41:11Galileo's initial telescope was able to magnify objects approximately 8 times.
01:41:17He continued to improve it until it reached about 20 times the magnifying power.
01:41:23But let's get back to the main story, shall we?
01:41:26When he first looked at those four moons of Jupiter,
01:41:29he believed he was simply looking at a bunch of stars.
01:41:32But he soon noticed that these space objects seemed to be moving in a regular pattern.
01:41:38It took him a couple of weeks to figure out that what he was looking at were not stars,
01:41:43but moons circling Jupiter.
01:41:47Galileo initially named those moons 1, 2, 3, and 4.
01:41:52But let's face it, those weren't the most creative names.
01:41:56As more moons in our galaxy were discovered later,
01:41:59the numerical system for naming them became confusing and impractical.
01:42:03So it lasted for just a few centuries.
01:42:06So, these days, those four satellites, Jupiter's largest,
01:42:10are named Io, Europa, Ganymede, and Callisto.
01:42:16They're collectively known as the Galilean moons to honor the man who first noticed them.
01:42:21Galileo's discovery was crucial for our later understanding of astronomy.
01:42:26It was initially believed that other objects revolved around the Earth
01:42:30since it was seen as the center of the universe.
01:42:34We now know that there are hundreds of moons in our solar system.
01:42:38However, large moons, like those discovered by Galileo Galilei,
01:42:42are not so commonly stumbled upon.
01:42:45A moon is considered large when it's the size of our planet or bigger.
01:42:50Ganymede, for instance, is bigger than Mercury.
01:42:53We basically call Ganymede a moon just because it orbits Jupiter.
01:42:57Otherwise, it has all the other characteristics of a planet.
01:43:01It's no surprise that Jupiter has the biggest moons in the area.
01:43:05It beats all the other planets in our solar system in both size and mass.
01:43:10So no wonder it pulled in a lot of other objects towards it.
01:43:14Jupiter is believed to have in total almost 80 moons,
01:43:19with only 53 of them being given official names until today.
01:43:25The first of those Jupiterian moons to be discovered by Galileo was Io.
01:43:30What sets it apart is the fact that it has a lot of volcanoes.
01:43:34Io is the only space object to have active volcanoes in our solar system,
01:43:39apart from Earth.
01:43:41It's also nicknamed the moon of fire and ice
01:43:44because of its sulfur dioxide snow fields.
01:43:47Io's outer layer is splotchy,
01:43:49featuring multiple colors like orange, black, yellow, white, and red.
01:43:55That's probably the reason why NASA described it as a giant pizza
01:43:59covered with melted cheese and splotches of tomato and ripe olives.
01:44:04Because of that sulfur, though, Io doesn't smell that appetizing,
01:44:08something similar to a rotten egg.
01:44:12There are more than 100 mountains on the surface of this moon.
01:44:15They are a lot larger than those we see on Earth,
01:44:18some being bigger than Mount Everest.
01:44:21On average, these mountains are 4 miles tall and 98 miles long.
01:44:28Because of those active volcanoes and the intense radiation on Io,
01:44:32there's little chance that life as we know it could exist here.
01:44:35But hey, who's to say it can't have life the way we don't know it?
01:44:41Next on the list of Galilean moons is Europa,
01:44:44the smallest of the four.
01:44:46It's comparable in size to the moon.
01:44:49Europa has an entirely icy surface
01:44:51with just a bunch of craters scattered here and there.
01:44:54Because of that outer layer,
01:44:56Europa is very reflective,
01:44:58making it one of the brightest moons out there.
01:45:01As for its age,
01:45:02scientists believe its surface to be somewhere between 20 to 180 million years old.
01:45:09Europa is about 4.5 billion years old.
01:45:15What lies beneath that icy surface is impressive.
01:45:18It may even hold the secret to life outside Earth.
01:45:22Ice forms here in two ways.
01:45:24The first is through congelation,
01:45:27a rather self-explanatory process.
01:45:29Ice just grows as the surrounding environment gets colder and colder.
01:45:34The other method, though, is a lot more fascinating.
01:45:37A layer of supercooled water found under the ice shell reacts when agitated.
01:45:42It then generates these crystals that make it look like it's snowing in reverse,
01:45:47floating upwards to the ice sheet they sit under.
01:45:51You can recreate this environment yourself at home.
01:45:54Take a bottle of purified water and place it into the freezer.
01:45:59If you don't have purified water anywhere near,
01:46:01just boil some water a couple of times to get rid of as many impurities as possible.
01:46:06Since there won't be any particles inside,
01:46:08once in the freezer, it won't turn solid.
01:46:12But if you take the bottle out of the freezer and give it a shake,
01:46:16the impact will make the water rapidly crystallize,
01:46:19transforming it into a slush-like consistency.
01:46:22There may be water on Europa,
01:46:24but there's little evidence so far that life exists on this moon.
01:46:28However, it's one of the highest candidates in the solar system for potential habitability.
01:46:34Some sort of life forms could adapt to live there in its under-ice ocean.
01:46:39That environment is most likely similar to what we can find in our planet's hydrothermal vents
01:46:44hidden deep within our oceans.
01:46:47The amount of oxygen in Europa's atmosphere is very little,
01:46:51but in 2013, NASA gave away some cool evidence.
01:46:56This yet again supports the theory that there's potential for life on this moon.
01:47:00It seems that Europa might be venting water into space.
01:47:05If this is confirmed by future observations,
01:47:07it could also mean that Europa is geologically active.
01:47:12It could also come in handy if we'd manage to study water sources one day.
01:47:18The largest of those Galilean moons is Ganymede.
01:47:21It's also the biggest moon in our solar system altogether.
01:47:25It's a low-density space object similar to Mercury in size,
01:47:29but having only half of its mass.
01:47:31However, Ganymede is the only moon out there to feature its own magnetic field.
01:47:36It's quite small though, and we can barely notice it from Earth
01:47:40since it's overshadowed by Jupiter's much more powerful magnetic field.
01:47:45Another cool aspect of Ganymede is that its atmosphere contains oxygen.
01:47:50Don't get too excited, it's not nearly enough to support any life forms living there.
01:47:56Back in December 2021, a 50-second audio clip was released
01:48:00which was previously recorded by NASA's probe on its Ganymede flyby.
01:48:06For the inexperienced, the sounds were more similar to those of an old dial-up internet connection,
01:48:12but because of its quirky tunes, Ganymede was soon nicknamed Jupiter's singing moon.
01:48:19Finishing up the list of Galilean moons is Callisto,
01:48:22or the most heavily cratered object in our solar system.
01:48:26What's interesting about this moon is that its landscape has barely changed since it formed,
01:48:31and scientists are still debating why this is happening.
01:48:35Most other space objects go through loads of changes throughout their lifetimes
01:48:40because of events such as collisions with other objects,
01:48:43changes in orientation or speed, or chemical reactions happening on their surface.
01:48:50Callisto is also about the size of the planet Mercury,
01:48:53but it has a lower density.
01:48:56Jupiter's magnetic field has a lesser impact here since Callisto is the furthest from the giant planet.
01:49:02Its surface is estimated to be a staggering 4 billion years old.
01:49:07As opposed to Io, Callisto is not geologically active,
01:49:11but scientists believe there might be an ocean hiding underneath the moon's surface,
01:49:16which may potentially harbor life.
01:49:18The fact that it's less impacted by Jupiter's magnetic field means that it features low levels of radiation.
01:49:25Given this suitable environment, we may one day end up setting a human base for future explorations here.
01:49:35When you look at photos taken from spaceships,
01:49:37or the International Space Station that show sunlit objects like Earth or the moon,
01:49:42something seems wrong.
01:49:44Space looks too empty.
01:49:46No magical scenery of a nighttime sky full of stars.
01:49:49It would be incredibly boring to go stargazing in space since the sky is always dark.
01:49:56During the daytime, the sky on our home planet is blue because of the diffusion of light.
01:50:01It happens when sunlight goes through the atmosphere.
01:50:03But if you were on the moon or somewhere else in space,
01:50:06there would be no atmosphere to spread this light around.
01:50:09That's why the sky there would always appear black.
01:50:12But it doesn't mean less bright out there.
01:50:14If you were looking out the window of the space station,
01:50:17you'd see just as much direct sunlight as you would gazing out of your apartment window during a cloudless day.
01:50:23Maybe even more.
01:50:25When taking a picture on a sunny day, you'll probably use a short exposure,
01:50:29together with the narrow aperture setting on your camera.
01:50:32This way, just a short burst of light will get in.
01:50:35That's similar to how our pupils contract in sunlight.
01:50:39And since it's just as bright up there in space,
01:50:41the process is the same when you take pictures of sunlit objects there.
01:50:45Using short exposure, you can get good, bright pictures of Earth or the surface of the moon.
01:50:50But it also means there will be no stars in the picture.
01:50:53Even up there, stars are relatively dim.
01:50:56They don't emit enough light to show up in photos taken with such settings.
01:51:00But if you were to take a picture of the moon,
01:51:04they don't emit enough light to show up in photos taken with such settings.
01:51:08Our home planet has a blue sky that slowly transforms into a beautiful orange-red palette at dusk and dawn.
01:51:15But if you ever get a chance to watch a sunset on Mars,
01:51:19you should expect the opposite, an orange-brown daytime sky that gets a bluish tint at sunset.
01:51:25First of all, Mars is farther away from the Sun than our planet.
01:51:29So, when you're looking at the Sun from the Martian surface,
01:51:32of course, it looks fainter and smaller.
01:51:35And not just that, the Sun observed from Mars is just a bluish-white dot surrounded by a blue halo.
01:51:41The thin atmosphere of the red planet contains large dust particles.
01:51:45They create an effect called Mie scattering.
01:51:48It occurs when the diameter of particles in the atmosphere is almost the same as the wavelength of the scattered light.
01:51:54This effect filters out the red light from the Sun's rays.
01:51:57So, only the blue light would reach your eyes on Mars.
01:52:02How come Earth doesn't have rings?
01:52:05All gas giants in our solar system, Jupiter, Saturn, Uranus, and Neptune have such rings,
01:52:11whereas the rocky planets Mercury, Venus, Earth, and Mars don't.
01:52:16There are two theories about how rings can appear around a planet.
01:52:20They might be just some material left from the times when the planet was forming.
01:52:24Or they may be the remains of a moon that got destroyed by a collision with some space body
01:52:29or torn apart by the strong gravitational pull of its parent planet.
01:52:33The gas giants formed in the outer regions of our solar system, while all the rocky planets are in the inner part.
01:52:39So maybe the inner planets were more protected from potential collisions that could have formed their rings.
01:52:45There are also more moons in the outer regions of our solar system,
01:52:49which could be another reason why the planets there have rings.
01:52:53Also, bigger planets have stronger gravity.
01:52:56It means that they can keep their rings stable after they form.
01:53:00Some experts believe Earth used to have a ring system a long time ago.
01:53:04A Mars-sized object might have collided with our home planet,
01:53:08which probably created a dense ring of debris around it.
01:53:12Some scientists think that this debris formed not a ring, but what we know today as the moon.
01:53:18There's probably a giant planet lurking at the edge of the solar system, far beyond Neptune.
01:53:24Scientists call this mysterious hypothetical world Planet 9.
01:53:28If it does exist, it's probably similar to Uranus or Neptune, and 10 times more massive than our home planet.
01:53:36It's likely to circle around the Sun, but in the outer reaches of the solar system, about 20 times farther than Neptune.
01:53:42Another interesting theory says that Planet 9 could actually be a black hole the size of a grapefruit
01:53:49that warps space in a similar way a large planet would.
01:53:54Even though we once thought it was a rare substance in space, water exists all over our solar system.
01:54:01For example, you can often find it in asteroids and comets.
01:54:05It's also in craters on the Moon and Mercury.
01:54:09We still don't know if there's enough water to support potential human colonies if we decide to move there,
01:54:14but some amount of water is definitely present there.
01:54:18Mars has water at its poles, too.
01:54:21It's mostly hidden in the layers of ice and probably under the planet's dusty surface.
01:54:26Europa, Jupiter's moon, has some water, too.
01:54:29This is the most likely candidate we know about to host life outside Earth.
01:54:34There's probably a whole ocean of liquid water under its frozen surface.
01:54:38It might actually contain twice as much water as all of Earth's oceans combined.
01:54:44Neptune is unexpectedly warm, even though it's 30 times as far from the Sun as our planet and receives less sunlight and heat.
01:54:52But it still radiates way more heat than it gets.
01:54:55It also has way more activity in its atmosphere than you'd suspect,
01:54:59especially if you compare it to its neighbor, Uranus.
01:55:03Both of these planets emit the same amount of heat, even though Uranus is much closer to the Sun.
01:55:09No one knows why.
01:55:11Neptune has extremely strong winds that can reach a speed of up to 1,500 miles per hour.
01:55:17Can they produce this heat?
01:55:19Or maybe it's because of the planet's core or its gravitational force?
01:55:24There's a monster black hole hurtling through space at a speed of 5 million miles per hour.
01:55:30Scientists located it with the Hubble Space Telescope.
01:55:33They believe it weighs as much as a billion suns.
01:55:36It was supposed to stay put in the center of its home galaxy,
01:55:40but some gravitational forces are pushing it around.
01:55:43At one point, this black hole is going to break free from its galaxy and continue roaming the universe.
01:55:49Luckily, it's still 8 billion years away from us.
01:55:53Solar storms are so powerful that they could leave us in complete darkness.
01:55:58Back in July 2012, the strongest solar storm in over 150 years narrowly missed Earth.
01:56:06Coronal mass ejections, or CMEs, are large bubbles of ionized gas.
01:56:11They tore through our orbit back then.
01:56:14If they had caught our planet in the crosshairs, we would have literally been in the firing line.
01:56:19We'd have faced solar matter hurtling towards Earth,
01:56:22damaging computers and causing power outages that would have lasted for months.
01:56:27A surprise solar storm hit us on June 25, 2022.
01:56:31One photographer even managed to capture stunning bright auroras that flashed across the dawn sky in Calgary, Canada,
01:56:38and lasted for five minutes.
01:56:40They were caused by the storm.
01:56:43Vampire stars are a real thing.
01:56:46They're part of a binary star, and they can literally drain the life out of the other star in the system.
01:56:51This is Neptune. The next stop is Pluto.
01:56:55Stand clear of the closing doors, please.
01:56:58One day, with top-notch future technologies,
01:57:01one stop from Neptune to Pluto won't seem much further than Times Square from Bryant Park today.
01:57:06There are huge ice mountains on Pluto,
01:57:09valleys that go further than your eyes can see,
01:57:12160-mile-large craters almost as big as the largest one on Earth,
01:57:16and no life.
01:57:18The reasons are obvious.
01:57:20The long distance between Pluto and the Sun guarantees freezing temperatures on that dwarf planet.
01:57:25It also ensures a trip of a few billion miles.
01:57:29Plus, it's smaller than the Moon,
01:57:31so it would get crowded very soon if people started dwelling there.
01:57:35Still, there's one reason which makes life there not that far-fetched.
01:57:39The Sun has a lifespan and cycles within it.
01:57:42Our solar system used to be nothing but a cloud of gas and dust.
01:57:46As a result of a gravitational collapse at the center of this cloud,
01:57:50the gas and dust started gathering in specific, denser places.
01:57:54These pulled more and more matter as time went on,
01:57:57and something called conservation momentum made the mass start rotating and heating up
01:58:02because of immense pressure.
01:58:04Later, there appeared a disk similar to what Saturn has,
01:58:08but it was made of entirely different substances.
01:58:11And right in the center, there was the ball that eventually became the Sun.
01:58:15A protostar is a young star that's still gathering its mass,
01:58:19and that's exactly what the Sun was
01:58:21before the temperatures and pressures inside of it lighted up its core.
01:58:25Millions of years later, it became the Sun we see every day.
01:58:29But it won't stay this way forever.
01:58:31It will heat up even more,
01:58:33and eventually get bigger and denser,
01:58:35turning into a red giant.
01:58:37It may one day get big enough to swallow up Venus and Mercury.
01:58:41Chances are, it might swallow even planet Earth.
01:58:45Even if it doesn't devour our planet,
01:58:47the Sun might get close enough to touch us.
01:58:49Well, if this happened, life on Earth wouldn't be possible.
01:58:52But then, in just a few minutes,
01:58:54the Sun loses about 40% of its mass
01:58:57and shrinks about 10 times what it used to be.
01:59:00It's not as bright, and indeed, not as hot as it used to be.
01:59:04By this moment, Earth will have already been deserted.
01:59:08People might want to start traveling around space,
01:59:10or settle down on another planet where life is sustainable,
01:59:14like the exoplanet Kepler-62f,
01:59:17which, by the way, is even bigger than Earth.
01:59:20While all of this was happening, Pluto was changing.
01:59:24Before, every resource was frozen inside of the dwarf planet.
01:59:28Water, gases like methane, carbon monoxide, you name it.
01:59:32But as the Sun was reaching its peak luminosity,
01:59:35Pluto was slowly warming up
01:59:37and losing a lot of what it had to the vastness of space.
01:59:40At the same time, an atmosphere formed up.
01:59:43If the atmosphere gets thick enough,
01:59:45it would create favorable life conditions.
01:59:47Then, instead of spaceships,
01:59:49a tiny percentage of us would be able to set up colonies on the dwarf planet.
01:59:54The temperature is comfortable there.
01:59:56Almost t-shirt weather.
01:59:58It even resembles Earth a tiny bit.
02:00:00Canyons filled with water,
02:00:02beautiful endless fields with trees,
02:00:04and lots of space to run around.
02:00:06And mineral water pockets on the ground, good enough to drink.
02:00:09Pluto's rotations are different than Earth's.
02:00:12An Earth day is 24 hours,
02:00:14and sometimes it still feels like it never ends.
02:00:17But on Pluto, a whole rotation around the Sun takes 153 hours,
02:00:22because it's pretty far away from the Sun.
02:00:24After several hours without sleep,
02:00:26we get tired and our eyes get red.
02:00:29It means we'd have to take several naps throughout the day on Pluto.
02:00:33A year on Pluto equals 248 Earth years.
02:00:36Unless we come up with some sort of technology to get us to live that long,
02:00:40our entire lifespan would be less than half a year on the dwarf planet.
02:00:45So, houses on Pluto might need to be equipped with cryo-chambers.
02:00:49Whenever you feel like dreaming for a long time,
02:00:52you jump in it and wake up 50 Pluto days later.
02:00:56On the dwarf planet, there are also seas and beaches.
02:00:59So it's just like a tiny Earth, far away from the actual Earth.
02:01:04The food on Pluto could be tastier.
02:01:06We might find a way to make the ingredients more savory,
02:01:09and even try to grow them faster during the trip.
02:01:11You plant a carrot, and two days later, it's ready to be in your salad.
02:01:16There could also be new ingredients for our salads on Pluto.
02:01:19Maybe two-meter-tall mushrooms we've never seen before.
02:01:22The animals we would take with us on the trip would get released into their new home forever.
02:01:27And with time, they would evolve and adapt to their new environments.
02:01:31The law of the jungle could change a bit, too.
02:01:34Lions might not be kings anymore.
02:01:36Deer are.
02:01:37Their antlers are twice the size of what they used to be.
02:01:40But to be fair, so are the deer.
02:01:43Most of the animals that were already here used to live underwater.
02:01:47But with time, the amphibians started shifting to the surface,
02:01:50just like Earth at the beginning of life.
02:01:52Pluto could only be a temporary home, though.
02:01:55Once the sun has finally reached its final phase,
02:01:58Pluto would get frozen and lifeless again.
02:02:02People instead would need to try to find a planet that stays in the Goldilocks zone of another galaxy.
02:02:08The Goldilocks zone is the exact proper distance from the star like the sun,
02:02:12where the temperature is perfect for the water to stay liquid.
02:02:15It's the rule scientists search for when looking for other planets that can sustain life.
02:02:20We can try setting new colonies on one such planet,
02:02:23or even try to set up our own artificial home.
02:02:25Not exactly a planet or a spaceship, but a combination of both.
02:02:29Something huge built right in space.
02:02:31Say, a wheel with gravity everywhere we go, so we don't fall off.
02:02:35It would float in space toward the new exoplanet,
02:02:38capable of fitting entire states in.
02:02:41This whole trip might happen just because the sun first grew too much.
02:02:45And then, having reached the culmination of its life cycle,
02:02:48it would finally become a white dwarf.
02:02:50It's going to be a pretty long journey, and entire generations will be born here.
02:02:55You'll have a choice.
02:02:56Sleep your way through the journey until humans finally reach their new exoplanet,
02:03:00or enjoy the trip in this fantastic spaceship.
02:03:03There's all you need on board.
02:03:05Malls bigger than those on Earth,
02:03:07large futuristic cities,
02:03:08even places to farm,
02:03:10fields with rich soil made artificially,
02:03:13and finally, after a long journey, the exoplanet.
02:03:17It's even somewhat better than Earth.
02:03:19The planet is giant and has more continents.
02:03:22The continent's center isn't as far from oceans,
02:03:25which means there aren't as many desert areas.
02:03:28Though the sun of this planet is an orange dwarf,
02:03:30it's not as hot as our yellow dwarf sun today.
02:03:33It's a bit smaller, but here's the kick.
02:03:36Orange dwarfs live somewhat longer.
02:03:38They remain stable for between 15 billion and 45 billion years.
02:03:43Despite that, this new planet is full of rainforests,
02:03:46because the planet itself is warmer.
02:03:49It means more biodiversity and creatures we've never seen before.
02:03:53But even if nothing out there is suitable,
02:03:55we could try and terraform this planet instead.
02:03:58If we take Mars as an example,
02:04:00we could create a greenhouse effect
02:04:02by smashing ice-rich comets
02:04:04and releasing ammonia in them,
02:04:06making the planet warmer.
02:04:08We could also start planting trees.
02:04:10We'd probably need some Earth soil to do that,
02:04:12or we'd have to modify Mars' soil to be similar to ours.
02:04:16Sooner rather than later,
02:04:17the atmosphere would be close to the one we have on Earth.
02:04:20We'd be able to breathe, too,
02:04:22because of the trees.
02:04:24Then we can melt Mars' polar ice caps,
02:04:27and voila, water.
02:04:29The problem is the solar winds and sun explosions
02:04:32that might strip it of an atmosphere
02:04:34just as quickly as we can create one,
02:04:36if not faster.
02:04:38It has no magnetosphere, either,
02:04:40which means it can't protect us from radiation.
02:04:43So long-term Mars wouldn't be a good choice.
02:04:46Maybe out there, in the vastness that is space,
02:04:49there is a perfect planet waiting for us.
02:04:53That's it for today.
02:04:54So, hey, if you pacified your curiosity,
02:04:56then give the video a like and share it with your friends.
02:04:59Or, if you want more,
02:05:00just click on these videos and stay on the Bright Side.

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