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Why you can't see stars in Space? Can you run faster than Usain Bolt on Mars? And why does one of Jupiter’s moons look like a pizza? Find the answers to these questions in this video!
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00:00When you look at photos taken from spaceships or the International Space Station that show sunlit objects like Earth or
00:07the Moon, something seems wrong.
00:09Space looks too empty.
00:11No magical scenery of a nighttime sky full of stars.
00:15It would be incredibly boring to go stargazing in space since the sky is always dark.
00:21During the daytime, the sky on our home planet is blue because of the diffusion of light.
00:27It happens when sunlight goes through the atmosphere.
00:30But if you were on the Moon or somewhere else in space, there would be no atmosphere to spread this
00:34light around.
00:35That's why the sky there would always appear black.
00:39But it doesn't mean less bright out there.
00:42If you were looking out the window of the space station, you'd see just as much direct sunlight as you
00:47would gazing out of your apartment window during a cloudless day.
00:50Maybe even more.
00:52When taking a picture on a sunny day, you'll probably use a short exposure, together with the narrow aperture setting
00:59on your camera.
01:00This way, just a short burst of light will get in.
01:03That's similar to how our pupils contract in sunlight so that they don't have to deal with too much light.
01:08And since it's just as bright up there in space, the process is the same when you take pictures of
01:13sunlit objects there.
01:15Using short exposure, you can get good, bright pictures of Earth or the surface of the Moon.
01:20But it also means there will be no stars in the picture.
01:24Even up there, stars are relatively dim.
01:27They don't emit enough light to show up in photos taken with such settings.
01:31Our home planet has a blue sky that slowly transforms into a beautiful orange-red palette at dusk and dawn.
01:38But if you ever get a chance to watch a sunset on Mars, you should expect the opposite, an orange
01:44-brown daytime sky that gets a bluish tint at sunset.
01:49First of all, Mars is farther away from the Sun than our planet.
01:52So, when you're looking at the Sun from the Martian surface, of course, it looks fainter and smaller.
01:58And not just that.
01:59The Sun observed from Mars is just a bluish-white dot surrounded by a blue halo.
02:04The thin atmosphere of the red planet contains large dust particles.
02:08They create an effect called mi-scattering.
02:11It occurs when the diameter of particles in the atmosphere is almost the same as the wavelength of the scattered
02:16light.
02:17This effect filters out the red light from the Sun's rays.
02:20So, only the blue light would reach your eyes on Mars.
02:25How come Earth doesn't have rings?
02:28All gas giants in our solar system, Jupiter, Saturn, Uranus, and Neptune, have such rings, whereas the rocky planets Mercury,
02:36Venus, Earth, and Mars don't.
02:39There are two theories about how rings can appear around a planet.
02:43They might be just some material left from the times when the planet was forming.
02:47Or, they may be the remains of a moon that got destroyed by a collision with some space body,
02:52or torn apart by the strong gravitational pull of its parent planet.
02:56The gas giants formed in the outer regions of our solar system, while all the rocky planets are in the
03:02inner part.
03:03So, maybe the inner planets were more protected from potential collisions that could have formed their rings.
03:09There are also more moons in the outer regions of our solar system,
03:12which could be another reason why the planets there have rings.
03:17Also, bigger planets have stronger gravity.
03:19It means that they can keep their rings stable after they form.
03:23Some experts believe Earth used to have a ring system a long time ago.
03:28A Mars-sized object might have collided with our home planet,
03:31which probably created a dense ring of debris around it.
03:35Some scientists think that this debris formed not a ring, but what we know today as the moon.
03:42There's probably a giant planet lurking at the edge of the solar system, far beyond Neptune.
03:47Scientists call this mysterious hypothetical world Planet 9.
03:52If it does exist, it's probably similar to Uranus or Neptune,
03:56and 10 times more massive than our home planet.
03:59It's likely to circle around the sun, but in the outer reaches of the solar system,
04:04about 20 times farther than Neptune.
04:07Another interesting theory says that Planet 9 could actually be a black hole the size of a grapefruit
04:13that warps space in a similar way a large planet would.
04:18Even though we once thought it was a rare substance in space,
04:22water exists all over our solar system.
04:24For example, you can often find it in asteroids and comets.
04:29It's also in craters on the moon and Mercury.
04:32We still don't know if there's enough water to support potential human colonies if we decide to move there,
04:37but some amount of water is definitely present there.
04:42Mars has water at its poles, too.
04:44It's mostly hidden in the layers of ice and probably under the planet's dusty surface.
04:49Europa, Jupiter's moon, has some water, too.
04:53This is the most likely candidate we know about to host life outside Earth.
04:57There's probably a whole ocean of liquid water under its frozen surface.
05:02It might actually contain twice as much water as all of Earth's oceans combined.
05:08Neptune is unexpectedly warm, even though it's 30 times as far from the sun as our planet and receives less
05:14sunlight and heat.
05:15But it still radiates way more heat than it gets.
05:19It also has way more activity in its atmosphere than you'd suspect,
05:23especially if you compare it to its neighbor, Uranus.
05:27Both of these planets emit the same amount of heat, even though Uranus is much closer to the sun.
05:33No one knows why.
05:34Neptune has extremely strong winds that can reach a speed of up to 1,500 miles per hour.
05:40Can they produce this heat?
05:42Or maybe it's because of the planet's core or its gravitational force?
05:48There's a monster black hole hurtling through space at a speed of 5 million miles per hour.
05:53Scientists located it with the Hubble Space Telescope.
05:56They believe it weighs as much as a billion suns.
06:00It was supposed to stay put in the center of its home galaxy.
06:03But some gravitational forces are pushing it around.
06:06At one point, this black hole is going to break free from its galaxy and continue roaming the universe.
06:12Luckily, it's still 8 billion years away from us.
06:16Solar storms are so powerful that they could leave us in complete darkness.
06:21Back in July 2012, the strongest solar storm in over 150 years narrowly missed Earth.
06:29Coronal mass ejections, or CMEs, are large bubbles of ionized gas.
06:34They tore through our orbit back then.
06:37If they had caught our planet in the crosshairs, we would have literally been in the firing line.
06:42We'd have faced solar matter hurtling towards Earth, damaging computers and causing power outages that would have lasted for months.
06:50A surprise solar storm hit us on June 25, 2022.
06:54One photographer even managed to capture stunning bright auroras that flashed across the dawn sky in Calgary, Canada, and lasted
07:02for 5 minutes.
07:03They were caused by the storm.
07:07Vampire stars are a real thing.
07:09They're part of a binary star, and they can literally drain the life out of the other star in the
07:14system.
07:14They do it to keep burning for a longer time.
07:17It works like this.
07:19A smaller star with a lower mass steals its sibling's hydrogen fuel to increase its own mass.
07:25This vampire star then becomes hotter.
07:27Plus, its color changes to striking blue.
07:31This way, it looks much younger.
07:33How sneaky!
07:35The color of the universe is dubbed Cosmic Latte.
07:39The light coming from our galaxies and stars within them, as well as clouds of gas and dust in the
07:44observable universe, have a specific color.
07:47It's an ivory tint, pretty close to white.
07:51The universe is beige because there are a bit more areas that produce green, yellow, and red light than those
07:57that emit blue.
07:59I hope you feel well-rested, because I've got a tough task for you.
08:03Don't worry, it's fun.
08:05You're going to visit different planets of our solar system and try to run on each of them.
08:10Let's figure out where you can run the fastest and where you can barely walk.
08:15The fastest man on Earth, Usain Bolt, can run with an average speed of about 23 miles per hour.
08:22But his top speed is higher, up to 27 miles per hour.
08:26Sadly, we can't all be Usain Bolts.
08:29The average person runs at a speed of 6 to 8 miles per hour.
08:33But maybe there's a planet out there where you can beat the famous Jamaican sprinter's records.
08:39But first things first, what will affect your speed when you run on other planets?
08:43For one thing, gravity.
08:46Depending on how strong it is on the planet you visit, it'll influence your weight.
08:50And in most cases, the heavier you are, the more slowly you run.
08:55Plus, on all other planets in our solar system except Earth, you'll have to wear a bulky space suit.
09:01Without it, your chances of survival there are non-existent.
09:04And don't forget about extreme weather conditions on most planets.
09:08It's either freezing cold or boiling hot.
09:11Or very, and I mean it, windy.
09:15Anyway, your amazing journey is about to begin.
09:18Buckle your seatbelt.
09:20The first planet on your itinerary is Mercury.
09:23As you sneak a peek at this world through the window of your spaceship,
09:26you notice that the planet looks eerily similar to the good old moon.
09:30But just a few moments later, you realize it's just an illusion.
09:34All over the surface of Mercury, you see craters left by space rocks.
09:40Hmm, this may make your task of running on this planet way harder.
09:44This and your bulky space suit.
09:47Duh.
09:47But you wouldn't survive on Mercury without this protection.
09:51The temperatures on the planet are extreme.
09:53800 degrees Fahrenheit during the day and negative 290 degrees Fahrenheit at night.
10:00But there's one thing that can work in your favor on this unfriendly planet.
10:04Let's say you weigh 155 pounds on Earth.
10:07Then on Mercury, you'd weigh around 58 pounds.
10:11Which means that despite your bulky space suit,
10:14you can move way faster than you do on Earth.
10:17And maybe your speed will even reach 13 miles per hour if you try really hard.
10:22The next planet on your itinerary is Venus, also called the Morning Star.
10:28While coming closer, you see a world very different from the bluish planet you might have seen in books.
10:34Before landing, you have to get through a super-dense atmosphere made up of carbon dioxide.
10:38And while your spacecraft is descending, you're watching thick clouds of sulfuric acid pass by.
10:46Venus is often called Earth's twin because these two planets are of similar size and density.
10:51No wonder that on Venus, you weigh almost as much as you do on Earth, 140 pounds.
10:57So your weight is a bit smaller here, but don't forget about your space suit.
11:03And still, because of almost the same conditions on the two planets,
11:07you'd be able to run a bit faster than on Earth at around 8.5 miles per hour.
11:13Your first impression of Mars is that it's freezing cold.
11:17The average temperature here is about negative 80 degrees Fahrenheit.
11:21Even from afar, the planet looks reddish.
11:23Once you make your first step on the Martian surface, you understand why.
11:28The ground's covered with rusty-colored dust.
11:31The same fine dust is floating in the air around you.
11:35Wherever you look, you see golden, brown, tan, and even greenish hues.
11:40They depend on the minerals that make up the soil.
11:43The size of the dust layer varies from area to area, but in most places, it's around 7 feet thick.
11:50Hmm, that can make running much more difficult.
11:54On Mars, your weight would be much smaller than on Earth, a mere 58 pounds.
12:00This will help you achieve an impressive speed of 12 miles per hour.
12:04Aren't you a champ?
12:07What's that on the horizon?
12:09It looks like a tornado.
12:10Is it a dust storm?
12:12Then it's time to make a run for it.
12:14Dust storms sometimes cover the entire planet, and you can even see the largest ones from Earth.
12:21And now, you're facing a problem.
12:24You see, Jupiter, as well as Saturn, is a gas giant.
12:28This means that the largest planet in the solar system, and Jupiter is so large it could swallow 1,300
12:34Earths, doesn't have any solid surface.
12:37Well, you'll just have to imagine what your running workout would look like if you could run on Jupiter.
12:42This planet has an atmosphere that consists of hydrogen and helium gas.
12:47During your descent, you admire thick brown, yellow, red, and white clouds.
12:52They make the planet look colorful and beautifully striped.
12:56On Jupiter, you'd weigh 390 pounds.
13:00You'd have to break a sweat to simply walk there, wearing your clumsy spacesuit.
13:04If you could step on the planet's surface, that is.
13:07If you tried to run there, your best result would probably be a speed of 1 or 2 miles per
13:12hour.
13:14To make matters worse, it's extremely windy on Jupiter, with the wind speeds ranging from 200 to 400 miles per
13:21hour.
13:22Do you see those rings?
13:24That's Saturn, another gas giant with no solid surface.
13:27This planet's made up of mostly hydrogen and helium.
13:30And its temperature and density change the deeper you go.
13:33If you decided to leave your spacecraft and step on Saturn's surface, you'd just fall into the planet.
13:41But from above, it looks as if Saturn does have a surface.
13:45The seemingly solid yellowish-brown sphere is surrounded by several layers of clouds.
13:50The visible outer layer is made up of ammonia clouds.
13:54Under them, there are hydrosulfide clouds.
13:57And the innermost layer is made up of clouds of water.
14:01Even though Saturn is a gas giant, your weight wouldn't be very different here, around 165 pounds.
14:08That's because the planet's gravity is similar to that of Earth.
14:12But because of the conditions on the planet, and your bulky, bulky spacesuit,
14:17you'd run a bit more slowly there, at a speed of about 4 miles per hour.
14:22Before leaving, you admire Saturn's most famous feature.
14:26Awesome gray, beige, and tan rings.
14:30These groups of tiny ringlets are made of chunks of rock and ice.
14:34You also spot several of the 53 moons of Saturn.
14:37Oh, that's Titan, an icy world bigger than our moon, and even Mercury.
14:42It's the second-largest moon in the solar system.
14:46The next planet on your way is a blue-green ball of ice and gas.
14:51That's ice giant Uranus.
14:53It has this beautiful hue because the light from the sun gets reflected off the planet's surface.
15:00Uranus isn't solid.
15:01Hit the brakes!
15:02If your spacecraft doesn't manage to stop in time,
15:05it'll fly through the upper atmosphere and sink into the icy liquid center of the planet.
15:10Hmm, I doubt you'll be able to conduct your running experiment here.
15:15So, let's just imagine what it'd look like.
15:19On Uranus, your weight would be around 138 pounds.
15:23And, against all odds, you could actually reach a good speed here, at least 8 miles per hour.
15:29If you didn't get caught in a hurricane, of course.
15:32Extreme storms occur on the planet in the summer, when Uranus is heated the most.
15:37Then, hurricanes can spread for more than 6,000 miles.
15:42The furthest planet from the sun, Neptune, is four times the size of Earth, but 17 times as heavy.
15:49The blue surface you see when approaching Neptune is actually a layer of swirling gas and permanent clouds.
15:57The planet's mantle is made up of water, ammonia, and methane ices.
16:02It's the closest thing Neptune has to a surface.
16:05And still, there isn't solid ground for you to walk on.
16:08So, once again, try to use your imagination.
16:13On Neptune, you'd weigh a bit more than you do on Earth, 174 pounds.
16:18But your running speed would be just a bit lower than on Earth, around 5 miles per hour.
16:25That's the end of your active adventure.
16:27Which planet did you like running on the most?
16:30It was January 7th in 1610, when Italian astronomer Galileo Galilei made an astonishing discovery using his homemade telescope.
16:41Four moons orbiting the planet Jupiter.
16:44By the way, these days you can make your own version of his telescope using cardboard tubes, lenses, and some
16:51superglue.
16:51The main point of this DIY telescope is to place two lenses at the correct distance from each other.
16:58You'll need two lenses.
17:00One lens should be concave, the other one convex.
17:03So, one lens is curved out, and the other one is curved in.
17:08Galileo's initial telescope was able to magnify objects approximately 8 times.
17:13He continued to improve it until it reached about 20 times the magnifying power.
17:19But let's get back to the main story, shall we?
17:23When he first looked at those four moons of Jupiter, he believed he was simply looking at a bunch of
17:28stars.
17:29But he soon noticed that these space objects seemed to be moving in a regular pattern.
17:34It took him a couple of weeks to figure out that what he was looking at were not stars.
17:40But moons circling Jupiter.
17:44Galileo initially named those moons 1, 2, 3, and 4.
17:49But, let's face it, those weren't the most creative names.
17:52As more moons in our galaxy were discovered later, the numerical system for naming them became confusing and impractical.
17:59So, it lasted for just a few centuries.
18:01So, these days, those four satellites, Jupiter's largest, are named Eo, Europa, Ganymede, and Callisto.
18:12They're collectively known as the Galilean moons to honor the man who first noticed them.
18:18Galileo's discovery was crucial for our later understanding of astronomy.
18:23It was initially believed that other objects revolved around the Earth since it was seen as the center of the
18:29universe.
18:31We now know that there are hundreds of moons in our solar system.
18:35However, large moons, like those discovered by Galileo Galilei, are not so commonly stumbled upon.
18:41A moon is considered large when it's the size of our planet or bigger.
18:47Ganymede, for instance, is bigger than Mercury.
18:50We basically call Ganymede a moon just because it orbits Jupiter.
18:54Otherwise, it has all the other characteristics of a planet.
18:58It's no surprise that Jupiter has the biggest moons in the area.
19:02It beats all the other planets in our solar system in both size and mass.
19:07So, no wonder it pulled in a lot of other objects towards it.
19:11Jupiter is believed to have in total almost 80 moons, with only 53 of them being given official names until
19:19today.
19:21The first of those Jupiterian moons to be discovered by Galileo was Eo.
19:26What sets it apart is the fact that it has a lot of volcanoes.
19:30Eo is the only space object to have active volcanoes in our solar system, apart from Earth.
19:37It's also nicknamed the moon of fire and ice because of its sulfur dioxide snow fields.
19:43Eo's outer layer is splotchy, featuring multiple colors like orange, black, yellow, white, and red.
19:51That's probably the reason why NASA described it as a giant pizza, covered with melted cheese and splotches of tomato
19:58and ripe olives.
20:00Because of that sulfur, though, Eo doesn't smell that appetizing.
20:04Something similar to a rotten egg.
20:08There are more than 100 mountains on the surface of this moon.
20:12They are a lot larger than those we see on Earth, some being bigger than Mount Everest.
20:18On average, these mountains are 4 miles tall and 98 miles long.
20:25Because of those active volcanoes and the intense radiation on Eo, there's little chance that life as we know it
20:31could exist here.
20:32But hey, who's to say it can't have life the way we don't know it?
20:38Next on the list of Galilean moons is Europa, the smallest of the four.
20:43It's comparable in size to the moon.
20:45Europa has an entirely icy surface, with just a bunch of craters scattered here and there.
20:51Because of that outer layer, Europa is very reflective, making it one of the brightest moons out there.
20:57As for its age, scientists believe its surface to be somewhere between 20 to 180 million years old.
21:06Europa is about 4.5 billion years old.
21:12What lies beneath that icy surface is impressive.
21:15It may even hold the secret to life outside Earth.
21:19Ice forms here in two ways.
21:21The first is through congelation.
21:23A rather self-explanatory process.
21:26Ice just grows as the surrounding environment gets colder and colder.
21:31The other method, though, is a lot more fascinating.
21:34A layer of super-cooled water found under the ice shell reacts when agitated.
21:39It then generates these crystals that make it look like it's snowing in reverse, floating upwards to the ice sheet
21:46they sit under.
21:48You can recreate this environment yourself at home.
21:51Take a bottle of purified water and place it into the freezer.
21:55If you don't have purified water anywhere near, just boil some water a couple of times to get rid of
22:00as many impurities as possible.
22:03Since there won't be any particles inside, once in the freezer, it won't turn solid.
22:09But if you take the bottle out of the freezer and give it a shake, the impact will make the
22:13water rapidly crystallize, transforming it into a slush-like consistency.
22:19There may be water on Europa, but there's little evidence so far that life exists on this moon.
22:25However, it's one of the highest candidates in the solar system for potential habitability.
22:30Some sort of lifeforms could adapt to live there in its under-ice ocean.
22:35That environment is most likely similar to what we can find in our planet's hydrothermal vents hidden deep within our
22:42oceans.
22:43The amount of oxygen in Europa's atmosphere is very little, but in 2013, NASA gave away some cool evidence.
22:52This yet again supports the theory that there's potential for life on this moon.
22:56It seems that Europa might be venting water into space.
23:01If this is confirmed by future observations, it could also mean that Europa is geologically active.
23:08It could also come in handy if we'd manage to study water sources one day.
23:14The largest of those Galilean moons is Ganymede.
23:17It's also the biggest moon in our solar system altogether.
23:21It's a low-density space object similar to Mercury in size, but having only half of its mass.
23:28However, Ganymede is the only moon out there to feature its own magnetic field.
23:33It's quite small though, and we can barely notice it from Earth, since it's overshadowed by Jupiter's much more powerful
23:40magnetic field.
23:42Another cool aspect of Ganymede is that its atmosphere contains oxygen.
23:46Don't get too excited, it's not nearly enough to support any lifeforms living there.
23:52Back in December 2021, a 50-second audio clip was released, which was previously recorded by NASA's probe on its
24:00Ganymede flyby.
24:03For the inexperienced, the sounds were more similar to those of an old dial-up internet connection.
24:09But because of its quirky tunes, Ganymede was soon nicknamed Jupiter's singing moon.
24:15Finishing up the list of Galilean moons is Callisto, or the most heavily cratered object in our solar system.
24:23What's interesting about this moon is that its landscape has barely changed since it formed, and scientists are still debating
24:30why this is happening.
24:32Most other space objects go through loads of changes throughout their lifetimes because of events such as collisions with other
24:39objects,
24:40changes in orientation or speed, or chemical reactions happening on their surface.
24:47Callisto is also about the size of the planet Mercury, but it has a lower density.
24:53Jupiter's magnetic field has a lesser impact here, since Callisto is the furthest from the giant planet.
24:59Its surface is estimated to be a staggering 4 billion years old.
25:04As opposed to Io, Callisto is not geologically active, but scientists believe there might be an ocean hiding underneath the
25:12moon's surface,
25:13which may potentially harbor life.
25:16The fact that it's less impacted by Jupiter's magnetic field means that it features low levels of radiation.
25:23Given this suitable environment, we may one day end up setting a human base for future explorations here.