How Many Planets There ACTUALLY Are

August 24 2006. if you're like me you remember this day well the international astronomical Union had just released an official announcement they decided on a final resolution on the definition of planets and one of them Pluto Pluto no longer made the cut the seemingly overnight Pluto went from being one of the nine planets to a dwarf planet something literally no one had ever heard of before more than that though the model so many people all over the world had been taught was suddenly wrong and as a result you might remember a lot of people being outspoken with their opinion about this decision but if you're like me meaning in 2006 you looked like this the reasoning behind this decision was less than clear why all of a sudden would you just demote a planet how was Pluto any different from the rest of them who even gets to decide these sorts of things these are all questions that eight-year-old me never got the answer to so they sort of just stayed trapped in here for the time being of course now I'm older and as it turns out finding this kind of information is actually pretty easy a quick Google search will bring you to the iau's website where you can read for yourself the three criteria they use to define a planet the first is simply that it's in orbit around the Sun and okay this one makes sense there's no argument here under this definition Pluto would be a planet but so would literally everything else floating around our solar system so I can see why a second criteria had to be added the object must also have sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium or nearly round shape or basically it has to be a sphere and yeah okay this one also makes a lot of sense it eliminates all the smaller things like asteroids while keeping the rest of the planets including Pluto problems only seem to arise when looking at the third and final criteria the object must have cleared the neighborhood around its orbit cleared the neighborhood around its orbit what does that even mean well okay let's keep researching maybe just I don't know copy and paste that and dub there you go the easiest way to explain this is to think about our sun right after its birth what would eventually condense into the planets was Instead at this time a primordial cloud of dust rocks and Ice forming a ring or What's called the protoplanetary disc around a young star as time progressed and the dust settled so to speak singular rocks accrued more and more of the material in their proximity slowly building themselves up into what can only be described as Proto planets from here their mass starts to generate a significant gravitational pull drawing in even more material from its surroundings making it more massive only further strengthening its gravitational pull bringing in even more material and so on until there comes a point where the object has a mast effectively everything in its orbital pathway it has cleared the neighborhood so if I have this straight this third criteria while it might seem a little complicated and more than a little arbitrary or even stupid well it is the only object this seemingly affected was Pluto which no hasn't quite cleared its orbital plane but the fact that I even had to explain what that meant makes it feel like this third criteria was written with the sole purpose of excluding Pluto now I'm not gonna go all conspiracy theorists on you guys and say the iau wrote this to intentionally downgrade Pluto and that's because the more I researched the more I found that well that is the reason they added it it's not a conspiracy by now it's well known the iau did not want Pluto to be considered a planet once I came to this realization the next question I had was why what had Pluto ever done to the iau why did so many astronomers around the world suddenly agree with this verdict what had changed to figure this all out it looked like I was gonna need to do some more research and what I found is that Pluto is really only the beginning or I guess the end of this story and the real reason for this third criteria was to hide how many planets there actually are foreign [Music] for thousands of years our model of the universe looked like this where we can see Mercury Venus Mars Jupiter and Saturn all with the naked eye while some might have had better eyesight than others as a whole this kept our knowledge of the solar system limited to what we could see for most of human history and so it would only be with the Advent of new technologies that would be able to peer further into space meaning from its earliest days astronomy has been inextricably linked to technological progress the first of these progressions came in 1608 when the earliest recorded telescope patent was submitted in the Netherlands by 1609 people like Galileo in Italy had gotten his hands on a Contraption like this and was using it to observe the night sky with this new tool Galileo took some of the very first up close looks at each of the known planets though when he got around to viewing Jupiter he noticed in Oddity what he described as four fixed Stars totally Invisible by their smallness all sitting in one straight line away from the planet what Galileo had glimpsed for the first time ever were Jupiter's innermost moons IO Europa Ganymede and Callisto an event widely considered to be the first real Discovery in the field of astronomy the next big advancement wouldn't come for nearly 200 years when in 1780 the limitations of refracting telescopes forced a British astronomer by the name of William Herschel to begin constructing his own instruments using his own homemade telescope Herschel pushed the limits of the eye even further when he noted a pale blue dot that didn't move quite like the rest of the stars in the sky its speed appeared to suggest it was only about twice as far away from us as Saturn which also helped to explain why it was so dim what Herschel thought he had discovered was a new Comet but upon closer examination by some of his peers they found it to be far larger than that roughly the size of the other planets after some debate a name for this new planet was chosen Uranus thrilled with his new claim to fame Herschel set about constructing an even larger telescope with the hope that he might be able to find even more distant objects over the next four years Herschel built a 40-foot long telescope the largest scientific instrument ever conceived of by this point to provide himself with the clearest view of space ever achieved effectively Herschel maxed out what we were capable of seeing using only lenses mirrors and our own two eyes but when he finally looked through it he found well nothing or at least nothing that hadn't already been found clearly disappointed by this Herschel drew the conclusion that there simply was nothing left to discover and so for nearly 20 years the model of the universe stood at seven planetary bodies though not everyone was convinced of this first and foremost being a collection of astronomers from all over Germany who teamed up to do the impossible to find a Planet without even looking at the night sky they called themselves get this the celestial police and they were about to get physical literally by applying the principles laid out by Isaac Newton less than a century earlier these men accurately calculated the orbits of all the known planets however in doing so they uncovered another Oddity plotting the planet's positions over a logarithmic graph they appear to occur in regular succession with the exception of this inexplicable Gap left between Mars and Jupiter hey everyone thought it looks like a planet should fit there now knowing where to look this group of nerds sent out a call to over 20 astronomers across Europe imploring them to turn their telescopes and search for this Planet one astronomer who heard this call was Giuseppe piazzi who just so happened to be put in charge of the newest and finest telescope Ferdinand the first king of the two sicilies goodbye to his amazement when piazzi checked where these Germans suggested he spotted exactly what they described another large object while this one wasn't quite as big or as blue as Uranus it was far closer allowing piazzi to see that it too was generally spherical from what he and everyone else could tell this was another the eighth planet and was quickly given a proper name to fit series afterward members of the same police force also found Palace Juno and Vesta all very similar if smaller objects all within the same vicinity of each other between Mars and Jupiter briefly many people considered these to be the 9th 10th and 11th play planets respectively but this didn't really make sense according to the calculations there was only room for one planet here not a whole bunch of them and so as more and more of these dull great objects were found in the same area people began to question if these really were planets or something else for the time being however they were considered planets the last anyone would find for another 40 years over this time a better and better understanding of orbital mechanics developed within the astronomical Community to the point where eventually people started to notice something odd about Uranus not my anus Uranus its orbit was a little wider and a little bit more off-center than it should be based on their models people started to suspect this might be explained by another large object Beyond Uranus pulling on it and soon the search for Planet 13 was underway one man however the French mathematician urbanier thought he could beat everyone to the punch by calculating how big an object it would take how fast it would need to be orbiting and how far away it needed to be to cause this perturbation in the first place using this information he could then determine where in its orbit the object should be currently which in turn let him figure out where in the sky from Earth he should look to find it he then sent the exact position he expected to find a new planet to his friend Johan Gaul who just so happened to work at the Berlin observatory in less than an hour Gaul spotted the object described by leverier another big blue dot the first planet said to be discovered with a pen and paper rather than a telescope following in the precedent of the last few planetary editions this ice giant was given the fitting name Neptune and the model of the solar system was bumped up to 13 planets though that number didn't last for long as even more and more objects were being found between Mars and Jupiter including Australia heebi Iris flora and Matisse and by 1850 the model of the universe included up to 18 planets but with the discovery of each additional cold gray rock opinion in the scientific Community started to shift these were starting to look like an entirely different class of object finally it was decided that this collection of rocks were not planets at all but something new asteroids which all occupied the same belt around the Sun this is how in 1851 we went from having anywhere between 18 to 23 planets down to eight planets and one asteroid belt basically what had happened was our ability to observe the universe first briefly exceeded our own understanding of the universe and it wasn't until that understanding had caught up that we were able to properly explain and correctly identify everything we were seeing at least for a Time pretty quickly after Neptune was discovered though people started analyzing its orbit and found it also to be ever so slightly out of line with what was expected just as Uranus had been by now people knew what this meant and it wasn't long before the search for planet nine began again the object they were looking for however was far too small far too dim and far too far away for even the most advanced telescopes of the time to detect it wouldn't be until the arrival of another technology cameras that finally made discoveries possible once more by 1929 the American astronomer Percy Lowell along with a team of students produced a prediction for where another planet might be hiding Beyond Neptune and handed over these findings to Clyde Tombaugh who ran Lowell's observatory in Flagstaff Arizona Tomba searched this section of the sky for nearly a year taking photos every night and comparing them to the ones from the night before looking for any sudden movements finally on January 23rd 1930 this picture was taken then six days later this picture was taken flipping between these two images most of the objects stay in place a sign that they are distant stars but one small spot of light moves much further indicating it was much closer these photos seemingly confirmed Planet 9 valid and by May of the same year the name Pluto was approved by both the American Astronomical Society and the Royal Astronomical Society but you see there was a problem Lowell knew it his math students knew it and anyone checking his work knew it too Pluto was too small based on the calculations they had made the gravitational force being exerted on Neptune was far greater than what puny Pluto could ever produce even if you include its rather sizable Moon Karen as well of course most people did not know this so they simply accepted Pluto and moved on but there were some that continued to see this as an unfinished problem and it didn't take long for the missing Mass to come to represent something else the potential for another planet planet 10 or I guess if we're going by Roman names Planet X fueling a new search despite This Promise Pluto was already so far and so dim that without substantially better instruments or knowing exactly where to look another 70 years would pass before technology caught up this puts us almost back to where we started in the early 2000s by this time new technologies like computers infrared and UltraViolet sensors lasers radio waves satellites and more all ushered in a new golden age in the study of the universe using advancements like these people like Chad Trujillo and Mike Brown teamed up to hunt for new planets using caltech's state-of-the-art Palomar observatory in California and it wasn't long before in 2002 they made their first significant find an object far larger than a typical asteroid big enough to crush itself into a sphere and orbiting further out than even Pluto immediately people in the astronomical Community started to whisper wondering if the tenth planet had finally been found it was even referred to as object X as it was being observed pretty soon though the significance of this find demanded that it be given a proper name which is important because by this point in astronomy you needed to follow very specific naming conventions for things like this rules which are now determined by you guessed it the international astronomical Union so if this new object was a planet it needed a name that fit into the rest of the Roman mythological Canon if it was an asteroid the rules were much looser and it could be named just about anything because of these strict rules in order to give object x a name we first needed to know if it was a planet an asteroid or something else entirely and it was up to the iau to figure this all out ultimately the name Kolar was decided on coming from the mythology of the tongva people who once lived where the Palomar Observatory is now indicating that it had been agreed upon that this was not a planet an assessment based almost entirely on the fact that it was smaller than Pluto despite still being perfectly planetary in shape while Trujillo and brown might have been a little disappointed by this classification the fact that they found anything at all was still highly encouraging and so they continued their search soon afterwards the discovery of orcas was announced on February 22nd then sedna on March 15th and salacia on May 6th rapidly it seemed the list of trans-neptunian objects was growing though with each new entry the line between planets and asteroids was also blurring soon enough Trujillo and brown were no longer even capable of classifying and therefore naming many of their discoveries as they didn't really fit into anything that had been described before what was becoming clear is that just like how Beyond Mars was the asteroid belt Beyond Neptune there appeared to be another belt of debris this time consisting mostly of ice rather than rock this is what we started calling the Kuiper belt while things might have been getting more and more complicated because none of the other objects located in the Kuiper belt were any bigger than Pluto for a Time its status remained unchallenged this all changed however on July 29 2005. when Trujillo and brown published the discovery of three planetary sized objects in the scattered Kuiper Belt the first was makeemake a reddish gray object about one-fourth the mass of Pluto this would have made makimake the second largest Kuiper Belt object ever discovered if it wasn't for the other two objects announced that day next there was how Maya an even bigger Rock one third Pluto's mass though this wasn't the only thing that made this find more notable over the time it was observed its brightness varied in a short four hour Rhythm which is strange for an object that's supposed to be only reflecting the Sun's light why would it be flashing the only way to explain such a regular fluctuation is for this change in brightness to be somehow linked to the object's rotation using its high mass its rapid rotational period and a whole lot of math the researchers came to a shocking conclusion how Maya must be rotating so fast that centrifugal forces have caused it to bulge around its equator transforming the object from a sphere into what's called a Jacobi ellipsoid viewing this ellipsoid from Earth we see it head on oscillating between more surface area reflecting more light and less surface area reflecting less light explaining why it seemingly twinkles if this discovery wasn't spectacular enough though how Maya was also found to be accompanied by a thin ring system and Two Moons making this quite the unique little system though if their names were any clue neither of these were accepted into the pantheon of planets but it was the third and final object announced that was considered by most to be truly groundbreaking object 2003 ub313 this one had 28 percent more mass than Pluto and its Moon Karen combined for the first time in 70 years this landed another object almost assuredly on the planet side of the line earning itself the classical name Eris though this name heiress was a little more perfect than most people realize in Greek mythology Eris is the goddess of strife and disagreement it was she who caused the Trojan War by creating Discord among the gods and it appeared she had returned once again to sow conflict among men the issue came from the fact that while heiress might have been more massive because it was composed of mostly dense iron instead of lightweight water ice like Pluto it ended up having a slightly smaller overall diameter somehow aerys was both bigger and smaller than Pluto which of course caused a lot of disagreement about what it should be classified as until this point the president had been that anything smaller than Pluto was not a planet but now it seemed that might have to change if Eris wasn't a planet this also called into question whether or not Pluto was a planet considering it was made up of less stuff but if heiress was to be considered a planet then by definition planets could be smaller in diameter than Pluto opening the door for haumea makeemaki quora and the rest to qualify as planets as well somehow some wear a new line had to be drawn and because they were in charge of naming things it was up to the international astronomical Union to determine where and how they could either concede that the term Planet refers to any spherical object within the solar system of which there are possibly 20 or more of or establish a new criteria for the term planet that preserves the short and simple list everyone was used to ultimately what it came down to was Mercury Venus Earth Mars Jupiter Saturn Uranus and Neptune was Far easier for anyone to remember than Mercury Venus Earth Mars series Jupiter Saturn Neptune Uranus Pluto aerys how Maya makimaki gong gong quora uh orcas sedna salacia uh varda ixion uh varuna chaos and who could forget um [Music] foreign Yes you heard correctly along with the rest mentioned are real objects that orbit around our sun and do in fact have just enough Mass to achieve what was it called the hydrostatic equilibrium it's pretty much a sphere is what I'm trying to say and that's not even mentioning all the unnamed objects that are just as big as some of these if I had to guess I'd say it was this seem seemingly endless list of dull gray balls that drove many astronomers to start looking for ways to exclude these objects in a arguably scientific Manner and to be honest I kind of understand their reasoning here think about it eight or nine planets is something even kids can remember but if that was replaced with an ever expanding list of increasingly challenging names if they even have names at all this list isn't really learnable or even useful anymore and I think a lot of people worry that if even the most basic set of astronomical objects became too complicated to teach then well people would stop teaching it so the iau's decision was clear it had to draw a line somewhere and keep things simple now the only question left was how of course anyone paying attention already knew where to draw the line it was through Pluto that the rest of these objects made their case for Planet Hood and so if the list of of planets was to remain short and sweet Pluto had to go just like how sarri's and its neighbors demanded the invention of the term asteroid so too did Pluto and the rest of the Kuiper belt objects need a new classification but a lot has changed since the discovery of Ceres and now you need some sort of scientific or mathematical means criteria if you will to actually draw a line between Pluto and the rest of the planets while I'm sure just about every astronomer on Earth had their own opinion on how to do this if we scroll further down the Wikipedia page for clearing the neighborhood we'll find the three most popular methods proposed Stern Levinson's Lambda soder's moo and margot's pie now I'm not gonna lie these all look and sound really complicated which is why we're only going to look at one of these soders which trust me is actually very simple you just take the mass of the planetary candidate and divide it by the total mass of all the other objects within the same orbital neighborhood yeah it's literally just a proportion what we get when we do this is eight objects with reasonably High numbers indicating they represent the vast majority of the mass in their orbital plane ending with Mars followed by numbers all very close to zero starting with series and continuing through Pluto heiress and the rest reflecting that these still represent less than half of the material floating around in their space this is what ultimately gave the iau at least one set of credible numbers to justify this third criteria and by August 26 the 2006 the announcement was made that Pluto along with the rest of the Kuiper belt objects were not planets after all but rather fell under the newly coined distinction dwarf planets though if you ask me this name sucks not only is it kind of demeaning but also doesn't really help to explain what these actually are and I think a much more fitting term would just be protoplanets though trust me I'm by no means the only person that felt this way which might be why two years later the iau released another announcement this one far less publicized than the last stating they had chosen a new name for solar system objects like Pluto which was to be drumroll please plutoid though I don't really know how I feel about this name either on the one hand it's definitely better than dwarf planet and it certainly gets the idea across that it is like Pluto but well what is Pluto in fact I have the same problem for the name asteroids too they were named when people literally thought they might be small Stars hence asteroids or Star like but now we know that asteroids are these scraps of rock left over from building the rest of the terrestrial planets while plutoids are composed mostly of water ice left over from building the ice giants so as long as we're tossing names like dwarf planet and plutoid out there can I make a suggestion if you ask me these are G asteroids G coming from Geo like the Earth or Rocky and the Frozen worlds Beyond Neptune would be cry asteroids cry coming from cryo meaning icy or cold no matter what it was called though I have a feeling the decision to downgrade Pluto still would have been a tough pill for most people to swallow even if when put into perspective it actually makes a lot of sense and it's in fact all the people protesting it in retrospect that kinda just seemed trivial or even worse uninformed I know how hard change can be for a lot of people but in science change is necessary for new and better ideas to rise above the old and outdated ones so while many might have seen Pluto's demotion as arbitrary or uncalled for what it really represents is our unrelenting Pursuit Of Truth science isn't about being right on your first try it's about receiving new information and updating your understanding which is exactly what happened here and is something that I hope by now you can see has been happening literally constantly ever since the invention of the telescope and really only seems to be speeding up in modern times where now it feels like we find a new amazing thing almost every day heck we still haven't even identified what's causing Neptune's orbit to deform leading many to reasonably believe there could still be an Undiscovered Planet lingering somewhere beyond the Kuiper or cry asteroid belt so to answer the title of the video how many planets are there actually well it's really up to you because no one really knows personally I think the iau's decision of 8 makes sense for the time being even if the way they got to it was a little convoluted eight planets was definitely easier for him to remember than 50. but if you disagree and still consider Pluto a planet well that's fine I get your reasoning too but if that's the case then that also means you should have no problem welcoming to the family heiress how Maya makimake of all the way to mahapara hey everyone that just about wraps up my very first Astro pro video but trust me there's plenty more to come so if you enjoyed and would like to continue seeing videos like this please consider subscribing I'm looking forward to exploring the cosmos with you all and I already have some really exciting videos planned so join me and together we'll embark on a New Journey into the final frontier

Channel: Astro Pro

Views: 389,873

Keywords: Space, astronomy, pluto, planet, dwarf, star, sun, solar, system, universe, moon, earth, mercury, venus, mars, ceres, eris, makemake, jupiter, io, europa, ganymede, callisto, haumea, gonggong, quaoar, varda, varuna, ixion

Id: UyK4MTeJJrQ

Length: 32min 22sec (1942 seconds)

Published: Tue Oct 18 2022