Halley's Comet: Earth's Constant Companion

this video is brought to you by blinkist the first 100 people to go to blinkist.com forward slash geographics we'll get one week to try it out for free you'll also get 25 percent off the cost of full membership more on them in just a bit it's been called humanity's constant companion every 75 or 76 years since the dawn of civilization a bright object has streaked across earth's skies hypnotizing those below the ancient chinese and babylonians recorded its movements the romans considered it a portent of defeat and destruction in the medieval period genghis khan is said to have proclaimed it his own personal star yet the great khan was wrong apart from being a star the object was a comet perhaps the most famous comet in history named after the british astronomer edmund haley its regular visits would revolutionize our understanding of the solar system prior to haley's discovery that this comet was the same one seen repeatedly across history no one knew that comets orbited the sun even after the truth was uncovered haley's comet remained a source of fascination and mystery from the life and death of mark twain to the challenger disaster via the great comet panic of 1910 this is the tale of both haley's comet itself and how this one distant ball of ice and dust helped shape our modern world if you were to jump in a handy tardis and travel back in time 4.5 billion years you'd be in for a hell of a sight our solar system as we know it didn't exist back then instead great clouds of dust swirled around our newborn sun chunks of debris slowly over millions of years coalescing into solid objects if you hung around long enough in this bygone age you'd eventually see most of that gas and dust become the planets but not all of it out at a place called the snow line far enough away from our young star for solid ice to exist a different class of objects would be forming eventually these icy objects would get scattered out joining a huge shell of debris surrounding our solar system called the oort cloud it's these primordial objects that would become our solar system's comets today we know of something in the region of 6600 comets the majority of these are long period comets beginning in the oort cloud and swinging in towards the inner solar system on journeys that can take up to a thousand years but there's another class of comments one with much shorter orbits it's within these short period comets that we find hayley's short period comments are typically broken into separate classes with the main two being jupiter family comets and haley type comets most fall into the jupiter family meaning at some point in the distant past they got snared into jupiter's gravity and now pool around our neighborhood whizzing past us every 20 years or so but slightly over a hundred fall into the haley type class including surprise surprise haley's comment a former long-period comet that got disrupted by the gravity of jupiter and saturn haley types are the oddballs of the comet family neither clinging to jupiter like a bad prom date nor zooming all the way out to the oort clouds to check in on old acquaintances their orbits can last anywhere from 20 years to 200 although haley's itself clocks in at around 76 exactly when it's settled into this orbit is a matter of speculation something sixteen thousand years ago while others put the figure at more like two hundred thousand if the latter is true that means this comet has been with us for almost the entirety of human history streaking periodically through the night sky since our earliest ancestors evolved on the plains of africa a witness to every 76th year of our species's story well on average at least the length of haley's journey actually changes depending on how its path gets disrupted by the outer planet's gravity it may only take 74 years or as many as 79. still there are some constants it's always visible to the naked eye when passing earth and it's the only comet it's possible to see twice in one lifetime without using a telescope but while halleys can be seen near earth at other times it's nearly invisible the core of every comet is something called its nucleus a chunk of ice mixed with dust when it swings by the sun that ice turns to vapor and escapes forming the bright long tail you see in the sky and shrouding the nucleus in a reflective corona a process known as outgassing but the nucleus of haley's comet has unbelievable amounts of dust in it so much so that the entire 15 kilometer by 18 kilometer surface is almost pitch black when not outgassing it reflects just three percent of the light to fall on it less than a lump of coal that means hayley's at different points in its orbit is both one of the brightest and darkest objects in the night sky yet that dust does more than just make the comet look like a big dirty snowball as hayley zips through our solar system it leaves a trail of debris in its wake every october and may the earth passes through that trail the dust burns up in our atmosphere becoming the orionid and aquirid meteor showers in other words if you go outside around the 21st of october and see a shooting star it's likely a fragment of our solar system's most famous comet cool as this is though it's only relatively recently that we've known these science facts for most of human history haley's comet was regarded not with wonder but with all and terror 466 bc was a pretty sketchy year in ancient greece at some point that summer a meteor the size of a wagon came crashing into the hellespont strait scaring the living crap out of locals and creating an instant tourist attraction if that wasn't enough a huge fiery body then appeared in the night sky that didn't vanish for 75 days today the 466 bc fireball is thought to be the first recorded sighting of haley's comet with the contemporary meteor strike either being an asteroid the comet disrupted from orbit or just a really weird coincidence but while it was the first the sighting in greece isn't the only ancient record that we have for halley's go through the history books and our constant companion is cropping up everywhere in han dynasty china for example a broom star was reported in the sky in what we'd call 240 bc the babylonians meanwhile tracked its movements on clay tablets in both 164 and 87 bc two orbits later in 6680 flavius josephus thought that it looked like a sword and declared it had been an omen that the romans would destroy jerusalem's second temple in fact the comet's appearance generally seemed to have been linked in roman times with stuff getting destroyed showing in 451 a.d capped off attila the huns legendary campaigns of conquest not that anyone knew these sightings were all the same comet though it can be easy to forget in a quick overview like this but no one prior to edmund haley figured out that comets were capable of returning so when haley's comic came cruising back for its closest ever encounter with earth in april 837 people weren't all like ah look cool the comets come back they're all more like the sky's on fire again why at just 5 million kilometers from earth haley's in 837 dominated the night sky its tail is said to have stretched a third of the way across the horizon perhaps unsurprisingly it caused terror everywhere in japan europe baghdad and imperial china people freaked the hell out astronomers were summoned to kings disasters were predicted calamities prepared for but it would be another 229 years before the predicted catastrophe struck at least from one country's point of view in 1066 the anglo-saxon chronicle records a long-haired star appearing in the sky over england if you know anything about british history you'll know that 1066 is a major year it's the year the norman king william the conqueror looked across the channel and decided it was time to live up to his nickname that october williams invading forces smashed those of english king harold ii at the battle of hastings the norman conquest was so total it forever altered english history the language you're watching this in well it would be completely different without this one event of course haley's comet didn't cause the battle of hastings any more than it caused the romans to smash up the second temple but william did consider its appearance as a good omen when it came time to record his achievements in the massive art brag we call the bear tapestry the comet featured prominently nor was william the only conqueror to link his good fortune with our celestial companion two orbits later in 1222 genghis khan is said to have both decided the comet was his own personal star and that it was telling him to take his mongol hordes and invade europe while the invasion carried out by his heirs wouldn't be quite as successful as the norman conquest it would briefly establish the largest contiguous empire in human history and note to any would-be conquerors out there july 2061 the date haley's next returns is definitely one to pencil into the diary yet while halley's comet would witness some transformative moments in human history the biggest moment came not from wars or conquest or meteor strikes but from two men two men armed with nothing more than some stuffy books and brains the size of your average planet together isaac newton and edmund haley were going to change how we viewed the night sky forever now before we continue with our story today how about an app that will change the way that you view books forever that's exactly what today's sponsor blinkist can do for you how many times have you seen a book and thought gee that looks really interesting i wonder if i could read it in 14 minutes well if you're like me this happens all the time i mean reading's great but i do have other stuff to do i can't just sit down for three days in the middle of the week and devour a book and bless him on holiday but i'm rarely on holiday fortunately there's blinkist which condenses that meaty hardback you've been staring at into 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the video for edmund haley the great comet of 1680 was a seminal event at the time the 24 year old englishman was traveling around europe meeting the great thinkers of his day it was a heck of a time to be doing so early in that century johannes kepler created his three laws of planetary motion revolutionizing her understanding of the sky now new more powerful telescopes were unveiling the mysteries of the cosmos pushing galileo's early discoveries to the limits it was the era of cassini of isaac newton of super brainy dudes being super interested in science and haley was about to join their ranks in 1680 haley was among the millions who looked skyward in wonder as the great comet streaked through the heavens it was an experience he'd never forget one that would lead to his name going down in history but not attached to the great comet that comet was a one-off event streaking in and then zooming away the comet that would bear haley's name wouldn't appear until two years later even then he wouldn't discover it yet it was the great comet that would give him the keys to his breakthrough simply because it gave him something to talk about with isaac newton when the two first met in 1682 haley was doubtless aware of newton's bad tempered reputation so he talked about something that would interest him the 1680 comet as a result newton wound up categorizing haley as not just another boring dude to ignore but as an almost friend for haley this friendship would pay off big time cut ahead two years to 1684. while with his friends robert hook and christopher wren haley got into a super brainy dissection of kepler's three laws the laws seemed to imply some unknown force keeping the planets in orbit around the sun but no one could say what this force actually was or how to use it for making calculations when haley dropped in on his new pal newton a few months later he mentioned the discussion only for newton to be all like yeah that's what i call gravity i figured it out ages ago what's for lunch forcing newton to develop and publish his theories quickly became haley's life work when newton ran into financial trouble haley bankrolled him well that was principia mathematica the basic starting point of physics as we know it but if you want to learn about that you can go watch our newton video over on the sister channel biographics for today's story the important point is that haley found in newton's work methods he could apply to other celestial objects objects like comets the next few years haley worked on his project to calculate the orbits of 24 comets but it was only when he started working on the comet of 1682 overshadowed at the time by the great comet that he found something wild if newton's theories were correct then the 1682 comet would come past earth every 75 or 76 years stunned haley looked for previous comet sightings to back his idea up he found one in 1607 recorded by kepler and another in 1531. as haley himself put it i am more and more confirmed that we have seen that comet now three times since year 1531. more importantly he made a bold prediction that the same comet would return again in 1758. let's pause for a moment and take in how ballsy this was some of the greatest minds of haley's day still thought comets were atmospheric phenomena even those who assumed they were celestial objects had never considered that they might be repeat visitors if haley's prediction came true it would change her understanding of the solar system of physics and that's exactly what happened at christmas 1758 the comet was spotted through a telescope right on schedule it became visible to the naked eye in march but haley of course was no longer around to see it the astronomer had died 17 years earlier at the age of 85 certain to the very end that his prediction would be proved right when it was french astronomer nicolas louis de la cal proposed the comet be named in his honor haley's comet has been carrying the visionary mathematician's memory ever since [Music] considering it was such a big deal in 1785 the next return of haley's comet in 1835 was something of a flop early 19th century people were all like way more into top hats than celestial phenomena and they basically ignored it in fact the only thing of note that happened around this time was mark twain being born two weeks after the comet passed through the sky in his old age twain would delight in noting that he came in with haley's comet and intended to go out with it again remarkably he died just one day after it reappeared in 1910 but most people in 1910 were way too busy freaking out to remark on the coincidence that's because haley's 1910 visit was accompanied by planet-wide hysteria back in 1908 a comet known as comet morehouse had appeared in the sky thanks to scientific advances it was one of the first comets to be photographed on plates and studied on spectra the results showed its tail containing the toxic gas cyanogen and this was a problem because earth's orbit was projected to pass right through the tail of haley's comet when it reappeared as 9010 approached worries about this gigantic cloud of poison began to ripple through the press in france the authorities decided to tackle the panic by asking a famous astronomer camille flamirion to address the public's fears unfortunately flamerion took this as an opportunity to terrify everybody in a spectacularly misjudged speech marion said that the comet probably didn't have enough toxic gas in its tail to cause a problem but if it did then all life on earth would be extinguished in minutes get to guess which part of that sentence the press focused on although other scientists rushed to assured the world that any cyanogen would decompose in earth's upper atmosphere the damage had been done flamerion's speech did for hayley's comment what shoddy research misreported blood clots can do for vaccines send people absolutely loco about in the u.s people tried to seal their doors and windows to keep the poison out in europe locals filled the streets of paris for one last dance in oklahoma a cult supposedly even tried sacrificing virgins to appease the angry comet although it's hard to find any contemporary sources backing that story up finally during the night of may the 18th to may the 19th 1910 the earth went zooming through hayley's dust tail and billions held their breath and of course nothing happened as you can probably tell from the fact you're watching this all animal life wasn't wiped out by haley's comet the worst happened was that a lot of people probably woke up the next morning feeling rather embarrassed about declaring their love to the cute girl at the apothecary the common panic of 1910 was a great example of a little bit of knowledge being a dangerous thing humanity had evolved beyond thinking comets were omens of doom only to then invent a scientific reason why we should still be scared of them thankfully the next time haley's returned we'd have moved beyond panics or even detached scientific observation this time humanity was going to get up close and personal with our constant companion while haley's was busy whizzing out beyond the orbit of neptune towards its aphelion or furthest point from the sun some 5.2 billion kilometers away scientists on earth were trying to figure out what exactly comets were we knew by now that they were celestial bodies and we also knew they weren't capable of mass poisoning the earth but what really were they what did they consist of the leading theories were the sand bank theory stating that the nucleus was a collection of dust and gases and then there's the dirty snowball which basically means the nucleus is solid ice with both theories sounding plausible it was eventually decided the best way to figure it out would just be to fly something up to the comet and see care to guess which comet they picked the first sighting of haley's return occurred on october 16 1982 when it was still beyond saturn by then plans were already in place for our first encounter with it sadly they would only lead to one of nasa's greatest tragedies the 1986 challenger disaster is remembered today for many reasons being broadcast live for being wholly preventable and for killing christa mcauliffe supposed to be the first teacher in space but what's less remembered is his connection to haley's comet one of the main reasons challenger took flight that fateful day was to deploy a satellite for monitoring hayley's as it passed earth parts of a multinational effort to image the comet up close instead america watched in horror as the challenger broke apart killing everyone on board the idea that comets are bad omens may be superstitious nonsense but sadly in this case it was also true with nasa out at the game the job of meeting hayley's comet fell to a scattering of probes known as the armada supplied by japan the ussr and the european space agency or esa they swung into action in march of 1986 taking pictures that would show us the comet as we'd never seen it before and boy did they ever succeed their shots of haley's nucleus surrounded by white jets of gas is one of the defining space images of the decade taken by the esa's probe from a distance of 600 kilometers they proved once and for all that comet nuclei are solid more than that though they allowed us to finally meet our long-term visitor tens or hundreds of thousands of years ago the first humans to spot the comet it looked skyward and been paralyzed with wonder or maybe fear at the sight of it for countless millennia since it had excited the passions of people on earth leading to scientific breakthroughs appearances in art maybe even invasions and conquest at long last seeing it as it really was a piece of primordial ice and dirt on a lonely journey through our solar system it was a moment no one prior to the 20th century could have imagined a spectacular human achievement and for now that's where we have to leave it after halley's retreated out the inner solar system it passed beyond the distance where even our most powerful telescopes could image it now there's nothing we can do but wait wait for our constant companion to come back around for another visit and see how things have changed already its return looks set to be spectacular when it passed earth in 1986 the comet was at its dimmest ever recorded that means almost no one alive today with the exception of super lucky people like kanye tanaka born in 1903 and still alive in spring 2021 have seen what it's really capable of but next time will be different on its next pass in july 2061 haley's comet is said to be much brighter than last time if you can hang on for another 40 years that means you're going to be in for a hell of a show what are the future though how much longer will our celestial companion be with us the answer is no one knows every time a comet the size of hayley swings around the sun it loses up to three meters of material from its nucleus as enough material is ejected the comet eventually dims losing its bright tail eventually it may just disintegrate or else get caught by jupiter's gravity and torn apart for the average periodic comet it's thought that this happens around the 1000th orbit since our time frame for haley's beginning its journey is anywhere between 16 000 and 200 thousand years ago that means it could die relatively soon or it could continue for tens of thousands more years however long it takes we know for certain that so long as it's around haley's comet will continue to watch over us to inspire us perhaps even terrify us like the best kind of old friend its novelty may wear off but we'll never grow tired of seeing it so i really hope you found that video interesting if you did please do hit that thumbs up button below don't forget to subscribe also please do check out fantastic sponsor blinkist linked to below and thank you for watching

Channel: Geographics

Views: 385,733

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Id: Gmvdnpnt50A

Length: 21min 0sec (1260 seconds)

Published: Mon Jun 07 2021