5 Billion Years Ago Something Odd Happened | Jupiter Origins and Asteroid Belt

so so so so this original stellar cluster were massive stars that would have dwarfed our own all burning hard and fast it appears that as one of these stars reached the end of its life its death created a supernova and with it a shock wave that rippled through the distant origins of our solar system causing dense regions within the pre-solar nebula to rapidly collapse this moment provided the precise conditions for a new star to form and thus the story of our solar system began for the first 50 million years after the sun was born our corner of the universe was shrouded in darkness the only light the dim red glow of our embryonic star a tea tauride type star struggling to shine through the very earliest years of its infancy from that original cloud of gas the sun forming at its center would swallow up 99 of all the matter in the solar system leaving just a tiny fraction that would go on to form the other planets yet when after around 50 million years the sun's nuclear furnace ignited its light revealed that one giant planet had already scooped up much of the remaining matter a world 300 times more massive than the earth is today jupiter the oldest of all the planets was there to witness the sun's first dawn in fact we think jupiter had been there from almost the very beginning of the solar system evidence suggests that just one million years after the birth of the sun jupiter had already formed a core 20 times more massive than the earth orbiting the dark sun and dividing the building material of the solar system into two distinct regions each with a slightly different chemical makeup that we would be able to observe in the signature of meteorites that fell to earth billions of years later within just a few million years this young giant was 50 times as massive as the earth and it would go on growing in the dark by the time the temperature and pressure at the center of the sun had risen so high that hydrogen began to fuse and light up the heavens entering the main sequence phase of its life in which it continues today jupiter was fully grown under the cover of darkness before the sun's first dawn this planet had taken up its position of power a formidable force that would transform the destiny of every planet that would follow to the romans jupiter was the king of the gods the ruler of the heavens and a figure of power who drove forward the all-conquering roman army with a thunderbolt in one hand and an eagle by his side the name jupiter itself means sky father and it's constructed from the latin words dies day or sky and parthair father and as is often the case with mythology there is a truth lurking amongst the legend in size alone jupiter is by far the biggest planet in the solar system its mass is a staggering 1 900 trillion trillion kilograms that's two and a half times bigger than all of the other planets in our solar system combined it's so big in fact that if you were an alien species observing our system from a distant part of the galaxy the sun and jupiter might well be all you could see with a diameter of 142 984 kilometers at the jovian equator the earth would fit inside jupiter over 1 300 times and yet this giant of a planet is made almost entirely of gas comprising 89 hydrogen and 10 helium it is far less condensed than any of the rocky planets and has a density far smaller than that of the earth 1.326 grams per cubic centimeter compared with earth's 5.513 grams per cubic centimeter for all of its size jupiter also has the shortest day of any planet completing a single rotation every 9 hours 55 minutes and 30 seconds as it whips around on its axis at 45 000 kilometers an hour in the last 50 years our knowledge of jupiter has grown exponentially and with it we've gained a deeper understanding of the role it has played in the shaping of the solar system no longer just the beautiful banded world we see through our telescopes this is a planet that we have explored up close our eyes and ears living within the jovian system for years at a time the first close-up glimpse of the giant planet came with the cameras of the pioneer 10 spacecraft in 1973 this was the first of our planetary explorers to cross the great boundary of the asteroid belt and from an approach of just over 130 000 kilometers it was able to take close-up images in total pioneer 10 sent back over 500 precious pictures of this distant world before flying onto the very edges of the solar system to complete its mission just over a year later pioneer 11 followed hot on the heels of its sibling craft and swept within 43 000 kilometers of jupiter's cloud tops before heading on towards saturn voyager 1 and 2 passed by jupiter in the late 1970s taking the first extraordinary images of not just the planet but its moons too as part of their own grand tour of the solar system this was an historic moment as fran bagonal scientist on the new horizons mission explains we had hints but it wasn't until voyager went up close and personal and took amazing pictures of the moons of the planet that we really began to get a sense of just how complex the worlds around jupiter are and what a variety there is the galileo spacecraft became our first explorer to actually live in the jovian system entering orbit around the planet on the 7th of december 1995 galileo spent two years touring jupiter and allowed us to explore as never before thanks to its audacious deep dive directly into the planet a probe that was released from the craft collected data for almost an hour as it parachuted down through 150 kilometers of jupiter's atmosphere before it was destroyed by the intense pressure and temperature galileo was also the first mission to explore the extraordinary moons of jupiter in any detail helping us to see for the first time that jupiter lies at the center of an extraordinary system with more natural satellites than any other planet holding 79 moons in its orbit at the time of writing 12 of these satellites have been discovered since the beginning of 2017 it's almost certain that the number will rise in the coming years too as we're able to explore the jovian system in even greater detail the vast majority of jupiter's moons 63 are not much more than fragments of rock none bigger than 10 kilometers in diameter and a captured asteroids that now orbit the planet rather than the sun but at the other end of the scale jupiter has four giant moons fiery io is the most volcanically active world in the solar system its surface littered with lakes of lava while icy europa is at the other extreme with its frozen surface protecting a global ocean of water beneath marbled ganymede is jupiter's largest satellite and the only moon we know of that has its own magnetic field while callisto the outermost of jupiter's galilean moons is also thought to be home to a subsurface ocean each moon has a unique intriguing character and they are all visible to us here on earth using nothing more than a pair of binoculars then in august 2011 nasa launched its latest mission to jupiter juno after traveling for five years the spacecraft reached jupiter in july 2016 and entered into a perilous elliptical orbit that took it from eight million to just four thousand kilometers above the cloud tops of jupiter's surface juno is a mission designed to probe for jupiter's origin and evolution which it does by carrying instruments to measure the planet's composition and its magnetic and gravitational fields allowing it to build up a detailed picture of the interior it also has the best camera we've ever pointed at jupiter which since 2016 has been sending back the most incredible images of the giant planet ever taken we'll let heidi becker a jet propulsion laboratory physicist and the radiation monitoring investigation lead on the juno mission explain the detail of this incredible piece of technology the star tracker is an 18 pound camera because it's passed with tungsten in order to keep the radiation out what junocam's images have shown us is that jupiter is like going to an impressionist art gallery it's seeing jupiter and those atmospheric features up close with the highest resolution that's ever been achieved we're seeing the zones and belts the jet streams of jupiter in more detail than ever before for all the majesty and wonder these probes have brought us jupiter remains a vast distant planet sitting on average 588 million kilometers away from us here on earth it's easy to think of this world as a benign beauty a jewel to marvel at but what makes jupiter the true king of the heavens is not just its beauty but its influence over the unfolding story of the solar system as we've explored this world ever closer we're discovering that jupiter's effect on the fates of entire planets is far more direct and violent than we ever imagined its massive gravitational field exerts control not just over its moons but also over every asteroid every world and every life force in the solar system whose destinies it still holds in its vast reach to understand the awesome power of jupiter we don't need a billion dollar spacecraft a rocket or even a telescope all we need to do is to look no further than the ground beneath our feet the surface of our planet is littered with the evidence of our distant godfather's meddling written across our planet in the violent gravitational handiwork of jupiter are at the most recent count 190 visible impact craters not to mention the thousands more that have long disappeared as the active geology of the earth's surface has continually renewed itself one of the most famous is the meteor crater also known as the barringer crater in the northern arizona desert which measures more than a thousand meters across and at its deepest point drops 100 meters below the crater rim in the late 19th century geologists believed this vast feature had been created by the san francisco volcanic field that lies just a handful of miles to the west but in 1903 daniel barringer a mining entrepreneur and sometime hunting friend of theodore roosevelt began an extensive investigation of the crater and published a set of findings suggesting that it had not been created by a volcano but rather by a large incoming projectile from outer space this was the first time anyone had suggested such a theory and barringer backed it up with a host of geological evidence including the discovery of around 30 tons of large iron oxide fragments from the suspect meteorite at the time there was much skepticism that an incoming meteor could create such a massive geological feature but ignoring the overwhelming scientific consensus barringer put his money and reputation firmly where his mouth was and formed the standard iron company the company was created with the sole aim of mining the crater for the 100 million tons of iron ore that barringer believed lay in the ground having been deposited by the incoming meteorite even at 1903 prices if he'd been right that amount of iron ore would have been worth over a billion dollars so unsurprisingly he continued to dig down to depths of over 400 meters in his pursuit of the meteoric remains unfortunately for barringer it would take him 27 years of mining to find out what we know today the meteorite that impacted in that arizona desert was not only much smaller than he predicted with current measurements suggesting it was around 300 000 tons 300 times less than he had thought but also with the benefit of advanced studies in such impacts since then most of the nikolai and meteorite that fell was vaporized as it struck the ground at around 43 000 kilometers per hour barringer's money evaporated not quite as quickly as the meteorite but by 1929 operations at the site had stopped and most of his fortune had gone it would be 50 years before barringer's work would be fully and finally verified with a landmark publication in 1963. analyze the similarities between the geology of the barringer site and the craters that had recently been created as a result of testing nuclear weapons in nevada shoemaker was able to show that the shocked quartz also known as cosight that was identified at barringer crater could only have been formed at the enormously high pressures and temperatures created by a nuclear explosion or in the case of the arizona crater by the extraordinary impact dynamics of a 300 000 ton meteorite crashing into the ground we know now that the giant rock that created the crater like most of the meteorites that strike the earth was once an asteroid just one of the millions of rocks that circle the sun between the orbits of mars and jupiter most of these have been in a stable orbit for billions of years the rocky leftovers of the birth of the solar system they orbit in an eternal junkyard of planetary cast offs but occasionally one of these huge rocks is propelled towards the inner solar system and more often than not we think the nudge that causes it comes from jupiter why this should happen and how jupiter exerts its power not just over the asteroid belt but over all the worlds around our sun is a story we are only just beginning to understand from our home here on earth it's hard to imagine the vast reaches of space that extend beyond our little bubble and the huge expanse of time over which events in the cosmos play out but all the evidence suggests that around 4.5 billion years ago jupiter's orbit began to change and as it did so it triggered a period of unprecedented violence during which the young solar system was utterly transformed we know this because the marauding planet left a trail of destruction in its wake that we've only just begun to explore as we've attempted to uncover the five billion year history of our solar system we've repeatedly looked to the eight planets and the moons that orbit them to provide clues that fill in the gaps in our story in the last 50 years dozens of missions have crossed our thin blue line on the way to those worlds but only once have we sent a spacecraft to explore a very different type of world to search amongst the rubble of our solar system's earliest days and explore the handful of worlds that never quite made it sometimes the answers lie in the gaps launched on the 27th of september 2007 the dawn space probe took off from cape canaveral on a mission to explore the two largest objects in the asteroid belt vesta and the dwarf planet series this 450 million dollar project was part of nasa's low-cost discovery program one of a series of missions designed to be faster and cheaper to deliver but this was no b-list mission for nasa equipped with the most advanced ion propulsion system ever used in outer space dawn would be able to reach the asteroid belt and become the first craft in the history of human exploration to enter orbit around ceres and yet without a major planet in its itinerary the attention of the world only seemed to glance towards this mission and for the most part its extraordinary findings slipped between the gaps of public attention the aim of the dawn mission was simple this would be the first spacecraft to travel to the asteroid belt the first to orbit an object in this uncharted region of the solar system and the first to visit a dwarf planet all in all this mission profile was designed to allow scientists a rare chance to travel deep into the past and glimpse the earliest moments in the origin of our solar system the mission allowed us to explore the evolution of vesta and two very different objects frozen in time for billions of years since they faltered and failed in the process of becoming fully fledged planets to travel to the asteroid belt would be a slow but steady voyage for dawn after hitching a conventional ride into space on the delta ii rocket the spaceship began firing its thrusters to orientate and propel itself away from the earth and towards mars the ion thrusters on dawn were an efficient but gentle form of propulsion for the spacecraft taking four days at full throttle to accelerate the craft from 96 kilometers per hour it's not exactly a sports car but when it comes to efficiency the ion propulsion system is difficult to beat powered by a 10 kilowatt solar array dawn's engines run for almost six years across the eleven year lifetime of the mission propelling the craft across space using less than four hundred kilograms of its xenon fuel supply while reaching speeds of forty one thousand three hundred and sixty kilometers per hour its trajectory took it on a 16 month journey to mars where a gravitational kick sent it on its way out to the asteroid belt and onwards towards vesta its first destination almost 500 million kilometers from the sun the asteroid belt lies halfway between mars and jupiter the boundary line between the four rocky worlds that orbit closest to the sun and the giant gas and ice planets that lie beyond made up of millions of pieces of rock from the dawn of the solar system it's a graveyard of failed planets remnants from the heyday of planetary construction we often imagine the asteroid belt to be a dense unnavigable mass of tumbling rock but in reality it's something quite different the total mass of all those rocks is estimated to be 3 times 10 to the power of 21 kilograms which although an enormous sounding number is just four percent of the mass of our moon with a third of that mass found just in the largest object series the rest of this cosmic junkyard is made up of objects covering a vast range of different sizes on one end of the scale we think there are at least a couple of hundred asteroids larger than 100 kilometers in size then come a million or so stretching to at least one kilometer or more and a countless spread of smaller objects number in the millions and billions depending on how small you want to go all of this sounds like it should make for a crowded environment full of collisions the perfect location to form the basis of a computer game or disaster movie but even with that many objects the space they occupy is so unimaginably vast spread out across 13 trillion trillion cubic miles of space making the average distance between any two large asteroids approximately two million miles or eight times the distance from the earth to the moon these distances are so large that when we send spacecraft to the outer solar system the chances of hitting anything are so small that the engineers don't need to make any course corrections to pass through in fact if you were standing on an asteroid you'd be lucky to see another one and if you did it would appear as little more than a tiny point of light in the darkness as it traveled through this vast emptiness in the early summer of 2011 the dawn spacecraft slowly began to bring its first target into view from a distance of over 1.2 million kilometers dawn took its first photograph of vesta against the backdrop of a thousand stars over the next two months dawn honed in on vesta chasing it across the vast reaches of space to arrive at this the second largest rock in the belt entering its orbit on the 16th of july 2011. dawn became the first spacecraft to enter within the gravitational hold of an object in the asteroid belt and for the next 14 months it would explore this extraordinary ancient object providing a glimpse of our solar system in the very earliest days of its life when for vesta to give it its full name was first discovered by the german astronomer heinrich albers in 1807 it was the fourth asteroid to be discovered after ceres palace and juno hence the four in its formal designation albers was convinced he had found the remains of a lost planet destroyed in some long ago collision even so just like the other three objects at first vesta was given full planetary status bringing the number of classified planets in the solar system at that time to 11. it wasn't until 1845 nearly 40 years later that a flood of further discoveries began that quickly increased the number of objects in this region to a point where it was clear they couldn't be classified as planets and so in the 1850s 15 planets became eight and the classification of these objects as a different class of minor planet asteroids had begun 160 years later as dawn began its year-long residency in the vicinity of vesta it soon became apparent that alba's suggestion that this was a fragment of a long-lost planet was not so far off vesta is a spheroid shaped rock 530 kilometers in diameter and pot marked with impact craters the most striking example of these is the crater rear silvia which at 500 kilometers wide and 20 kilometers deep is one of the largest impact craters in the solar system at its center is a mountain that rises into the blackness 22 kilometers from the crater floor making it the second tallest peak in the solar system after mars olympus mons what's particularly extraordinary about this crater is that we've long suspected that a particular class of meteorite found on earth known as hed meteorites actually come from material that was blown off the surface of vesta when this impact occurred around a billion years or so ago using dawn's instrumentation we were able to directly measure the geology of rocks in reya sylvia and when compared with the samples on earth we were able to conclude that they are of the same origin in one of the most beautiful examples of geological analysis in the history of the subject we now know that we can hold a piece of this far away asteroid in our hands and directly analyze the secrets hidden within it when taken all together the hed meteorites and the findings from the dawn spacecraft have enabled us to paint a detailed picture not just a vesta today but also of its history dawn has revealed to us that vesta has a metal rich core just like all of the terrestrial planets including mercury mars venus and earth and analysis of its surface geology has enabled us to date the formation of the asteroid to a couple of million years after the first solid objects began to take shape in the solar system these are just two of the clues that point us to an extraordinary conclusion vesta is perhaps the last remaining example of a proto-planet a half-formed world from the very earliest days of the solar system frozen in time this is a stage that every world we know of passed through including the earth vesta was on the way to becoming a planet almost 4.5 billion years ago but something happened to stop its progress while other worlds went on to flourish and other proto-planets disintegrated in the violent collisions of the early solar system vesta somehow seemed to survive a fossil of planetary formation for us to not only look at but through a quirk of fate actually hold but this was not the end of dawn's dive into our deep history departing vesta after 14 months of study dawn fired its ion drive leaving the orbit and heading off for its second planetoid rendezvous at the largest of all the asteroids ceres dawn arrived at the dwarf planet series in early march 2015 and from the very first moments of its observations it sent back some astonishing images very little was known about ceres before our spaceship arrived but it soon became clear that this was a rock with far more of a story to tell than we could ever have imagined a story that would help reveal a new perspective on the deep history of our solar system and the enormous influence jupiter has exerted over it the italian astronomer giuseppe piazzi discovered series on the 1st of january 1801 and at first he reported his findings as the discovery of a new comet in the region of space between mars and jupiter but it seems from the start that all of his instincts told him this was something else in announcing his observations in a letter to two fellow astronomers he noted that since its movement is so slow and rather uniform it has occurred to me several times that it might be something better than a comet piazzi and his colleagues speculated that rather than a comet they might have found something even more spectacular a new planet but after just 41 days of observation piazzi fell ill the path of the newly discovered object strayed into the direct glare of the sun and in a twist of high astronomical drama the newly found planet series was lost with just a tiny number of observations across a small piece of sky calculating series orbit was deemed impossible using the mathematics of the time and many contemporary great mathematical minds predicted it might never be found again it would take the work of a young german mathematician friedrich gauss to solve the problem attracted to the difficulty and elegance of using mathematics to compute the orbit from just a few coordinates gauss pioneered a novel mathematical method that allowed him to calculate the path of series using just three of piazzi's original observations on the very last day of 1801 two astronomers using gauss's methods searched the region of the sky to which the calculations guided them and to everyone's delight and relief recovered series from the darkness gauss became a mathematical superstar and series firmly back in our sites were stamped with the classification of a planet for the next 50 years ceres and its companions vesta palace and juno remained listed as planets until as we have seen the discovery of a raft of other objects in this region of space gave rise to our identification of the asteroid belt and for series it was downhill from there on until in 2006 it was classified as a dwarf planet for the next 160 years little was known about this tiny planet orbiting the sun at a distance of 413 million kilometers we knew that it was the biggest object in the asteroid belt and the only object amongst the millions of asteroids that was large enough to have been rounded by its own gravity we could also make a good approximation of its size at around 1 000 kilometers in diameter and composition rock and ice what else but when it came to surface features even the powerful eye of the hubble space telescope could make out only the vaguest of features intriguingly strewn across its surface it would take dawn's arrival for us to truly understand the complexity of this world and its history even in the early approach phase of the mission dawn was able to capture a quality of imagery that at once gave a new perspective on the long hidden surface it was no surprise to find it heavily crated but while speeding towards ceres dawn beamed back a series of mysterious images revealing a number of bright spots on the surface of what we had thought would be a dull dead and frozen world not what you would expect on a planet that was assumed to be entirely geologically inactive the brightest of all of these highly reflective areas was imaged near a massive crater known as arcata at 92 kilometers wide and two kilometers deep it's one of the biggest on the surface of series spot five as it became known is in the center of the crater and became the focus of intense investigation as dawn began its three and a half year residency in orbit around ceres the crater is thought to have formed from a large scale impact around 80 million years ago and so the presence of what appeared to be geological active material on the surface was particularly surprising and at first left the mission scientists perplexed not only that but a haze was also seen to periodically appear above spot five suggesting something was going on beneath the surface after detailed analysis using dawn's full range of imaging and spectroscopic capabilities we now believe that spot 5 is the result of a geological hot spot the brightness created by the highest concentration of carbonate minerals ever found outside the earth in a dome structure right in the center of the crater why does this matter well we know that this type of salt can only be formed in the presence of liquid water and it's almost certain that an impacting asteroid could not have delivered such material to the surface of ceres so the upwelling in which it's found suggests that it comes from deep within this world it now seems that spot five is the remains of an ice volcano one that is perhaps still partially active and thus able to create the haze we have observed the two brightly colored patches inside it are thought to be the salty residue left by this ancient formation deposits of sodium carbonate from an erupting ice volcano that may have first been triggered by the impact that created the crater however the dome-like shape upon which the deposits sit is almost certainly evidence of geological activity below the surface suggesting that hydrothermal activity was involved in bringing the salts to the surface and spot five is far from isolated we've now seen areas like the ones in occata all over the surface of ceres and this begins to paint a tantalizing picture of ceres's past a past where heat from within the planet created a subsurface ocean or at least localized pockets of water that surged upwards in the form of great ice volcanoes bringing with them on the asteroid the carbonate sorts that we see sparkling today as dawn delved deeper beneath the surface the surprises kept coming thick and fast dawn was able to accurately measure the overall density of series and found it to be 2.16 grams per cubic centimeter which is less than you'd expect for a rocky body ceres is about two-thirds the density of our moon which suggests that as well as rock the asteroid must also hold significant amounts of water ice this had been suspected long before dawn arrived but with our eyes and ears now at work as dawn circled series it was able to take precise measurements and so uncover anomalies in its orbit that revealed something remarkable about this lump of rock and ice by carefully mapping the shape and gravitational field we found that the rock and ice weren't evenly distributed it appears that series interior is nothing like that of other asteroids in the belt instead it appears to have a rocky core surrounded by an ice-rich crust this is not the jumbled structure of an asteroid the differentiation into layers that was discovered by dawn is something we only see in planets it seems that around 4.5 billion years ago ceres had taken its first steps to becoming a fully fledged world and then something went catastrophically wrong so we now think that 4.57 billion years ago a young rocky planet began to form in the region we call the asteroid belt in its infancy this proto planet was a water world warmed from within by the heat left over from the violence of its birth even in this frozen region of space orbiting 413 million kilometers away from the weak young sun a deep saltwater ocean encircled the young series protected from the freezing temperatures of space beneath a thin layer of ice across this ancient embryonic world ice volcanoes broke through transforming and renewing the surface as it was bombarded by the bodies that swarmed around it today we see just the lifeless remains of this geologically active world in the distinct mountainous landscape and sparkling salts that clothe it but the subsurface ocean is long gone locked away as a thick layer of ice between the surface and the core this is a nascent planet that has been in deep stasis for billions of years frozen in time it is a precious piece of history an artifact that allows us to glimpse our origins and understand just how precarious a time this was for every planet including our own we now think that before ceres could fulfill her potential a great disturbance sent shock waves through what would eventually become the asteroid belt and cut its young life short the vast amounts of rock and ice that made this part of the young solar system such a rich breeding ground for the birth of planets was wiped clean of almost all of its building material leaving just a fraction of the material needed to build a planet and nothing from which series could grow computer simulations suggest that originally the asteroid belt contained enough material to build a planet the size of earth and perhaps that was once ceres's destiny perhaps it was even destined to become a subterranean water world capable of supporting and nurturing life but before any carbon chemistry could spark into seeds of life ceres's fate was sealed triggered by the wanderings of a giant that lay beyond in the darkness we now suspect that at this early time in the life of the solar system as jupiter circled the young sun something caused the giant planet to change course and spiral inwards towards the sun plowing right through the asteroid belt the resulting gravitational chaos scattered the contents of the asteroid belt far and wide embryonic planets were knocked out from their orbits the building material of these planetesimals was thrown out and in towards the sun jupiter's charge displaced 99.9 percent of the material in this region of space leaving series half formed half built but with nothing more from which to grow in this part of the solar system at least the planetary construction business was shut down for good you

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Length: 41min 1sec (2461 seconds)

Published: Sat Nov 28 2020