I find flat-Earthers fascinating. I don’t agree with their picture of reality, but if I surrounded myself with people who agreed with me all the time, things would get boring. It’s often a good idea to “fraternise with the enemy” because you get exposed to fascinating and even surprising perspectives.
People outside the flat-Earth community tend to assume flat-Earthers are backward, torch-bearing yokels too busy marrying their cousins and doping up to understand how the world works. But I think flat-Earthers have a healthier outlook than people give them credit for. After all, flat-Earthers:
1) Are skeptical of accepted theories
2) Refuse to accept facts on authority
3) Want to do research
4) Follow evidence wherever it leads, even if that means public ridicule
Many flat-Earthers I’ve spoken to emphasise reproducible experimentation and the importance of a posteriori reasoning. They admit ignorance about questions the flat-Earth model presents e.g. what’s underneath it, what stops the moon falling, how do eclipses happen, what generates the magnetic field, how does retrograde motion occur etc. and this is a very honest, even refreshing, approach.
Let me be clear: I’m confident the world is an oblate spheroid orbiting the Sun elliptically at a mean distance of 150 million kilometers, but I don’t think flat-Earthers are idiots for disagreeing with that. In fact, I think flat-Earthers have a sensible-ish approach to analysing the world, just the wrong conclusions.
Bully for the Globe
The sad truth is that most people are taught "the Earth is round" as a brute fact. They are rarely given evidence for how we arrived at such a strange conclusion and when they get older they begin to ask questions...which is what we want them to do! We want a generation of people who aren't afraid to challenge convention. Being skeptical is half of what Science is about. It’s just that the other half is about how we arrive at good answers and that’s where flat-Earthers have been misled. But I don't think it's their fault.
Honestly, some Flat-Earth arguments sound pretty good at first. I came across one guy pointing out that gyroscopes spin vertically no matter what surface they rest on; if the Earth is round then why don’t we see gyroscopes in airplanes tilting as they curve over the surface of the planet? Or what about the fact we can see Mercury or Venus at night, despite them being inner planets and at night we are facing away from the Sun. There are simple and obvious explanations to these quetions of course, but they do initially make one go "hmmmm, that's curious."
Point is, the flat-Earth movement has questions and none of them should be answered with “you’re a dumbass”. The motto of the Royal Institution is Nullius Et Verbia which translates to “don’t take anybody’s word for it”. That should include our word too.
Science is built on the idea that every claim is open to question and we’re setting a bad example by mocking flat-Earthers. It’s essentially saying “be skeptical and question everything...but not that bit, don’t ask about that!” Some flat-Earthers can’t be reasoned with sure, but those who are prepared to listen to globists have the right to answers rather than abuse...which is what they usually get.
One of the flat-Earthers I know told me that not only does he get regular harassment from people online, he receives death threats aimed at his daughter. Now come on guys, think that through. If you want people to listen to what you have to say, don’t threaten to murder their children.
Another flat-Earther told me a story from when he was in school. He asked his Science teacher a reasonable question: if the Earth is round why don’t Australians fall off the bottom? The response he got was laughter. Twenty years later, he’s Flat-Earth and proud.
If you want to open a dialogue with people who don’t share your view, you need to approach them with dignity. By all means explain the flaws with their arguments (as I’m about to do) and if they’re open-minded they will take you seriously, but don’t be mean about it. Nobody gets bullied into the truth.
Who is this blog for?
What I’m not about to do is debunk the flat-Earth claims currently looping around the internet. That’s been done by far better writers than me. What I am going to do is discuss some common themes and mistakes which crop up again and again when discussing the whole issue.
I’ll be frank: if you are a proud flat-Earther, my blog is unlikely to change your mind. You probably spent months coming to your conclusion and I’m not arrogant enough to think I’ll change that in five minutes. My best hope is that I might give you one or two moments of “fair enough, that’s an interesting point”.
Really, this blog is for people who aren’t flat-Earthers, but are interested in it. People who’ve just come across the growing movement and are beginning to wonder if there might be something worthy of consideration. What I’m going to show, before your mind is made up, is why you need to be cautious of flat-Earth arguments and what the common traps to watch out for are.
Mistake One - Thinking Scientists Trust Each Other
One flat-Earther I debated for a long time (and enjoyed a reasonable friendship with) had a very bizarre view of Science. He would talk about how Scientists revere people like Einstein and Newton as if they were kings of knowledge, whose theories were trusted as law. I tried to explain to him that we never trusted them, just the experiments which proved their ideas correct, but he was having none of it.
A lot of people get this wrong in fact. They seem to think Scientists automatically trust whoever the most prestigious Scientist is. But there are no heads of Science, no organisations in charge of deciding facts and no Scientific authorities; only experts. There is never an official decision to promote a hypothesis to fact, it just happens gradually by consensus. And we certainly don’t listen to each other and agree blindly. Scientists actually spend half their time trying to disprove other Scientists... especially if they're famous.
Newton's gravitational law turned out to work extremely well, but he also claimed you could turn lead into gold using magic. We accepted his first claim but not his second because the first one agreed with experiment and the second didn't. Nobody trusted Newton "because he was Newton".
I mean, just pointing out the obvious here, at the time Newton suggested gravitation, nobody even knew who he was. He was an obscure, antisocial wierdo who kept to himself and barely left his bedroom. The most famous Scientist at the time was actually Robert Hooke, but his ideas couldn't cut the cosmic mustard so they were abandoned.
You need to be very wary of a flat-Earth argument which talks about Scientists believing claims of other Scientists. Scientists trust evidence and they criticise something which doesn’t sound right. Just like flat-Earthers today. In fact, flat-Earthers are part of the system which keeps Science honest. They ask questions to see if Scientists can answer them. Well...they certainly used to...
Mistake Two - Forgetting Scientists were flat-Earthers once
As I keep saying, it’s good when people ask questions of Scientists, but I’ve yet to come across a flat-Earth argument which is new. Scientists have heard all these arguments before because we invented most of them.
There were plenty of skeptical thinkers around when Eratosthenes suggested the globe and there were plenty more during the renaissance when the heliocentric model was revisited. The scientific community in both time periods comprised of flat-Earthers or geocentrists. They attempted to debunk the globe hypothesis, failed miserably, and so they switched sides. Flat-Earthers today aren’t some new breed of thinker destined to take down the global tyrrany. They are re-hashing questions we have already dealt with.
I think this might be why scientists sometimes get frustrated. It’s not because we think flat-Earthers are dumb (well, I don’t), it’s because we feel like a teacher who answers a question and then another student asks it thirty seconds later. Modern flat-Earth arguments sound like the kid who wasn’t listening the first time. Really, Johnny? I just explained this!
If you want to question a claim Scientists are making then question something like dark matter or dark energy or psychiatric medication vs placebos. Question the really weird stuff like quantum entanglement or information-loss in black holes. Those are debates happening right now and they’re awesome. Sure, flat-Earth arguments were exciting at the time, but the dust has settled on them now and the answer was pretty clear.
Mistake Three - Asking Questions = Puncturing the Theory
I accept that the burden of proof lies with globe-Earthers - we are the ones trying to prove the remarkable claim - but flat-Earthers have to set their bar reasonably. The mistake they often make is assuming that noticing an apparent puzzle or contradiction with a theory means they’ve undermined the entire thing. But it doesn't mean that. Not at all.
For example, if someone says water boils at 100 degrees Celsius, you could point out that puddles evaporate on cold days when the ground isn’t that hot. It’s a good query, but it hasn’t debunked the existence of boiling water (fun fact: if Earth was truly flat, water would't boil at 100 degrees C in the first place). Or when you learn the theory of sexual reproduction and you notice porcupines are spikey, you could ask how they have sex at all. Again, it's an excellent question but it doesn't destroy the theory of sex or the existence of porcupines.
It's the same with a huge number of flat-Earth “proofs”. Most of them aren’t proofs at all, they’re just intriguing “how comes?” or “what abouts?”. Interesting and worth discussing for sure, but questioning a theory is not the same as putting a theory in checkmate.
Mistake Four - Flat-Earth is Easy to Understand
There is a well-known principle in scientific thinking called Occam’s razor which says that if you have two explanations which account for all the data, the simpler one is more likely to be correct.
For example if you see footprints in your house, there are a few explanations available: it’s possible someone was walking here earlier, but it’s also possible it was a dog on its hind legs wearing shoes. Both explanations account for the data but it’s more likely to be the human than the dog.
The problem is that Occam’s razor sometimes get perverted into: the simplest explanation is correct. And that’s obviously not true. Dogs can be trained to walk on their hind legs wearing shoes, so you have be prepared to accept that explanation even though it wouldn’t be your first guess.
The simple human explanation is clearly more likely, but suppose you discovered paw marks on the door-handles and somebody had opened the cupboard and poured out Kibbles’n’bits. At this point the two explanations are no longer equal. The human story doesn’t explain everything anymore, so you have to consider the counter-intuitive and more complicated hypothesis.
It’s permissable to say “I don’t know the truth” of course...that’s always allowed in Science. If you find the dog-shoes idea a bit of a stretch then you don’t have to accept it. But you’re not allowed to return to the inadequate hypothesis. It no longer acounts for all the data, so there is no reason to use it any more. But this approach is common in flat-Earth arguments. They are so damn easy to understand that they hardly explain anything!
Consider gravity. Flat-Earthers don’t believe in gravity because gravity would have pulled the Earth into a ball by now. So they put forward a much simpler explanation for why apples fall from trees: dense objects fall through air and sparse objects like Helium balloons rise due to air’s buoyancy. Sounds good, but there’s a big problem.
The “things fall because they’re dense” explanation is easy to understand but misses pretty much everything else. It doesn’t explain why masses hung on strings tilt toward mountains (because they do). It doesn’t explain why objects get faster as they fall rather than dropping at a steady rate. It doesn’t explain why airplanes (denser than air) are able to float by accelerating into it. It doesn’t explain why comets occur with regularity or what keeps the moon at the same distance from us.
In fact, the more you look into it the more you realise the density explanation hardly covers anything. And, as it happens, Newton already knew about the density/buoyancy principle (as did everyone else in 1687). What he was trying to explain wasn’t why things fall. He was trying to explain how everything moved the way it did. Some flat-Earthers don’t seem to be aware of this however and stick to overly simplified explanations of overly simplified problems.
A simple explanation for a simple phenomenon is fine. But a simple explanation for a complicated range of phenomena is a sign somebody hasn’t done enough research.
Mistake Five - Rejecting Equations
This flaw with many flat-Earth arguments is similar to the last one, but quite specific. It’s an unfortunate fact that many heliocentric proofs happen to look like an intimidating wall of equations. This makes things awkward because the explanations for globe-theory are often so complicated they can look fantastical. Sadly, I’ve seen a lot of flat-Earthers get around this by deciding that equations are just a bunch of made up symbols which scientists use to blind people with...well, science.
Flat-Earthers do have a valid point in that equations don’t mean anything by themselves. Particles and fields don’t know to behave a certain way because someone wrote some symbols on paper. But what equations can do is track things which are too bizarre for our heads. The equation doesn’t mean anything but it describes something which does. So when Scientists present you with mathematical proofs they aren’t hoping to blind you. It’s because equations are sometimes the most accurate way of describing the world.
Take the following experiment: if you get into a room with 23 other people and ask everyone what their birthday is, two people in the room will often have the same one. But that doesn’t sound right! It feels like you should need more people. There are 365 days in a year so shouldn’t you need 366 people to get a birthday match? Nope. Once you get to 24 there's around a 50% chance it'll work. Try it for yourself and prepare to be spooked.
What this shows is that the human mind isn’t very good at guessing how things really work, especially when it comes to patterns and numbers. If you want to explain how something like this happens, you have to accept that nature is beyond what your mind can comfortably grasp. If you’re really committed to understanding a complex universe you have to accept complex explanations, including mathematical ones.
If you don’t feel confident with equations that’s absolutely fine, but you can't reject them because you don't understand them. That's like rejecting a German person’s opinion because you don’t speak German.
We invented mathematical techniques not to make things confusing but because the world is confusing and unless we invoke maths we get the wrong answers. The complicated equipment and calculations Scientists use are far more reliable than your eyes and ears. Although most flat-Earthers seem to be misled about this point too.
Mistake Six - Trusting Your Senses
Leonardo da Vinci once said “Experience is a truer guide than the words of others”. It’s a great quotation but we have to be careful. By "experience" he is referring to testing things for yourself. He doesn’t mean “trust your senses”. Well, maybe he did mean that, I didn’t know Da Vinci that well. But if he did think human senses were trustworthy, he was wrong. Come at me Da Vinci.
A huge number of flat-Earth “proofs” rely on you making simple observations with your senses.
I’ve heard flat-Earthers talk about how you can’t feel the Earth spinning beneath us, how we don't see clouds or rocket trails blown backwards across the sky or how the North star and Ursa Major appear fixed in place throughout the year. All of these are casual observations which appear to give the impression of a flat, stationary world. But guess what? They’re all wrong.
Your senses are not very good at interpreting their surroundings. This can be an uncomfortable thing to accept if you believe your senses are engineered to be trustworthy, but it’s unfortunately true. Your senses will mislead you at every opportunity. That’s one of the reasons we invented Science in the first place - to check what nature is really trying to say.
If you think your senses are giving you an honest picture then check out the image below. It is not a spiral, it’s a series of concentric circles. But even knowing that fact is true, your eyes and brain will trick you and tell you it’s a spiral.
Or if you want a really pertinent example, here is an optical illusion where your eyes mistake curvature for flatness. The wavy lines below are consistenly curvy, but the patches in grey look flat and angular. They aren’t.
Your senses, even when your logical brain knows you are being tricked, will still fool you. You can look at something which is absolutely curved but be tricked into seeing something straight. It works the other way round too. I’ve heard flat-Earthers claiming satellites are a myth because nobody has ever seen them with the naked eye from Earth. I’m afraid this one is just embarassing. You can see satellites with the naked eye! If you’ve not seen them in your city suburb it’s because your eyes aren’t good enough at picking out faint lights. Go out in the countryside some night and look up.
Mistake Seven - Cynicism
This is the saddest mistake every flat-Earth argument falls foul of and it’s a real tragedy. Most of the other mistakes I’ve listed are intellectual curiosities, worthy of debate. But this one just makes me unhappy and it’s the hardest to undo.
If you want to believe a flat-Earth argument you have to reject not only all the evidence for the globe Earth...but all the people presenting it. This doesn’t just mean millions of professional Scientists and astronomers. It doesn’t just mean every member of NASA, the ESA and every other space agency. It also means all the commerical pilots and air-traffic controllers. It means all the military navigators, mobile-phone engineers, sailors and meteorologists. It means every amateur backyard-astronomer. It means every kid with a telescope. We are talking tens of millions of people who’s job or hobby involves taking the shape of the Earth into account.
All these people agree the Earth is round and they have evidence to back it. Flat-Earth arguments must logically claim these people are lying. To believe the Earth is truly flat is to believe there is a conspiracy keeping the flat-Earth truth suppressed, with not a single honest whistleblower among them. Forgive me for saying, but that’s an intellectually dishonest approach to take, not to mention a mean-spirited one.
To question an accepted belief is skepticism and that’s great. But making the assumption (and it is an assumption) that every teacher, populariser or user of science is trying to trick everyone is not skepticism...it’s cynicism. It’s pre-deciding that Scientists are corrupt. It’s making a judgement withut evidence and it’s not how we do things as adults.
I understand people criticisng me and my fellow Scientists for being awkward or difficult. I accept that we sometimes preach facts and don’t respond well to questioning like we should. I accept that some Scientists can be arrogant. I even accept that some enjoy feeling superior to the lay-public. But the accusation that we are part of a giant conspiracy to mislead everybody? That’s not putting forward a decent argument, it’s just slander and it debases everyone on both sides.
There are evil scientists yes, but there are good ones too. Scientists who are trying to cure diseases, introduce clean water to poor countries, provide heating, lighting and shelter to millions, and to inspire kids who want to learn. Being a flat-Earther means you have to not only reject a lot of cool and amazing ideas but the cool and amazing people behind them. You have to accept a narrower, simpler, crueller view of who Scientists are and why we do what we do. You have to believe we are trying to decieve you. And that’s not a healthy outlook. I am a teacher because I want to open minds, not trick them. It's simply unkind to assume otherwise. What evidence have you got that I'm evil?
I agree that you should always seek evidence for a claim rather than taking it on faith. Having faith in facts is never a good idea. But having faith in people? That's not so bad.
Alessandro Manzoni: kym-cdn
Flat Earth Map: tfes.org
Admiral Akbar: telegraph
Newton magic: gnosticwarrior
Frustrated teacher: shutterstock
Dog shoes: Daily Mail
Spiral Illusion: croexpress
Curves and lines illusion: Sciencealert
Satellite timelapse: Quora
Trust People: humanengineers
It’s all fun and games until someone loses a planet
In 2006, the International Astronomical Union decided that Pluto was no longer a planet and was instead to be referred to as a “dwarf planet”. Outcry ensued and eleven years later it has not abated.
The physicist Sean Carroll writes in one of his recent books “Pluto is the ninth planet and it’s my book so I’ll call it what I like”, while Neil deGrasse Tyson writes in one of his own “Pluto isn’t a planet, get over it.” There’s even an episode of Rick and Morty where Jerry delivers a speech to the Plutonians, declaring that Earth’s scientists were mistaken in reclassifying it.
The man largely responsible for the monumentous decision, Mike Brown, uses the twitter handle @plutokiller and has the Death star destroying Alderaan for his banner picture. So perhaps it’s all a matter of whimsy and tongue-in-cheek sport. Pluto is, after all, the furthest planet/dwarf from the Sun. Does it really matter what we call it?
I am going to argue that it does, not because astronomical terminology is crucial to our lives but because this debate reflects something important about how Science operates. So hold onto your preconceptions folks! Well, actually don’t. Let go of our preconceptions. But hang onto something.
I’m a Believer
I remember hearing the Pluto news on the radio and thinking it was pedantic nonsense. You can’t just change what Pluto is because someone decides to tweak a definition! I had images of pencil-pushing smart-alecs smarming away to themselves at how clever they were, with no concern for public opinion.
Don’t misunderstand me here, public opinion does not dictate truth and reality is not flexible. But the definitions of words are, and the accepted meaning of a word should reflect its common usage. If everyone agrees on a particular definition, an organisation would be foolish to redefine it.
I also remember thinking the whole thing was bad for Science PR because organisations like the IAU should serve the public not dictate to them. If we use the word “planet” to refer to something which Pluto clearly is, that’s enough reason to preserve its status. But here’s the thing: Pluto doesn’t match the public definition of a planet. That’s why the IAU changed it.
What I was getting wrong eleven years ago was that the IAU genuinely was taking public opinion into account. The reclassification of Pluto was done out of respect for the lay public, not in spite of them.
The First Planets
Every ancient culture monitored the skies, charting the mysterious lights which roam above our heads, and every single one of them made the same discovery. The majority of the twinkling dots follow a clear pattern, changing position on a predictable 365 day-cycle...but five of them do not.
Five of the bright sky-things move on bizarre trajectories, weaving and wailing without rhythm or logic. The Greeks called these five objects “wanderers” (planetes in Greek) because they appeared to wander as if conscious beings. They were assumed to be Gods and were identified as Hermes, Aphrodite, Ares, Zeus and Chronos, later re-named for their Roman counterparts Mercury, Venus, Mars, Jupiter and Saturn.
The first definition of “planet” was therefore extremely simple. A planet was one of the bright lights which moved in non-predictable ways.
But thanks to the work of people like Eratosthenes, Ptolemy, Newton, Buridan, Copernicus, Kepler, Brahe and Galileo, we figured out that the planets were following a pattern, albeit a complex one.
The Sun was sitting at the centre of a circular plane with the planets orbiting at different speeds, one of which was the Earth we stood on. Sometimes Earth would be behind another planet and sometimes it would overtake it, giving the impression of the other planet zig-zagging across the sky - what astronomers call retrograde motion.
To further complicate things, it turned out this view was only about 90% accurate. Firstly, planets move in ellipses rather than circles and secondly, they aren’t going around the Sun at all. Planets and the Sun are actually orbiting each other, it’s just that the Sun is so much bigger so its movements are small. If you assume the Sun is stationary with planets moving around it (what you were probably taught in primary school) you will get the wrong answers when trying to account for planetary motion.
Nature does complicated things so we have to accept equally complicated explanations, even if they contravene what we learned when we were young.
Six and Beyond
By the 18th Century, the definition of a planet had evolved to “something which shares a common centre of mass with the Sun and has a fixed elliptical orbit”. In fairness, that definition is a mouthful so “things which orbit the Sun” will do in a pinch. And there were six planets rather than five, because Earth was one of them.
Then in 1781, the astronomer William Herschel discovered that one of the dimmest stars visible to the naked eye does the retrograde-motion thing. By carefully measuring its position with a telescope, Herschel realised this object wasn’t a star at all, it was orbiting our Sun. This made Herschel the first person in modern history to discover a planet, yielding Mercury, Venus, Earth, Mars, Jupiter, Saturn and George.
The name George didn’t catch on in France however, where King George was despised, so it was eventually renamed after the God of the sky: Uranus. One of the most majestic and powerful figures in classical mythology. Today, it has come to mean something else...well...strictly speaking it should be pronounced “yor-ann-us” but the other way is definitely more fun. As a physics teacher I’m pretty sure I’ve heard every permutation of this joke but I have to be honest, I still find Uranus hilarious.
Then in 1801, Giuseppe Piazzi discovered the eighth planet, Ceres, lurking between Jupiter and Mars. Ceres was the smallest planet discovered to date, at least ten times smaller than the moon, but it orbited the Sun just like the others, so Jupiter was bumped down the list to become the sixth planet, Saturn the seventh and so on. Inconvenient, but as a scientist you change your view when the data forces you.
A few months later Heinrich Olbers discovered another planet at the same distance to the Sun, which he named Pallas. Then in 1804 Karl Harding discovered Juno. In 1807 Olbers discovered Vesta and in 1845 Karl Hencke discovered Astraea.
The thirteenth planet was a little different though. This one was discovered by equation rather than telescope. In 1821, Alexis Bouvard was taking precise measurements of Uranus (hur hur hur) and found that it didn’t move in a standard ellipse. Instead, it seemed to be pulled to the side as if there were another object attracting it and in 1846 Johann Galle finally observed it with a telescope, giving us Neptune.
Then Karl Hencke discovered the planet Hebe in 1847 along the same Mars/Jupiter orbit as most of the others. The fifteenth, Iris, was discovered the same year by John Russell Hind, the sixteenth, Metis, in 1848 by Andrew Graham and the seventeenth, Hygiea, in 1949 by Annibale Gasparis. Hold on a moment...
Back up, back up
Any textbook on astronomy in the 1850s would have listed our solar system as boasting seventeen planets. But as our telescopes got better we discovered more and more objects floating between Mars and Jupiter and by the 1860s there were over a hundred of them, which led to a problem.
When people heard the word “planet” they imagined great big round things with their own orbits, not scraggly space-debris circling the Sun like a moat around a castle. Either we kept the definition of planet to mean “thing which goes round the Sun” or we start using it the way the general public used it, even though it would disqualify the rocks between Mars and Jupiter. After much deliberation we went with the second option.
Although never formally defined, astronomers started using the word planet to refer to what the general public thought the word meant. This meant we needed a new word for the thousands of rocky clumps swimming between Mars and Jupiter and the term “asteroid” was coined.
Really, the problem arose because language evolves slower than Scientific knowledge. We get a word like planet in our vocabulary and it hangs around for hundreds of years, colouring our perceptions. If we discover that reality has nuances to it, we either keep using the old terminology or we invent a new word to describe the stuff we didn’t originally know was there.
The goofy story about Pluto
In 1906, the astronomer (and millionaire) Percival Lowell decided it was time we discovered a ninth planet. He had good reason to suspect there might be something there - minor disturbances in Neptune’s orbit - but mostly he was motivated by the passionate desire to look beyond the edge of what was known. He poured a lot of money and resources into searching for “Planet X” and hired some of the world’s best astronomers to work at his observatory.
Sadly, Lowell died in 1916 before Planet X was discovered, but the mission continued in his absence. Under the direction of Vesto Slipher (who also discovered the redshift effect) Clyde Tombaugh was set the task of searching the sky beyond Neptune and on February 18th 1930, he captured images of what Lowell had hoped for - a ninth planet, roughly the size of the Earth.
Planet X-fever gripped the world and international headlines proclaimed the discovery of the first proper planet since Neptune. A competition was held to decide what we were going to call it and over a thousand names were suggested. The name Pluto was proposed by eleven-year-old Venetia Burney, and ultimately won by popular vote.
By 1948 however, precise measurements were taken on Pluto’s size and it turned out we had been a little premature in declaring it the same mass as the Earth. It was actually about a tenth as heavy. Never mind though, it was still bigger than Mercury.
Except it wasn’t. By 1978 we learned that Pluto was actually about a six hundredth the mass of the Earth, smaller than Mercury and even our planetary moon, making it the smallest planet in the solar system. But it still satisfied the main criterias for it to be a “planet”. It was orbiting the Sun, it was big enough to be round and it occupied a unique orbit. Except it didn’t.
The Second Belt
In 1992, the astronomer Jane Luu discovered a second object floating on Pluto’s orbit which she nicknamed Smiley but was given the official designation 1992-QB1. Then in 2003, the astronomer Mike Brown discovered an asteroid at the same distance, which he called Sedna. He went on to discover Haumea and Orcus in 2004, and then Makemake in 2005. But then, most disconcertingly, Brown discovered Eris, which turned out to be 25% heavier than Pluto.
We can argue that Pluto is a planet on the grounds of it being round, and we can dismiss all the small rocks nearby as asteroids. But when we discover objects heavier or bigger than Pluto on the same orbit, it’s time to rethink things.
Turns out there are over 2,000 objects orbiting past Neptune and Pluto is only one of them. Our solar system doesn’t have one asteroid belt, it has two! This second one has been called the Kuiper belt (pronounced Kie-pur) and its asteroids are very different from the ones we’re familiar with. A lot of them are huge chunks of ice and rock, often many times bigger than planetary moons. Pluto, it turned out, was Ceres all over again - the first object discovered in an asteroid belt and accidentally labeled as a planet.
So what do we do? If we keep calling Pluto a planet then we're misleading people. It’s not very big and it’s not a lone body, it’s just a fat asteroid which happened to get noticed first. But if we want to keep calling Pluto a planet, we need to redefine what that word actually means.
Eventually the IAU decided to repeat what was done in the 1860s. The definition of planet was fixed in people’s minds, so we left it and came up with a new word to fit the new thing: “dwarf planet”.
The definition of a planet is the same as it always has been. Something which a) goes round the Sun, b) is roughly spherical due to gravity and c) has cleared its orbit path so it’s the only dog in town. A dwarf planet is something which hasn’t done the third one...it’s big enough to be interesting, but it’s part of an asteroid belt. This means our solar systerm really has six dwarf planets: Ceres (reclassified from asteroid), Pluto, 2007-OR10, Eris, Haumea and Makemake. And there’s a good chance more will be discovered in the Kuiper belt with time.
I think the IAU made the right call. They were faced with either inventing a new word or changing the meaning of an old one. And the former option is usually the better idea. You can’t force people to change the words they’ve always used, but you can introduce new ones.
When I was a young warthog...
People get annoyed about the whole thing because Pluto, it would appear, has been unfairly demoted. But the thing is, it hasn’t at all. Pluto hasn’t been changed into a different thing - we just discovered what it was all along, like taking the mask off a Scooby-Doo villain.
Imagine you had nine spoons of sugar in front of you. You’re told by everyone that it’s definitely sugar in each one and you believe that for a long time. If you eventually discover the end one is really salt, what you’d say is “oh, I guess we made a mistake”. It would be bizarre to say “I’ve always been taught there are nine tablespoons of sugar and I still believe that’s true. I’m going to redefine what I mean by sugar as ‘any white powder’.”
You’re welcome to do that of course, but in doing so you’re bending the definition away from what everyone means. You’ve also redefined the word to include things like sherbert and powdered glass. Unless you’re extremely stubborn (in which case can I watch you eat your powdered glass cake?) you know what the sensible thing to do is, even if you don’t like it. The intellectually honest approach is to accept that you were taught a mistake. It wasn’t anyone’s fault and nobody lied to you, but you got told something incorrect.
So why do people object to learning the truth? Why do people get upset when a faulty fact is corrected? Shouldn’t that be a good thing?
In the process of writing this blog I consulted with my father, a passionate astronomer (the guy has a five-foot Russian-built telescope with a motor to compensate for Earth’s rotation in his garden shed) and he made a very important point: for a lot of people, this kind of thing can be more about emotion than intellect. If you grow up learning something, it can feel like the rug being pulled out from under you if it turns out to be wrong.
This is a fair point. When I tell the Pluto story to my younger students they are fine with it. I explain that there was a large asteroid which got mistaken for a planet and as soon as we realised the mistake we corrected it. There is no objection to this because “it was mistakenly identifed as a planet” is part of the fact they learn.
It’s only when we are victims of the mistake that it can be a human instinct to fight back. Intellectually we might accept Pluto’s status, but emotionally we are irritated because we are creatures of habit and familiarity.
The same way people objected to Ceres and Pallas being reclassified in the 1860s, people in the 2000s objected to Pluto going the same way. And, just like Ceres and Pallas, people growing up after that decision are fine with Pluto being a dwarf planet. Finding out as an adult that one of your childhood facts was wrong can feel like a piece of your childhood has been knocked away. Nobody likes having their childhood messed with.
Why it Matters
Science offers us insight and knowledge, but it comes at a price - we have to be prepared to let go of familiar beliefs if they turn out to be wrong. This is one of the hardest parts of Science but it’s also one of the most important. It’s the reason we no longer believe the Earth is the centre of the Universe. It’s the reason we no longer believe the planets are Olympian Gods. It’s the reason we make progress in the first place.
And it doesn’t have to be a bad thing. Alright, we lost a planet. That sucks. But technically we gained six dwarf planets as well, so if you want a solar system full of planets, the 2006 ruling gave you exactly that. And, most importantly, we gained a deeper understanding of how complicated the solar system really is.
There are eight planets, hundreds of moons, thousands of asteroids in two different belts (as well as two clumps of asteroids called the Greeks and Trojans orbiting near Jupiter) and probably dozens of dwarf-planets. Not to mention comets from the Oort cloud.
We had to abandon our simple view of reality to get to this astonishing point, and it’s very probable some of what we currently “know” will turn out to be wrong ten years from now. When people are young, they learn a simple view of reality, just as out entire species did. Science is the thing which allows us to move beyond that and gain a more sophisticated and beautiful view of the Universe. It can be painful letting go, but it can be eye-opening and wonderful as well.
Right, now let's deal with this whole "conventional current" malarky...
Mr Arnold from Jurassic Park: blogspot
Arrogant IAU Member: ehowcdn
King Leonidas: huffingtonpost
Fred Durst: impericon
Pluto and Goofy: urdogs
Double belt: blogspot
The Last Jedi: Wallpapersite
Orbit animations: exploremars
I love science, let me tell you why.