Constellations : The Beautiful Nebulas And Galaxies Within Them | Cosmic Vistas | Spark

[Music] for our prehistoric ancestors recognizing patterns was a key to survival as they made their way in the world they saw patterns in the landscape patterns in the weather and patterns in the behavior of birds and animals and when they looked up at the night sky they saw patterns too [Music] what they found is that the stars aren't spread evenly across the sky many of the brightest stars seem to be grouped in a way that naturally draws the eye [Music] and as earth turns these stars seem to move together reinforcing the impression that they are related [Music] by playing connect the dots with these groups of stars ancient people transformed them into pictures often of mythical creatures and characters from great legends [Music] we know them as the constellations [Music] the constellations are still with us today and they're a reminder of our ancestors enduring fascination with the stars but there can be even more to these ancient star pictures than meets the eye sometimes stars we see together in the sky really are related a case in point is one of the most familiar star patterns of them all the big dipper the name reflects the way these seven stars are arranged in the sky together they resemble the outline of a pot with a handle there are other ways of seeing it though in some folk traditions it's not the dipper but the wagon or the plow and for the ancient greeks and romans it was the great bear ursa major in latin the official name astronomers still use for this constellation to modern eyes turning these stars into the image of a bear seems a bit of a stretch [Music] the bear is usually portrayed with the handle of the big dipper as its long tail even though real bears don't have long tails but the bear connection makes more sense when we consider that the ancient greeks called this constellation arctos a name that gives us the word arctic [Music] arctos or ursa major may be our link to a much older tradition of bear legends one that stretches back to the end of the last ice age when the inhabitants of europe and asia were nomads wandering in a great northern wilderness perhaps they were the ones who first connected the most powerful animal in their world to the most prominent star pattern in their sky so it seems fitting that in more recent times astronomers have learned that the stars of the big dipper are themselves a wandering band of stellar nomads this became clear in 1869 when british astronomer richard proctor noticed that five out of the seven main stars in the dipper are all moving through space at the same speed in the same direction like airplanes flying in formation proctor had discovered what we now call the ursa major association half a billion years ago these stars formed together in a cloud of gas and dust today we can find the same kind of raw material adrift in other regions of our galaxy [Music] one of the nearest is called the taurus molecular cloud in this gorgeous view from the european southern observatory we can see sections of the cloud wafting across the starry background over time gravity can concentrate dark clouds like this turning them into clusters of brilliant young stars but even though they are siblings such stars are unlikely to stay together forever instead star clusters tend to spread apart as they drift through the galaxy and that means the ursa major group may be a lot bigger than it seems extending well beyond the five big dipper stars that proctor once connected even sirius the brightest star in the night sky was once thought to be a member of this group more recent data now suggest it's too young to have formed along with the ursa major association in 2003 a detailed survey based on data from the hipparcos satellite found that 59 stars are likely members these stars are scattered across 30 light years of space with the center of the group located about 80 light years from our solar system in galactic terms this is remarkably close [Music] it's purely by chance that our existence happens to coincide with the moment when earth is on the outskirts of this passing system millions of years from now those stars will have moved on and the big dipper will be no more but astronomers have discovered that ursa major is not the only constellation with a hidden connection among its stars [Music] throughout history when adventurers and traders headed east or west to distant lands they knew they were bringing their constellations with them as earth turns places on the globe that are at similar latitudes like europe asia and north america will see the same stars but those who travel south experience something very different earth doesn't turn north to south so there are stars and constellations that can never be seen from northern latitudes it's here in the south that we find centaurus it's a sprawling constellation that the ancient greeks pictured as a spear-wielding centaur the imaginary creature that is half-man half horse like ursa major the great bear the outline of the centaur may not seem obvious to modern eyes but there's no mistaking the two brightest stars in this constellation known as alpha and beta centauri together they point to another group of four stars which the ancients also imagined as part of the centaur today we identify this group as a separate constellation and it's one of the most famous the southern cross whether it's one constellation or two the combination of the southern cross with alpha and beta centauri forms the dominant star pattern of the southern hemisphere but how did the ancient greek astronomers know about these stars which can't even be seen from greece the answer is precession it's a term that describes a gradual change in the direction of earth's axis as our planet slowly swivels around like a big gyroscope in space because of procession the stars of centaurus and the southern cross have shifted over the centuries once long ago they were visible from europe now they've become for the south what the big dipper is in the north many of the stars in centaurus and the southern cross are moving through space with a similar speed and direction but this association is far younger than the ursa major group and it contains stars that are much brighter many are blue giant stars thousands of times more luminous than our sun [Music] blue stars burn out quickly the hottest ones only last a few million years a tiny fraction of our sun's age as they use up their fuel blue stars eventually expand and change into red super giants this has already happened to the brightest member of the group the brilliant red star antares antares is part of scorpius a different constellation but its motion connects it to the stars of the centaur and the cross collectively they are the scorpius centaurus association the ultimate fate of these bright stars is to die in spectacular fashion as each one runs short of fuel its core will collapse triggering a supernova a violent stellar explosion that rips the star apart the explosion produces a blast of energized gas that spreads out into the surrounding space for hundreds of light years this too has already happened in the scorpius centaurus association the entire group including most of the stars of the southern cross sit inside a bubble about 400 light years across astronomers suspect the bubble was formed by one or more of the association's stars going supernova during the past 15 million years the bubble can't be seen with an ordinary telescope but in this map of the milky way in radio waves part of it shows up as a giant loop in the foreground [Music] astronomers call it loop one our own solar system lies just outside loop one in another smaller bubble this local bubble may also have been caused by one or more supernovas perhaps when the scorpius centaurus association was closer to earth than it is now this idea was strengthened in 2004 when researchers discovered a rare isotope called iron 60 in sediment deposited at the bottom of the pacific ocean iron 60 is produced in supernova explosions this suggests that sometime in the last three million years earth was in close proximity to a supernova such an event may have had serious consequences for life one group of researchers has even speculated that a major extinction of corals and other marine life about two and a half million years ago was caused by a supernova blasting earth's atmosphere with radiation temporarily destroying the ozone layer so far this idea remains speculative and there are reasons to be skeptical astronomers have calculated that a supernova would have to be within 26 light years of earth to cause such severe damage to our planet while that's not impossible a supernova going off so close to us so recently would be quite a coincidence what we do know is that our planet did change at that time with some creatures dying out and some new groups appearing including the first members of our own genus homo [Music] whether our pre-human ancestors were somehow affected by a nearby supernova remains an open question but when we look to centaurus and the southern cross we're reminded that hidden connections between the stars may sometimes include us winter in the northern hemisphere is the time when many of the brightest stars can be seen high overhead among them are castor and pollux these stars almost identical in brightness are the gemini twins they're part of a constellation that depicts two brothers in the heavens but these stars are not related at just 34 light years from earth pollux is both closer and older than castor which is 50 light years away they are siblings in name only it's the same story with another well-known winter constellation cassiopeia named after a mythical queen the five brightest stars in cassiopeia form a w pattern that's easy to spot in the northern sky but in this case the grouping is pure coincidence the stars in the w are spread out along a line of sight that ranges from about 50 to over 500 light years away they too are not related nevertheless most stars must have relatives somewhere because stars tend to form in clusters within vast clouds of dust and gas if we look towards the stars of the southern cross we can see a recent example near the cross but six thousand light years further away lies one of the greatest treasures of the southern sky in the 19th century astronomer john herschel called this the jewel box star cluster with its concentration of hot blue stars and bright red giants the cluster reminded herschel of a casket full of precious stones today astronomers estimate the cluster contains about 100 stars that formed around 12 million years ago as the cluster ages the brightest stars will quickly exhaust their fuel and burn out in some cases going supernova like the stars of the scorpius centaurus association those stars that remain will continue to travel together like the ursa major group but over billions of years they're destined to drift apart and lose each other among the stars of the milky way our own son is one such star now four and a half billion years old it too must have relatives somewhere out there in the galaxy some of those sibling stars could have planets and even life since life here is based on the chemical ingredients that went into forming the sun it would be fascinating to see what happened to the same ingredients elsewhere but could we find the sun's long lost relatives are they hidden somewhere among the familiar constellations [Music] one approach to answering these questions is to look at the nearest stars and see if any have strong similarities to our sun the nearest star of all is alpha centauri although it appears to the eye as a single point of light alpha centauri is actually a multiple system made up of three stars in orbit around each other the smallest is a red dwarf star known as proxima centauri because it's also the closest of the three the entire system is only 4.3 light years from us that's still thousands of times further than the most distant planet in our solar system but for a star it's very very close in fact it's so close that alpha centauri can't be a member of the scorpius centaurus association it just happens to be in the foreground when we look toward those stars similarly someone living on a planet in the alpha centauri system would see our sun as part of the constellation cassiopeia giving the w an extra zigzag but even if such a planet exists we already know that any creatures living there cannot be our galactic cousins the alpha centauri system is older than the sun and it's moving on its own separate course after its closest approach about 27 000 years from now the system will gradually start to pull away from us and it will eventually fade into the starry background meanwhile the search for our son's true siblings continues in 2013 astronomers conducted a careful study of 30 stars known to have ages compositions and motions similar to the sun after a close examination only one of the 30 qualified as a possible true sibling to the sun it lies just over 100 light years away in the constellation hercules it doesn't have a name just a catalog number hd162826 this one candidate sibling could soon be joined by others in december 2013 europe launched the gaia mission it's a space telescope that will help construct a 3d catalog of nearly a billion stars roughly one percent of the milky way's total stellar population as never before gaia will reveal precisely where all the stars are around us and show us how they're moving in doing so it will reveal which stars are truly associated with one another including those that might have a connection to our sun long ago our ancestors looked for patterns in the stars and they invented the constellations groups of stars that have a story to tell now gaia is giving us a more sophisticated way of observing the stars but we're still looking for patterns what we find will reveal the unseen relationships among the stars around us and give us a new set of stories it may even give us a story that includes us [Music] the story of a great family of stars that formed together in a cloud spread out into the galaxy and along the way brought the galaxy to life

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Keywords: Blue Ant International, Spark, amazing videos, ancient celestial bodies, astronomical observations, astronomical phenomena, beyond our earthly realm, celestial wonders, exoplanets, exploring beyond our galaxy, glimpses of the unknown, heavenly bodies, heavens, knowledge, space facts, space photography, space travel, star clusters, subscriptions, surprises

Id: PVk_aGZ2-6Q

Length: 22min 15sec (1335 seconds)

Published: Wed Sep 08 2021