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What do we know about planets? They look absolutely stunning but leave us with many questions. Let's answer some of them!
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00:00This may look like a scene from a cool sci-fi movie, or an astonishing painting, but it's actually real
00:05-life footage of Mars, the very planet known for its bright rust color.
00:10Layers of rock and dust cover the planet's surface. They consist of iron-rich minerals. That's why dust on Mars
00:16is mostly iron oxide.
00:18It floats in the atmosphere and creates an orange-red haze around the planet.
00:22But Mars has some even more amazing things, like these blue speckles on its surface.
00:27They look like a wind-sculpted sea of dunes around 19 miles wide.
00:33Astronauts saw these dunes at the northern polar cap of the planet.
00:37That's a region that covers an area approximately as big as Texas.
00:41The blue dunes, formed by winds, are shaped like long weaving lines.
00:46The winds on Mars are relentless and strong.
00:48They turn the barren surface of the planet into terrains of grand beauty.
00:52These winds are influenced by many different factors.
00:55For example, temperature fluctuations, to the way the planet's atmosphere circulates.
01:01The atmosphere is thin on Mars.
01:03That's the reason liquid water most likely can exist there for any long period of time.
01:08That's why, even though Mars is only half the diameter of our planet, it has the same amount of dry
01:13land as Earth.
01:14A thin atmosphere is also the reason why wind needs to be exceptionally strong and fast
01:19to move the sand and form such shapes as these dunes.
01:22Winds usually move at 10 to 20 miles per hour on Mars.
01:27Anyway, even though the image looks pretty colorful, the dunes aren't actually blue.
01:31The bluish patches represent colder parts, while the warmer regions are yellowish-orange.
01:37The images were part of a set of photos released to celebrate the 20th anniversary of Odyssey,
01:42a spacecraft orbiting Mars.
01:44Mars has numerous sand dunes in different locations all over its surface.
01:48Some of them formed a billion years ago, like the ones in the Valles-Marineris region.
01:53They haven't changed because both the atmospheric pressure and wind patterns there have remained the same.
01:58But some things do change.
02:00For example, some dunes get covered with frost.
02:03Here, the main dune has a series of dark patterns.
02:06It may be because frost comes and goes, depending on the season.
02:11Mars has four seasons, just like Earth, but they're twice as long as ours.
02:15It's because Mars needs around two Earth years to orbit the Sun.
02:20Seasons are harsher in the south of the planet than in the north.
02:23During southern winter, the planet is farthest away from the Sun.
02:27Mars moves pretty slowly, and its orbit is elliptical, different from the orbit of Earth, which is almost circular.
02:33Spring on Mars is a season with plenty of dust storms that start in one part of the planet and,
02:38eventually, turn into huge storms.
02:41They become so large, they blanket the entire planet.
02:45Each planet of our solar system has something that makes it special.
02:49Jupiter, for example, is not only the largest planet, more than twice as big as all other planets combined,
02:55but it also has the biggest ocean in the solar system.
02:59Jupiter is made of similar elements to the Sun.
03:01They're mostly helium and hydrogen.
03:04In the deeper parts of the planet's atmosphere, temperature and pressure increase.
03:08That's why the hydrogen gas gets compressed and turns into liquid.
03:12That gives Jupiter the biggest ocean, but it's made of hydrogen, not water.
03:17There's also a theory that somewhere halfway to Jupiter's center,
03:21the pressure increases so much that electrons start getting squeezed out of hydrogen atoms.
03:26This allows the liquid to conduct electricity as effectively as most metals do.
03:31Jupiter is rotating fast, which creates electrical currents and generates a strong magnetic field.
03:37But as a gas giant, the planet doesn't have a firm surface.
03:41Jupiter also has the iconic Great Red Spot, which is an insanely large storm with crimson-colored clouds,
03:48spinning counterclockwise.
03:49Winds there are way faster than any hurricane on our planet.
03:53The Great Red Spot has slightly changed throughout time and is currently bigger than our planet.
03:59It's 1.3 times as wide as Earth.
04:02Scientists have discovered that its roots extend more than 200 miles into Jupiter's atmosphere.
04:07A regular tropical cyclone we see on our planet can only extend 9 miles from the top to the bottom
04:13of the storm.
04:14These days, the Red Spot is becoming smaller and taller at the same time.
04:17Jupiter also has dozens of moons and a couple of rings.
04:22But unlike Saturn's rings, these are quite faint and mostly made of dust, not ice.
04:27Also, there's a salty ocean under the surface of Jupiter's biggest moon, Gonomede.
04:32It's hidden below a thick icy crust.
04:34It's likely to contain more water than all surface water reservoirs we have on Earth combined.
04:39The theory says this ocean is around 60 miles deep, 10 times greater than the deepest point of our planet's
04:46oceans.
04:47Jupiter and Saturn contain 10 million tons of precious stones.
04:51The pressure inside these planets' atmospheres can actually turn carbon into small pieces of diamonds.
04:56If you put these diamonds under extreme temperatures and pressure, they can melt.
05:01This would probably result in some sort of diamond rain.
05:04In the beginning, our solar system was just a swirling cloud of gas and dust.
05:09It eventually developed into a spinning disk with a central star in the middle.
05:14Almost all planets in our solar system move counterclockwise around the sun.
05:18Venus is the only planet that rotates in a clockwise direction, and Uranus rotates on its side.
05:24These planets are most likely different because long ago, huge asteroids collided with them and kind of knocked them off
05:30their course.
05:32There's a chance, Venus could be a habitable planet.
05:35It's definitely not a place you'd want to live now, not with its sulfuric acid clouds and tremendous atmospheric pressure.
05:41It's 90 times greater than that on Earth.
05:44At here insanely high temperatures, the conditions on Venus are very unfavorable for people.
05:50At 863 degrees Fahrenheit, Venus is hotter than Mercury, even though it's further away from the sun.
05:57This happens because there's too much carbon dioxide in Venus's atmosphere.
06:01It traps heat, which causes the temperature to rise way higher than it's supposed to.
06:06But simulations show that around 700 million years ago, Venus might have been a nice place with moderate temperatures and
06:13liquid water.
06:14Those conditions were slightly similar to those we have on Earth now.
06:18Uranus is not a gas giant.
06:19It's actually made of ice.
06:21The atmosphere contains methane, which makes the planet look blue.
06:25It has 27 moons, two sets of rings, and lots of ice in its atmosphere.
06:30A day on Uranus lasts just a little bit over 17 hours.
06:34That's how long it takes the planet to complete a single rotation on its axis.
06:38But its tilt is so pronounced that most of the time, either one or the other pole is pointed toward
06:43the sun.
06:44That's why the daytime length at the North Pole is almost half a year.
06:48And a year on Uranus is as long as 84 years.
06:51If you lived on Uranus closer to its north pole, you'd be able to see the sun in the sky
06:56for 42 years.
06:57That would be the summer.
07:00After this, the sun would go down, and you'd have to live the next 42 years in the darkness.
07:05It'd be the winter on the planet.
07:08Neptune is the most distant and the smallest of the gas giants.
07:11The gravity on the planet is similar to the one we have on Earth.
07:14But you wouldn't be able to stand on Neptune's surface.
07:17It's gas, not solid land.
07:20Triton, the biggest of the planet's moons, orbits Neptune in a very unusual way.
07:25It moves backward compared to the rest of the planet's moons.
07:28Triton is also slowly spiraling inward toward Neptune.
07:32One day, billions of years from now, it's likely to get torn apart by the planet's gravitational forces
07:37and become just a ring around Neptune.
07:40This ring will continue being pulled inward until it eventually crashes into the planet.
07:44Pluto is a dwarf planet, and a year there lasts 248 Earth years.
07:49But even though it's not even a planet, Pluto still has several interesting things to offer,
07:55like floating mountains.
07:56Pluto's nitrogen glaciers carry countless isolated hills, each up to several miles across.
08:02They're likely to be fragments of water ice from the dwarf planet's surrounding uplands.
08:07Nitrogen ice is denser than water ice, so scientists think water ice hills float in a sea of frozen nitrogen,
08:13just like icebergs in the Arctic Ocean here on Earth.
08:20The Milky Way is one of the biggest mysteries out there, literally.
08:24It's hard to figure out how big our home galaxy is.
08:27And one of the main reasons is because we live in it.
08:30Think of it as walking around a mall.
08:32You can tell it's big, but you can't be certain until you actually see it from a bird's eye view.
08:37The Milky Way consists of billions of distant stars that look like a string of lights from afar.
08:42So, you just need to measure the distance between these stars, and voila, you have the answer.
08:48Not really.
08:49I might have forgotten to mention opaque clouds of dust blocking your view.
08:54Some scientists were stubborn enough to run computer models of how galaxies form and evolve.
08:59There's a halo around our galaxy.
09:01So, the scientists wanted to see if there was some sort of a dead end in the Milky Way.
09:06They found out that the Milky Way spreads for 100,000 light-years away from its center.
09:11It likely means that the entire galaxy is around 200,000 light-years across.
09:16The problem with this estimation is that halos don't tend to have some final border since they simply fade away.
09:23It's like pointing a flashlight and trying to see precisely where the light ends.
09:28In 2013, the Hubble Space Telescope captured an image of something 25 million light-years away.
09:34It turned out to be a spiral galaxy, later called ESO 3738, with at least seven other galactic neighbors.
09:41And this galaxy is as thin as a pancake.
09:44A very shiny pancake.
09:46The telescope also took a photo of another galaxy cluster 65 million light-years away.
09:51It was called IC335.
09:54It's another glorious glittering pancake floating in the vastness of space.
09:58The images the telescope took aren't the most accurate.
10:01It's hard to tell what exactly you're looking at.
10:04These disk galaxies have lots of dust clouds that can stretch for hundreds of light-years across.
10:10They're mainly located near the centers of galaxies and are invisible in regular light.
10:14But they can be detected with the help of a blue filter.
10:18Anyway, this IC335 galaxy is an oval disk with huge clouds of gas and dust.
10:24This means stars constantly appear there.
10:27But not all galaxies create stars.
10:29A galaxy is born as a giant ball of slowly rotating gas that is steadily collapsing in on itself.
10:36As it starts spinning faster and faster, the pancake shape is formed.
10:40Ooh, pass me the syrup.
10:42It's like spinning pizza dough in the air after rolling it into a ball.
10:46The topping is stars.
10:47And the sauce is clouds of dust and gas.
10:50Are you getting hungry like me?
10:51Some galaxies can lose their gas and dust if they become part of a galaxy cluster.
10:57Then all these mini-galaxies orbit their common center of mass, with gas separating them.
11:02When a disk galaxy dashes through them like a speeding train, the pressure can blow away this dust and gas.
11:09From far away, it looks like you're staring at a DVD you're about to play.
11:13But if you traveled millions of light years to get a closer look, you'd see a dim disk filled with
11:18stars.
11:19You wouldn't even be able to tell you're inside it.
11:22You'd also see a bright blob of dust left by the red giants in the middle of the galaxy.
11:27Red giants are massive and very bright stars with low surface temperatures.
11:31But the images of these galaxies don't actually show us their real color.
11:35Cameras make up some of these hues so that you don't have to look at something fuzzy or greeny.
11:40People don't actually know the real colors of distant galaxies.
11:44Our galaxy has a lot of gas inside, like me.
11:48So we don't need to expect our home to dry up anytime soon.
11:51In fact, the Milky Way still produces new stars around seven a year.
11:55But some galaxies fade out when they can no longer create stars.
11:59In the industry, they call it strangulation.
12:02And it happens when galaxies run out of gas.
12:05Which means there's no more new material that can be used for star making.
12:10Gas and dust aren't the only things you can find in a galaxy.
12:13Just like a magician pulling a rabbit, flowers, or other things out of their magic hat, galaxies have other surprises.
12:20Like planets, those balls of matter spinning around themselves and around other things.
12:25Well, technically, planets are far from being perfectly round in shape.
12:30But they aren't also flat like spiral galaxies.
12:33It's mostly because of gravity.
12:35It's force is so strong that a planet pulls everything towards its center, taking the shape of a sphere.
12:41In the process, all the edges and anything else that might stick out get smoothed out.
12:46But the smaller a space body is, the less round it is.
12:50Take a comet.
12:51It doesn't always have a smooth surface.
12:53It's small, and therefore, its edges are rugged and pointy.
12:57Given the size of Earth, it's safe to say the gravity is strong here, compared to that of the Moon
13:02or any smaller-sized space object.
13:04And because of our planet's constant rotation, there's an outward bulge on Earth.
13:09This tug-of-war between the gravity pulling inward and the planet's spin doesn't allow Earth to be a perfect
13:15ball.
13:16On top of Earth not being a perfect sphere, the planet is also tilted.
13:20This design flaw is responsible for the seasons we have.
13:24This tilt could happen because millions of years after Earth was formed, it probably collided with a protoplanet, a large
13:31space body developing into a planet.
13:34Venus is unique because it rotates backward compared to the rest of its peers.
13:39If you were standing on Venus, the hottest planet in our solar system, you'd see the Sun rise in the
13:44west and set in the east.
13:45But you'd have to make it on time to observe this phenomenon.
13:49A day on Venus lasts for more than 240 Earth days.
13:53For a long time, scientists believed that the Sun's strong pull on Venus was responsible for such a long day.
13:59But new theory claims that Venus used to spin just like Earth and the rest of the planets.
14:05But at one point, it just flipped its axis 180 degrees.
14:09It doesn't mean the planet abruptly stopped halfway through the rotation and started to move backward.
14:15When theory suggests that a large comet or object struck the planet in the past,
14:20this might have caused it to change the direction of its rotation.
14:23But many scientists doubt this theory.
14:25If you observe the Moon for some time, you may notice that it's the same face staring at you every
14:31night.
14:32The truth is that the Moon does rotate, but very slowly.
14:36It takes our planet's natural satellite 27 Earth days to rotate around its axis.
14:41Plus, the Moon rotates at the same rate that it orbits Earth.
14:45The side we always see is called the near side of the Moon.
14:49And the side that's not facing us is, you guessed it, the far side of the Moon.
14:53It also has the nickname the dark side of the Moon.
14:57Uranus' rotation axis is 98 degrees relative to the plane of the solar system.
15:03Which basically means that the planet spins on its side.
15:06For a while, scientists believed that a large object firing through space knocked into Uranus, causing it to tilt.
15:13But here's one problem.
15:15Uranus' moons are covered in ice.
15:16A collision so powerful that it made the planet tilt would have resulted in disrupting the Moon's movement and their
15:23position.
15:23But they seem relatively untouched.
15:26And all the ice covering them is still intact.
15:29But any major changes happening with Uranus would have generated enough energy to melt the ice.
15:35Another reason for Uranus' strange position might be its rings.
15:39Yup, Uranus has rings just like Saturn, except they're lighter and fainter.
15:43Saturn's rings are mostly billions of chunks of ice and rock floating in orbit.
15:48Some particles can be the size of a pebble, while others can reach the size of a house.
15:53Wow.
15:54Other particles are broken-up comets, asteroids, and moons torn apart by Saturn's gravity.
15:59If you observe the rings from afar, they look like colorful stripes made up of thousands of different streaks.
16:05But there are actually only eight layers of rings.
16:09Uranus might have had rings that were just as glorious as Saturn's around 4.5 billion years ago.
16:15The balance between Saturn's gravity and its rings might be responsible for keeping the planet upright, so that it doesn't
16:21tilt over.
16:22If Uranus had the same rings, they could prevent the planet from toppling over.
16:27The way to solve Uranus' tilting problem might be for the planet to get its rings back.
16:32They would help Uranus keep its balance.
16:34On the other hand, hey, we like it just the way it is.
16:38Our solar system might have some more planets up its sleeve.
16:41We know about eight official planets, but they're not the only ones that survived the chaotic formation of our solar
16:48system 4.5 billion years ago.
16:51Astronomers say there are three categories of planets in our solar system.
16:55We're in the first one.
16:57The four rocky inner planets, Mercury, Venus, Earth, and Mars, that peacefully orbit the Sun.
17:03They're located within the main asteroid belt that separates Mars from Jupiter, which is in category number two.
17:10That one's a group of planets in the outer solar system, the gas giants, Jupiter, Saturn, Uranus, and Neptune.
17:17These planets have huge amounts of ice and gas around what scientists believe to be their rocky cores.
17:22The third group lies beyond the area where our local planets are, somewhere further than Neptune.
17:29It's the realm where you'll find dwarf planets such as Pluto, Eris, and Sedna, and many smaller space bodies like
17:36comets.
17:37But new findings say there could be something else lurking in the dark, besides dwarf planets and tiny space bodies.
17:44Maybe even a new planet!
17:47Models scientists made say that our solar system used to have one or more rocky planets, the size of Mars
17:53or Earth.
17:54Over time, these rocky wanderers interacted with the wide gravity fields of our gas giants.
18:00This kicked them into a far-out orbit, away from the neighborhood.
18:04The question is, if one of those Mars-sized planets survived, and could really be somewhere out there.
18:11Scientists have made simulations to see what potentially happened.
18:15These showed that in half of such cases, where planets interact with the gravity of gas giants, they get ejected
18:21into interstellar space.
18:23In the remaining half, there's this one rogue planet, left in an orbit similar to the ones the Kuiper Belt
18:29objects are following.
18:31There's only one thing left to do now.
18:33Find it.
18:35Astronomers found the loneliest planet in the universe.
18:38They were trying to find distant brown dwarf stars, or failed stars, ones that never become massive enough to start
18:44shining.
18:45Stars are born with big masses, which means they also have strong self-gravity.
18:50The star squeezes in on itself.
18:53That causes high internal temperatures and enables the star to shine.
18:57But instead, they found a lonely wanderer, CFBD-SIR-2149.
19:04The planet is between 50 and 120 million years old, and has a surface temperature of 750 degrees Fahrenheit.
19:11Compared to stars, that's cold.
19:13At first, scientists thought it could be a brown dwarf star, but in that case, it would be way older.
19:20This starless planet floats around through space, passing only 130 light-years away from our planet.
19:27Our galaxy, the Milky Way, is 100,000 light-years wide, so that's relatively close.
19:33The lonely traveler is actually a gas giant, four to seven times bigger than Jupiter.
19:39Maybe it was kicked out from its own solar system because of gravitational forces, or getting into another planet's orbit.
19:46Or it was formed away from its parent star.
19:48Far beyond Pluto, on the edge of our solar system, there's a space body about as big as Pluto, but
19:55a little bit colder and way denser.
19:58It's probably a big, rocky body covered in a thin, icy mantle.
20:02It's the dwarf planet Eris.
20:05Both Pluto and Eris occupy the Kuiper Belt, which is the distant ring of frigid space bodies that lies beyond
20:12Neptune.
20:13A day there lasts 25.9 hours, pretty similar to Earth.
20:17But Eris circles our Sun in the distance three times farther than Pluto, which means its year is pretty long,
20:25557 Earth-years.
20:27Eris has a bright, icy surface.
20:30It's one of the most reflective bodies in our solar system.
20:33It bounces back more than 95% of the light that strikes it.
20:37Somewhere out there, even farther, there's a Super Saturn, J1407b, much larger than Jupiter or Saturn.
20:45Saturn. It's an exoplanet, which means a planet that orbits a star other than our Sun.
20:51Super Saturn is 434 light-years away from Earth, in the constellation of Centaurus.
20:57It's the only exoplanet we know about with rings similar to Saturn.
21:01It actually has a huge ring system, 200 times bigger than Saturn's rings.
21:06There are more than 30 rings, each of them tens of millions of miles in diameter.
21:12There are gaps in the rings, which means there could be some interesting satellites, exomoons, around.
21:18If this Super Saturn could swap places with our regular Saturn, its rings would absolutely dominate our sky.
21:25You could look up and easily see them.
21:27The view would be amazing, because they would appear much bigger than a full moon.
21:33Scientists have found thousands of planets outside of our solar system.
21:38Some are dense as iron, while others are airy in light.
21:41And then, there's the water world, GJ-1214b, a steamy world, bigger than Earth and smaller than Uranus,
21:5040 light-years away from us, in the constellation of Ophiuchus.
21:54It's a watery planet, surrounded by a thick atmosphere, 2.7 times Earth's diameter,
22:00and almost 7 times heavier than our home planet.
22:03It was most likely formed somewhere farther from its star, where there was plenty of water ice,
22:08but later migrated to where it is today.
22:10Its surface temperature is 440 degrees Fahrenheit, which is too hot to host life like on Earth.
22:16It also has much less rock, and much more water than our planet.
22:20Imagine a planet with no land, but only endless oceans covering all of its surface.
22:26High pressures and temperatures would form things like superfluid water or hot ice.
22:32Some pretty exotic materials that we can't see on our planet.
22:36Gliese 436b.
22:38It's a Neptune-sized exoplanet 30 light-years away from our planet, in the constellation of Leo.
22:44It makes one full orbit around its star in a little more than two days.
22:48This planet defies the laws of physics.
22:51It orbits its star, Gliese 436, which is smaller, cooler, and less luminous than our sun,
22:58at a distance 15 times closer than Mercury is to the sun.
23:02When we typically think of ice, we picture a frozen cube.
23:06But this planet has an icy surface, even though the temperature there is 980 degrees Fahrenheit.
23:12This temperature is way above the melting point, but the ice remains solid and burning hot.
23:19This happens because of very strong gravity.
23:21It compresses the water vapor in the atmosphere into solid ice.
23:26The pressure here doesn't allow the ice to melt, no matter how hot the surface is.
23:31Now imagine being on a mysterious planet, and it suddenly starts raining sapphires and rubies.
23:37One distant exoplanet, HAT-P7b, a gas giant 1,000 light-years away from Earth,
23:43in the constellation of Cygnus, and 16 times bigger, has specific weather and pretty violent storms.
23:50Rubies and sapphires are scattered across the planet when it's raining.
23:54On the planet's night side, there's a high amount of corundum in the atmosphere.
23:59And corundum is what mineral gems such as sapphires and rubies are made of.
24:03Clouds of corundum give such an amazing view.
24:07The planet is plagued by severe winds that often turn into powerful storms
24:11that push huge masses of those clouds across the planet.
24:15Although the planet is uninhabitable, it would certainly be cool to come there and pick up some gems.
24:20Still, the weather is pretty wild.
24:22Plus, the temperatures are over 4,600 degrees Fahrenheit.
24:26By comparison, Venus is the hottest planet in our solar system,
24:30and its temperature is only 900 degrees Fahrenheit.
24:34Looking over the expanse of space, you can see a beautiful little blue dot in the endless darkness.
24:40It's an exoplanet, HD 189733b, that lies 63 light-years from us in the constellation of Volpecula.
24:49But it's way hotter and larger than our planet, around the size of Jupiter,
24:54and it completes its orbit around its host star in only 2.2 Earth days.
24:58That orbit is so close that the planet is most likely tidily locked.
25:03That means it's always showing only one face to its star,
25:07like our moon always shows one side to Earth.
25:10The weather here is crazy.
25:12The winds blow at up to 5,400 miles per hour,
25:15which is seven times the speed of sound.
25:17The fastest wind on Earth only hit the mark of 230 miles per hour.
25:22And it gets better.
25:23The rain here is not made of water, but of molten glass.
25:27Clouds are made of silicate atoms and particles.
25:30They are the key element that gives the planet its cobalt blue color,
25:34not the reflection of oceans, which is the case with Earth.
25:37Earth used to be purple.
25:39Today, even when you look at our planet from space, you see a lot of green.
25:44The green we see in nature is there because of photosynthesis,
25:47the process where plants transform energy coming from the sun
25:51into energy they need to live and to produce oxygen for us.
25:54The main part of the process that gives plants the green color is the chlorophyll pigment.
25:59A long time ago, instead of chlorophyll, there was a molecule called retinol.
26:04Its pigments absorb yellow and green light and turn it into red and blue.
26:08So the Earth was more purple.
26:10And then, there's a pink planet, GJ504b, far away from us, in the Virgo constellation.
26:18Four times more massive than Jupiter.
26:20It's a newly formed exoplanet, around 160 million years old.
26:24By comparison, the Earth is 4.5 billion years old.
26:28If we could go there, we would see an incredible world that glows from the heat of its formation.
26:34Everything around you would be colored magenta.