Pratique du Shadowing: Scientists Are REALLY Close To Finding Planet 9 - Apprendre l'anglais à l'oral avec la vidéo
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Okay, there is something strange happening in the outer solar system and we need to talk about it.
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Astronomers have found a number of icy rocks that seemingly disobey the laws of physics.
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They are moving through our solar system on strange orbits that can't be explained using the gravity of our known planets.
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So what if there was something hiding?
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A ninth planet.
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In the outer reaches of our solar system there could be a huge icy world hidden in darkness and astronomers are getting really close to finding it.
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So to get to the bottom of this, I called up the lead researcher hunting down Planet Nine.
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I'm Konstantin Batygin.
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I'm a professor of planetary astrophysics at California Institute of Technology and one of my obsessions over the last decade has been the search for Planet Nine.
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The craziest thing is, I left that interview convinced that Planet Nine exists and surprisingly I think we might find it sooner than you think.
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Throughout history, we have developed new tools and methods for searching the cosmos.
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Each time there has been innovation, we have typically found a few new planets.
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The five bright planets, Mercury, Venus, Mars, Jupiter and Saturn have been known for thousands of years.
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Initially, they were just thought to be wandering stars, brightly shining and moving through our sky.
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In fact, the word planet actually means wanderer in Greek.
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Then in 1781, with the invention of the telescope, there was another breakthrough.
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William Herschel turned his telescope towards the universe and noticed a faint star moving between each night of observation.
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A new planet, Uranus.
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But it was initially actually named George in honor of King George III.
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And then the search for new planets went dark.
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For over 60 years, astronomers kept searching and found nothing.
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Some people even thought we had found all of the planets in the solar system.
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But there was a problem.
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Uranus wasn't following its predicted orbit.
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It was moving off course, and no one knew why.
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Scientists hypothesized about why this could be, and an exciting idea jumped to mind.
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What if there was a huge planet we haven't seen yet shifting the orbit of Uranus?
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And it was one of the greatest achievements of celestial mechanics in kind of the mid -1800s.
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Urbain Le Verrier figured out that the orbital anomalies of the planet Uranus can only be explained if there's an extra planet.
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The mathematician Urbain Le Verrier calculated how big such a planet would have to be and where to look for it.
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They pointed their telescopes at the predicted spot, and there it was, Neptune, just one degree off Le Verrier's position.
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When that planet that he predicted was in fact found, suddenly everybody wanted to do it.
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By the 1900s, the solar system started to look pretty much complete.
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It looked like there was a wobble in Neptune's orbit, and so astronomers predicted there might be another planet even further out.
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So using new telescopes, they once again searched the outer reaches of the solar system, eventually finding the baby planet Pluto, somewhat by accident.
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Pluto was the ninth planet of the solar system, but it did eventually face controversies.
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As we enter the 2000s, massive survey telescopes started to find hundreds of new objects out past Neptune.
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These objects were both big and small, some of them even being bigger than Pluto itself.
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This field of icy rocks became known as the Kuiper Belt.
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Pluto was eventually demoted to dwarf planet in 2006.
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The solar system once again had just eight planets.
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And that is where we are today.
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But there is something strange happening out there in the Kuiper Belt, something that hints at the existence of a huge ninth planet.
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There have been lots of searches for things kind of like this.
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They're all wrong.
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Just before we dive into the evidence for Planet 9, I want to thank the sponsor of this video, Foundation Galactic Frontier.
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Now, let's go find Planet 9.
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In 2014, astronomers were observing the Kuiper Belt objects when they noticed something.
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The most distant objects seemed to be clustered in this weird way.
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They were all pointed out in the same direction.
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It was as if they were being pulled out there by something.
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This kind of alignment is extremely unlikely to occur just by chance.
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It looks like they're all swinging out into the same direction.
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They're all tilted by a common angle.
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And I'm like, oh, what's all that's going on is there's orbital alignment.
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We had our first hint of something strange.
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Two years later, Konstantin Batygin and Mike Brown, astronomers at Caltech, took this idea and ran with it.
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They ran simulations to figure out what could explain such strange orbits.
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Their solution?
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A huge planet extremely far out on an eccentric and inclined orbit.
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They found that the planet would cause the objects to cluster on the opposite side of the sun to the planet itself.
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This keeps the objects out of the way of the planet, meaning this alignment would be stable for billions of years.
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Their simulation predicted this massive orbit, around 400 times further out than the Earth at its most distant point.
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It would take the planet 10 to 15 ,000 years to complete one full orbit of the sun.
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The orbit would also be tilted like this relative to the rest of the planets in the solar system.
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The planet itself would be about six times Earth's mass, making it a super Earth or a mini Neptune.
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This would probably also make it about two to three times bigger than our planet, and more than likely a rocky, icy world.
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Amazingly, as we have learnt more about exoplanets in the Milky Way, it seems like this size of planet is the most common in the universe.
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But we don't have one in our solar system.
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That is, unless Planet 9 is really lurking out there.
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The evidence for Planet 9 doesn't just stop at these clustered objects out in the Kuiper Belt.
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There's also these so-called detached objects even further out that are behaving really strangely.
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In the outer solar system, Neptune kind of acts like a security guard.
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Any small objects that come close to it get ejected out into the Kuiper Belt.
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There is a dwarf planet called Sedna that takes on this extremely distant orbit.
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It never comes close enough to Neptune to be affected by its gravity.
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This makes it a detached object.
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But that is the problem.
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How did it get put into this far out orbit away from the gas giant planets without the gravity of the giants pushing them out there?
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They need another explanation.
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Enter Planet 9.
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Over millions of years, our predicted Planet 9 would gently bump these distant objects, pushing them further and further away from the gas giants, detaching them from Neptune's influence.
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And it's not just Sedna.
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There are four of these detached objects that have been confirmed, and all of their motion is perfectly explained by the presence of Planet 9.
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Planet 9's gravity doesn't just cluster these objects and detach them.
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It can also stir them up in all different kinds of ways.
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There is a weird number of objects that orbit the Sun like this, extremely off axis compared to the rest of the solar system, and even objects that orbit in the wrong direction, moving backwards around the Sun.
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Before Planet 9, there was no real explanation for how these objects got to orbit like this.
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But similar to the detached objects, when they ran simulations, Planet 9 acts like a guide.
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Over millions of years, moving these objects into these extremely high orbits by gently tugging on them. I was really curious about these simulations, how they replicate the entire solar system to try and figure out where Planet 9 should be.
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So it seems like they essentially just build this simulation of the solar system, one with Planet 9 and one without it, and then they run it for billions of years, seeing how they differ.
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When you include Planet 9, these small bodies in the outer reaches of the solar system aren't random.
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They become ordered in the exact ways I've shown you so far.
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These are distinct patterns, fingerprints of Planet 9 left on the outer solar system.
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And Constantine told me about a new prediction that the simulations have made that I haven't seen spoken about on YouTube anywhere.
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The newest line of evidence that we have for Planet 9, if this process is happening, right, if Planet 9 is really there, not only did this process happen like over the last four and a half billion years, but it's really happening right now.
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There should be a flux of bodies, like kind of a river of outer solar system material currently being jammed into kind of orbits between Jupiter and Neptune.
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There should be objects that cross Neptune's orbit.
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If Planet 9 didn't exist, then you would expect Neptune to just throw them away to the outer solar system, given enough time.
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But if Planet 9 does exist, then this region should be continuously replenished with objects being thrown inward.
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Planet 9 and Neptune kind of playing this game of catch with these icy rocks.
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In the simulations, Planet 9's gravity grabs some of the objects out in the Oort cloud and sends them inward past Neptune.
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Without Planet 9, nearly no objects would do this.
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They would either stay beyond the orbit of Neptune or just quickly get ejected.
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This gives us a new prediction to test.
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If Planet 9 does exist, then around 3 % of the objects out past Neptune should be on a path that crosses with Neptune's orbit.
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If it doesn't exist, only around 0.5 % of them would cross the orbit.
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So my next question was obviously, have we found any of these objects?
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They have found around 29 of these objects so far.
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When they compare them to the results from the simulations with and without Planet 9, even making sure to correct for biases in the telescope surveys, the result was, the real orbits of the 29 objects we found agree with the Planet 9 simulation, and the solar system without Planet 9 is rejected at 5 Sigma.
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In case you don't know, 5 Sigma is basically the gold standard test for a result in science.
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If something is said to be measured at 5 Sigma, it means there is about a 1 in 3.5 million chance that the result was just some random fluke or anomaly.
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They are essentially saying that this result entirely rules out the possibility that Planet 9 doesn't exist.
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But slow down.
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They only have 29 objects, and only around half of them have their orbits really well defined.
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These objects are faint and tricky to observe.
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As you'll see later though, this is all about to change thanks to a very special telescope.
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Now I need to answer the question that I know so many of you are screaming at the screen right now.
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If we know its orbit and size well enough to make all of these predictions, why can't they just point a telescope at the patch of sky where Planet 9 should be and take a picture?
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I mean, they did the exact same thing with Neptune after all.
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And I hear you.
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I had the exact same question.
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We actually don't know where to look, okay?
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We can calculate the orbit.
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We cannot calculate where it is on the orbit.
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And the reason we cannot do that is that we haven't seen the Kuiper Belt objects themselves complete their orbits.
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So essentially, we have the orbit, but Planet 9 could be really anywhere along this orbit right now.
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And since it takes 10 to 15,000 years to complete a loop of the sun, we need to really pinpoint its location if we want to find it.
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And then there's the problem of brightness.
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It's far away, okay?
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So it's really, really dim, okay?
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So it's not like, oh, go out, fire up a telescope, you know, point to the sky, you know, light up a SIG and just watch the data roll in, right?
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It is at the edge, perhaps slightly beyond the edge of what's possible with the largest telescopes on Earth today.
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To see Planet 9, we need to push our very best telescopes on Earth to their absolute limit, taking long exposures and stacking multiple images to try and reveal what's hidden in the darkness.
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They have already tried a number of these searches for Planet 9.
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The Subaru Telescope in Japan did some of the deepest wide-field imaging in a 2020 search.
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They found more of the little icy rocks that supported Planet 9's existence, but no Planet 9 itself.
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The Pan-STARRS Telescope in Hawaii actually did search back in the 2010s, but it wasn't able to look for faint enough objects.
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The Dark Energy Survey covered 12% of the entire sky from 2013 to 2019, and once again found no Planet 9 candidates.
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The point I'm trying to get at is up until recently, the telescopes and data that we had just wasn't good enough to properly search for Planet 9.
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And this is where the game changer comes in, the Vera Rubin Observatory.
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I actually visited the observatory in Chile a few months ago right as they finished completing it.
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I made a full video deep diving into all of the science, so if you haven't seen that one already, then definitely check it out.
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Vera Rubin has a huge 8.4m mirror and literally the biggest camera ever made.
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It's a feat of modern engineering genius and it's about to conduct the biggest survey of the sky ever taken.
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The real game changer with Rubin is its speed.
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This observatory can take these huge images and does so extremely fast.
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It can completely scan the entire visible sky and image it to unmatched depths every three nights.
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Something that would have taken previous telescopes months or even years.
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And it is so sensitive it could spot a single candle lit on the surface of the moon.
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They are literally taking a 10-year time lapse of the entire sky.
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Rubin will definitely be able to tell us whether Planet 9 exists or not.
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And it won't take that long.
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Within the next year or two, we will know.
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Rubin will find so many more of these strange objects we've spoken about, giving scientists the statistics needed to refine the model of Planet 9.
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So if it does exist, I think within two years, we would know at least on a statistical level.
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This telescope is literally a planet hunter's dream tool.
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It's like having the world's most sensitive security camera of all time, constantly scanning the sky looking for the elusive Planet 9.
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Okay, so just personally, I do feel like Rubin will actually find Planet 9.
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That's just what my bet is.
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But say it doesn't.
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What are the other possible explanations?
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The principal argument against Planet 9 has always been, oh, this is just observational bias.
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Maybe these orbital anomalies just don't actually exist at all.
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Maybe we've just fooled ourselves by only looking in certain areas.
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Maybe these clustered objects are really just a snapshot of a truly random distribution.
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If this is the case, Rubin will fill in those gaps.
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Another possible explanation is these strange orbits could be explained using Neptune's past migration outward.
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Four billion years ago, Neptune moved outwards and it could have captured some of these objects in that process, putting them into these clustered patterns that we observe today.
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But there have been other ideas in the literature, like some people have proposed that it's actually a primordial black hole.
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It would have the same mass as our predicted planet, but its event horizon would be just a few centimetres across.
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Basically impossible to directly observe from Earth.
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This would solve the why haven't we seen it yet problem, but it's pretty speculative.
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It would be kind of surprising if the solar system had a binary, black hole companion, but that's an idea that's been out in the literature.
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We have never observed a primordial black hole.
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Some people even think they could be the source of dark matter.
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So if we did find one in our solar system, it could revolutionise all of cosmology.
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Constantine and his collaborator Mike Brown have previously said that they would place the likelihood of Planet 9 existing up to around 90%.
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And after having spent months researching this topic, I would say this.
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It seems like there are really two major camps of astronomers when it comes to this problem.
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People who believe in Planet 9, and those who think it's just this observational bias.
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You know, at this point, that's looking quite unlikely as the explanation.
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If you believe in the data, then Planet 9 is the natural conclusion.
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And regardless of whose camp you're in, Vera Rubin is going to reveal the truth, and it's going to do it soon.
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If Planet 9 does exist all the way out there, then my question was, how did it get there?
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The leading theory is that Planet 9 was in the starting stages of forming an ice giant, like Neptune or Uranus, before it was ejected from the early solar system, sent flying to the cold outer reaches.
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This would make Planet 9 the rejected core of an ice giant planet that never got to finish forming, now wandering out far away from the rest of the planet family.
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It didn't form there.
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There's no material that the solar system's disk could not have reached 500 AU, right?
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Such a disk would almost certainly be gravitationally unstable.
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If it didn't get ejected, then the only other real possibility is that it's a captured rogue planet from another star that we stole during a close pass by.
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The sun was born in a cluster of stars, and we might have exchanged planets between the systems before parting ways.
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Now of course, the final question I had to ask was, if we find Planet 9, what should we name it?
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Since all the planets are named after Greek or Roman mythological figures, it will be up to the IAU and its discoverers to ultimately pick a name.
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Some options that aren't taken are Persephone, Minerva, Oceanus, or even Vulcan.
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But to be honest, I kind of like Constantine's idea.
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Whether it's named Bowie or Persephone, I think we will find Planet 9 in the next few years, and hopefully once and for all have completed our solar system family.
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À propos de cette leçon
Vous vous entraînez en anglais avec "Scientists Are REALLY Close To Finding Planet 9" en utilisant la technique du Shadowing.
Qu'est-ce que la technique du Shadowing ?
Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.