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Did our solar system really lose a planet? Discover the shocking truth behind its disappearance! Plus, explore the strangest stars in the universe that continue to baffle astronomers!
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00:00Let's see, there's Mercury, Venus, Earth, Mars, Phaeton, Jupiter, wait, hold on, what
00:12Phaeton am I talking about?
00:14Well, let's see.
00:15It was the beginning of the 19th century, and the asteroid belt hadn't been discovered
00:20yet.
00:21In the year 1801, one man named Giuseppe Piazzi spotted the largest asteroid in the solar
00:28system, Ceres.
00:30At that time, people believed that there was a planet orbiting between Mars and Jupiter,
00:35and Ceres seemed to fit the bill.
00:38But the next year, another astronomer, Heinrich Olbers, found one more space body following
00:44a similar orbit.
00:46It was an asteroid which was later called Pallas.
00:49This discovery helped Olbers to figure out that these two space objects could be fragments
00:54of a planet.
00:55The discovery of two more asteroids, Vesta and Juno, seemed to confirm this theory.
01:01It was believed that the planet, which was named Phaeton in the 20th century, appeared
01:07in the early days of the solar system and was later destroyed, and its debris formed the
01:12asteroid belt.
01:13Olbers' idea was called the disruption theory.
01:16To astronomers at that time, it seemed obvious that the planet once collided with a large
01:21space object, which led to its demise.
01:25The most likely candidate was Nemesis, a hypothetical red or brown dwarf orbiting our Sun.
01:32Another theory claimed that Phaeton could have gone through an internal cataclysm, which could
01:37have broken the planet into pieces.
01:39There was one more idea – Phaeton could have come too close to Jupiter and got torn apart
01:45by the gas giant's immense gravity.
01:48These days, though, astronomers don't believe in the disruption theory anymore.
01:53A new idea has replaced it.
01:55It's known as the accretion theory.
01:58It claims that the asteroid belt is all that is left of the protoplanetary disk.
02:03Supposedly, this disk had been originally orbiting the Sun, even before the planets formed.
02:09Unfortunately, because of Jupiter's gravitational forces, it never managed to coalesce into a
02:14planet.
02:15But what is this asteroid belt we keep talking about?
02:19This region is located between the orbits of Jupiter and Mars.
02:23Tons of asteroids and even minor planets are found there.
02:26Some of them can sometimes migrate or even get thrown out of the asteroid belt to the outer
02:32solar system.
02:33The four largest asteroids in that area are Ceres, Vesta, Pallas, and Hygieia.
02:40They make up half the mass of the entire belt.
02:43As for the rest of the mass, countless smaller bodies make up for it.
02:48In loads of sci-fi movies about space, the main character gets into an asteroid belt and has
02:55to try hard to get away from countless rocks threatening to smash their spacecraft.
03:00Well, it has nothing to do with the real thing.
03:03Even though there are thousands of asteroids in this region, they're so widely spaced that
03:08the chance of collision is next to nothing.
03:11Hey, but it's a movie, right?
03:14Anyway, when the asteroid belt was forming, some objects started to come together and form
03:20what we know as protoplanets.
03:23But the gravitational pull that was caused by the formation of Jupiter made such collisions
03:28too rough, and instead of forming large space bodies like planets, asteroids shuddered.
03:35Astronomers think that as a result of such collisions, more than 99.99% of the original
03:41mass of the asteroid belt was lost in the first 100 million years of the history of the solar
03:47system.
03:49Only the largest asteroids have enough gravity to get a spherical shape.
03:54Small ones are just often piles of rubble, loosely held together by gravity.
03:59And the tiniest objects in the asteroid belt resemble dust, so small they are.
04:05And all these objects, giant and tiny, orbit the sun.
04:09There are several types of asteroids, depending on their composition and albedo, which is the
04:14proportion of light or radiation reflected by a surface.
04:18The main types are carbon asteroids, which have a very dark surface, silicon ones, you
04:24can also call them stone asteroids, and metal ones.
04:29The first two types account for around 75% and 17% of asteroids that we know about.
04:36For the first time, the asteroid belt was crossed by a spacecraft in 1972.
04:41It was the Pioneer 10 space probe.
04:44The spaceship managed to refute the theory that the belt was filled with dust that could easily
04:49damage all gadgets on board.
04:51It didn't happen.
04:52And since that time, eight more probes have traveled through the asteroid belt.
04:57And now, I'm going to tell you some cool facts about the solar system itself.
05:02Try to count how many of these facts you've known before and write your answer down in the comments below.
05:08The solar system is a staggering 4.5 billion years old.
05:13Scientists came to this conclusion after studying meteorites, the oldest material they managed to find.
05:20But our solar system isn't the only one in the Milky Way galaxy.
05:24The galaxy we live in houses about 100 billion star systems.
05:29And if it's just our galaxy alone, what can we say about the whole universe?
05:35Now, our sun is also insanely massive.
05:38Here's the proof.
05:3999.86% of all the mass of the solar system is the mass of the sun.
05:45In particular, hydrogen and helium that it's made of.
05:48The remaining 0.14% is mostly the mass of the solar system's eight planets.
05:55Oh, by the way, contrary to popular misconception, outer space isn't a perfect vacuum.
06:02It contains not only stars and planets, but also clouds of interstellar dust, space plasma, and cosmic rays.
06:09Those are atom fragments dashing from the outskirts of the solar system.
06:14Now, one phenomenon astronauts should worry about while exploring space is cold welding.
06:21If two pieces of the same kind of metal touch in space, they bond and get permanently stuck together.
06:28Kind of like galaxy gloom.
06:30It doesn't happen on Earth, since water and air keep pieces separate.
06:35You can see solar eclipses, even though the moon is 400 times smaller than the sun, it's also 400 times
06:42closer to Earth.
06:43So it's perfectly capable of obscuring the star.
06:47But in 600 million years, the moon won't be able to block the sun completely because of the satellite's changing
06:54orbit.
06:56Behind the orbit of Neptune, there is the mysterious Kuiper belt, filled with massy, icy objects.
07:03The most curious thing about this space formation, though, is that the scientists fail to explain the pattern of its
07:09movement.
07:10The only explanation they have is that Neptune might be hiding a ginormous planet.
07:16This hypothetical planet has already got the name Planet 9, and all we have to do is wait until its
07:23existence is confirmed, or not.
07:26The ocean on Jupiter is larger than any body of water on other planets of the solar system.
07:32But it's not the ocean you think about.
07:35The one on Jupiter isn't made of water.
07:37This mesmerizing thing consists of metallic hydrogen.
07:41And its depth is around 25,000 miles, which is actually almost the same as the circumference of Earth.
07:50Now, people got to know about beautiful Saturn's rings in the 1600s.
07:55But now we know that Saturn isn't the only ringed planet.
07:59All the giant gas planets, Uranus, Neptune, and Jupiter, have rings of their own.
08:04But they're thin and almost impossible to see.
08:07As for Mars, Venus, and Earth, they're made of rocky material and have no rings.
08:13At the same time, Saturn's moon Rhea might have a ring system consisting of three narrow bands.
08:20If astronomers manage to confirm it, it'll be the first time for people to discover rings around a moon.
08:27Oh, and Mars might get a set of rings of its own in the next 70 million years.
08:32The red planet's largest moon, called Phobos, is orbiting closer and closer to the planet.
08:39One day, it's likely to get broken apart by the gravitational pull of the red planet and turn into a
08:44ring that can last for millions of years.
08:47And another cool fact about Mars.
08:50You've probably heard of methane gas, a byproduct of such natural processes as volcanic activity and cow emissions.
08:58Anyways, this gas is not only a part of the Martian atmosphere, but also the thing that confuses astronomers to
09:05no end.
09:05The thing is that the volume of methane on Mars keeps wavering, and scientists just can't figure out where it
09:12might be coming from.
09:14Can there be life on Mars?
09:16Can there be cows on Mars?
09:17Chbilsky's star was discovered in the 1960s.
09:21Since then, astronomers have been intrigued by its unique chemical makeup.
09:26The star is suspected to contain ultra-rare elements verging on the almost impossible.
09:32Using special equipment on the European Southern Observatory's telescope in Chile, researchers took readings of the star's magnetic field.
09:40They discovered that the star's rotation period, which is the time it takes to finish one revolution on its axis,
09:47stretches out over almost 200 years, which is super slow.
09:52Of course, there are even more bizarre objects called ap-stars.
09:57They're a chemically interesting category of stars that rotate extremely slowly, with one rotation taking up to 1,000 years.
10:05What makes these stars even more peculiar is a wide range of chemical elements astronomers detect when analyzing their stellar
10:13spectrums.
10:14But if we look at Chbilsky's star, we'll see that it's both similar to and different from other ap-stars.
10:21It contains unusually low amounts of iron and nickel.
10:25Our Sun has 10 times more and incredibly high amounts of rare, heavy elements.
10:30Those might include strontium, caesium, and neodymium.
10:34As well as at least two undiscovered elements.
10:38They wouldn't occur through any natural processes we currently understand.
10:43There's a hypothesis that the presence of such heavy elements could be caused by a star's unseen companion, like a
10:49neutron star.
10:51Some people go as far as to say that such an incredible chemical makeup could be a sign of an
10:56alien techno-signature.
10:59Any specialist will tell you that it's the strangest stellar spectrum they've ever observed.
11:03Some even claim that there are so many chemical indicator lines you can't immediately understand what you're looking at while
11:09observing the star's spectrum.
11:12Chbilsky's star also contains high levels of radioactive elements that take a few thousand years to decay.
11:19And here's where another mystery lies.
11:22They should have long vanished from the star.
11:25After all, it's almost a billion and a half years old.
11:28Scientists haven't managed to figure out the reason for the presence of these elements yet.
11:33Maybe it's the combination of the star's rare qualities.
11:37It spins very slowly, it's hot, and it has a strong magnetic field.
11:41This could raise to the surface atoms that would normally be mixed inside the star.
11:47There's another theory that explains the presence of these radioactive elements.
11:51They could be there as if they were themselves decayed forms of ultra-heavy elements that we haven't discovered yet.
11:58So far, no one has been able to prove this theory.
12:01Even the discovery of Chbilsky's star's super-slow rotation doesn't bring us closer to the answer.
12:07It's obvious that there's a lot to learn about the bizarre star, and who knows which secret it still has
12:13up its sleeve.
12:14Another not less mysterious star is called Tabby's star.
12:19It's a sun-like orb around 1,500 light-years away from Earth, sitting in Cygnus the Swan.
12:26Unlike our sun, this star dims randomly by 5 to 22%, and it lasts for days at a time.
12:34The reason could be a giant planet passing in front of the star, but then the eclipses would be more
12:40regular and not so random.
12:42And if it was a Jupiter-sized planet, it would also need to block around 1% of the star's
12:47light,
12:48which would make it unique and unlike anything we know.
12:52After American astronomer Tabitha Boyajian discovered the star's massive and irregular fluctuations in 2015,
12:59further observations followed.
13:01They show that the overall magnitude of the star has been gradually dimming over the years.
13:07Some theories trying to explain this phenomenon are quite believable.
13:11For example, some scientists think that these brightness changes are intrinsic to the star.
13:17They could be caused by its magnetism, or changes in heat flow in its interior.
13:22Other ideas are more daring, including some kinds of activity of an extraterrestrial civilization.
13:28One of the most plausible theories, though, is that the dimming is caused by the chunks of an orphaned exomoon.
13:34It could have been pulled away from its parent planet by gravitational interactions with Tabi's star.
13:41As the moon approached the star, it exploded, sending dust clouds into stellar orbit.
13:46These countless chunks of rock and dust are now moving between Tabi's star and Earth in a giant, clumpy cloud.
13:53It could indeed explain why we observe such irregular brightness variations.
13:59Usually, when astronomers spot a spiral arm structure, it turns out to be a galaxy.
14:04But not in this case.
14:07SAO 206462, located 460 light-years away from our home planet, is a young star.
14:13It's surrounded by a circular disk of gas and clearly defined spiral arms.
14:19The bizarre star was spotted during an exoplanet search with the help of the Subaru telescope located in Hawaii.
14:26Instead of finding fully-fledged planets around a young star, astronomers discovered planets that were still in formation.
14:33These baby planets are growing out of the disk of gas and dust surrounding the star.
14:39The disk extends out to around 80 astronomical units, which is twice the orbit of Pluto.
14:46At least two of these planets have stretched the disk into its extremely unusual spiral shape.
14:52A different planet is responsible for each arm.
14:58In our home galaxy, there's a giant star that is a real stellar wind machine.
15:03At the moment, this monster is just waiting to burst and send a wave of radiation and hot gas towards
15:10Earth.
15:10All because it's a wolf ray-et, a star which is at that precarious point before it goes supernova.
15:18Its core doesn't have any more helium left to burn.
15:21Instead, the star is forced to churn through much heavier elements, for example, oxygen.
15:27Unfortunately, it disrupts the careful balance between gravity and fusion, leading to the star shedding its layers.
15:34When the oxygen eventually runs out, the star will go supernova.
15:38But this time, the show will be different.
15:40The thing is, WR-104 is one half of a binary pair,
15:46which means that two stars are feeding into each other, spinning up their stellar winds.
15:51It will continue until they start going incredibly fast.
15:55Is the potential explosion going to harm Earth?
15:58On the one hand, we're far away enough for even a directed supernova to not hurt our planet.
16:04At the same time, there's a threat of an extremely dangerous gamma-ray burst.
16:09Luckily for us, it takes a very specific and unlikely train of events for a wolf ray-et to produce
16:15a gamma-ray burst.
16:16Plus, even if it does, the star might be pointed far away enough for the danger to miss us.
16:22Anyway, astronomers are still watching the star, just in case.
16:26A star sitting in the constellation of Centaurus keeps a secret not many know about.
16:32At first glance, it looks like a dim white dwarf.
16:35But when astronomers analyzed it, it turns out to be incredibly dense.
16:39Take the mass of the Sun and cram it into something that is only a third the diameter of Earth.
16:45This space wonder is also rather cool.
16:49Its core temperature is a mere 11,900 degrees Fahrenheit.
16:53For comparison, the Sun's core temperature is around 27 million degrees Fahrenheit.
16:58At such low temperatures, stars begin to vibrate.
17:02And then, scientists can use these vibrations to sneak a peek inside a star.
17:06And in the case with the star in question, which was later named Lucy,
17:11they discovered that its carbon core had crystallized.
17:14In other words, it formed a giant diamond 10 billion trillion trillion carats in size.
17:20Since the discovery of Lucy, a few other crystallized stars have been spotted.
17:24Some of them have diamond hearts the size of our planet.
17:27The last bizarre star for today is called Vega, and it's squashed.
17:32The star's bulging waistline is caused by an extremely high spin rate.
17:37Vega rotates once every 12 and a half hours.
17:40This pushes the material around its equator outward.
17:43It also leads to the phenomenon known as gravity darkening,
17:47when stellar material further from the center of the star experiences less gravity,
17:52which makes it cooler and darker.
17:53So when Vega faces Earth pull and on, it looks perfectly round.
17:59But the dark halo around its middle is a telltale sign of Vega's oblate shape.
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