The Universe: THE WORLD-DESTROYING DEATH OF STARS *2 Hour Marathon*

they are cosmic Killers they're the end of stars they're the deaths of stars spectacular Stellar detonations 100 billion times as bright as the sun that for an instant outshine a whole galaxy the most massive energetic event in the universe since the big bag out of this exceptional Cosmic catastrophe comes creation but if one struck near here life on Earth would cease the universe the cosmic crime scene for a most violent and mysterious Force super [Music] noas supernovas The Sensational and exceptional death of stars produce the biggest blasts in the universe now only a small minority of stars actually explode but those that do just go cam blowing themselves to Smither releasing more energy than the sun does in its entire lifetime by more than a billion the spectac detonation blasts vast amounts of lethal radiation into the universe if a star at the center Planet system would go supernova and explode it would probably wipe out all forms of life in that planetary system radiation would basically sterilize all forms of life on any planet in a planetary system like homicide detectives pouring over Clues to a cosmic crime scientists use state-of-the-art tools telescopes and Technology to find supernovas and to solve the mystery of how and why they occur it's an interesting thing because the explosion the event has already taken place and then we get these Clues which we gather with our telescopes and try to figure out what happened as the Stellar investigators know supernovas have a personality they have absolute power to destroy and at the same time they are fundamental to Creation itself when a supernova goes off the explosion produces a lot of light but it also produces heavy elements out of the light ones so for example iron or calcium or sodium or any of the elements of the periodic table those things came from exploding stars that went off before the sun was formed the elements produced in these enormous Stellar explosions actually make planets plants and people the calcium in your bones and the oxygen that you breathe were all cooked up in stars and blown out into space the shock waves from exploding Stars can come press nearby clouds of gas and Trigger their gravitational collapse so that they begin the renewed process of formation of new stars planets and ultimately life thanks to circumstantial Cosmic evidence collected experts estimate that a mighty Supernova goes off somewhere in the universe once every single second so that's something like 30 million per year and that's been going on for the last 10 billion years or so of the universe's existence giving us a sense of how big the universe is in a typical Galaxy like our Milky Way a supernova suddenly occurs only once or twice a century however nobody knows when the next one might come it's a completely random process so we we have no idea when the next one will occur it could be tomorrow could be you know 5 minutes ago could be another hundred years we don't know if it is very close you would see a very bright event in the sky it could be even brighter than the the Venus or the planets or even the moon or maybe even the sun if it's bright enough if a supernova is too close to you it can definitely destroy life The Flash disrupts the atmosphere Burns things up astronomers are constantly policing the skies keeping a weary eye on at least two stars in the Milky Way that have the potential to catastrophically explode close to Earth one that threatens to blow lies in the heart of the Ada Karina nebula about 9,000 light years away Ada Kina is one that we know about which is a very massive star maybe even a 100 times the mass of the Sun has a very short life and it could be that the end of that life uh will take place sometime very soon another star in danger of going Supernova is Beetlejuice a star in the Orion constellation this seething star is 15 times the size of the sun this one is even closer than Ada Karina to Earth it's roughly 500 light years away it'll be a spectacularly brilliant site visible even in the daytime there's no question Bal juice is going to blow up it could be tonight for all our ignorance it could be 10,000 years from now short on an astronomical time scale but it could be tonight that we're sufficiently ignorant about it so it is worth looking at every night to see whether it's blown up not only do the massive Supernova explosions create and Destroy stars planets and people they also unleash powerful energy in the form of cosmic rays these highly energetic charged particles strike our planet each and every day what's more they have the capacity to alter Evolution we live in a what I call a disturbed Galactic ecology it is a very eruptive energetic Galaxy out there and our planet is going to get pummeled by that that stuff experts say they can and do change Life as we know it well we know that there are genetic mutations that take place when cosmic rays hit living things it disrupts the DNA inside cells and if there were a supernova nearby there could be a lot more cosmic rays like a 100 or a thousand or a million times more than we ordinarily get if you're the old species it might lead to your demise but it also might lead to new species being developed so uh Supernova could be an agent of change and it could be For Better or For [Music] Worse knowing that supernovas have the power to create and alter life makes it imperative that humankind unravel the riddle of what makes these Stellar time bombs tick what have you got here all right so uh this is the Supernova Factory Supernova uh the key to unlocking the mystery lies in the detailed analysis of what is ejected into the cosmos by a supernova I'm glad this one did not Escape our attention cuz it was a winner yeah it's a great Supernova Nature has given us this puzzle it says I make these objects easily and we as theorists have to figure out how nature does it5 as with any crime scene critical Clues are contained in what is Left Behind like a gunshot hot gases and explosive debris are propelled through space by these deadly Stellar explosions just as these gunshots are driving a shock wave and you can hear this strong noise from the shock wave it's actually compressing the matter and heating it up shock wave in a supernova is doing the same thing as these pieces of shrapnel are hurdling very fast through space they collide with the material around it and what forms is a shock wave the fence fantastic Stellar detonation shoots vast amounts of ballistic Supernova evidence Cosmic debris called remnants into the universe so the reps are produced as the shock wave keeps on moving out through the universe it actually produces this very pictures image of the shock moving outward the gases that made up that star uh are ejected at tremendous velocities 10,000 m a second and so they create the expanding shell and eventually that can become very very large these things go for thousands of years or even tens of thousands of years so sometimes we can see the sight of a supernova explosion tens of thousands of years after the event has taken place the high-speed Collision of Stellar debris in the shock wave produces intense heat and light in wavelengths invisible to the human eye they include radio infrared all the way to X-rays and gamma rays fortunately for astronomers sophisticated space-based instruments like Hubble Spitzer and the Chandra x-ray telescope can help the cosmic detectives see them all so basically every instrument in every way you can gives you a somewhat different perspective on what's going on so then you try to put all that together as an intellectual Enterprise like a fingerprint each Supernova has a unique pattern and they can be analyzed in several different ways one thing we can do is measure how bright the Supernova is and that's what we call the light curve the other thing that we can measure that is really helpful is what we call the Spectrum we take the light from a supernova at a telescope spread it out into a little Rainbow using a prism or a grading and then measure how much light there is uh at each color or wavelength analysis of that line can tell us lots of interesting things like the chemical composition of the Supernova the temperature the pressures and densities of the gases how quickly they're expanding and so on information gleaned from the light curve and Spectrum reveals distinctions between each supernova so it is much like a detective job where you get different Clues from the light curve or from the Spectrum and try to figure out what kind of star it was what made it explode what the products of the explosion were and what the effects of that explosion might be as time goes on we can see deeper and deeper into what the star originally was so we can actually get uh what the composition of the star was at the time it exploded by comparing the light curves and Spectra from literally hundreds of supernova cases scientists have been able to classify supernovas into two main types type 1A Supernova release No hydrogen the explosions are uniform in size and Luminosity type two Supernova release large amounts of hydrogen the explosions vary greatly in size and Luminosity but why would there be such distinct types of exploding Stars might they be blowing themselves apart in different ways scientists focused their efforts on uncovering the mammoth question what drives these Stellar monsters to destroy themselves like Bounty Hunters looking for Bandits today's astronomers scour the cosmos looking for deadly supernovas with their Keen eyes on the sky they belong to a long lineage of Stellar observers in fact the first Supernova ever witnessed by man occurred in China in 185 ad 2,000 years ago the Chinese astronomers kept very meticulous records about what they saw in the sky specifically when something new appeared they recorded how bright it was where it was how long it was there using the Royal Chinese records Stellar investigators today have recently found the remnant of this ancient Supernova it is identified ified as RCW 86 and is in the constellation Centaurus near two Bright Stars known as Alpha and beta centor 1,400 years after the Chinese Discovery the first European Observer witnessed a supernova on November 11th 1572 26-year-old Danish astronomer Tao brah was taking a walk when he witnessed a shocking stellar phenomenon in the northern sky it was right next to the W etched by the brightest stars in the constellation copia even though he saw it and even though he was the leading astronomer of his age he did not believe the sense of his own eyes a few years after Tao's remarkable sighting his former pupil johans Kepler made his own groundbreaking observation of a new new star he measured from star to star around it the distance and we can use that now to recreate exactly the position of where it exploded when contemporary investigators took a closer look at Kepler's 16004 Remnant they found something very strange about it a detailed analysis of the chemical composition of the ejected and expanding gases indicated that there were two stars that somehow joined to produce a gigantic explosion so how did this companion caused the Stellar catastrophe many stars are in binary systems so they have a partner that is orbiting around them and we think what happens is that one star puts Mass onto the other experts have since found that the companion or binary scenario is the Hallmark of what is called a type 1A SU Supernova the type one Supernova we think are the explosion of white dwarfs so a star like the sun will produce a little dense nugget about the size of the Earth when a star like the Sun dies it ejects its outer layers and leaves behind just a small dense burnt out core called a white dwarf the ashes of the sun will be a carbon and oxygen white dwarf left by to its phone devices that will just last forever and cool off but when a star has a companion like a partner in crime it can lead to catastrophe one star puts Mass onto that white dwarf pushes its mass up to the point where it becomes unstable and that there is burning that takes place in the center and very very rapidly the star goes from being a kind of boring white dwarf to being a tremendously violent and Brilliant supernova but why do some white dwarfs catastrophically explode that was figured out in 1930 by a brilliant young astrophysicist subaman Chandra seikar the Sherlock Holmes of astrophysics on a boat trip from India to England during this long Voyage he used the newly developed fields of quantum physics and special relativity to come up with the idea that a white dwarf can have only a certain maximum limiting Mass you cannot go beyond a certain Mass about 40% bigger than that of our sun 1.4 solar masses and this came to be known as the chundra sear limit and at that point an uncontrolled runaway chain of nuclear reaction ensues but for decades scientific investigators remain puzzled by just how this explosive Chain Reaction worked and what it looked like when it did computer models could never recreate what seemed to be happening in nature but then in 2006 astrophysicists from the University of Chicago's prestigious flash Center literally cracked the code the Chicago team was the first to create a superc Compu program capable of processing the vast amounts of data it had to be to simulate the complicated Dynamics involved in the explosion of a whole star we call this extreme Computing the computers we use some of them have 128,000 processors so they're really 120 8,000 desktop computers all linked together even with all that power it took almost 60,000 hours of computing time the astrophysicists decided not to start their simulated explosion exactly at the center of the star reason that we decided to start slightly off center rather than right at the center is that it's just very very improbable that the flame will ignite exactly or even really close to the Center there's just no volume there there's no there there according to the remarkable simulation in 1 second a flame bubble forms inside the star so what you see right in the center of the star is the bubble Rising quickly growing expanding as the burning takes place and breaking through the surface of the star the molten bubble initially measures approximately 10 m across and right Rises more than 1200 mil to the surface of the star it's spreading over the star about 3,000 miles a second and it collides at the opposite point on the surface of the star and produces extremely energetic Jets one that's moving outward at about 40,000 m a second and another jet that's punching in towards a star and that ignites a detonation wave which you've just seen raiseed to the star T temp temperatures depicted using a standard color scale reach an unfathomable 3 billion de F and you can see the moment is just detonated and going through the star takes less than half a second the whole burning phase takes less than 3 seconds expert analysis reveals that each type 1A Supernova is remarkably similar in size and Brilliance this explosion is equivalent to completely detonating aass the size of the sun this groundbreaking computer simulation illustrates for the first time how the explosions could occur in a type 1A Supernova but type twos seem to be a radically different Animal by examining the Stellar debris scientists have reasoned That Type 2 supernovas are not the result of exploding white dwarfs but rather the huge blasts of massive dying stars at least 10 times the mass of the Sun but how do these Mega explosions work the answer to the cosmic conundrum would come in the middle of the 20th century that's when Supernova gum shoes for the first time in history pounded The Intergalactic Pavements syst systematically seeking gigantic exploding stars like detectives on a Stakeout Cosmic investigators constantly scan the night sky they're looking for The Telltale bright lights that are evidence of a supernova to carry out their surveillance they use an impressive array of high-tech telescopes scattered across the globe historically we discover Supernova with groundbased telescope are scanning the sky constantly to look for new Supernova explosions the cosmic Supernova hunt began in the 1930s Maverick astrophysicist Fritz swii led the charge he was the first to methodically search catalog and quantify by new and exploding Stars he was one of the real Pioneers in finding exploding stars and then he wanted to physically understand what they are the trailblazing astrophysicist proposed that these enormous and spectacular Stellar events were the result of whole stars exploding swii predicted that a certain kind of exploding star can occur when a massive star's core collapses and then rebounds creating a colossal explosion during the collapse they said a compact Remnant should be formed a ball of neutrons a neutron star essentially ordinary matter is made out of protons and neutrons and electrons in this collapse of an iron core the the the protons and the electrons that make up the iron atoms combined to make neutrons a neutron star is an incredibly dense object now if you were to take a large building like the Empire State Building in New York and compress it to the density of a neutron star it would be about the size of a marble they uh have a very high density and in fact a teaspoon of neutron star material would weigh as much as 1 billion tons on earth scientists today believe that only huge stars at least 10 times the mass of the Sun have the potential to generate this core collapse type explosion the massive star generates energy by fusing hydrogen to helium it confuse helium into carbon and oxygen and it keeps on going all the way up to make iron iron is the most tightly bound nucleus so when a star has made Iron it's really at the end of The L and it's ready for dis disaster the iron core forms in the last day of the star's life and then it becomes so massive that essentially it collapses under its own weight just collapses gravitationally very quickly it takes less than a second for the core of the star to Crunch down from something about the size of the Earth to a neutron star which is maybe 10 or 15 mil across but this dense iron core doesn't settle down peacefully into its New Life as a neutron star but instead of reaching an equilibrium configuration right away the neutron star rebounds off of itself just as the gymnast rebounds off of the trampoline and goes upward again well this rebounding neutron star collides with the material surrounding it and impart s some of its energy to that colliding material thus initiating an ejection however unlike a gymnast for whom gravity ultimately prevails pulling him back to Earth in a core collapse scenario something else continues to drive the ejection outward the question became what was this mysterious Force driving the blast into space experts calculated that in order for a successful explosion to occur one more ingredient was needed they suspected something called neutrinos ghostly energy bearing particles that had been predicted but never observed astrophysicists believe that during a core collapse when the electrons are pushed so close to prot protons in the nuclei of atoms that they combine to become neutrons in the process they release these tiny mysterious neutrino particles the neutrinos are kind of interesting particles they don't have any electric charge so they don't interact with light they only interact by what physicists call the weak force and the weak force is aptly named it means that these particles can go right through the Earth they can go through long chunks of matter so they're they're like ghosts they just go through [Music] things for centuries modern astronomers had been studying the remnants of supernovas in far away galaxies from the distant past but in 1987 they would get a front row seat to an explosion of their very own it was the brightest Supernova scene in nearly four centuries long after after the development of the telescope so we could use our full arsenal of equipment to study this fantastic blast in 1987 the most fantastic Stellar event near our galaxy since the invention of the telescope occurred the first to witness it was young Chilean astronomer Oscar delal his and astronomy's good fortune came on the night of February 23rd 1987 a telescope operator at L lasanas observatories Oscar dual put water on for coffee and went outside to take a look at the sky and when Oscar went out there he looked at the large melenic Cloud which he knows very well and he noticed that there was an extra star so he discovered this super of explosion while basically running outside the telescope building and saw with his own eyes when a star explodes astrophysicists like investigators looking for Clues to a crime know that the first few hours after the Stell death are the most critical so in 1987 when the closest Supernova in nearly 400 years appeared they knew they had to act fast it was only about 170,000 light years away a mere Stones Throw for an astronomer Supernova 1987a was in a small Galaxy called the large melenic Cloud a dwarf Galaxy that orbits around our much bigger Milky Way galaxy being the first Supernova of that year the exceptional and nearby exploding star was simply labeled sn1987a but this time dozens of seasoned astronomers all over the planet were ready for action armed with sophisticated tools and telescopes they turned their mindes and machines to the heavens and closely scrutinized Supernova 1987a knowing that an exploding star is at its hottest in the first few hours and is emitting lots of light in ultraviolet wavelengths the astral detectives sprung into action at the time of the explosion we saw the fastest moving stuff was coming toward us at a tenth of the speed of light so that was the actual star blowing up scientists had their explosion now they wanted to know the name of the victim they dug through a catalog that lists all known stars and their positions in the sky when they struck Pay Dirt they found the star that exploded it was tagged SK 6922 they also determined that it was a huge star 20 times the mass of the Sun examining the spectral evidence science s could see strong lines of hydrogen sn1 1987a bore the Hallmarks of a type 2 core collapse Supernova but to confirm their suspicions and prove the core collapse theories experts had to have one more piece of physical evidence they needed neutrinos those ghostly particles that scientists predicted would be Unleashed during the blast in the early 1980s scientists had built a handful of nutrino detectors around the world they consisted of Tanks deep underground filled with tons of pure water but these detectors had yet to capture a single Supernova nutrino we've had this story for a long time that most of the energy of a supernova explosion a core collapsed Supernova explosion goes into neutrinos but we had never seen those neutrinos as luck would have it on February 23rd 1987 they got their neutrinos two detectors one beneath the city of Kamika Japan and the other under Lake Erie in Ohio captured a dozen of The elusive particles there were light detectors on this uh volume of water that were used to see this little flash caused by the neutrino inter interacting with matter inside the tank for the first time ever scientists on Earth saw tangible evidence of the mysterious nutrino particles generated in the core of an exploding star astronomers now knew the theories first proposed in the 1930s were right Supernova 1987a showed beyond a shadow of a doubt that the massive iron core of a very massive star collapsed and formed a neutron star because in that process a lot of neutrinos should be emitted with the deployment of powerful space-based telescopes astronomers today have built on the astonishing discoveries made in the wake of supernova 1987a [Music] in 2006 30-year-old astronomer Robert Quimby would once again turn conventional thinking on its head and revolutionize the way astronomers searched for supernovas most Supernova searches they just want to find as many Supernova as possible so they'll look once every two weeks every one week just just so you can find them and so you can look at as many fields as possible and get as many Supernova as possible so I decided to look at a limited number of fields and look at them as often as I can the enterprising Cosmic gumshoe programmed his robotic telescope to systematically sweep the targeted field every night like an Interstellar search light it honed in on and methodically scanned the same small dark corner of the cosmos looking for Supernova suspects I had software that can very quickly process the data and tell me if there's anything there that wasn't there before and when that happens if I think it could be a supernova I'll get a spectrum of it and then that spectrum of it will tell me exactly what it is is it a supernova what type is it Etc on September 18th 2006 Quimby got his big break he found the brightest Supernova ever this is my fourth Supernova I didn't think that I should be so lucky and others looked at the Spectra and they started taking their own measurements of the of the photometry how bright it was and they figured out that in fact 2006 gy was brighter than any other published Supernova very slowly took uh over two months 70 days to get the maximum light and then faded again so it was a supernova unlike anything we'd ever seen before discovered by this fourth year graduate student that the University of Texas analysis of the remnant indicated that the star before it exploded was 100 times the size of the sun and with lots of hydrogen showing in its Spectrum the brightest Supernova ever recorded wor the stamp of a type 2 event then Quimby topped himself when he finally analyzed a seemingly insignificant Supernova he found earlier called sn2 2005 AP he made a stunning Discovery it was something like 100 billion times as bright as the sun as compared to for type 1A Supernova the peak may be only 6 billion times as bright as the sun it was even brighter than SN 2006gy like circumstantial evidence astonishing discoveries of new ultra bright supernovas like 200 5 AP and others have opened up a whole new Avenue of inquiry into exploding stars and their MO the basic idea we have is that perhaps this is connected somehow to gamma ray verse gamma rays are the most powerful form of light known in the universe by analyzing supernovas investigators are getting closer than ever to solving some of the most confounding Riddles In the cosmos how one of them makes gamma rays and the other makes an ordinary Supernova is still one of the big Mysteries and nobody really knows how that works what astronomers do know is that supernovas and the gamma ray bursts associated with them are the brightest beacons in the universe on the galactic Highway that is the cosmos supernovas serve as Celestial signposts pointing astronomers to the beginning and the end of time time and space NASA's powerful Swift satellite launched in 2004 was designed specifically to sweep the sky and detect gamma ray bursts in the universe like Cosmic First Responders astrophysicist at NASA's GD space flight center in Baltimore Maryland are standing by 24/7 waiting for a 911 call from Swift basically less than two minutes after Swift discovered a g reverse the satellite sends down emails directly to our black bars when a recent Supernova recorded as SN 2006 AJ appeared the Swift satellite caught the shocking gamma ray it gener at and that g burst was very interesting because first of all it was a very long duration G burst usually G bursts are very shli phenomena only fractions of a second a few seconds but this gum burst was visible for like 35 minutes we saw 3 Days Later a supernova explosion going off at the exact same location and this solved one of the important mysteries of G burst because he found out at least uh parts of gurst are due to massive stars that are exploding astronomers today can see hundreds of supernovas and the deadly gamma raay bursts they generate on the cosmic Highway scientists use these Stellar headlights to ascertain the bounds and breadth of the universe you can use Supernova it's a pro Universe CU if they're very dim you know they were very far away and then you can study the curvature of SpaceTime and all the cosmology that you can study with them for example if you're on a desert highway and you're looking out at the lights of the cars you can tell which are nearby and which are far away from the apparent brightness of the lights the ones that are nearby look bright the ones that are far away look dim measuring how far away things are very systematically will tell you about the size the age the shape the history the future of the universe it turns out that type 1A supernovas are the best suited for this purpose one of the things that's really interesting about the type 1 a supern noi the ones that are exploding white dwarfs is that there is this fixed Mass this chandrakar mass that sets how big the explosion is how much stuff is involved and the consequence of that is that many of these have very nearly the same brightness if the explosion produces the same amount of light then we can measure how much light we see and figure out how far away the Supernova is this is known as the standard candle principle type 1A supern noi are like standard candles they all have about the same Peak power the same Peak Luminosity so if you look at them from different distances they appear different apparent brightnesses they look dimmer if they're farther away and brighter if they're more nearby so if we find type 1A Supernova in distant galaxies and measure their apparent brightness and compare that with the known power of a nearby type 1A Supernova we can determine the distance of that Supernova and hence of the Galaxy in which it's located the trailblazing technique has also LED Astro investigators to some radical conclusions basically we you can use the distances to supern noi to figure out what the universe is doing how how old it is and we now know that from various lines of evidence that it's a little less than 14 billion years old but in particular found out the universe was accelerating when we thought it was decelerating in the grip of the gravitational materials in it that's just caused an intellectual Revolution like throwing a ball up towards the ceiling and rather than having it come back down into your hand it goes faster and faster and faster towards the ceiling is completely counterintuitive basically all the text astronomy textbooks out there all said that the universe should be decelerating that is gravity should be slowing down the expansion rate but what this result showed is that instead of slowing down it was actually expanding faster and faster and faster while the examination of supernovas has helped scientists unravel many Monumental Cosmic Mysteries experts believe that if they continue to follow the clues Left Behind when huge Stars explod explode they'll be able to answer the biggest unanswered questions today scientists know that someday soon we could each witness for ourselves The Marvelous and Almighty force of a supernova our galaxy is 100,000 light years across so that means there's light from a thousand supern noi that's on its way to us now it could even happen in our very own Milky Way in our galaxy we are expected to have on average about two Supernova explosions per Century the problem is that the last Supernova that we saw in our galaxy is almost 400 years ago so our galaxy long do if it did happen in our own Galaxy we like the titans of space and time Tao Kepler Chandra seikar and Zi would bear Witness to the most destructive and the most creative force in the universe the Supernova they've intrigued man for centuries captivating astronomers and astrologers alike a mysterious alignment between the Great Pyramids of Giza and the stars of Orion could have been more than a coincidence and instead of 12 zodiac constellations we actually have 13 what is our 13th sign and why was it forgotten the patterns that once navigated Mariners across treacherous Waters Now guide astronomers to uncover the Mysteries that lie within the constellations before the internet before movies the night sky and the constellations were the greatest show in town this gallery of stars forms more than just pretty pictures it contains an enormous sampling of star types through constellations we can learn a lot about the Galaxy and the universe beyond before we had high-tech navigation devices GPS or even compasses we had stars like landmarks along the road constellations can help us find our way they give us Direction distance and a sense of where to go so on earth when we want to tell where something is we give its coordinates in latitude and longitude what that means on Earth is it's a measure of latitude is a measure of the distance between the North Pole and the South Pole and longitude is the East West distance so the other direction similarly we have a Celestial coordinate system but the coordinates they're not called latitude and longitude they're called declination and right Ascension they are just direct extensions of latitude and longitude on Earth projected out into the sky ancient Navigators used this imaginary grid to plot stars and Orient themselves across the seas not a precise kind of indicator of Direction uh but certainly a cue to keep people reminded of what the broad uh pathways through the Seas might be by using a seant Mariners were able to use guide stars like Polaris to navigate this is a seon it's a tool you used in Celestial navigation once a sles of body hits what's called its lower limb to the Horizon you mark the position using the time and the numbers on this sexon you can then use it in fixing your position at C to today's navigation uses man-made Stars Satellites with the use of our man-made Stars per se our GPS positions and uh differential GPS we're able to fix the ship's position within a few yards instantaneously anywhere we are in the world now that GPS has replaced sexon Celestial coordinates are more important to astronomers than they are to Sailors even though the coordinate system gives them an idea of where to point their telescopes the grid falls short in a serious way it assumes all the stars are all the same distance from us an assumption that's flat out wrong when you look at the stars in the night sky they all appear to be about the same distance away as if they were in the same plane the same happens when you look at a a city skyline from a distance away such as we are from the Chicago skyline so why while those buildings look like they're the same distance they're really at many different distances away the same is true of the Stars while they all look like they're at the same distance some are close some are much further away so how do we know which stars are close and which are far away as it turns out that's the most difficult question of all that's been the single greatest frustration in all of astronomy looking at the night sky even with telescopes you cannot tell distances that's been the Holy Grail of astronomy for centuries we're here in the Angeles National Forest and I've got with me a handy trail map and I'd like to take a hike uh maybe going to say Switzer Falls which on my map looks like it's not very far only maybe a mile but the trouble is I could badly underestimate the difficulty of this hike because my flat map here fails to take into account one very significant factor which is the elevation so in fact my simple on M hike could turn out to be a 5,000 ft climb so does my constellation map failed to tell me about the true distance between two stars even though in a constellation they might look like they're right next to each other in fact one could be much farther away than the other and I would never know it if I just looked at the celestial coordinates only like hikers in the woods astronomers rely on Clues to help them gauge the distances in our vast and Mysterious Universe so when we're hiking in the forest even if we don't have a map that tells us elevation we can use our knowledge of the local topography and types of trees to tell us something about our altitude for example certain trees prefer lower elevation whereas other trees prefer higher altitudes similarly astronomers use certain types of reference stars as guid posts familiar guide poost as a gauge of distance the First Tool in the astronomer's kit is the phenomenon of Parallax it's something we use on a smaller scale every day to see the world in three dimensions the way to think of parallx is a very simple exercise exerise that everybody can do so take a look at your finger and look at something really really far away if you use your right eye and line up your finger with the distant object and then use your left eye you'll see that your finger actually appears to move quite dramatically this apparent shift is caused by the distance between our two eyes astronomers measure Parallax by looking at a star at one position and then looking at it again 6 months later when it's moved as far as it could go from our vantage point 6 months is really when the earth is as far away from that original position as it can be the closer the star the greater The Parallax the problem is that stars aren't very close even The Parallax angle of our closest star Proxima centor is difficult to measure it's less than a second of AR what's a second of art there's 360° in a circle in every degree there are 60 Minutes of Ark and in every minute of Ark there are 60 seconds of Arc Proxima centar has a parallax of7 seconds of Arc so it's very small to span the distance to more far-flung stars astronomers count on a familiar guide post to lead them much like the Coast Guard uses a lighthouse the men and women of the Coast Guard know that every Lighthouse has a particular pulsation frequency one might flash two times a minute another four times they can use this to determine exactly their position just based on the pattern in the same way astronomers can use a cosmic Lighthouse called a seate variable star the constellation sephus named after the mythical king of Ethiopia claims 57 visible stars including Delta sephi a variable star that is the prototype for seid variables by a quirk of nature seids keep time like a metronome the bigger and brighter the sepid the slower it will puls at so what you do is find a seate variable measure its pulsation period it might be 10 days or 60 days and then you've got a standard candle you can determine how far away that star is a standard candle is a basis of comparison a star of known luminosity and distance that we can compare similar Stars against you know a light bulb gives off the amount of light it gives off a certain amount of Watts but that light is going to look a lot brighter if you're right up close to that light bulb than if you are 10 ft away and so the Luminosity of a star doesn't change you know that is what it is but apparent magnitude you know depends on where you are how far away you are whether you're right up close to something or you're seeing it from the other side of the street if a Sephia doesn't appear that bright then it must be far away astronomers can calculate how far it is based on how dim it appears looking at my Cate variable and plotting the light curve how long it takes to go from brightness to dim back to brightness again tells me what the intrinsic brightness of that star is so I can calculate distance to variable Stars by observing the period of their variation that's how Edwin Hubble was able to determine that Andromeda was 2 million light years outside our galaxy but seiad variables have their limits to measure distances far beyond Andromeda astronomers rely on supernovas it turns out that supern noi can also be categorized as standard candles type one a supernova are all the same throughout the Universe we know how to calibrate them and that's how we determine the distances out to the Big Bang in the very edges of the universe peering into the Big Bang scientists can nearly see the beginning of time 300,000 years after the big bang even our most familiar constellations have a lot to teach us about the cosmos Orion which is Greek for Hunter has 77 visible stars alok alnilam and minaka make up the three stars in Orion's Belt in modern times astronomers have hunted Orion finding a variety of astonishing objects when I see Orion I also see the life and death of stars s just below the belt there's a little smudge called the Orion Nebula and that's a nursery a nursery for baby stars and you can actually see that with the naked eye Orion has also bagged a pair of Stellar gems if you look at the upper left hand shoulder of Orion you see the Red Giant Beetle Juice and if you immediately look right down to the lower right star the star that's sort of his his leg uh you'll see the blue super giant Riel Beetlejuice as a red super giant is a star in its death throws a red super giant is a star that is actually quite a bit cooler than our sun but much much larger Beetle Juice is 14 times more massive than our sun when it runs out of nuclear fuel Beetlejuice will become unstable and implode in a colossal Supernova it can detonate at any time and when it explodes it will light up the entire night sky and it will even be visible during daytime and maybe it's already blown up it's 427 light years from Earth which means that perhaps it has already exploded but light hasn't had time to reach us yet the Supernova will draw more attention to a sky that's been captivating us for thousands of years the ancient Egyptians consulted the Heavens to tell them when to plant and when to harvest every Star possessed a sacred meaning they called Sirius in the constellation Canis Major the star of Isis sirus's appearance Before Dawn during the summer solstice forecasted the annual rise of the Nile River other constellations like Orion might have had a certain architectural significance egyptologists have often asked the question why did the ancient Egyptians build three Great Pyramids that are slightly misaligned did they have bad ruler sticks thousands of years ago the three pyramids seem to be aligned to the three constellation stars of Orion what does this alignment mean was it a coincidence or were the Pyramids intentionally engineered this way the Pyramids of Giza seduce us with archaeological mystery and historical Intrigue some scientists think the pyramids have a certain astronomical importance it has been claimed that the layout of the three major pyramids on the Giza Plateau including the Great Pyramid are set on the ground to mimic the three stars in Orion's Belt it's one of my favorite connections between event on Earth and events in the sky but the ancient Egyptians didn't see a hunter in Orion like we do they saw Osirus God of rebirth some speculate that air shafts within the great pyramids were specifically designed to catapult The Souls of pharaohs to the heavens in those pyramids we have two different shafts and those shafts one Points North one point south the South shaft points toward Orion so the soul of the Pharaoh would be launched through that shaft in order to be connected to Osiris Orion and be resurrected again enjoying eternal life but others are a bit more skeptical in order to make it match correctly you have to flip it upside down on the ground or in the sky that the Egyptians did place an importance on North and on South in the pyramid and it doesn't make any sense to say well yes they line the Stars upright but then when it came to mapping on the ground it was perfectly okay to flip everything around and make it upside down the north shaft points toward one specific star the one pointing North points to the pole star at the time 2,000 years before Christ 2,000 BC 3000 BC and that poar was thuban thuban is located in the constellation Draco or the dragon Draco has 79 ible Stars thuin has been replaced by our generation's pole star Polaris polarus illuminates the Arctic governing our sky as a beacon over the North Pole lying in the constellation Ursa Minor it's 2500 times brighter than the sun outshining its companion Stars Polaris ab and B although it's ruled the heavens as our North Star for as long as we can remember its rain won't last forever as Earth orbits the sun it Teeters back and forth this wobbling is called procession if Earth was a perfect sphere it wouldn't precess but the gravitational poles of the Moon and Sun tug at the bulging equator upsetting Earth's spin now the Earth is like a gyroscope or a spinning top notice that if I spin this very rapidly and then I move the axis it points in the same direction this is the earth pointing toward Polaris that as the earth goes around the Sun it always points in the same direction however procession is caused by gravitational interference so the Earth begins to wobble as Earth wobbles its axis draws a circle in the sky it takes 26,000 years to make one complete circle the north Celestial pole will move further and further away from the position of Polaris in about 14,000 years from now about halfway around its Circle it will be very close to the bright star Vega but because Vega is so much brighter than any other star in that part of the sky it will be a very significant North Polar Star in 26,000 years Earth's axis centered on the North Pole will make one complete circle and it will point back to where it is today and Polaris will overthrow Vega and reclaim its title as our North Star the closer a star is to one of Earth's poles the more its position remains fixed in the sky astronomers call these Stars circumpolar meaning that they're visible all year long in fact all of the constellation of Northern Stars such as the Little Dipper and the Big Dipper just go around in a fairly small circle so the result of that they go around Polaris without ever rising and setting the further south you go the more constellations actually rise say at the beginning of the night and set at the end of the night and so they don't have that magical property Stars vary in size density and also brightness instead of shining with a steady glow like most stars variable Stars pulsate brightening and dimming in a hypnotic pattern a variable star is like a pot of tea you take a kettle and put it on a burner and it starts to expand and then it releases its excess energy and then drops and then it starts to build up pressure and then it drops again so kind of in the same way the variable Stars atmospheres expand and shrink with time and this makes the star appear to get brighter and dimmer sometimes this happens over a matter of hours sometimes it can be days or even mons a special class of variable Stars called Tori Stars pulsate because they're young and unstable like stubborn teenagers Tori stars have erratic outbursts except their Tantrums involve a struggle with gravity as the uh nulear forces push it outward gravity pulls it back in and it misses that equilibrium position sort of like a pendulum and it oscillates back and forth Tories will outgrow their pulsations as they age they'll reach equilibrium becoming stable stars in fact before our sun matured scientists think that it used to be a Tori this probably gives us our best look at what our solar system and our sun looked like when it had just formed and its earliest Evolution and we know that for example that the clouds of dust and gas around these stars are very messy and it must have been a pretty violent scene with many lunks and chunks of rock colliding into each other and bombarding each other the first Tori stars were identified in the constell ation Taurus Taurus the Bull possesses 98 visible stars aldeberan a red giant star is the Bull's bloodshot eye Taurus is one of the zodiac constellations that lie near the plane of the ecliptic it's called the ecliptic plane because that's the only circle around the sky where eclipses can occur the moon has to pass pass through the ecliptic for example in order to give us an eclipse of the sun it's also the path that our Earth travels along as we orbit the sun 8° above and below the ecliptic lies a region called the Zodiac every constellation that falls within this band is referred to as a Zodiac constellation at any given time the sun is in a constellation of the zodiac the sun lies between us on the earth and a certain constellation because we orbit our sun the Sun appears to move through zodiac constellations that are fixed in the sky during night time the opposite portion of our sky is lit by the sun astrologers linked each of the 12 zodiac constellations to the month that the sun passes through so in June the sun sweeps through cancer and in July it Glides across Leo but you see there's a problem with that each constellation is of different sizes some are small some are big it takes the sun 7 days to pass through Scorpius the smallest Zodiac constellation and 44 days to clear Virgo the largest so you cannot divide the year into 12 equal pieces with 12 equally shaped constellations a lot of people put a great deal of significance on their zodiac sign their sun sign but in reality since the Earth is processing the constellation in which the Sun appears today is different from the constellation in which it appeared 2,000 years ago so the next time someone tells you that you're competitive because you're a Scorpio tell them well you know today I'm really not a Scorpio anymore from the infamous what's your sign line to predicting fortunes and defining personality traits the 12 signs of the zodiac have played a substantial role in pop culture but where do these signs come from and who named the stars we have original names for stars in some cases that came to us from Mesopotamia some names were added to the Stars by the Greeks and the Romans some of those survived some of them did not with the collapse of the Roman Empire in about 450 ad much of this knowledge was lost however it was preserved by the Arabs in fact much of astronomy survives today because of the Arabic astronomers preserving and augmenting the calculations and work of the Greek and Roman astronomers in 150 ad Greek scientists Claudius tmy merged his own observations with historical writings labeling more than 1,000 Stars and out of all the constellations that cover our skies we've learned that 12 are zodiac constellations but in reality there are 13 Even if we're not followers of astrology most of us know what our astrological sign is what most of us don't know is that instead of having 12 zodiac constellations there are actually 13 ucus which is Greek for the serpent Bearer is our forgotten sign it has 55 visible stars and is home to Bernard Star which is the fastest moving star through our night sky nestled between Scorpius and Sagittarius ucus dwarfs the constellations it surrounds although it was one of the original 48 star patterns that tmy cataloged some scientists speculate that it might have been dropped as a zodiac sign to keep an even number of 12 others think that precession could have nudged ucus off the Zodiac but the real answer remains a mystery the only star in the universe that doesn't belong to a specific constellation is our sun comparatively speaking the Sun is a typical aging star with an average mass but stars that have about 50 to 100 times the mass of our sun are called wolf Rea Stars the brightest observable wolf reier is called gamma vorum in the constellation vaa these massive stars are incredibly luminous and are in their final stages of evolution the reason they get so luminous that they're pouring out energy and radiation so furiously it's actually powerful enough to push off the outer layers of the Stars atmosphere these Stars literally evaporate themselves from all the Heat and radiation that they're generating leaving behind just the very very hot Central core although scientists haven't directly observed the death of any they speculate that wolf Rea Stars will end their lives in colossal Supernova explosions or possibly collapse into massive black holes but before they do they put on a very spectacular show of blowing out all of their outer layers of gas into the interstellar medium today our network of grounded space-based telescopes allows astronomers to see any point in the sky but ancient astronomers in the northern hemisphere couldn't see that the southern hemisphere looks out on an entirely different View if you're in the southern hemisphere the most prominent feature in the night sky is the Milky Way and in the Milky Way you have these zones that are dark they're dust clouds but when you look at them from Earth they're just dark against the backdrop of the very bright Milky Way in all the stars it's the most noticeable thing these dark clouds appear as holes within the Milky Way's Starry swath there's such a distinctive pattern these holes that some civilizations in particular the Incas in South America identified these black splotches these absorptions as constellations themselves these dense patches of dust are known as dark cloud constellations there is an amazing complete blackout of stars in a region near the center the direction near the center of the Galaxy and it's called the ksac it's just such a dense ploud of dust it just blocks out all the light from the stars behind it today the coal sack lies in the constellation krux krux commonly called the Southern Cross is the smallest constellation and 20 stars are visible Sailors relied on Alpha and Gamma Crux to locate the South Pole since there is no pole star like Polaris in the southern hemisphere as astronomy developed the scientific community realized it needed to unify the names and shapes of the constellations in 1922 a group formed called the international astronomical Union they were sort of the political body of scientists assigned to divide up the sky set up boundaries so that everybody could agree here are the boundaries those boundaries were based on historic constellations the IOU adopted most of tm's original constellations and added more to include every visible star with no overlaps some of them were named more recently in the southern hemisphere uh when Western Europeans uh got a really good look at the southern skies in all 88 official constellations cover the night sky but there are other small collections of stars that form obvious patterns called asterisms like the Little Dipper and Big Dipper the Big Dipper is made out of Ursa Major's brightest stars Ursa Major or the Great Bear has 71 visible stars the Big Dipper is recognized by its resemblance to a ladle the Big Dipper is probably the easiest object in the sky to find even if you don't know anything else for being such a familiar asterism the Big Dipper is still full of surprises the second star in its handle named misar looks like a single point of light but a closer look reveals that it's five blazing stars signis the swan claims 79 visible stars a star named denb is a thermonuclear Powerhouse that forms the swan's tail at 200 times the diameter of our sun and is much as 250,000 times as bright denb is one of the largest examples of a white super giant star it's a star in a very unusual phase of its Evolution there's very few stars like that and they don't spend very much time of their lives in such a l High Luminosity State white super Giants are rare because the star is transitioning from a red to a blue super giant a phase that only lasts a few million years this may sound like a long time by human stand standards but for a star it's less than 1% of its lifetime for a constellation named after a graceful bird signis Bears the scars of a violent past so signis is also home to something called The signis Loop which is a supernova Remnant uh there was a star that blew itself to bits basically a gaping black hole called signis X1 lies in the swan's heart signis X1 is an 8.7 solar mass black hole so it's 8.7 times the mass of our sun that's orbiting another star signis X1 was the first black hole to ever be recorded in fact we first detected sign X1 not so much because of the black hole because it's black it's very hard to see but because of its effect on its companion uh which is this giant star and in fact the black hole is slowly devouring the companion and eventually we'll probably swallow it up and when it does a constellation will lose a star and our perception of the night sky will change [Music] forever our night sky is in constant change within each constellation stars are born While others are swallowed by black holes every supern explosion exotic star and nebula has one thing in common they are identified by the constellation they're located in but even before we invented High powerered telescopes to see them constellations served an important purpose they brought people the Nightly News that they dared not ignore it was a question of life and death you see the night sky is a calendar that was the very first scientific invention of us humans the calendar in the sky the rising and setting of the Sun the changing phases of the moon the seasonal reappearances and disappearances of the Stars people see that there is in fact an order to the world they in fact see order in the sky that is useful for them to anticipate what's happening on the earth that's a tool for survival when you look at the sky you see these groups of stars that are connected to important events that will prompt you to behave in certain ways or to move in certain ways or to plant or harvest besides seeing the pattern of stars changing with the seasons the Ancients made another crucial observation the shifting Stellar canopy shaped their world Travelers who went a Long Way South for example from Greece started being able to see different constellations from any of the constellations that have been visible in their Hometown so it's telling you that you're really moving on a curved surface and changing your perspective today we understand the shape of the earth and the parade of the seasons but constellations haven't outlived their usefulness instead of telling us about the Earth they're helping us make sense of the Stars a constellation is a lot like an art museum in an art museum you'll see artists who have used different kinds of materials painting photographs and ordinary objects a constellation also has similar objects but made of different materials some of them have more helium or hydrogen or carbon silicon iron and yet we can group them together in both cases the objects that are gathered in an art museum or a constellation they're art official collections that we've put together for some reason like countries constellations divide the sky into territories when you say Orion I know exactly what part of the sky you're talking about so to an astronomer a constellation really is kind of a handy map it's just a way of organizing things so we kind of know where stuff is and even though the night sky is infinite we can see only a sampling of stars before dust and distance blocks our view you'll probably see on a very dark night maybe 1500 to 2,000 stars with your naked eye if you're not using binoculars or anything so what we're seeing is only a tiny tiny fraction of what's really out there that would be sort of like looking at the whole population of the United States 350 million Americans and seeing five people Centaurus or the centur contains 101 visible Stars two of its Stars Alpha and beta centor are the brightest stars in our night sky Centaurus holds Alpha centor the star nearest to the Earth after our own sun and a closer look reveals that Alpha centori is actually a triple star system It's Not Unusual for stars to share the spotlight with one or two orbiting co-stars in fact fact it's the norm over 60% of the Stars you see in the heavens are actually double Stars triple Stars quadruple Stars our sun is an exception our sun apparently has no companion while our sun makes its lonely Voyage Through space the stars of Omega centor never Lack company it is the brightest globular star cluster that you can see without a telescope just with a naked eye because it is a giant cluster of about 10 million stars Omega centor is the largest star cluster in our galaxy these tightly bound stars all have different complicated orbits but they still manage to move together as a single group where the cluster comes from is anyone's guess it's an unusual object and a lot of astronomers suspect that this might be the center of a Galaxy which got eaten consumed by the Milky Way when it fell in it certainly happens fairly often that big galaxies are cannibals and they eat little galaxies and Omega centor may be a remnant of this process the light from alpha centor takes about 4.2 years to reach us but when we look at Omega centor we're seeing light that's traveled 16,000 years that's some indication of how large Centaurus really is it also shows that a constellation exists only in our Mind's Eye and each star like every piece of art begs to be explored the constellations organize the night sky and make it almost comprehensible as we gaze at the twinkling light it's easy to forget that each is one of billions of Blazing Suns fusing elements and possibly creating new worlds our distance gives us no sense of the star's power it also gives us no sense of the Endless depth of space we're peering into the flat Plains of the constellations are an illusion as you start getting away from the Sun by several light years the nearby stars begin shifting uh relative to the more distant background Stars so the constellations start distorting by the time you're out at 10 20 30 light years you probably would recognize few of the constellations so if you lived on a planet going around uh Vega let's say that's 25 light years away from here you'd have a different set of constellations in your sky Millennia of stargazing have made the Grand sweep of the constellations predictable our rotation around the Sun carries us through their annual cycle the stars in the constellations are in constant motion not just as the Galaxy spins but also as each star's gravity tugs and pulls on its neighbors the fastest motion of the stars is 150 m/ second we don't have any man-made object that can go that fast the random motions of these stars with respect to each other are more likee 10 or 20 m a second and that is comparable to the speed of our fastest spacecraft that's of course way way faster than a high-speed bullet the stars are always moving and their distance from us masks their enormous speed it's like looking out the window of a speeding automobile the fence posts and trees closest to the highway whiz by while the distant landscape creeps slowly past over our lifetime in fact close to a thousand lifetimes most stars don't appear to move at all it just intrigues me to think that if I could find one of our quote recent relatives of crom magnon man for example he would probably correct me because he would be more familiar with this sky and he would know the constellations a little bit better than the people do today but little by little our star maps are reaching their expiration dates in 10,000 years the Stars would be noticeably different the constellations be noticeably different than what we see now in 500,000 years they'd be unrecognizable and if you truly could see a time-lapse photo over a period of million years you would in fact See Stars Racing around the sky the constellations are a snapshot a flattened portrait of the night sky and like a portrait it's a good likeness but not the whole story if we could fly into space and see them from another angle these old familiar star formations would be unidentifiable but right here right now the 88 constellations provide reassuring guideposts while reminding us of our past the constellations really don't fulfill the functions that they fulfilled originally for the people that devised them for them there was a direct cause and effect connection between something that was of interest to them and their lives they watched Sirius because it was a seasonal indicator we don't use the sky that way anymore but the stories are resilient in the images are resilient we hold on to those constellations and frankly I'm delighted we do instead of telling stories of the past modern astronomy compels us to look at constellations as a grouping of possibilities most of the constellations have three to five planets inside them and in a few more years we're going to identify perhaps hundreds of earthlike planets orbiting other stars so we will have this epiphany every night realizing that when we look at the constellations somebody may be looking back in a space so vast that we can only see a small fraction of our universe we look to the Stars wondering what it all means making patterns inventing stories attempting to solve the Mysteries that our constellations hold does our son have a deadly Nemesis that Dooms life on our planet is it possible to travel through time it is one of the greatest questions what happened to matters evil twin the Mind hunts for an [Music] explanation how did the water on Mars disappear and what came before the Big Bang this is the greatest mystery in all of science big questions and Cutting Edge science the universe Unexplained [Music] Mysteries Among The Unexplained Mysteries in the universe one has a particular urgency for those of us who enjoy living on planet Earth do earthlings have a regularly scheduled date with Extinction once every 26 million years and if so what causes this periodic hard reign of Destruction you have this an enormous explosion anything within within thousands of miles will be killed you're talking here first of the blast wave of the tsunami you're talking about the enormous heat fires all around the globe and then Darkness for millions of years enormous objects from space have slammed into Earth with disastrous results One impact in the waters of the ucatan peninsula is blamed for the extinction of the dinosaurs 65 million years ago but this wasn't the first mass extinction on Earth and it probably won't be the last and it wasn't the biggest mass extinction event of all time because that one was the peran extinction in which 95% of the species in the oceans died and about 80% of those on land so radical Extinction events have happened some scientists believe these periods of death and destruction happen like clockwork some paleontologists found a very strange pattern what they found were the great extinctions such as the ones that killed the dinosaurs but others too didn't happen at random times but seemed to occur on a regular time schedule that was very strange they were disappearing every 26 million years was begging for an explanation astrophysicist Richard Muller believes the EXP explanation for this periodic destruction is a dim Red Dwarf star lurking on the edge of the solar system a star that he fittingly calls Nemesis according to his theory Nemesis is an Undiscovered companion star to our own Sun it travels between 1 and three light years from the center of the solar system on an elongated elliptical orbit as Nemesis makes its closest approach to the Sun every 26 million years its orbit takes it right through the or Cloud a collection of an estimated trillion comets surrounding our solar system that's when the order of the solar system turns especially chaotic when that that happens Nemesis gets close to the comets and perturbs their orbit according to Muller's Theory the gravitational disruption caused by this small innocuous star causes long undisturbed comets to break away from their orbits in the orc Cloud pulled towards the Sun by its gravity a billion comets are sent careening toward the inner solar system a handful inevitably cross paths with the Earth resulting in massive impacts and mass extinctions the claim that our son has an Undiscovered companion death star is [Music] controversial most scientists believe that the sun is a solitary AR STAR with no companions but in the universe binary or even triplet Stars grouped together by gravity are the norm the majority of stars in our galaxy are parts of either binary or triple stars and so the idea that the sun conceivably could be part of a bin isn't isn't crazy from that point of view at all it's uh it's an interesting question even if the sun could conceivably have a binary companion astronomers have never observed a binary system in which the pair of stars are as far apart as Muller claims our son and Nemesis would be mer needed proof that Nemesis was real in 1997 a NASA Mission began that had the potential to shed light on the mystery the two Micron all Sky survey or two Mass use twin infrared telescopes to scour the universe for previously unknown Stars Tass specialized in hard to find bodies in and near our galaxy and to date has produced over 2 million images if Nemesis was out there Tass should have spotted it but the survey never detected anything fitting the description of Mueller's Death Star we've looked we've looked real hard for Death Star for Nemesis and we can't find it anywhere but Muller isn't surprised two Mass didn't find his Nemesis the reason is at a distance of about one light year which is the distance it would have in order to have a 26 million year orbit its motion is very little and so it would have been missed by the standard surveys that look for nearby Stars another possibility is that Nemesis may actually be a brown dwarf these failed stars are much smaller than red dwarfs and with a highly elliptical orbit a brown dwarf would remain far from Earth most of the time and out of the watchful eye of astronomers if that's the case Nemesis could have easily slipped under the two Mass radar Richard Mueller vows to continue looking and plans yet another more detailed study he believes it's only a matter of time before Nemesis is found there are lots of stars out there there were millions of them but when you find a needle in a hay stack you could look at and say well that's not hay similarly with this when we find Nemesis we'll measure the orbit and we'll prove that it's nemesis of all the Unexplained Mysteries in our universe perhaps the most tantalizing and controversial is whether it's possible to travel through time can we really travel back into the past can we really alter our destiny it is one of the greatest [Music] questions in 1955 Ron Mallet was only 10 years old when his father died of a heart attack grief stricken young Mallet yearned for a way he could see his father again and perhaps save his life about a year after he died I came across HG wells's book The time machine and that is what saved me because I thought if I could build a time machine as HG Wells talked about then I could go back into the past and try to save his life and see him again and so I became obsessed with the notion of trying to build a time machine gentlemen I am talking about traveling through time the time machine was a work of fiction but m soon discovered there was science to support the mysterious notion of time travel and the source was none other than Albert Einstein Einstein theorized that space and time were linked so that one could imagine SpaceTime as a sort of fabric or sheet with his general theory of relativity Einstein showed that a massive object like a planet a star or black hole actually warps the f fac of space and time in fact Einstein believed that gravity the force that binds us to the Earth keeps the Earth in orbit around the Sun is really just an effect of this warping for Mallet this mind and universe bending idea has far-reaching implications because if you could generate enough gravity to twist time into a loop perhaps you could create a pathway for for moving backwards and forwards Through Time Einstein's theories fueled Ron mallett's quest to learn how to build his own time machine but time travel wasn't a subject that could be studied by serious scientists out in the open as a matter of fact I used a cover story that worked for me I studied black holes because black holes allowed me to understand how Einstein's theory affected time and every it was a crazy idea but it was considered legitimate crazy so I built my career on studying that and being able to use Einstein's general theory of relativity black holes the massive remnants of collapsed stars have an almost unmatched gravitational power to distort space and time which is exactly what Mallet wanted to do but how could he create in the laboratory something jam-packed with enough matter to actually warp space time for inspiration Mallet turned again to Einstein and his most famous equation eal mc² which showed that matter and energy are just different forms of the same thing so following Einstein's theory light which is energy should be able to warp space and time just like a massive object does we're used to the notion that gravity is created by matter but it turns out that in Einstein's theory light can create gravity and that is what my work is based on in other words If gravity can affect time and light can create gravity then light can fect [Music] time Mallet has built a model to demonstrate his concept that a circulating laser beam can create a tunnel of light that twists space and time it has four intersecting laser beams the region within that column of light would represent the region in which space is being twisted and eventually time would also get Twisted by this column of life and this would allow us to travel back into the past the first time traveler will have to be something much smaller than a human being a subatomic particle like a neutron what we're trying to do is not human beings but to try to send subatomic particles and information to pass and that is a huge leap in itself because imagine if we can send information back into the past that could tell us about future disasters and be able to avert those disasters we can understand how circulating Light Beam twist space and time by a simple analogy with a cup of coffee if we think of the coffee and the cup as being like empty space and we think of the spoon is being like a circulating Light Beam then you can see what happens to the coffee as I stir it the coffee swirls around well that's what the circulating Light Beam is doing to empty space and we can see the effect of this in case of the coffee by putting in a coffee bean as I Swirl It Around The Coffee Bean gets swirled around in the case of the laser as the beam is circulating we put a subatomic particle called a Neutron in and as we stir the space around the neutron will get swirled around just like the coffee bee now remember in Einstein's theory space and time are connected so that swirling of space will cause the straight line of time to be swirled into a loop and along that Loop in time we can go from the past to the present to the Future and then back into the past science fiction has depicted time machines as allowing unrestrained travel forward and backwards in time but Mallet cautions that a time traveler could only Journey back as far as the moment that the time machine was first turned on another words if I turn the device on today and I leave it on for 100 years then someone 100 years years from now I could travel back 75 years 50 years 25 years all the way back to the moment I turn the device on but they can't travel earlier than that because the device didn't exist earlier than that and it's the device that's creating the effect so there's nothing for them time travel to materialize into this limitation means that malet's time machine could never give him the capability to travel back to 1955 to save his father's life to do that would take some technology from out of this world theoretically an advanced alien civilization might have a time machine that was switched on thousands of years ago we may be able to use their time travel to go back to visit our ancient past because if they have developed time travel let's say 10,000 years ago it would still have the same Lim limitation but once we encounter them we could use it and perhaps someday we may be able to visit ancient Egypt and ancient Rome for now Mallet is focused on getting his time machine built a project that will require a quarter of a million dollars in startup costs alone money is just one obstacle facing any physicist daring to dabble in time travel there are also certain paradoxes that many believe make time travel impossible like the infamous grandfather Paradox imagine you go back in time and kill your own grandfather before he meets your grandmother therefore you never would have been born and therefore couldn't have gone back in time in the first place and then a loop is set up of possible impossible happened it didn't happen but Mallet believes recent advances in theoretical physics suggest that these paradoxes aren't a problem at all many physicists now believe in the far out notion that our universe is just one of many parallel universes so that when you go back in time you might actually be entering a parallel universe in which you can alter events without affecting the universe you came from we believe that the river of time can have whirlpools whirl pools by which you may be able to go back and meet your parents before you're born or perhaps even Fork into two rivers by which you can actually alter the past to create an alternate universe these are all theories that are at the very Forefront of modern physics today Mallet believes we may be as little as a centur away from time travel by humans still too late for him to travel back in time to save his father okay thank you very much remember what's happening to the space it's swirling around but his personal loss has opened a door for a new world for future Generations I develop the basic equations for this it has led to my being able to share something with the world that I would never have been able to share before and I feel that that is actually a fitting Memorial to my father that I've been able to do that and I feel very good about [Music] that as the universe was first forming scientists believe it was comprised of more than just the regular matter that now makes up everything around us they believe it had an almost equal amount of antimatter matter is elusive evil in if you go back to the very early Universe it turns out that it was made of matter and antimatter it turns out that every particle has an anti-particle and it sounds kind of crazy but it's real it's sort of sci-fi you know antimatter but what is this mysterious antimatter and where did all of it Go antimatter is exactly like matter the difference between it is the fact that it has completely different charge associated with regular matter is made of atoms which in turn are made of subatomic particles like negatively charged electrons and positively charged protons antimatter are the opposite of these particles they have the same mass but the opposite electrical charge proton is a positively charged particle that's the nucleus the atom the antiproton would be a negatively charged proton that has exactly the same mass in our universe Opposites Attract and particles and antiparticles are pulled together one would think this is a relationship made for the heavens but every time matter comes in contact with antimatter the outcome is the [Music] same they annihilate each other imagine two spaceships hurdling through space on a collision course one is made of regular matter the other is an antimatter craft built by an alien civilization the impact would be spectacular and there will be no pack AG Left Behind for Cosmic crash investigators to examine the matter and the antimatter disappear poof they're they're gone but the the energy doesn't disappear the energy reemerges in the form of two very energetic gamma rays photons and the amount of energy locked up in a tiny amount of mass is is quite astonishing if you take matter and antimatter and combine it it is explosive and in fact it is one of the greatest sources of energy in the universe the Collision of matter and antimatter so if I were you I would not put antimatter in your pocket if you know what good for you volatile as antimatter is when it meets matter there's a tremendous energy potential if we knew how to harness it so to get an idea how much energy is lock up in matter uh if you imagine for a minute that these two piles of sand are that one is matter and one is antimatter and you let them come together they would annihilate and produce energy how much energy enough energy to power all of California for a week just in those two piles of sand the biggest mystery surrounding antimatter is this if there were nearly equal amounts of matter an antimatter in the early Universe then where is all the antimatter now one of the great Mysteries of the universe is what happened to our evil twin antimatter everywhere we look in the heavens we see ordinary matter we don't see antimatter there's only a small amount of antimatter coming out of the center of the Milky Way galaxy why this universe appears to be made entirely of matter and there isn't much antimatter to be seen out there is a mystery I don't think it'll ever be explained anyway but um the Mind hunts for an explanation one possibility is that perhaps there was a slightly higher percentage of matter than antimatter in the early universe so as the particles and antiparticles collide glided in a war of annihilation that small percentage of matter survived the last living Veterans of our most ancient battlefield for every billion antiprotons you need a billion in one protons then the billion all annihilate and you're left with that one proton and the leftover is us we are the residue we are the leftover of this Titanic blast of energy released by The Collision of matter and antimatter at the instant of time our most advanced theories cannot explain why there was this asymmetry between matter and antimatter but thank God it exists otherwise we wouldn't be here but even though matter prevailed to make up everything we see around us could there be distant galaxies or regions of space where antimatter still Reigns Supreme it may be that there are entire galaxies that are just 99.9% antimatter just like this one is matter and if an antimatter Galaxy were to run into a matter Galaxy then they both would be annihilated in some stupendous flash of light and power as strange as it is scientists have learned how to create minute quantities of antimatter in laboratory accelerators for medical purposes particles of antimatter from decaying radio R active material are injected into the body to create pet scans of the brain many people don't realize that when they go to the hospital and have a pet scan they're actually being injected with a source of antimatter the p in pet corresponds to positrons positrons are anti- electrons and when and it goes to some part of the body that trying to figure out what's going on and then uh when the itron emitted finds an electron very quickly annihilates with it and the gamma rays come out of the body and are detected it concentrates in the parts of the brain where there's mental activity and then we can detect the emission of positron radiation so this allows brain scans to give us gorgeous photographs of the thinking brain made possible by antimatter while antimatter has helped to unlock the secrets of the human brain the human brain has yet to unlock all the secrets of antimatter we do not know why the universe is made of matter now but we are making progress towards answering that question you know Little Steps at a time like many mysteries in our Ever Changing Universe the truth about antimatter May remain for now in the realm of The Unexplained Mars and mystery have always gone handin hand but the most intriguing mystery of the red planet has nothing to do with Alien Invaders scientific evidence suggests that Mars was once a more earthlike planet with one of the key elements to support life water water exists in an abundance on Wars we find the evidence of old flows we see a little tiny bit of water vapor in the atmosphere there are even features on Mars that look like Old river valleys and flood Plains it was once a tropical planet with oceans and seas but all that water disappeared how could all the water on Mars have simply vanished and why did it disappear these are Mysteries that scientists are struggling to solve geologic evidence gathered by by the Mars rovers and orbiters suggest that 3.5 billion years ago Mars watery surface changed dramatically the once temperate Planet became a cold dry place and the water vanished but figuring out when the water disappeared doesn't tell you where it went or why the water on Mars was lost a very very very long time ago and I'm talking billions of years and the clues that would lead you to know where that water went are long [Music] glump a series of events on Mars appears to have drastically changed the watery landscape Mars endured an intense period of volcanism that spewed lava across the surface when it finally ended the planet's molten iron core solidified this may have been what caused Mars to lose its magnetic field and protective ozone layer this left the atmosphere vulnerable to the solar wind from our sun which is quite powerful solar winds pummeled the planet for millions of years stripping any remaining atmosphere now water vapor that once fell as snow or rain escaped the planet's small gravitational field the water is brought up into the atmosphere as water vapor and it's bombarded by ultraviolet radiation which can split water which is H2O and hydrogen and oxygen and the hydrogen being the lightest gas known floats up to the top of the atmosphere and can get Swept Away by the uh the solar winds another theory for the loss of Mars water involves a threat from outside the planet there's evidence that in the early years of the solar system Mars resided in a deadly flight path there's one cluster about 3.9 billion years ago called the great bombardment that really must have peppered that planet with many many impacts and that kind of an event would have actually thrown material and atmosphere right off of the planet and outside of the gravitational uh field let's imagine that we have an asteroid here and this asteroid is really the size of a mountain and imagine this is tumbling through space at very high speed and we're talking tens of thousands of miles per hour if we come zipping in at high speed Splat it's lost to space bu of it will sink in some will become atmospheric gases sputtered away to space some will be lost other answers to the mystery of Mars disappearing water may be hidden deep inside the red planet some of the water combined with carbon dioxide to form polar ice caps up to 2 m deep and a permafrost that covers much of the surface but there's evidence that beneath the ice liquid water still flows much of the water on Mars has gone underground and some of it certainly has migrated down to a depth where it's warm enough for it to exist is liquid water and then when it gets colder it's going to be frozen into a cryosphere if you like an ice part of the uh subsurface then near the surface is going to dry out as the water can move through the soil and go into the atmosphere University of Arizona scientist Peter Smith is eager to solve the mystery of Mars disappearing water okay I'm digging a little trench here to show you what happens if you get below the absolute hyper Aid surface and go down just a foot or so because this is similar to what we're going to be doing on Mars Smith is the principal investigator for NASA's Phoenix Mars mission it's a robotic probe with one simple objective land on Mars and follow the water what happened to that water could have frozen into underground ice or even aquifers of liquid water these are something we're looking for today using radio and radar to penetrate through the surface and try and locate these uh reservoirs of water Smith believes that Arizona's Wilcox pla reflects what scientists will find when Phoenix finally scratches the red Martian surface even though the surface is parched and salty and dry just within 6 Ines of the surface is a very wet clay like a reservoir of water and there's a whole ecosystem of life that's living in these wet soils and these Clays when it rains it comes to the surface and in fact you see little pools were actually brine shrimp that are locked into these soils we wonder if we get down under the surface in the right place on Mars and that is the permafrost region can we find find the same sort of ecosystem around the ice melting over time as climate changes that's habitable for some sort of uh Martian life forms some believe that life on Earth originated on Mars and that its strange transformation foretells our destiny if that's true finding Mars water may lead us back to our Cosmic beginnings and into the future when it comes to the universe what we know is surpassed only by what we have yet to learn and of all the Unexplained Mysteries one Remains the greatest of all did anything come before the Big Bang or was that event truly the beginning of everything and if it was what was the spark that Lit it this is the greatest mystery in all of science what started creation itself Big Bang Theory has this tremendous hole in it we are clueless we are clu as to what set the Big Bang into motion the Big Bang is the cosmological model for the birth of our universe 13.7 billion years ago everything in our universe can be be traced back to that moment there seems to be this mysterious point at the beginning and we call that the singularity but it even though it's mysterious and has um many open questions associated with it it still makes a good starting point for our timeline but our scientific instruments are blind and deaf to the period before the Big Bang if such a period existed at all The Singularity is like a horizon that we can never see beyond because in the creation time was created along with space and along with matter and the Big Bang is just that sort of event and therefore it's impossible to know what happened before the creation event nevertheless scientific speculation as to what happened before the Big Bang is something that intrigues the greatest Minds in [Music] astrophysics some theorists believe that our universe experiences Big Bangs at regular intervals this cyclic model proposes that every trillion years there's a big bang after which the universe expands before again collapsing setting the stage for another big bang there's interesting ways that can connect with the story of a previous Universe the end of one Universe can bring the beginning of another maybe there never was a start that it it's somehow been ongoing from an ear earlier moment and and never had a uh Creator in at all but we might be closer to an explanation of the pre- Big Bang than we know the cosmic reverberations from The Big Bang that still echo through the universe may actually hold the answer to the moment before the singularity turns out these standing waves are key to how we understand the universe today inflation gives the universe one big hit at the beginning just like I'm hitting the pot right here it forms a standing waves and we can look for those symmetrical patterns in the cosmic radiation today so we send our satellites out we observe the radiation the symmetrical standing waves a new wave of detectors gravity wave detectors will be launched into outer space in the next decade connected by laser beams any shock wave from the incident of creation will jiggle these laser beams and will be able to then record the vibrations left over from The Big Bang itself that's why I'm confident that we'll be able to probe not just the Big Bang itself but even the pre-big bang era in the coming decades the lasers will also detect sources of inflationary energy and perhaps determine the mechanism that created the Big Bang if we struggle to solve the greatest mystery of all how can we ever hope to really understand the universe whenever you get an answer to a question it almost always leads to more questions you make progress and Mysteries can get solved but then there'll always be more [Music] Mysteries we are the result of the universe attempting to understand itself that's my conception of our place in the universe and so that makes it difficult to understand but nevertheless it might be possible the universe is constantly changing but the laws the laws of physics are immutable they don't change and that gives us hope that out of all this chaos we'll be able to explain how it all got here to to begin with in our everchanging universe The Unexplained Mysteries will continue to elude us but we are edging ever closer to unlocking the ultimate Secrets the keys to our past and the pathways to our future while science has made sense of many things there is still plenty left to be discovered about our vast dark and mysterious universe

Channel: HISTORY

Views: 1,163,310

Keywords: history, history channel, history shows, documentary, history channel full episodes, stellar explosion, supernova, death of a star, astronomical events, cosmic phenomena, The Universe show, full episode marathon, bright supernovas, energy radiation, sun's energy, space science, astronomy, cosmic wonders, celestial events, space exploration, universe secrets, astrophysics, galaxy mysteries, science education, space documentaries, astronomical marvels, universe exploration

Id: UKJrvttI5Yc

Length: 132min 28sec (7948 seconds)

Published: Fri Dec 29 2023