The Universe: Explore the Alien Worlds of Outer Space *3 Hour Marathon*

in the distant corners of our solar system ice giants Uranus and Neptune are violent worlds blanketed with Smoky hazes these outer planets are frenzied turbulent and unpredictable Neptune claims the fastest winds in our solar system like an apparition its great dark spots surfaces and vanishes without warning Uranus's inner swarm of moons Dash around the planet in less than a day and collisions are unavoidable the most controversial of the far off planets isn't even a planet anymore so why was Pluto demoted the man who killed Pluto makes his case as we explore the outer planets meet the man who killed Pluto Pluto had it coming for a long time Caltech astronomer Mike Brown set in motion a chain of events that reduced the long established number number of planets in our solar system from nine to just eight yet he feels No Remorse there was no way that Pluto could survive the the its its status as the single lonely ice ball but it was it was going to it was going to fall and it certainly fell among our planets Pluto was long considered to be a bit different much smaller than the rest it has the largest moon in proportion to its own size it also has the most inclined and eccentric orbit its orbit is uh sort of shaped like an egg Pluto's orbit causes it to get significantly closer to the Sun and then further away from the Sun this Cosmic needle in aast stack eluded Planet Hunters for decades the eighth planet Neptune had been discovered in 1846 and astronomers at the turn of the century were convinced there was a ninth planet in the far reaches of our solar system the search for Pluto was started by pel L at L Observatory he thought there was a Planet X there that was perturbing the orbits of Uranus and Neptune before finding the elusive Planet l passed away but the observatory's research assistant Clyde Tomba continued his quest in 1930 at the age of 24 Tomba captured an image of an object that seemed to validate lol's predictions the discovery was announced to the world and the object was given an official name Pluto but was Pluto Planet X some scientists argued that Pluto was far too small and didn't have enough Mass to significantly perturb the orbits of its neighboring gas giants Uranus and Neptune astronomers have since realized that there is no such Planet X it had been predicted using inaccurate estimates of Neptune's Mass even though Pluto wasn't Planet X could it still be classified as a planet the first term for planet just meant Wanderer in the sky it was the things that moved relative to the Stars so to the ancient Greeks the moon was a planet the sun was a planet the Earth was not of course when we realize that uh the Earth is actually going around the Sun and that the moon is going around the earth the definition of planet changed again Earth became a planet the sun and the moon were taken away and they were finally six and over time uh Uranus was discovered and Neptune was discovered so there were there were seven there were eight although it later proved to be smaller than our Moon Pluto was originally thought to be as large as Mars so tomba's Discovery was anointed as Planet number nine no one really thought much else about it it was a strange object it was sort of this lonely Oddball at the edge of the solar system but nothing else to call it so it was called a plant because of its great distance from the Sun Pluto takes its name from the Roman god of the underworld at its closest Pluto is 2.7 billion miles from Earth its diameter is 1,485 M half the width of the United States it takes 248 Earth years for Pluto to orbit the sun and a day on the planet is equivalent to about 6 and 1/2 Earth days a 150 lb Earthling would weigh only 10 lb on Pluto it's a testament to modern technology that we know anything at all about the surface of [Music] Pluto we can hardly see this thing even with a Hubble Space Telescope we get maybe four pixels across maybe 12 pixels total but even with that we see that parts of Pluto are is dark as coal and parts of Pluto are as bright as snow even from afar scientists can measure the composition of the planet they believe that the bright areas of the surface are made up of three types of ice one is carbon monoxide one is methane which is the same as natural gas and then the third is nitrogen the same stuff that we have breathing here in our atmosphere the dark areas are probably Solid Rock the darker areas are almost certainly silicat of some sort um silicat not unlike the rocks that we see here that means there's there's silicon in them and there's oxygen in them we're up here in Rocky Mountain National Park in Colorado there's some snow around there's some rocks around this is similar to what we see what we're going to see on the surface of Pluto a traveler to Pluto would find that despite the snowy surface it is a very dim place about 30 or 40 times further away from the Sun than the Earth is this means that the the sunlight hitting the surface of Pluto is about a thousand times fainter than it is on the earth it's maybe about the same brightness as being outside under a dim street light at night you could probably you know you could take a you could take a book you could probably read it there take a headlamp though take a flashlight it it would help out its distance from The Sun Also makes Pluto one of the coldest places in the solar system with a bone chilling average temperature of -3 188° F and because of its small size and low density gravity on Pluto's surface is far weaker than on earth now some things are going to be a little easy to do on Pluto if you're really into rock clim I'm doing some vertical climbing here um well it's always exciting but uh but gravity is always the challenge Pluto's gravity is roughly 115th of the Earth's it's not like if you're standing on the surface you would float away now if you fell off that face when you were when you were climbing up Pluto you'd still want to have your rope there you'd still accelerate down to the surface so uh don't leave the Rope at [Applause] [Music] home scientists would love love to chip away at the surface of Pluto because hidden within its rocks is a whole missing chapter in the history of our solar system Pluto is Pluto is a great Planet I mean it's what what I think is really great about it um it's sort of the the ultimate time machine in our in our solar system it really shows us what the what the environment of the solar system was like 4 and a half billion years ago when it's formed this the the surface there is much more ancient that you're than you're going to find almost anywhere else in the solar system and if you're looking for rock on the earth the earth has been been uh been around for for that same time period four and a half billion years or so but if you're looking for rock that's that old on the earth you're not going to find it that's because the Earth is sort of constantly recycling its material you have plate tectonics going on that sucks all this material back into the mantle you have volcanism going on that pumps out new material and uh processes the surface so it's really a much younger surface on the earth compared with the ancient surface that we're going to see on Pluto the rocks that we're sitting on here have been processed by the high pressures and the in the u u in the Earth on Pluto it's more primitive primitive but far from pristine Pluto is likely riddled with impact craters impact craters are caused by asteroids or meteoroids impacting the surface these are essentially pieces of solar system that we never made into Planet out of the surface of Pluto you don't have an atmosphere you don't have glacious you don't have wind you don't have rain you don't have erosion and so the one dominant feature that you see on the surface is probably going to be a lot of impact craters Pluto's popm Mark surface undergo a transformation as it orbits near the sun under the additional heat some of the Frozen and gases evaporate to form a temporary atmosphere as Pluto recedes from the Sun the gases freeze again and fall back down to the surface for more than 75 years this far out icy object staked its claim as our ninth planet so why is this little piece of snowy Rock now causing such controversy why was Pluto kicked out of the solar systems most exclusive Club it's a quiet office at the Caltech campus in Pasadena California and it was from here that Pluto's demise as a planet began but astronomer Mike Brown was never looking to destroy a planet equipped with Palomar observatory's 48-in telescope he was seeking out Pluto sized Worlds at the far reaches of our solar system and in 2005 he found one an object bigger than Pluto with its own Moon both orbiting the Sun when I first found this thing that's bigger than Pluto I was looking through the images that the telescope had taken um just before and I found it in the screen and did a very quick calculation realized it was bigger than Pluto um and the very first thing I did was picked up the phone and called my wife and told her I just found a planet indeed if Pluto was a planet and for more than 70 years it had been then why wouldn't Brown's new world be considered a planet 2 I thought it was the 10th Planet I uh for a long time that's how I described it it was a planet and so I definitely felt like I had found the 10th Planet it's 5% bigger than Pluto it's probably made out of the same materials on the inside Rock on the inside ice on the outside and a little thin layer of frost on the very outside that sometimes puffs up into an atmosphere and sometimes doesn't very similar to Pluto in that way it has a moon that goes around it once every 16 17 days Pluto has a moon also so it's in many ways I I like to think of it as as almost as twins this is just the twin that just ate a little bit more when it was a baby got a little bigger Brown considered naming his object Zena after TV's warrior princess but eventually the name chosen was ays after the Greek goddess of Discord as it turned out this name was entirely appropriate the discovery kicked off a firestorm in the astronomical [Music] Community now the very definition of a planet was being hotly debated would ays officially become our 10th planet or would Pluto sized objects be re-evaluated as a whole the argument was brought to the table in a 2006 meeting of the international astronomical Union in Prague a vote was taken and the term planet was defined scientifically for the first time those uh who are in favor of resolution 6A which introduces this new category of trans munian objects with pruto as a prot the recommendation is that we consider Pluto and other similar trans neptunian objects to be in a special class we didn't reconsider Pluto status because we learned anything new about Pluto that made it less interesting instead scientists say the issue was addressed because they learned about ays and other large Kyper belt objects the Kyper belt is a 3.5 billion mile wide region in the outer solar system near Pluto it's home to hundreds of thousands of icy objects the first of which was discovered in 1992 so historically we've thought of the outer solar system where you've got Uranus and Neptune out there you've there these big gaseous planets giant planets and then just beyond that you've got this little straggler Pluto that doesn't really fit into the picture well now we found all these other Kyper objects what we're seeing is that maybe Pluto is really the just the first of these many many bodies of the Kyper belt that are uh this wide diversity of of icy small icy bodies at the outer solar system the result of the IU vote stipulated that a planet is a spherical object that orbits the Sun and clears out the neighborhood around its orbital path since the area around Pluto is full of other Kyper belt objects the new definition would leave Clyde tomba's great icy Discovery out in the cold Pluto's 76-year reign as the ninth planet was over our solar system would now officially consist of only eight planets objects like Pluto and ays were given the new classification dwarf planets dwarf planets possess the same characteristics as planets but do not have a clear orbital path under the new definition sirri the largest asteroid in our solar system is also a dwarf planet we have this new terminology because there's more things in the outer solar system than we used to think it's like all you could see is one skyscraper and now all of a sudden you have a whole city in in front of you we have a whole city full of objects in the outer solar system now the IU vote was meant to settle the debate Fate on what constitutes a planet but many scientists refuse to accept the outcome there are astronomers who want it to be a planet still and they just keep ripping those scabs off whenever possible and uh they they want to they want to keep it fresh I believe Pluto is a planet and I don't think the question of whether or not Pluto is a planet is really that important fundamentally it's not a scientific question it's a question of names but in a way in an odd way it's become one of the highly visible subjects of planetary science people always ask whether Pluto is a planet or not there's not one easy dividing line there's one not where where uh you move from being a planet over here to being a planet over here to being not a planet over here just like there's no real dividing line between a stone and a pebble it's really more of a sociological question it's a question of definitions of words rather than a question of [Music] science although no longer officially a planet scientific interest in Pluto hasn't waned even as the vote was being taken in Prague a NASA spacecraft called New Horizons was already on its way to exploring this far off world the New Horizon's Mission will be the first spacecraft ever to visit Pluto by going to Pluto studying Pluto we it's no longer a mission to a singular object it's but it's actually a mission to one of a class of objects that we'll get to learn about but New Horizons needs to travel at warp speed or a valuable research opportunity to study Pluto's atmosphere will be lost for at least the next 200 years the New Horizon spacecraft is headed for a Rond f with Pluto we have confirmation of spacecraft [Applause] separation but scientists are trying to beat the clock because as Pluto recedes from the Sun its 62e long winter is coming and when winter comes to Pluto the dwarf planet's atmosphere will freeze and fall to the ground if it collapses too much it might just be a lot less interesting you might not have as interesting chemistry and we want to know what the temperature and the composition and the structure and the winds on the the atmosphere to get there in time New Horizons is blazing through the solar system at more than 45,000 mph that's 12 m a second at that speed a trip from Los Angeles to New York would take about three and a half minutes so this is the fastest spacecraft that was ever launched from the earth in fact took about 6 hours to get out to the quar million miles to make it out to the Moon uh you can compare that to the couple of days that it took the AP Polo astronauts to get out that that same distance New Horizons was passed by Jupiter in just 13 months but the outer solar system is so big that it's going to take us another 8 years years to get to Pluto even with its unprecedented speed New Horizons won't reach Pluto until July of 2015 Pluto is just a big mystery it's exciting to me that there's a spacecraft on its way there and that in a few years we you know this sort of blank slate of a world will be richly filled in with with pictures and detailed data about 4 billion miles from Pluto Uranus is a mesmerizing Blue Marble and it's really strikingly beautiful and different from the other planets it's a giant blue pale blue fuzzy ball sitting there in space against the darkness of space and it's just that that striking blue color and the almost pure featureless of it it it seems unreal it looks as though it was sort of created by some movie special effects person CU how could you have a planet that large and that perfect and this giant featureless [Music] blue Uranus is 1.6 billion miles from Earth it has a diameter of nearly 32,000 M four times Earth's diameter it takes 84 earth years for Uranus to orbit the sun one day on Uranus is a little over 17 hours if you weigh 150 lb on Earth you would weigh 133 lbs on Uranus named after the Greek god of the sky Uranus has the most off-kilter axis of any planet in the solar system at an angle of 98° the planet is actually spinning on its side what that means is that at one time of the year only one hemisphere is pointing towards the Sun the other hemisphere is complete darkness the time for for Uranus to orbit the Sun is about 84 years which means that for half of that time of 40 years one hemisphere is in sunlight and the other hemisphere is in dark it's like the Arctic Circle on earth except for it's the whole planet that tilt is so extreme that that in a sense the whole northern hemisphere is the Arctic and the whole southern hemisphere is is is the Antarctic Uranus owes its cool bluish green color to methane the methane absorbs red and orange wavelengths from sunlight but reflects blue and green and its soft appearance is due to something that's familiar to anyone who lives in a big city smog in Southern California we're used to smog which is photochemically produced Haze material which uh gives this hazy appearance in the atmosphere this is similar to the atmosphere of the four gas giants in the outer planets there's methane which is natural gas sunlight converts it to complex Pol particles as well which forms a haze which is the reason the planets don't have a very sharp but have a fuzzy look to them scientists speculate that Uranus and its Celestial neighbor Neptune form the same way as the early protoplanetary dis of gas and dust in our solar system settled Jupiter and Saturn gathered up the most material and became the largest of the gas giants as Jupiter and Saturn's orbits grew they destabilized the planetary system as a whole dynamic interactions pushed Uranus and Neptune outward to the edge of the solar system at an accelerated rate where they feasted on icy objects they have a lot of that initial gas but they also gathered a lot of icy material and some rocky material in their formation so consequently although they have this surrounding envelope of hydrogen and helium gas and some methane some nitrogen some other stuff they also have a lot of icy material in the inside these icy Interiors have led some to call Uranus and Neptune the ice giants but it's incorrect to imagine them as balls of solid ice that an astronaut could walk across well if we dropped it an astronaut or a probe uh towards the center of of Uranus or Neptune well first of all they'd be in a lot of trouble um there's really no solid surface that they could stand on there may be a small rocky core at the center of these planets but the pressure that they would be experiencing from the atmosphere overhead and this this liquidy icy region would crush them it would be millions of times the the pressure that we have from our own atmosphere for example so they would be flattened well before they ever reach the solid surface while the other gas giants have wild weather patterns Uranus seems to be relatively Calm And scientists think they know why Uranus is unique among the gas giant planets in that it is the only one that doesn't have an internal heating Source Jupiter Saturn and Neptune all have heat coming from deep within the planet and that helps Drive the circulation and explains why we see a lot of the Bandit structure that we do on those other three planets Uranus doesn't have this internal heating source Uranus has another claim to fame the way in which it was discovered by astronomer William hersel in 1781 at the time the only known planets were the six visible to the naked eye from Earth but herel first laid eyes on Uranus through a telescope herel was an amateur astronomer professional musician and an optician so he had the knowledge and ability to generate the best telescopes in the world at the time the discovery of Uranus was incredibly significant in the history of humanity because it was the first planet discovered by telescope the first planet that the Ancients didn't know about in 1977 NASA's Kyer Airborne Observatory made another exciting Discovery when astronomers aimed their telescope at Uranus they were planning to watch a fairly common astronomical event the passage of the planet in front of a star but as Uranus closed in the star suddenly winked in fact it seemed to flicker on and off five times as it neared the planet and then several more times as it emerged on the other side what was the cause of this strange phenomenon the flickering star was actually passing behind Five planetary Rings features that had only previously been seen on Saturn subsequent observations from the ground and then the Voyager spacecraft confirmed the Ring's existence and observations made in 2005 from the Hubble Space Telescope found a second set of rings orbiting almost twice as far away from the planet as the previously known Rings unlike Saturn's thick icy Rings Uranus are dim and thin comprised of dark Rocky dust some of Uranus's Dusty Rings were likely formed by the impact of a meteor or a comet with one of the planet's 27 moons the inner Rings could be the result of collisions between the moons themselves especially the 13 that orbit in the planet's kinetic inner swarm there are a lot of inner moons around Uranus moons that are very small small and close to the planet they tend to have very fast orbits on the order of maybe a day other moons zip around Uranus in just 12 hours by comparison our moon circles a planet four times as small and takes 28 days to do it with Uranus's Moon speeding around the planet likee race cars it's only a matter of time before two of them end up in another Cosmic Collision circling the planet Uranus is a swirling system of moons even within the last decade substantial changes have been detected in their unruly orbits scientists believe it's only a matter of time before two of them cross p paths we can be very certain that in a period of a million or a few million years that some of them will collide with each other I'm thinking particularly of of cupid and Belinda which are are two small moons that happen to be orbiting very close to each other traveling at just a few hundred miles apart scientists expect that at some point these moons due to gravitational forces that they impart upon each other will eventually Collide and rip each other apart it will be a bad day for the moons but a welcome event for the planet's ring system the debris that's released from that can potentially generate a new ring around Uranus Uranus shares the outer solar system with its sister planet Neptune a gleaming Sapphire some 3 billion miles away from the sun with the demotion of Pluto Neptune is now our outermost planet Neptune takes its name from the Roman god of the seas Neptune is 2.68 billion miles from Earth measuring roughly 30,000 mil NE Neptune's diameter is four times that of Earth's a year on Neptune is equivalent to 165 Earth years and a day lasts 16.1 hours if you weigh 150 lb on Earth you would tilt the scales at 169 lb on Neptune like all the outer planets Neptune rotates much faster than Earth and this rapid spin helps to create violent winds in fact the highest winds recorded on any planet in the solar system are on Neptune you have winds of sometimes over 1,000 mph and commonly um 750 m hour raging in that upper atmosphere and we're not quite sure why so there's a little bit of mystery what puzzles scientists is why Neptune's winds blow even stronger than those on on the other outer planets with speeds two to three times faster than in Jupiter's blustery Great Red Spot JPL researcher Michael mishna studies what drives weather on other planets he's intrigued by Neptune's mysteriously strong winds if we were to put one of these windmills up on Neptune depending on the altitude that we put it we would either see motion similar to what we see now or if we were to place it at the altitudes in which the winds are going 1,000 miles an hour we actually might not see very much motion at all and that's because the atmosphere is so thin that there's just not enough oomph and not enough force from that wind to actually turn the propellers of the turbine so you might not actually see any motion at all on Earth we see high pressure and low pressure systems if we look at weather maps and same to an extent can be seen on the outer planets we can't exactly identify a big H in this location or a big L in this location but there are generally regions that are warmer and have higher pressure than other areas which are are colder and may have lower pressure and that generates the winds that blow from high to low a key factor in the creation of wind is an energy source to heat the air on Earth the Sun provides this energy but the wind swept Planet never Nune is 30 times farther from the Sun than Earth and it gets only about 1 1900th as much solar energy it's simply not enough to power Neptune's colossal winds scientists believe that Neptune gets its additional power from within measurements taken by Voyager 2 showed that Neptune radiates twice as much heat from it its interior as it gets from the Sun the highest ratio of heat outflow to inflow of any planet in the solar system Neptune has a relatively large amount of internal heating which is coming from radioactive decay of materials inside and other chemical processes that are occurring and that releases a lot of heat from the inside just why the interior of Neptune generates so much heat remains a mystery it's LED some to speculate that the planet is still in the process of forming and the infalling gases are releasing heat as they are compacted by gravity this internal heat Source could also explain the convection of gases in Neptune's atmosphere that leads to fascinating Cloud patterns there are many bright white clouds that appear in the atmosphere there are different regions of very bright and dark banding on the surface so we'd be able to distinguish different latitudes by the brightness of the [Music] Bands scientists believe that the banding patterns have something to do with Neptune's Cloud composition these are probably made of methane uh and they move very fast around the the planet as well Neptune's wind movement is unlike anything we are accustomed to these are giant storm systems storm systems that would dwarf anything that we see on Earth in 1989 Voyager 2 snapped a photograph that shocked the mission scientists Neptune had a huge storm a Great Dark Spot in its southern hemisphere stretching 8,000 M wide large enough for our Earth to fit in the center Center the storm resembled Jupiter's Infamous Great Red Spot the Great Red Spot is a huge anticyclone which is fed by many smaller storms that keeps it alive if you like otherwise it would dissipate and disappear in the case of the Great Dark Spot we believe it's more of an instability in the atmosphere which rocks back and forth uh because of the flows in that very fast atmosphere just 5 years after the spot was first discovered scientists were in for another surprise the Hubble Space Telescope turned its eye toward Neptune only to see that the largest storm on the planet was gone what happened to Neptune's Great Dark dark spot within a span of 5 years the largest storm on the planet simply vanished from the southern hemisphere but that didn't mean the end of Mega storms on Neptune astronomers using the Hubble Space Telescope observed that a new Great Dark Spot had appeared but this time in the planet's Northern Hemisphere it seem that on Neptune the storm systems that manifest as these big spots you can see with a spacecraft or a telescope they sort of come and go on shorter time scales than say the Great Red Spot on Jupiter which has been there for hundreds of years not only are these storm systems transient they're also eccentric scientists observe that the size of the Great Dark Spot oscillated by several thousand square miles within a span of just 8 8 Days The Disappearance and reappearance and overall erratic movement make Neptune storm systems some of the most unpredictable in the solar system similar to its outer planet neighbors Neptune has a complex system of moons 13 have been discovered so far some of Neptune's moons may have originally formed elsewhere in the solar system Neptune's probably capturing these moons from the vast amount of material that's actually in our solar system beyond the orbit of Neptune and Pluto there is a lot of of very icy bodies small bodies planet tmals and other Rocky things that pass through our solar system and other debris every so often some of this debris might collide with each other and then they get pushed in towards the solar system some of these icy bodies end up as comets but if one is pushed in the right direction at the right time it can be captured by a planet's gravitational pole becoming a moon Neptune's largest moon Triton is roughly the size of Earth's moon it is the coldest object in our solar system ever observed by astronomers even more frigid than Pluto only 40° above absolute zero aboutus 390° f so cold that the nitrogen which would normally be in a gases form forms an icy polar cap on this Moon Triton's so cold primarily because the surface is so reflective about 70% of the light that hits the surface of Triton is reflected back and with that much light not being absorbed by the planet it just gets very very cold Triton could well be similar in composition to Pluto we see IES on the surface there one of the fascinating things that we see on the surface of Triton actually plumes essentially volcanoes we see these plumes we've actually seen them coming out in real time with a Voyager spacecraft when when it went past uh Neptune and Triton unlike Earth's volcanoes Triton's geyser like er ions spew a mixture of liquid nitrogen methane and ammonia and an upsurge instantly freezes as it Rockets 5 m High into its thin atmosphere once Airborne the ice can be carried along for Miles by winds in the atmosphere before snowing back down onto the surface geological activity on Triton makes scientists wonder if there's water perhaps being heated under Triton's icy exterior and as the theory goes where there's water life could be present if that's the case Neptune's largest moon could be home to one of the biggest discoveries of all time but due to planning and transit times it will be at least two decades before we approach Uranus or Neptune again we've had discussions but there are no current plans we could with voyager where we just had a brief flyby and we managed to collect a lot of Discovery but in fact we need to get back to pursue those discoveries in the meantime science scientist will be focused on New Horizons as it Rockets even closer to Pluto on board in addition to a cluster of scientific instruments is a small canister of Ashes those of Pluto's Discoverer Clyde Tomba who died in 1997 at the age of 90 I'm not involved in New Horizon Missions at all but I can tell you from my point of view I'm I'm very excited about it we really don't have any good ideas of what the actual features on the surface of Pluto are going to be like that's why these small scale pictures getting getting actual closeups is going to be so important as spacecraft probes and telescopes are sent to the far reaches of our Celestial neighborhood we come one step closer to deciphering the expansive Universe our technology and our imaginations can help bring these far-off alien worlds to life as we look at them with awe and wonder we can only fathom what unexplored Mysteries lie deep within each star you see twinkling in the night sky is a luminous sphere of superheated gas much larger than any planet and each has a story to tell a traumatic birth a life on the edge gravity collects the star in the first place and then gravity wants to crush it and a death that rattles the heavens the whole thing goes off in a blinding Flash the biggest explosion in the universe the universe at its most volatile and action-packed life and death of a star like glittering cities in the desert galaxies arise out of the great darkness of the universe galaxies made of billions of Blazing lights called stars there are billions and billions of stars in fact in our galaxy there are 400 billion stars just in our galaxy but how were these stars born how will they die and how can it be that all human beings on Earth owe their lives to the deaths of stars The Quest For answers begins here in a cloud of dust and gas hovering in the interstellar desert you are looking at The Pillars of Creation the pillars of creation are a stellar Nursery new stars are in the process of being born in the central regions located 7,000 light years from Earth the pillars are part of the Eagle Nebula which is just one of billions of star forming regions in the universe the pillars are towering clouds of dust and hydrogen gas if you remember the periodic table of elements from chemistry class you have the Light Elements up at the top hydrogen helium lithium this sort of thing and then the really heavy ones as you get lower down it's hydrogen the lightest simplest most abundant element in the universe that is the key component of stars within a nebula clumps of this gas and dust slowly coales into smaller clouds over millions of years pulled together by a very familiar Force the same force that connects us here to the Earth that keeps us on the earth gravity is the same force that pull things together in a way that gives us planets and stars and galaxies in the universe gravity in many senses is the most important force in astronomy and when gravity acts in the universe one of the basic things that it produces is Stars stars are sort of the most basic unit of mass that is produced when gravity pulls Mass together each Contracting Cloud can produce anywhere from a few dozen to thousands of stars to form a star like our sun which is a million miles across it takes a clump of gas and dust a 100 times the size of our solar system these clouds start off their lives bitterly cold with temperatures hundreds of degrees below 0 f but as gravity fragments and compresses them the heat begins to soar within a few hundred, years the cloud spins into a flattened disc Gravity coalesces the center of the disc into a sphere where the heat rises to a scorching 2 million degrees this glowing system is now known as a protostar 10 million years later the Searing hydrogen core of the fledgling star Soares past 18 million de and something incredible happens the core becomes so hot it can sustain thermonuclear Fusion thermonuclear Fusion it's a lot of syllables but it just means it's hot there and small atoms become big atoms hydrogen atoms are moving fast enough that they actually will um will fuse together and will form a helium atom it's this nuclear reaction that produces the energy to power the star throughout its life giving it a constant source of light and heat it's self luminous generates its own heat and that's the essence of of what makes a star a star if you've got Fusion you've got a star once born a star's life will be a constant battle an allout war against gravity gravity collects the star in the first place and then gravity wants to crush it gravity never gives up gravity wants to pull everything together and so if the star is going to have a life and a long life it has to find a way to fight against gravity you feel gravity all the time when you try to jump or you try to climb a rock there's always gravity pulling you back down and in order to fight against gravity you have to have some way of applying a force which works in the opposite direction of gravity so if there's a rope you can use your muscles to pull on the rope and therefore resist and even overcome gravity but that doesn't mean gravity gives up gravity is always working uh and so you have to keep applying this force in order to not fall off and if you give up or let go or the Rope breaks gravity immediately winds and you fall the same kind of thing happens with stars stars are also uh trying to hold themselves up against gravitational collapse gravity wants to crush the star down to the middle for stars nuclear fusion provides the rope in the form of pressure the heat gets all the particles in the star moving around quickly and they bang outwards and that produces a pressure which can actually hold the star up against Against Gravity the amount of pressure pushing out on the star just matches the amount of gravity pulling in on the star and it can sit there and burn happily until something changes a star will spend most of its life in this state of equilibrium it's a phase scientists call the main sequence so our sun is in the main sequence we're very happy it's in the main sequence it provides us the same amount of energy almost every day and that's what makes life possible all stars on the main sequence aren't alike some are much smaller and cooler than the sun others much larger and hotter so it turns out that how hot something is is related to the color of the light that it emits so a star like the sun most of the light that comes out from the Sun is sort of a yellow type color if the sun were much hotter the predominant wavelengths of light would come out into the blue or or even into the ultraviolet and cooler Stars emit more red light small cool red stars like Proxima centori the nearest star to the sun are known as red dwarfs they can be as little as 1/10th the mass of the sun with surface temperatures thousands of degrees cooler red dwarfs are the most common type of stars in the universe there are many many more of these sort of very dim uh red dwarfs floating out in space than there are stars like the sun now of course when you look in the night sky you don't see the most common kinds of stars you don't see these red dwarfs CU they're so faint you merely see the very rare very bright stars that turn out to be very very far away on the opposite end of the spectrum are the large Blue main sequence Stars averaging a surface temperature of 45,000 de F they can be 20 times the mass of the Sun and 10,000 times more luminous in the life and death of a star size definitely matters mass is the fundamental thing which drives the life history of a star the more massive stars live much shorter lives than the less massive stars and that's perhaps a little bit strange sounding because the massive stars have more fuel to burn you'd think they'd live longer so it's counterintuitive that more massive stars will burn through their fuel uh more quickly than the lower Mass Stars imagine two gamblers sitting down at a blackjack table you would expect the one with the most money the most fuel to burn would last the longest but what if the big time Gambler is making huge bets on every hand a gambler that is gambling with a lot more money and putting down $10,000 at a time it's going to burn through that money much more quickly and so the more mass you have the higher temperature the higher pressure the higher the fusion rate and it goes much more quickly with the more mass you have and it's always just simply the calculation how much fuel do you have and at what rate are you converting it the high mass stars live their lives faster they burn their candle at both ends there's Life in the Fast Lane a high mass star could die within a million years a star 10 times as massive as our sun might live for only 1 1,000th as long so our son will live for about 10 billion years in total a star 10 times as massive as our sun might live only 10 million years in total while massive stars have lifespans measured in millions of years the lowest mass stars measure their lives in tens of billions if not trillions of years every low mass star that has ever been born in the universe and the universe has been making stars for more than 10 billion years all of those stars are still in their infancy no such star that's ever been born has ever come close to dying but for all stars including our own Sun Life on the main sequence can't go on forever it can only last as long as the star has fuel to burn if it runs out of fuel Fusion stops and gravity wins gravity never gives up whereas fuel of course can run out after a while and so the star and the climber both have the this terrible problem that if they don't maintain their Fight Against Gravity they will end in a death a cataclysmic death not only does the size of a star influence how long it will live it also determines how it will die massive stars explode from the scene in violent Fury while smaller ones are doomed to slowly fade away for 5 billion years our son a lower Mass middle-aged star has been happily burning through its supply of hydrogen fuel like a gambler slowly plowing through a pile of chips The Gambler May sit there for a long period of time just like a star Burns its hydrogen for a really long period of time however at some point she's going to run out of money scientists predict that 5 billion years in the future our sun will reach this critical Crossroads its supply of hydrogen fuel will have been completely exhausted nuclear fusion will cease and gravity will begin to crush the star at that point the situation is desperate in order to survive a sunlike star must find a new source of fuel it has helium on hand but in order to start burning helium the core has to be 10 times hotter than it was during its lifetime burning hydrogen it won't be able to fuse that helium into heavier elements like carbon and oxygen until the core gets sufficiently hot and that's because it's harder to get the helium nuclei close enough together for the strong nuclear force to take over grab them and cause them to fuse together as it continues to contract inward nature throws the star a lifeline the core actually becomes super heated by the very gravitational pressure that's trying to crush it when it reaches 180 million de it can start fusing helium into carbon in a desperate gamble to survive so the desperate Gambler might go take out a loan on their house and get more money but in getting more money to burn through it's really just delaying the inevitable which is to go bust and for a star the inevitable is to Die the star which took 10 billion years to burn through its hydrogen now Powers through its supply of helium in a mere 100 million years and then the action begins it runs out of hydrogen starts fusing helium runs out of helium attempts to fuse carbon and will fail but all the action all the what's going on now happens in the last 10 10% of a star's life the Searing heat of the helium burning actually causes the outer layers of the star to swell at that point the outer atmosphere of our star will be held in by gravity so weakly that it'll start sort of just evaporating away through a series of what I call Cosmic burps it will actually eject the outer envelope of gases which are only weakly held by gravity that'll send some shells of gas outward illuminated by the hot Central Star and that will cause What's called the planetary nebula phenomenon beautiful shells of glowing gas surrounding the dying core of our sun with the core unable to muster any more nuclear Fusion can it possibly survive gravity's crushing grip as a star the size of our sun dies it ejects its outer layers with no nuclear reactions to generate outward pressure gravity gains the upper hand the star begins to fall in on itself like a climber too tired to hold on to his rope there's one possibility that the rock climber might be able to use if he gets too tired to hold on to the Rope anymore and that is if he can find a ledge on the rock that he's climbing gravity can pull on him all he wants but the ledge itself will support him against gravity and he doesn't have to provide any more energy to win his fight there's a certain kind of star and our sun is actually an example of this where the star finds that it has an out in this fight against Gravity the Contracting star Finds Its Ledge in a surprising Place electrons tiny negatively charged atomic particles electrons don't like being compressed so that they're very close to one another because electrons effectively don't like each other if you compact the electrons hard enough the pressure of the electrons themselves is able to hold up the star Against Gravity when the core of our dying sunlike star is crushed to a the size of the Earth this so-called electron degeneracy pressure takes over gravity can collapse the star no further it's left to slowly cool into a bizarre Stellar Remnant known as a white dwarf like this one serus B which can be seen only faintly aside its companion Sirus the brightest star in our Sky now a white dwarf is a very strange type of star it's very very dense the white dwarf has about 300,000 times the mass of the Earth compressed into a volume the size of the Earth if you had just a teaspoonful of material it would weigh several tons so it's really amazing stuff a white dwarf is the final stage in the light of a sunlike star but it's not quite dead yet it will continue to shine for billions of years as it gradually radiates away a lifetime of energy I like to call white dwarfs retired stars in the sense that all of the light that they are shining is energy that they accumulated during their normal lives as stars while they were fusing Light Elements into heavy elements as as our son is doing right now so it's spending its life savings it's a retired star that will be the fate of our son but some white dwarfs can have one last Harrah thanks to a friend who lends a helping hand because although our son is a cosmic loner more than half of All Stars travel through life with at least one companion most stars are members of binaries or possibly even multiple star systems close binary Stars can have very different Fates from your ordinary single Stars if a white dwarf is gravitationally bound to another star as part of a binary system it can essentially steal the lifeblood from its companion the small but dense white dwarf exerts such a strong gravitational pole that it will start siphoning off a stream of hydrogen gas if it gathers material from a companion star and it is able to grow in Mass then eventually the mass of the white dwarf can reach an unstable limit roughly 40% more than the mass of our son at that point the white dwarf undergos a catastrophic explosion where the whole thing goes off in a blinding flash what's called a thermonuclear runaway of the entire star this Mammoth explosion is known as a type 1A Supernova so if our sun were to do this and it won't it'll die in a relatively quiet way but if it were to do this you'd need sun block or supernova block of a few billion in order to protect yourself from the blinding [Music] flash University of California Berkeley Astron Romer Alex filipenko is one of the world's most successful Supernova Hunters his team has found over 600 of them in the past decade an incredible feat considering they occur perhaps twice per Century in each Galaxy searching for supernovas is akin to scanning a crowded football stadium with binoculars in hopes of catching the one person who might be taking a flash photograph at a given point in time if you were to look at each person individually one by one you would have a hard time finding the person who happens to be taking a flash photo filipenko increases his odds by expanding his search Beyond single stars or even single galaxies to do this he enlists the help of a very Hightech assistant so this is a robotic search engine for exploding Stars supern noi it has been been programmed to robotically take photographs of over a thousand galaxies a night and over the course of a week it does seven or 8 thousand galaxies and then it repeats the process comparing the new pictures of each Galaxy with old pictures now usually there's nothing new in the new picture but occasionally a star blows up a supernova goes off and then you can see in the new picture a bright point of light that wasn't there in any of the old pictures though a supernova is visually very very bright the visible light is only 1% of 1% of the total energy 1,000th of the entire energy emitted by this colossal explosion although type 1A supernovas come from exploding white dwarves many other known as type 2 supernovas signal the dramatic deaths of much more massive stars perhaps eight or 10 times more massive than the sun unlike their smaller cousins when massive stars exhaust their hydrogen fuel they have the raw power to start fusing other elements the ashes of each set of nuclear reactions become fuel for the next so that near the end of its life a massive star resembles an onion in cross-section with an outer layer of the original fuel hydrogen surrounding layer after layer of heavier and heavier elements it goes through its normal life fusing hydrogen into helium then helium into carbon and oxygen then oxygen into neon and magnesium and then silicon and sulfur and then iron the massive star builds up a core of iron but Fusion of iron into heavier elements doesn't do the star any good it doesn't keep the star hot inside because Fusion of iron into heavier elements requires energy it absorbs energy it doesn't liberate energy so the iron core builds up without fusing and eventually becomes unstable when it reaches something like 1 and 1 half times the mass of our sun it collapses and the collapse is violent within half a second a core the size of the Earth is crushed into an object roughly 10 mil across for a moment the collapsing core rebounds smashing into the outer layers of the star and kicking off one of the most massive explosions in our universe since the Big Bang the collapse of the iron cord blows apart the rest of the star in a colossal explosion it's truly an amazing incredible event scientists are convinced that supernovas mean much more to the universe than spectacular light shows they are in fact the source of the heavy elements that make up everything around us all of the iron in this Foundry came from exploding stars from gigantic explosions all of it all the iron you see everywhere came from exp floding stars and in fact all the elements heavier than iron directly or indirectly were made by exploding stars and those elements were ejected into the cosmos by these gansan explosions as material from these explosions spread out through the universe it became the stuff of planets moons new stars and something even more extraordinary if you could trace your ancestry back to its earliest reaches you would find an exploding star in your family tree we are essentially made of star stuff or Stardust as Carl Sean used to say the elements in your body not just generically but specifically the elements in your body heavier than hydrogen and helium came from long dead stars the calcium in your bones the oxygen that you breathe the iron in your red blood cells the carbon in most of your cells all those things were created in Stars through nuclear reactions and then ejected by supern noi and the heaviest elements iron and above were produced by the explosions themselves by the supernova while the explosion of a type 2 Supernova showers the universe with heavy elements the core of the exploding star is left intact destroying that is gravity's job but to crush the core any smaller than the size of a white dwarf it will have to overcome that strange Force electron degeneracy pressure gravity actually finds a way of defeating that t the electrons have to push each other apart by combining the electrons with the protons and turning them into neutrons you now have an object which is made almost entirely out of neutrons and gravity winds it it now allows the system to collapse further they're no longer electrons stopping that and gravity seems to win except neutrons it turns out also don't like each other and you end up with a new stable object even smaller even more dense called a neutron star compared to normal Stars neutron stars are cosmic Pebbles they can be as small as 10 m across so imagine you take a star about 1 and a half times the size of our sun and then you can press all of that material down into a very small space about the size of Manhattan you've just made yourself a neutron star squeezing that amount of mass into such a small space makes for an extremely dense object one teaspoonful of neutron star material would weigh a billion tons neutron stars are some of the most exciting and weird objects in the universe that astronomers study if a human being were to stand on the neutron star it it would be a somewhat uncomfortable experience on Earth if they weighed about 150 lb on a neutron star they would weigh something like 10 billion tons a biology can't stand that amount of pressure and so a human being would essentially be squashed flat against the surface of the star in addition to that neutron stars are spinning at an incredibly High rate hundreds of times per second in some cases it's this rapid spin that enabled astronomers to First identify neutron stars some neutron stars are spinning really rapidly and they have a really amazingly High magnetic field that magnetic field together with the spin forces a bunch of charged particles electrons to go along the axis of the magnetic field and those accelerated electrons give off light they produce a well focused beam of light now this is like a lighthouse whose beam is always on but you only see it when the lighthouse beam intersects your line of sight in a similar way we might see The Shining neutron star only when the beam points at us that object is called a pulsar some stars are so massive perhaps 25 or 40 times the mass of the Sun that not even a neutron star can hold up under the weight of their collapse and gravity will crush them even further into an object of infinite density and almost equally Limitless fascination a black hole in some sense a black hole represents the Ultimate Death of a star a black hole is basically gravity's um victory over Mass it is complete collapse of a star a very massive star this collapse creates a region of space where matter is compressed into such a high density that its gravitational field is inescapable black holes are REM able in that nothing can escape from them not even the fastest moving thing we know of which is light you shine a flashlight beam up and even it won't leave the beam will curve back around so you won't be able to see it from the outside hence the name black hole a common misperception is that black holes just go sucking up everything in the universe like that just like Cosmic vacuum cleaners sucking up everything in their vicinity that's actually not true now objects that are very close to black holes do get sucked in but if you're comfortably far away with the proper trajectory you won't get sucked in scientists have long suspected that there is yet another class of supernova involving even bigger stars and even more powerful explosions stars that collapse so catastrophically that they leave behind no Remnant not even a black hole but no one had ever seen one until now even after billions of years the universe is still surprising us with its raw power in the fall of 2006 astronomers observe the largest Stellar explosion ever witnessed by man 240 million light years away from Earth a massive star blew itself apart Alex filipenko and his team at the University of California Berkeley were amazed at the power of the explosion and the total energy emitted was 100 times as much as the energy of a normal massive explosion it's an amazing really powerful explosion a normal Supernova comes from the explosion of a star 10 times more massive than our our sun incredibly Supernova 2006gy as astronomers have dubbed it seems to have signaled the death of a star 150 or even 200 times more massive that's about as massive as a star can get scientists are still studying the aftermath of the explosion but they think Supernova 2006gy has a lot to teach us about the first stars that populated our Universe we actually think that the first generation of stars tended to be really massive and they probably exploded by this mechanism it's these Mega explosions that likely seeded the early Universe with heavy elements these extremely massive stars are the largest iron factories in the universe a single star 150 times the mass of the Sun can produce 20 or 25 solar masses of iron it's incredible in the cycle of life not only here on Earth but in the cosmos as stars die particularly those that die spectacular deaths the high mass stars that manufactured heavy elements in their ques those give the seeds of the next Generations of stars that then increase the likelihood that that next generation will have planets and planets that contain the ingredients of life itself supernovas aren't the only energetic events in the life and death of a star right now Across the Universe there are a thousand pairs of stars engaged in brilliant dances of fire for some this dance will end in catastrophe astrophysicist Joshua Barn of the University of Hawaii studies what happens when stars [Music] collide we don't have the luxury of watching stars collide a pair of stars as they draw close enough to collide would just be a single dot of light even in the largest telescopes that we have so we need to investigate these things with a computer using computer models astrophysicists can take any two types of stars and find out what happens if they become involved in a stellar smashup the models pose hypothetical situations and then see what happens and you could sort of Imagine This is like studying collisions of cars and you were taking them out and smashing them together in the parking lot one after the other to see what came out of them among the most explosive collisions modeled by astrophysicists is The Clash of two orbiting neutron stars typically they're bound together as a pair orbiting one another and as they orbit they disturb the space these time around them and create waves of energy and the energy to do that slows the Stars down so they get closer and closer together as they get really close together they're orbiting around hundreds or even a thousand times per second the final event is very dramatic when two neutron stars collide they're moving at nearly the speed of light although the final Collision takes only a fraction of a second it unleashes more energy than the sun will generate in its entire lifetime thanks to computer modeling we can also predict what would happen if a highly dense white dwarf collided with our sun it would be a frightening Collision when it got close enough the gravitational field of the white dwarf would start to distort the Sun so the sun would no longer remain a sphere it would sort of turn into an egg shape as this thing came close as the white dwarf plows into the Sun at supersonic speed its gravity would send an enormous shock wave throughout the star and that would produce so much thermonuclear energy to essentially explode the sun amazingly it would take only about an hour for the white dwarf to plow through the Sun and annihilate it if this scenario came to pass life on Earth would be doomed fortunately the chances of this happening are slim because the sun is in a very uncrowded part of the Milky Way galaxy individual stars are kind of jostling and weaving as they make their great circuit around the galactic center so it's a complicated traffic situation but because the space between the stars is so great there's not much chance of a collision if you were to wait out here on this beach until you saw the collision between the Sun and another star you would wait a long time even over its entire life the sun has probably a billion in one chance of colliding with another star but there are places within galaxies where the odds of a collision are much greater regions where hundreds of thousands or even millions of stars are crowded together by gravity into a globular cluster compared to the spiral arms of the Milky Way a globular cluster is like a demolition [Music] derby the odds of two stars colliding in the spiral arms of our galaxy are only about one in a billion but within a globular cluster stars are packed a million times more densely than elsewhere in the Milky Way in the Milky Way everybody is pretty much going in the same direction but in a globular cluster there's no organized motion they're basically all orbiting around the center on orbits which are aligned in all sorts of different directions so some are going one way some are going the opposite way in these crowded chaotic conditions stars collide on average once every 10,000 years every Star in a cluster was born at roughly the same time so when astronomers look at an old cluster they don't expect to see any young stars but strangely a globular cluster usually conceals some mysterious strangers large Blue Stars far younger than the small dim Stars surrounding them these seemingly impossible stars are known as blue stragg the mystery of blue stragglers is that they're in some sense younger than they have any right to be all of the stars of that mass and that Luminosity would have died off uh billions of years ago in these clusters so the puzzle is where did these things come from how did they get into these star clusters astrophysicist Joshua Barnes thinks he knows the answer he believes blue stragglers are the result of collisions between older dimmer main sequence Stars a collision of two main sequence Stars two sunlike stars is actually relatively gentle the mutual gravity of the Stars locks them in a spiral they've lost energy of motion and they will come back and have multiple subsequent passages they heat up and swell up and kind of spiral around each other making several passes each closer than the last one until they finally come together and stars merge in the end rather than triggering a catastrophe the two stars merge to form one more massive star uh what you're basically doing is taking two small old Stars piling them together to make one star now which is twice as massive and therefore being more massive it's brighter and Bluer Than the Rest of the stars in the cluster so it seems to be straggling behind the rest of the Stars while the mystery of the blue stragglers seems to have been solved the heavens are bursting with unusual objects that dare science to explain them black holes neutron stars and white dwarves all represent the end of remarkable Stellar lives but there are other strange celestial objects that never got a chance to shine not quite planets not quite Stars these are the brown dwarfs brown dwarf is basically a failed star University of Hawaii astronomer Michael leou searches for these elusive objects stars produce a lot of light they're very easy to see a long ways away but Brown dwarfs are very low temperature and so they emit very very little light uh because they're so dim it means we can only see them if they're very close to us a brown DF DF has the same ingredients as a star but it simply doesn't have enough Mass to sustain nuclear fusion if something is born with less than 8% the mass of the Sun then it's uh it can't produce its own energy it's essentially a failed star without Fusion these failed Stars start to act more like planets if you were flying in a spaceship across the surface of a star you wouldn't really see any anything that looked like clouds or mountains or anything like that when you go go to a brown dwarf things begin to change we think their atmospheres in some ways might be similar to things like very massive versions of the planet Jupiter uh if you're familiar with pictures of Jupiter you see Jupiter has all sorts of banding structure and clouds on its surface although we've never taken a picture of the surface of a brown dwarf we think Brown dwarfs may also have similar Cloud structure now these aren't normal kinds of clouds like we know about on the earth you have iron Vapor making these clouds and then the clouds may get thick enough that you get iron droplets raining out of the clouds obviously a person wouldn't want to be there cuz these are molten iron to date astronomers have located only a couple hundred Brown dwarfs and they still have many questions about these elusive objects for one they know some brown dwarfs have discs of dust and gas around them might those diss form into planets that's just just one of many Mysteries yet to be solved as we continue to probe the stars but already science has revealed the universe to be a magical realm of dwarfs and Giants stragglers and supernovas and hidden within the explosive life story of stars they have found the very history of the cosmos and a key to understanding our own Origins our sun is one of billions of stars in the Milky Way galaxy and our galaxy is one of hundreds of billions maybe a trillion in the known universe from the Hubble Space Telescope comes a view of the universe that was a magnificent trip through the Mists of history and back nearly all the way to the Big Bang each smudge each Clump each blob of light a billion stars here a trillion stars there if you want to know our place in the universe take a look up and far far away to the realm of Alien Galaxies ours is a universe of motion expansion light and Blackness we think the universe is about 13.6 billion years old so just to put that in context Tex the earth and the solar system is just over 4 billion years old so the universe is just over three times older than the earth across the vast reaches of the interstellar void distant stars are held together by The Long Reach of gravity's unyielding grip over billions of years these stars have come together to form galaxies a galaxy is a collection of a 100 billion or so stars and these Stars Are by no means touching each other or actually anywhere near each other compared to their sizes they're very very far apart from one another the thing that blows my mind about galaxies is what monsters they are they are incredibly huge if the sun were the size of a period on a page of the dot of an eye our our galaxy would be the size of the continental United States so they're gigantic astronomers have always known there was something special about the band of stars and dust that seemed to encircle the night sky above them it's our galaxy a white smudge they called the Milky Way That Band of light is the collected light of hundreds of thousands of stars that you can't see individually with your eye and that was named by the Greeks they thought it looked like a Milky River so they called it the Milky Way There are 100 billion stars in our galaxy and there are 100 billion galaxies in the observable universe that's more stars in the universe than grains of sand on the beaches of the Earth if you imagine a Galaxy itself is the size of a hockey puck then the galaxies are spaced from one to another about a few diameters apart so if there's a puck here and a puck over there that's kind of the way the galaxies are spaced in the universe picture from the Hubble Space Telescope show the wide variety of Alien Galaxies the Sombrero Galaxy also known as m104 one of the most massive objects in a gigantic cluster of galaxies the Sombrero Galaxy contains nearly 800 billion times as much mass as our sun compared to the Milky Way Sombrero has a much larger bulge relative to its highly wound disc this image of the Sombrero Galaxy is also a prime example of what happens when three of the world's top space telescopes join forces the Shandra x-ray Observatory taking an image of the high-powered x-rays emitted by the Sombrero Galaxy the Hubble Space Telescope snapping an optical picture capturing the visual light that's made the multi-million Lightyear journey to Earth and the Spitzer Space Telescope capturing an infrared version looking at the somero Galaxy's Heat Signature melded together these three images provide a stunning and Unforgettable look at a Galaxy 28 million light years away M51 the whirlpool Galaxy its spiral arms twisting like cotton candy being spun the center of the whirlpool Galaxy is so densely packed with stars anyone living on planets there would be under a constant bright Sky day or night Centaurus a a Galaxy sending out massive amounts of radio waves think of it as an Interstellar broadcaster beaming its signal throughout the Universe all day every day it's the closest of the so-called active galaxies galaxies that pour out tremendous amounts of energy from their cores this is the Hubble Ultra Deep Field image created using the Hubble Space Telescope it shows us how truly vast and distant the universe really is and how those far off spaces are anything but empty when you look very deep in the universe you're looking back in time so you're looking back at galaxies right back to when they were very very young when they were only a few percent of their current age so the Hubble Ultra Deep Field is it's really like a Time Tunnel that gives us a glimpse of galaxies as they were before the Earth was in existence the Earth is 4 billion years old we're seeing galaxies as they were 13 billion years old so the light left these objects before there was any Earth at to the nearest large Galaxy to ours the Andromeda galaxy is about 2 million light years away so the light from the Andromeda galaxy takes 2 million years to get here so for seeing it as it looked 2 million years ago and that's one of the more nearby galaxies as we look farther and farther out in space then we're looking farther and farther back in [Music] time to get a better idea of the concept just visit one of the most spectacular Vistas on Earth The Majestic Grand Canyon as you look down the layers you get older and older rocks and we can tell what the different environments were so we can actually look at the geologic history of this area over time and in essence look back through the environment that was located right here back over hundreds of millions of years of the Earth's history so by looking at stars that are further and further away from the earth astronomers can get an idea of the evolution of the universe from the earliest days of Galactic astronomy observers noticed galaxies came in a variety of shapes and sizes the two main types of galaxies are spiral galaxies like our Milky Way which have spiral arms in a thin disc and then elliptical galaxies which are sort of more spherically or elliptically shaped and they don't have spiral arms the spiral galaxies have a lot of gas and dust in them from which new stars are forming right now whereas the elliptical galaxies seem to have formed Their Stars long ago they don't have that much gas and dust so they're not forming Stars right now there's also some dular galaxies which generally have a lot of gas and dust but not in a nice spiral form detecting these far off accumulations of stars is made easier when astronomers search for the streaming blasting beacons found near the center of many of them violent and erratic hearts beat at the center of many Alien Galaxies sending out so much energy they can overwhelm the amount of energy produced by all of the other stars within them these are the active Galactic nuclei so we look at some galaxies and we find that they have at their very centers very powerful engines that are producing a tremendous amount of light we can tell that they're very far away and yet they're still very bright when we look at them so they must be tremendously powerful dumping a lot of energy out every second among the most violent and Powerful of the active Galactic nuclei the mysterious phenomenon called quazars when we look at quazars quasi Stellar objects and see how far away they are some of them are tremendously bright the brightest one of them is about a trillion times as bright as our sun spectacular streams of electromagnetic energy bright beacons lighting up the sky for billions of Miles these high energy sources provide a stunning reminder of the universe's power to illuminate a quazar itself can be brighter than an entire galaxy so when we look at aazar like 3c273 the Hubble Space Telescope took some images of this and we found that it has a big jet of material shooting out of the side of it almost the size of the Galaxy itself these are really weird things these active Galactic nuclei as active Galactic nuclei show space is a violent place and as it turns out there's a massive Collision going on right in our own backyard the culprit a Galaxy called the Canis Major dwarf Galaxy as the name implies dwarf galaxies are small making them even more difficult to detect now the kis major dwarf Galaxy is taking aim at the Milky Way two galaxies on a collision course from which thanks to gravity There Is No Escape when a small Galaxy comes too close to a large Galaxy the tidal effects cause it to be stretched out and distorted so the gravitational attraction of the larger Galaxy will actually pull and stretch the stars in the smaller Galaxy so a collection of galaxies that has a relative spacing compared to their size about like the way these pucks are laid out on the ice all these galaxies would be moving through space with respect to one another but every once in a while one of these galaxies is going to Bonk into another one now when that happens the shape of the galaxies would actually become distorted and Str out pucks are solid galaxies are made of individual Stars Each of which feels the gravity of all the others and they become distorted and torn into title tals a big swooping Arc of stars in either direction and that's how the once far off stars from an alien Galaxy blazing through space for Millions upon billions of miles can end up blending right in with our own but what caused these stars to Clump together in galaxies why has the matter and mass of the universe fused into these spectacular structures to find the answer we have to turn our clocks back millions and billions of years ago go back far enough and you reach a point where all the matter and space and time become compressed and compacted into an infinitely small point a gravitational singularity of infinite Dimension it's a point that exploded with a spectacular Big Bang a long time ago the matter and energy that would make up every alien Galaxy wasn't far away everything that ever became an alien Galaxy sprung forth from a gravitational singularity that has come to be known as The Big Bang if you run a film of the universe backwards in your mind eventually you get to a point where the density would become extremely high if you go far enough all the mass and energy that we have in the universe would be in a single location and you would find infinite density we think that the expansion of the universe is telling us something very profound that the Universe has a beginning point in time in those moments after the big bang the rules of our universe and stars took shape and one of the biggest rules was the law of gravity after the big bang the universe of course was expanding but there were some parts that were denser than others those denser Parts started gravitationally Contracting and they formed galaxies pockets of gas within those gravitationally Contracting clouds formed stars because those Pockets gravitationally contracted even more than the general cloud of gas it would take hundreds of millions of years for the first Galaxy to coales into existence we don't know exactly when this happened but we can see pretty mature galaxies about a billion years after the big bang and the earliest objects that I can see at about 500 million years after the big bang so it's within this period that we think the very earliest objects switched on but we haven't yet found a time when there were no galaxies at all to learn more about Alien Galaxies we need to solve the many mysteries of our Milky Way's own place in the universe when we want to look at the structure of our galaxy The difficulty that we run into is that we're inside of it we can only see what we can see from inside moreover there's dust and gas blocking our lines of sight so we can't see very far from our position in our galaxy in many different directions we think the Milky Way is a barred spiral galaxy reaching about a 100,000 light years across with a 3 ,000 Lightyear thick core most galaxies in the universe are [Music] smaller the Milky Way and many Alien Galaxies are like cities with a central dense core and less dense suburbs for spiral galaxies like our own Milky Way that means a trip to visit the BDS is not unlike a trip on the freeways all the stars in our galaxy are orbiting around the center we're about 30,000 light years away from the center and it takes us about 250 million years to make one orbit around the Galaxy now the stars are all in their orbits they're all moving around the Galaxy so what causes these beautiful spiral arms that we see well they're sort of a density wave an area where the stars in the galaxy are just a little bit denser more packed together than the rest of the Galaxy different stars move into the density wave different stars move out but the density wave stays there and that's the spiral arm it's a lot the same way that traffic jams get started on the freeway something happens that makes maybe one star slow down some sort of gravitational interaction and other stars cars slow down in response to it and all of a sudden you got a traffic jam so galaxies seem to naturally form these spiral density waves 2 and 1/2 million light years away a menacing counterpart to our galaxy sits and swirls casting a weary eye toward the Milky Way it's it's the dance partner for our galaxy our biggest neighbor and our biggest Nemesis it's called M31 better known as the Andromeda galaxy the Andromeda galaxy is about the same size as our Milky Way it's about 100,000 light years across it's a spiral galaxy it has perhaps a little bit less active star formation going on right now now than our Milky Way but otherwise it's quite similar Andromeda is probably also the product of several smaller galaxies that coales or interacted over time one of those galaxies may be responsible for andromeda's double nucleus two huge clumps of stars found at its Center on Earth we've been keeping an eye on our trillion star neighbor for centuries Persian texts from the 10th Century mention this small cloud in the skies but at the time there was no way of knowing that Andromeda was an entirely separate Galaxy two and a half million light years away that makes it the furthest object in the universe you can see with the naked eye while the Milky Way may be able to absorb the impact of a colliding dwarf Galaxy a clash with the Andromeda galaxy is not only inevitable but will forever change the local Galactic [Music] landscape Gravity the universe's most prolific power is the force that's pulling Andromeda and the Milky Way closer and closer and someday in the far off Future these two spiral Titans will collide if you look at the Milky Way galaxy and the Andromeda galaxy the nearest large Galaxy to us they're actually approaching each other at a fairly astounding rate several hundred kilom every second they're very far apart right now but in the next few billion years sometime they will be right up against each other and so a collision is in a sense imminent probably no stars will physically hit each other there's just so much space between the stars but when Andromeda collides with us it will have a huge impact on the Milky Way some things will get thrown into the black hole in the middle some Stars will get ripped off and thrown away into space so it'll be dramatic and the entire night sky will change the constant motion of Alien Galaxies and the time frames involved may be hard to comprehend Andromeda is close enough enough to the Milky Way that their gravitational attraction brings them closer together but elsewhere almost all of the Alien Galaxies we see are moving away from us and our common experience like an exploding bomb everything explodes away from a center now is there an empty Center to our universe are we on a shell of galaxies flying away from wherever the original explosion was no and that's the amazing thing in our universe space itself is expanding every little bit of space the space right here between my hands has a pressure to expand it's this expansion first detected by astronomer Edwin Hubble that laid the foundation for much of modern [Music] astronomy so the universe expands with time and space itself is actually expanding now if you take a one-dimensional example of the universe here here's a hypothetical Universe where I've got these pingpong balls which are the galaxies on this rubber h hose I can expand that hose and all the galaxies move away from the others see that and in fact if we focus our attention on this one here the ones that are farther away from that move faster than the ones that are closer in because there's more space there's more tube between this one here and the distant ones than between this one and the nearby ones so that in a sense is a good model for Hubble's observation that at a given time the more distant galaxies move faster than the nearby galaxies notice also that no Galaxy can claim that it's the unique center of the universe sure from this one's perspective all the others are moving away but if I were to put myself on this one here I would say that all the galaxies are moving away from that one as well so no matter which Galaxy you're on you see the others moving away from you that's what happens in a uniformly expanding Universe there is no Galaxy that can say that it's the unique center of the universe if you think back to earlier times it was thought that the Earth was the center of everything it was the center of the universe and the planets and the sun all orbited around the earth and the Stars every day made one trip around the earth then we discovered that our sun was one of many stars and that our sun was cruising around in through the universe as we knew it but this discovery by Hubble told us that Not only was our planet one of many planets and our star our sun one of many stars but our galaxy was one of many galaxies presumably like any other it really changed our worldview and our place in the universe to think that our galaxy is an ordinary Galaxy so just what's in our Galactic neighborhood meet the local group of galaxies a group with ever increasing membership our local group of galaxies is a small group or cluster of about three dozen galaxies our Milky Way and the Andromeda galaxy M31 are the two dominant galaxies most of the galaxies in our local group are small dwarf [Music] galaxies these galaxies each have collections of small satellite galaxies that are in their thr that orbit around them and these big galaxies all feel the influence of each other's mass and orbit around each other so all of these galaxies the small galaxies are orbiting the big galaxies and the big galaxies are all sort of orbiting each other it's a group of about 30 or so galaxies that are all sort of orbiting around a Common Center of mass the most well-known dwarf members of the local group two galaxies known as the large and small melonic clouds [Music] scientists now think the clouds orbit the Milky Way thanks to the tidal influence of our galaxy gravity of course is a two-way street it's believed the gravitational pull from these clouds has also distorted parts of our own Galactic dis by measuring the energy that emits from the stars in the small and large melonic clouds astronomers believe they are made of different stuff than our galaxy the clouds are richer in hydrogen and helium than the Milky Way and with fewer Metals scientists think this means the Stars are younger in the clouds the gravitational dance between the clouds and the Milky Way has likely been going on for billions of years but all the while a different and much more mysterious battle is going on back in the center of the Milky Way because when you head for the center of our galaxy once you get through all the dust and gas and older stars you'll find something so insanely frightening the normal rules of time and space do not apply for lurking at the heart of the Milky Way and perhaps every alien Galaxy is a massive Beast with a ravenous appetite a beast from which There Is No Escape there is a region at the core of our galaxy The Milky Way where nothing escapes this is the point of no return a super massive black hole a black hole is an astrophysical object that has so much mass and such a small volume that the gravitational force is so strong that even light doesn't have enough energy to escape it black holes can form either when a massive star explodes at the end of its life and the core of the star collapses into a black hole or you can have super massive black holes at the centers of galaxies how massive try nearly 4 million times the mass of our sun sometimes black holes swallow entire Stars creating Fierce explosions called Gamay bursts in order to emit a Gamay an object has to be billions of degrees in temperature or even trillions so we're seeing something incredibly hot in some cases the galaxies were as much as 10 billion light years away and the Gamay bursters had been so bright that if you had had a pair of binoculars and you were actually looking at the right part of the sky at the right time you would have been able to see a visible light Afterglow from the gamma ray that's using binoculars to see something that's on the other side of the universe 10 billion Lighty years away can you imagine what sort of an explosion that was so if there's a super massive black hole at the center of our galaxy might similar black holes lurk at the center of all Alien Galaxies when we look at neighboring galaxies and this is a recent result we find that most galaxies appear to have very massive black holes in their Center ranging from Millions to even billions of times as massive as our sun it appears to be a very common and ordinary aspect of a [Music] galaxy black holes swallow matter but less than 1 half of 1% of our universe is believed to be made up of observable matter such as stars planets gas and dust so what accounts for the rest of the stuff created in the aftermath of the Big Bang what really fills up Alien Galaxies scientists best guess is a mysterious substance called Dark Matter dark matter is fantastic stuff we know that it exists we know that it gravitationally pulls on things one of the best pieces of evidence for the existence of dark matter is that spiral galaxies are spinning more quickly than they would be spinning unless there were extra unseen material causing them to spin that fast Caltech Professor Richard Ellis has pioneered a new technique to create a three-dimensional map of the universe including the Dark Matter this is the first hint uh from dynamical data that there's a lot of dark matter in the universe we can also detect dark matter by a really remarkable phenomenon which was predicted by Einstein and is now in great use in astronomy which we call gravitational lensing Dark Matter bends the light passing through it much like a curved piece of glass so light rays are bent by material and and where we can see the signature of this bending of the light rays we can infer that there's a lot of dark matter present we don't have to see the Dark Matter directly it doesn't shine it doesn't scatter light but we can infer its presence from the effect it has on light rays that are coming through clumps of dark matter so we know that the dark matter is there we can make maps of How It's distributed even if we can't see it directly so one further advantage of gravitational lensing is it's just like a magnifying glass so when you look through it things are bigger and brighter than they would be if you didn't have it so if you think about it it's like a natural telescope in space while Dark Matter plays a central role in the birth and evolving life of galaxies there's another dark force partly responsible for their growth on a Cosmic scale the galaxies are rushing away from us due to the continuing expansion of the universe so if the universe is expanding what's driving it the only answer scientists can come up with for now a mysterious Dark Energy dark energy is even Stranger In some ways than dark matter dark energy is causing the UN un to expand right now faster and faster with time this expansion set in motion at the universe's conception has accelerated over the last few billion years because the dark energy that creates the movement has increased over time by Nature the gravitational force that binds galaxies together decreases over time as the space between them increases so instead of having a gravitational pull instead of slowing down the expansion of the universe dark energy is speeding up the expansion of the universe and it's been doing that for the past four or five billion years in perhaps a billion trillion more years the fate of the universe and the impact its black holes dark matter and dark energy have on mankind will finally be known when a star gets too close to the black hole at the heart of an alien Galaxy chaos erupts that's one of the findings from the Galaxy Evolution Explorer Mission or GX the Galaxy evolution explor is an UltraViolet telescope that observes the universe at ultraviolet wavelengths and at these wavelengths you're very sensitive to studying young stars and star formation um in galaxies back to half the age of the universe billions of years ago however we also look in the ultraviolet for these luminous flares from when a star is swallowed by a black hole the star can't hold itself together anymore and it's ripped apart and the gas from the Star plunges into the black hole some of the gas will be ejected from the system at high velocities but some fraction of the gas will plunge into the black hole and in that process will heat up to very high temperatures and give off a luminous flare of ultraviolet and x-ray radiation thanks to GX sui gazari and other researchers were able to watch it all happen 4 billion light years [Music] away GX Hubble and the Spitzer Space Telescope will soon be getting a new neighbor designed to help capture images of Alien Galaxies the James web Space Telescope is due to to launch in 2013 designed to explore the infrared Spectrum like never before using the web telescope scientists hope to be able to see through the dust and stars that block our view of the Milky Way Center and provide a more complete picture of not just our galaxy but of all Alien [Music] Galaxies the James web Space Telescope differs from the Hubble Space Telescope in two respects firstly it's more powerful it's a bigger mirror secondly it is actually working at slightly longer infrared wavelengths what Hubble and web have in common is the power to see beyond atmospheric turbulence that prevents astronomers from getting Picture Perfect images from 99% of the sky Earth's atmosphere is turbulent it blurs out images from Stars so if the Earth had no atmosphere we would see stars as basically uh really uh perfect dots of light but what happens is that because as the light passes through the atmosphere it's distorted it turns into a fuzzy blob it turns out there are two ways to fix this one way is to go into space the other way is to instead fix the telescope on the ground so that that it removes the effects of this turbulence and that's a technology known as Adaptive Optics Adaptive Optics measures the image of a galaxy by the way its light reflects off another lighted object like a nearby bright star to do adaptive optic sensing you need a very bright star because of course you're making measurements of the atmosphere hundreds or thousands of times per second so you need something bright to look at most stars are not bright enough to do this at observatories like kek in Hawaii Adaptive Optics uses a laser beam to help create the light needed for the snapshots you can point it anywhere you want on the sky and so instead of looking at only 1% of the sky you can look at most of the sky with a very very high uh resolution very sharp images in this way you can make images 10 to 20 times sharper from the ground than you could without Adaptive Optics it's just another tool in the kit of course designed to bring the Fantastic reaches of Alien Galaxies back down to earth the universe of course is home to many things larger than our small planet Earth larger than our solar system larger than our galaxy to think that our Milky Way is just one of hundreds of billions of galaxies in the observable universe it really really makes you feel like you're a part of something much larger than our small planet Earth like it or not this is our place in the universe a speck on a speck on a speck just one tiny blue green Oasis Of Life swimming in a vast ocean of Alien [Music] Galaxies the universe is vast wondrous electrifying but for space Travelers looking for a Thrill Ride it could be a one-way ticket it's a place from which you can't return or at least not in the form in which you went in go where no one has dared to venture take a virtual tour of the deadliest places in our galaxy and Beyond it's the ultimate Frontier Adventure space [Music] travel but when trekking through the galactic jungles one must steer clear of the cosmic hot zones places teaming with violence and intrigue there are dangerous places certainly very energetic phenomena that are a lot more powerful than atomic bombs being detonated infinitely more powerful the universe does seem to be a very violent place seem to have been born in a violent explosion called The Big Bang and there's all sorts of violent processes going on [Music] on December 27th 2004 satellites picked up the greatest cosmic explosion ever recorded a blast 30,000 light years away which had the power to briefly alter our planet's upper atmosphere [Music] the blast was caused by a magnetar the densest and one of the most dangerous stars in Space the magnetic field strength of a magnetar is about a th000 trillion times the magnetic field energy of the earth and for reference this would uh wipe the information off a credit card at a distance of about 100,000 miles away now this distance is sort of half the distance to the Moon so it's very nearby and and by astronomical standards these mischievous stars have the strongest magnetic field in the universe scientists have confirmed 12 of these rare stars in our galaxy and there may be more caltech's Brian Cameron scans the Milky Way for these strange [Music] stars magnetars are a special class of neutron stars with ultra strong magnetic fields the densest form of matter in the universe the first magnetar showed itself uh in the form of a high event that was detected in the late' 7s although at the time we didn't know that it was a magnetar it wasn't until the early 9s that researchers suggested that these objects were dominated by magnetic fields and that the magnetar theory was actually confirmed magnetars are born out of the Death Rows of massive stars when a star dies it begins to collapse and go Supernova sometimes a dense neutron star forms from the centers of that Supernova explosion during the process a few neutron stars become magnetars which possess a strong magnetic field these Stars eject high energy emissions of X-rays and gamma rays we think that normal neutron stars are born from regular stars that are something like 10 or 20 times the mass of the Sun but there's evidence that magnetars are born from possibly even more massive stars than this something like 40 times the mass of the Sun typically a star of such Mass would be too heavy to form a neutron star instead its mass would collapse into a black hole black holes are formed from pramming a certain amount of mass and a certain volume and for whatever reason these stars are unable to do that one theory is that some massive stars undergo a weight loss program right before exploding as a supernova losing 90% of their Mass so instead of collapsing into a black hole the emaciated star becomes a neutron star with extreme magnetic powers when the magnetic force gets incredibly strong it deforms the magnar's crust creating seismic events called starquakes on its surface and eventually this crust breaks under the stress and the magnetic field reconfigures itself into a lower energy State and when this happens a fireball is launched off uh you know off the side of the star so star Quakes on neutron star surfaces are thought to give rise to these giant flares that we see after a magnetar undergo one of these flares it outshines uh all the stars in the galaxy for a few for the few ten of a second that it's taking place within these giant flares are short bursts of gamma rays which move at the speed of light the giant flares from magnetars are Gam Ray bursts they're very short in duration less than a second and have very hard x-ray Spectra compared to another class of Gamay burst if a deep space traveler veered off course and was unlucky enough to pass within 700 mil of one of these massive objects the consequences would be horrific the magnetic field of the magnetar can literally warp the atom ATS in human flesh and its gravitational forces would tear a person apart so then how close would a magnetar have to be to wreak havoc in our solar system some suggest that a blast from a magnetar even 10 light years away could produce Cosmic chaos that would destroy our ozone layer and cause mass extinctions the chances of that happening are so low that you know they're completely implausible it would be no different than a regular star passing through the solar system and we know that the regular star has not passed through the Solar System since the solar system formed scientists think that magnetars are only a few thousand years old and will become dim after 10,000 years we're just now starting to understand the life cycle of magnetars we think that they're very young but how young is still UNC in addition to magnetar satellites and ground-based observatories have been picking up other violent things in space scientists have now confirmed the existence of a Phantom likee Force that's so strong that it might very well be the most vicious phenomenon in the universe stealthy villains haunt each and every [Music] Galaxy one particular Beast tears up anything in its path and gobbles it down like a cocktail or der it's one of the most bizarre and destructive phenomenon in the universe a black hole I think a black hole is the place which is more violent than anywhere else in our universe it's like going over the edge and you can't get back it's Fatal Attraction I suppose a black hole is a region of space where the pull of gravity is so immense that nothing can escape it not even [Music] light astrophysicist and triathlete F Al oel is attempting to unlock the Mysteries surrounding this elusive Cosmic Force in a black hole the gravity is so strong that no other force can compete with it so everything collapses to a single point oel says whatever has a close encounter with a black hole will fall victim to its Relentless tidal force of gravity if imagine you're swimming in a pool and there is no current you can go whichever direction you want now imagine you're taken out of this poool and you're in a river imagine a current that is much much much stronger that the only direction that you could go would be with this current the space around the black hole acts like this Wild River you could never fight this enormous drag that you feel as an object approaches the edge of the black hole called The Event Horizon it reaches the point of no return as you come closer and closer to this event horizon you would already be approaching in this extremely fast motion of space under you and your only future direction is now into the black hle the idea of the black hole as a whole sometimes can be a little bit confusing what it really is in some sense it's a place from which you can't return or at least not in the form in which you went in black holes are difficult to detect because as the name suggests you cannot see one by itself because it's black but scientists have spotted a black hole when its gravity affects something else in space such as a passing star uh compl completely isolated black hole would not be visible what we really see from a black hole is actually the hot material that's swirling around it and that's being sucked into it so in the neighborhood of these powerful black holes you'll get a lot of radiation resulting from the black hole pulling in material and stretching it and twisting it as it's falling in black holes consume anything in close range and there are billions upon billions of them prowling the universe astrophysicist Andrea gz is one of the world's leading black hole [Music] Hunters black holes are not picky eaters they'll dine on whatever get nearby by so they will happily eat gas they will happily consume a star or a planet when a black hole dines in a star it does so first by tearing it apart you might think of silly putty being stretched out and then it just streams on in sort of like water going down a drain it's completely pulverized black holes are produced We Believe by the collapse of the core of a massive star something like 25 or 30 times the mass of the Sun or more when it comes to the end of its lifetime a massive star Burns its core all the way past helium carbon nitrogen oxygen all the way to iron which has no more nuclear Fuel and when that iron core builds up to a certain Mass there comes a point where it can no longer support itself and the core will collapse all the way to a black hole producing at the same time a supernova the Supernova sends out explosive amounts of energy so anything in its vicinity will get obliterated then the remnants of the explosion fall into a newly formed black hole and it seems the key to the black hole's Allure is gravity gravity will pull things around just like the Sun's gravity pulls the planets around in fact Stars will happily orbit the black hole for most of its life and won't actually be sucked in these stars are actually safe from the uh the Fatal Attraction of the black hole but if you do venture too close extremely close to the edge then you do get sucked in scientists believe there are millions of wayward black holes throughout our galaxy The Milky Way and because we can't readily see them one could be right next door so how close does something have to be to get sucked into a black hole too close to a black hole is about the distance between the Sun and the Earth but that is certainly too [Music] close for future space Travelers death by a black hole would be a violent way to go the method by which a black hole could kill you depends on how big the black hole is they come in in two categories most of them are the Stellar Mass black holes which are 5 to 30 times the mass of our sun if the black hole is Stellar sized then the tidal forces near the black hole are strong enough that it will tear you apart tidily even well outside the Event Horizon if you want it to fall into a black hole you certainly wouldn't want to fall into one of those it will spaghettify you but in addition to the Stellar sized black holes there are others that are MTH Millions to a billion times the mass of the [Music] Sun and now scientists believe that these monsters hold Center Court in every Galaxy including our [Music] own black holes they're one of the most mysterious and potentially dangerous Oddities in space a black hole has a ravinous appetite it sucks in everything in its path and spits out what it doesn't devour and now scientists have discovered there are super massive black holes which are millions of times bigger than their Stellar Mass cousins and evidence suggests that super massive black holes were born after the big bang when the universe was first created the leading idea is that they would have formed just like a stellar black holes from the collapse of the core of a massive star but then they grew by feeding grossly from the gas from other galaxies which collided with them scientists have discovered that these black oders wield their power in the center of galaxies the super massive black holes are at the center of the Galaxy most likely because they're the most massive object within the Galaxy um massive objects tend to sink to the middle so um you'll always find them at the center of a galaxy for a long time scientists didn't think a super massive black hole existed in our neck of the universe the Milky Way but in 1995 astrophysicist Andrea gz set out to prove one exists we've done an experiment over the last 10 years to ask the question is there a supermassive black hole at the center of our galaxy and the way we did this experiment is to use the Motions of stars at the center of our galaxy to test whether or not there's a large amount of mass inside a very small volume and that's the proof of a black hole [Music] at the cek observatory in Hawaii which houses one of the largest telescopes in the world gz began using a groundbreaking technology called Adaptive Optics which brings into Focus farway objects so this is without Adaptive Optics this is what you would see in this big square there's nothing we turn Adaptive Optics on and you see the stars this region contains the stars that provide the keys to our experiment so we want to watch how these stars move gz noticed that there was a large cluster of stars orbiting around an invisible object at the center of our galaxy and they were moving at an unusually rapid rate so we can actually see these stars that are really close to the center and we can watch them go around the stars go around the black hole just the way the planets orbit the Sun the orbits tell us where the black hole is so it's located right where the star is that's the center of our galaxy and the details of exactly how fast these stars are going around and how tight the orbits are um tells us um the mass of the black hole which we think today is 4 million times the mass of our sun for gz confirming that a super massive black hole indeed exists at the heart of our galaxy was like summiting Mount Everest it was incredibly exciting to discover the super massive black hole at the center of our galaxy simply because it was a question we had set out to address the question is there a super massive black hole we could design an experiment that actually got at it astrophysicist Andrew Hamilton says death by a super massive black hole would be much different than by a smaller Stellar Mass relatives if you want to go and be a tourist and have the ultimate experience of falling inside a black hole and finding out what's really there go visit a supermassive black hole much better idea unlike a stellar black hole which would rip you to shreds before entering its deadly Vortex a space Explorer could actually experience Free Falling inside a super massive black hole inside a super massive black hole it turns out that even though the black hole is more massive it's also much larger in size and that means that the tidal forces weak enough that you could pass through the Event Horizon and fall deep inside the black hole without being tily torn apart but deep down inside the black hole the centrifugal force of the rotation of the black hole provides effectively a repulsion if there's any matter at all inside it then stuff that's falling in will tend to collide with stuff that's trying to get out and the result of that Collision of energies is an unimaginable L chaotic mestrom of super hot dense plasma and in that case your fate is that it can roast you so how close would space Travelers have to be to get sucked into a super massive black hole in the center of a galaxy for a super massive black hole you would have to be about a million to a billion miles from the black hole to feel its influence over the years the Shandra x-ray Observatory has caught our Galaxy's super massive black hole nibbling on Cosmic matter not binging like other super massive black holes our black hole is today in active compared to other black holes our galaxy has very little gas at the center and so there's nothing really for the black hole to feed on it's not eating very much it's going on a bit of a starvation diet our galaxy super massive black hole appears to be fasting this is partly due to the fact that as a Galaxy ages less and less matter is present for it to gorge on but in the future it might be quite a bit more active uh if it ever gets a fresh supply of gas at it Center to feed off of one way to rejuvenate our super massive black holes appetite is to collide with another galaxy sound implausible 2 million Lighty years away our closest neighbor the Andromeda galaxy is charging toward us at almost 75 m/ second or 270,000 [Music] mph in the future scientists predict the two galaxies will collide and upon impact the larger Galaxy May engage in one of the most primitive acts known in the universe [Music] it's one of the most barbaric rituals in space a larger Galaxy eats a smaller [Music] one the scenario isn't a science fiction writer's fantasy it's a cosmic reality it's called Galactic [Music] cannibalism the ghastly event can occur on the celestial Highway when two Galaxies have a head-on collision both eventually meld together in a less than harmonious merger if you're a Galaxy it's very violent you're torn to [Music] shreds Joshua Barnes studies Galaxy mergers acting like a crime scene investigator he admits his research is a bit like inspecting a car [Applause] crash imagine that you come across the scene of a car [Applause] crash two wrecked vehicles but no Witnesses nobody to tell you what happened all you have is the physical evidence that's basically what we have to do when we study colliding galaxies so there are no witnesses to a galactic Collision all that you have is the present state of the wreckage so you have to conduct a sort of forensic investigation to try and figure out what happened on the basis of what you have today if they collided headon you would know because the fronts were squashed up but if they say sideswiped each other which is actually more likely in Galactic collisions that would leave you a completely different pattern of wreckage and you could interpret that so what causes Galaxy mergers what gravity everything in the universe is falling freely through space and where you've got two large objects like galaxies their Mutual gravity pulls them together so they fall into each other so it's really just the force of gravity pulling things around the galaxies that we're seeing colliding today most of them have been bound and destined to collide for upwards of 10 15 billion years and they're only now just making it to that first [Music] Collision our own galaxy The Milky Way is moving toward our neighbor Andromeda both galaxies are spiral in shape but Andromeda is about twice as massive with a super massive black hole the mass of 30 Million [Music] Suns it'll look a lot like a dance can you see the two galaxies come close together so they kind of dance around each other getting closer and closer and moving faster and faster before they finally come together but at the point of impact these Galactic dancers will do more than pette each one has a spiral disc of stars and then surrounding that a Halo of Dark Matter invisible material that uh we can detect by its gravitational field these two dark halos which are much larger will overlap as the galaxies pass by eventually as the two galaxies spiral around each other closer and closer you can no longer distinguish them as separate systems and finally the nuclei [Applause] merge when Andromeda and the Milky Way Collide that's going to be the biggest Collision that the Milky Way has seen something like 5 billion years time the good news is is that we the solar system will have a grandstand view what will happen is the two galaxies their spiral discs are going to get tily torn apart into Fantastical [Music] shapes when the discs start to get close to each other they'll throw off long streamers of stars so-called tidal tals and what happens to the sun and the solar system should we still be around really is is hard to predict we could get lucky and be on one of those tidal tales and get a sort of bird's eye view of the whole process as we fly out or we could get thrown into an orbit plunging towards the center of the merging galaxies uh there's basically no way to say during the merger if our solar system moves through the suburbs or the edges of Andromeda we might not notice anything on the other hand countless stars and space material could be propelled towards the planets potentially disrupting their orbits around the Sun moreover the entire galaxy could face Cosmic upheaval we could have consequences which would would Ness be dangerous first of all we could have a lot of star formation as a consequence of the merger currently both the mil and Andromeda galaxy have plenty of interstellar gas the raw material from which stars are born now that would mean a lot more evolved Star supernova going off in our vicinity and that could create shock waves blast waves bursts of cosmic rays which would have nasty consequences after the merger the fate of our solar system is uncertain as the super massive black holes of Andromeda and the Milky Way VI for power in the newly jumbled Galaxy when they merge they're going to form a new Galaxy and there two super massive black holes will um gradually spiral into the the middle of the new Galaxy they will be a binary black hole for a short time and these black holes will start to swallow gas as the Collision stirs things up gas will fall into those black holes they're going to turn on they're going to start emitting radiation but the potential for fireworks possibly for fueling the black holes at the centers of the galaxies matter falling into them possibilities like that do exist and then the only safe place to watch the process would be on one of those tidal taals riding out and escaping the the Collision some scientists think that andromeda's larger super massive black hole will eventually consume the Milky Ways the two black holes will spiral in the center and become a binary black hole and ultimately will merge with one another to become yet an even bigger super massive black hole so a small Galaxy colliding with a large Galaxy is likely to be dominated by the larger Galaxy it'll essentially have most of its material absorbed by that Galaxy and become subsumed into it scientists believe Galaxy mergers are a way of life in the universe modern Galaxy GES including the Milky Way have grown larger by cannibalizing smaller galaxies every Galaxy that we see has probably been through many collisions the Milky Way has a central bulge of stars which are probably the relic of a previous Collision most scientists agree that the much anticipated merger between the Milky Way and Andromeda won't happen for at least 3 billion years but there may be more immediate dangers in space in Cosmic neighborhoods millions of light years away there are hyperactive galaxies that have become the big bullies on the Block at the heart of some galaxies lives a cosmic monster it transforms a run-of-the-mill Galaxy into one of the brightest and deadliest in space quazars are peculiar objects each powered by a super massive black hole that continually swallows large amounts of matter 10 to 20 Stars every year at the core of these objects lives a very large black hole and the role of that black hole is to actually generate a huge amount of energy quazars are the most energy efficient mechanisms in the cosmos they give off more power than 100 normal galaxies and they're 10 trillion times brighter than our sun so how are quazars created in the universe there's a fairly good connection between the last stages of a galactic merger and the so-called quazar phenomenon if that really happens in the case of the Milky Way and Andromeda we could have for a period of some tens or possibly even 100 million years a quazar active in the center of the merged galaxies and a quazar puts out about a 100 times as much energy as a typical Galaxy and if we were actually thrown into an orbit which took us towards the center of the Galaxy uh we could get very close to that quazar and really get scorched the word quazar stands for quasi Stellar radio source which means star-like emitters of radio waves the word was coined when the quazar phenomena was still a mystery now we know they're not starlike at all in addition to emitting radio waves and visible light quazars also give off ultraviolet rays infrared waves X-rays and gamma rays all deadly if something or someone gets too close a quazar is a super massive black hole at large distance that is active it's powerful it's emitting light and we can observe it in many wave bands quazars were first discovered in the 1960s but as radio telescope Imaging got better astronomers discovered that some of those quazars also have powerful Jets beaming out of them these particular quazars are called blazars probably some of the most violent phenomena in the universe blazar empowered by black holes just like quazar but they're somewhat different in that all of that energy is being focused or a large amount of that energy is being focused into Jets which are streaming out a blaz R's aggressive plasma Jets produce radiation in the form of radio waves all the way through the Spectrum up to high energy gamma rays astrophysicist Glenn Piner has been investigating the physical conditions at the centers of these exotic galaxies we can use this Fountain to visualize the geometry of a blazar if that circular base of the fountain represents the accretion disc then the jet of water that's coming up represents the jet of plasma coming out from the blazar and if the Earth is sitting up in the direction that that water is going then we would see this object as a blazar to an astronomer it's like looking down a fire hose it really gets you in the eye you see this bright blazing thing that we call a blazar these blazar Jets move exceptionally fast the fastest observed move at 99.9% the speed of light if you were to take a small object like this bowling ball and you wanted to accelerate it up to to 99.9% of the speed of light you would have to give this bowling ball all the energy produced in the world for an entire week to accelerated to that speed and in these blazars we're accelerating not just small objects like bowling balls but large masses of the mass of the planet Jupiter or larger to those speeds so they're being given incredible amounts of energy by this efficient engine blazars pose unimaginable consequences to Cosmic objects that get too close to its deadly jet if there was a planet relatively close a few light years from the actual jet the radiation on that planet could be millions of times what it gets from the Star it would be continually exposed to high levels of radiation so I don't think we want to look for life on a planet that would be orbiting a star that's that's in a blazar jet scientists link radio telescopes all over the world to achieve the magnification needed to zoom in on a blazar jet so to give you an analogy for what kind of magnification that is that would be magnification sufficient to read a newspaper that someone was holding in New York from Los Angeles we'd love to look as close to the central black hole as possible so we could actually figure out how nature is accelerating these Jets and getting them up to such high speeds and we'd also like to know what it is actually that the Jets are made of because it turns out that's something that's currently not [Music] known until more is known about blazars astronomers will keep a neighborhood watch for them as well as all the other dangerous places in our uncontrollable universe definitely there are violent events going on in the universe much much more energy than we can even imagine on Earth there are trillions of suns shining all at once those are the kinds of energies that we're talking about but in that case the fact that we are far away from them helps the survival of our species if we're actually traveling through space then definitely we will have to be worrying about these [Music] events

Channel: HISTORY

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Keywords: history, history channel, history shows, history channel shows, the history channel, documentary history channel, history documentary, documentary, documentaries, history channel documentaries, the universe, history the universe, the universe show, the universe full episodes, full episodes, the universe episode clips, the universe episodes, history and science, space documentaries, the solar system, solar system, the universe history channel, the universe full episode

Id: mT6QhV9Qyzw

Length: 176min 33sec (10593 seconds)

Published: Sun Oct 15 2023