Neil deGrasse Tyson Explains Why Stars Twinkle

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as broad or as targeted as you'd like up your customer service by creating a help center page making it easy for patrons to find information themselves or meet them where they are and better assist them by connecting your email phone and social channels click the link below and check out the website for yourself you will not be sorry and thanks again to salesforce for sponsoring a portion of this show chuck hey got another one for you all right um these are never ending just so you know that's a good thing okay they're always always entertaining so i'm i'm anxious to see what we're gonna talk about now all right so advice for life you ready okay never never wish your astronomy friends an evening of twinkling stars really yeah so what what is the problem with it's a big problem all right but if and it's it's even made it into the song right twinkle twinkle little how i wonder what you are what you are of course i never sang that song because i know what stars are right that's that's a pre-scientific era lyric were you were you uh a preschool neil degrasse tyson and heard this little nursery rhyme and how i wonder what you are and it's just like i'll tell you what it is i mean this this really isn't that tough guys okay it's a big ball of plasma okay so but anyhow the twinkle is it's a it's a romantic concept right because it's not just a pinpoint of light it actually uh sparkles in some way yeah and we like sparkly objects right and in fact the very word sparkle implies that it's constantly changing right right so here's what's going on the stars are as large as they are right like the sun take it as a sort of a middle-sized star if it was hollowed out you could pour a million earths into it and still have room left over wow it's huge it's big it's big it's big and it's not even a big star it's not even it's like it's that is huge and it's not even a big star it's right they get bigger some get as big as the size of earth's orbit oh my gosh yeah yeah so now you want to talk big we talk big so uh that's the problem if you're writing an astronomy book you exhaust your adjectives very your superlative adjectives it's like this was a massive planet right well isn't the star a thousand times more massive okay it was a massive star right the black hole this was a massive part super duper super massive right right exactly yeah so you got to like apportion your adjectives in my field so here's here's the thing as big as stars are they are so far away that they're basically just pinpoints of light from this distance all right and i can i actually did a calculation that i might tweet one day to to give you a sense of how far away stars are all right so if you shrink the sun down to a to the size of the period that ends a sentence in a book okay so that's the side make that the size of the sun so everything sort of shrinks so that that's true okay you can ask how far away is the nearest star okay how far away is the universe star four miles away four miles away yes if the sun is if the sun is that big that's correct that's a really long way away space is empty empty freaking empty okay so that's a whole other conversation empty spaces i mean i'm picturing that you you're it's it's it's a it's a period we're talking about yes i mean that's and that is four miles away from the next from the next star so stars are not accidentally bumping in the night okay that's crazy crazy that's a crazy distance man space is big and space is empty okay wow okay all right it's hard to get over it's actually i mean seriously because when you're i gotta go for it when you make that scale in your brain when you're making that scale in your brain it's it's kind of overwhelming you're like wait a minute i got another one for you the thing i go like this end of sentence now take that thing and put it four miles away from me that's the closest start that's insane man yeah go ahead go ahead it's completely insane yes yes okay here's another one ready so if this is the the earth you know the size of a school room globe like how far away is the moon where would you put it okay most people would put it like you know maybe a couple of feet away because that's how they see it drawn in books exactly you see earth on the left side and then the moon no it's 30 feet away so it's not even in the same room it's not in the same room because you couldn't fit it in the book okay all right so here's an interesting fact and i don't take credit for first coming up with this reference you ready if you take all the planets okay if you position them adjacent to one another right you can fit all planets in the gap between earth and the moon that's how far away the moon is from earth oh my god that's that's pretty big man yeah jupiter is ten times as wide as earth is and so is saturn basically yeah you just line all these up you can fit them all easily between the earth moon just so i'm just saying let me get back to twinkling stars so let's get back to twitter it starts all right so space is space is super big and super empty basically is what we just found out it's a point of light so here is a perfect point of light okay that's traveled who knows how long okay depending if it's near us or on the other side of the galaxy or across the universe it is a point of light okay a stream of photons coming down right then it hits our atmosphere so in this last part of this long journey that these photons took it's got to get through the air to get to your eyeball right okay and the air has many different temperature layers okay there's something called the thermosphere up there where the sun's energy is absorbed by ozone and the temperature goes up in that section of the atmosphere below that the temperature is dropping okay and it drops continuously until you get to that layer not only that the ground is not evenly heated by the sun because some areas reflect light like the the water and snow and other places absorb light like dark areas and so so so that that heats the air at different rates so these pockets of air that have different why does hot air rise why does hot air rise uh because it's lighter it's lighter it's less dense right that's what you're going to say because it's hotter that's enhanced hot air rises okay because it's hotter so hot air expands becomes less dense it becomes more buoyant and it rises okay and for every pocket of air that rises it doesn't leave a vacuum down there what happens some other pocket of air takes its place okay so you get what's called convection all right on a kitchen stove it's called boiling all right but convection is you heat down here it rises up it drops back whole pockets of air are moving all right this is going on all the time all over earth's atmosphere okay okay now hold that aside for a moment have you ever been in a hot desert climate and you have the and you have the road the road is probably darker than the sands that surround it right because it's asphalt or whatever or so a darker form of it probably don't use asphalt because it it gets too hot in the summer but whatever it is it's dark okay if you drop down low in mid afternoon summer and look you see this sort of way wavy the wavy gravy of summer heat the weight oh i like that chuck they're very poetic of you the wavy gravy of summer heat and so this is the this is the origin of mirages right because the way the light the way this uh these turbulent layers of heat mess with the air it makes you think there's a pocket of water there that you think is an oasis we're saved okay so uh we're safe and it's a no it's a water fountain right no no way so so there you are experiencing this at this level and that's clearly completely wreaking havoc with your image and what i'm saying is that is happening over 100 miles stretch into earth's atmosphere but on a smaller level okay because it's not that hot as you get higher up but it's not as small as a pocket of air here pocket of air there so the light comes down and as the light comes down it goes into a slightly cooler pocket of air if you go from one density of air to another air the light bends it refracts because it's going between two different densities this is what happens when a straw is bent coming out of your glass of water does anyone still use straws all right um it's bent because the air has a different pathway of light than the water does okay it bends all right so and i'm not talking about a bendy straw i'm talking about a straight straw not a crazy straw not a crazy store no it's great i love crazy stores when i was a kid who does anyone oh no they're still around they're still not okay i love crazy stores i i drink out of them all the time especially if i'm at a very fancy restaurant i'm like please and your kids are saying damn right i'm like i'd like a manhattan and please with a crazy straw so you need james bond doing that right a bit martini shaking not stirring that's pretty funny and then he goes out to his tricycle but anyhow so what happens is this light is refracting its way through the atmosphere one pocket of air at a time of different density and the act of doing this in fact these air pockets are moving it means when you try to see where the star is the actual the the point of light that hits your eye at any moment is always changing it's jumping around it's jumping around oh man that sucks and so the net effect is that it sparkles now if you take a time photo of it timeless so in astronomy we always take photos that last a long time to to build on the light what happens is the star is moving around during the photo so by the time you're done the star is this blurred blob in your image oh man now i get it that's why you guys hate twinkling stars we hate twinkling stars we hate it and so uh it has forced us to be really clever so let's go back to isaac newton isaac newton said i wonder if you put a telescope on the top of a mountain where the air is clear and calm whether you get better views of the night sky i think i knew you should be putting telescopes on mountaintops and they're still there to this day to this day all the observatories are on big mountaintops because most of that turbulence is happening right at the ground level there's some happening way up you can't avoid that but a lot is happening at ground level so first you go to a mountaintop that gets you away from most of the ground that had been around you okay then you're above other turbulent layers of weather they're mauna kea in hawaii 14 000 feet they're half the time they're clouds beneath them all right they're above the low cumulus cloud layers that often are delivering sort of summer rains or you know uh afternoon um you know rain showers you know those temporary rain showers that's a height above where those clouds hang out so not only do you get clear skies because you're above many the clouds often you get stable skies all right now you see so so and by the way we have a uh a noun we borrowed a verb and made a noun of it it's called seeing okay seeing how good is your seeing on this mountaintop and you want that number to be as small as possible right it's how much you couldn't go with sight you just don't know see you can just do sight it's an official term look it up it's my people we can't wait it's our turn all right seeing is how sharp is the image that you're looking at all right so now um so you go to mountaintop the seeing is much better but it's still not perfect okay so we tried to figure out is there a way to track this refraction of the star so that we can compensate for this so we we put some of our top people working on it then i forgot what year was it 1993 i forgot the year we're at a conference and somebody who worked for the military said oh by the way here's how you correct for that it had just been declassified and so we now have a mechanism by which we can track these pockets of air moving above the telescope and once we track it we communicate that information to a telescope mirror that is flexible and we distort the mirror to compensate for the moving around of the star image so chuck we have a term for it's called adaptive optics adaptive adaptive you know how we do it you know how we do it okay we do it ready okay volume we take we take a laser beam that excites sodium atoms this is one way to do this there's there's a layer of sodium atoms up high in the atmosphere we take a laser beam it excites them and then they when you excite an atom and then it de-excites it emits light right so we create an artificial star in the atmosphere above these layers and we know exactly what this laser beam path should look like right and as the laser beam moves it communicates this information to the mirror the mirror deforms and it undistorts the star image and you get perfect spots of starlight you know what i am never going to complain when somebody's taking too long to take a picture of me again what oh you think they're they're they're adjusting the optics yes exactly they're just using adaptive optics that's all yes wow so here's an interesting fact that got so good and it beca it came of age in the in the 1990s that the hubble telescope which the primary reason for launching it into the atmos above the atmosphere was so that it wouldn't have seeing problem right that was the main reason right it's just a regular optical telescope that we have here on earth's surface but we put it in so that we don't have the smearing blurring once we were able to compensate for that on earth the singular advantage of the hubble telescope was diminished we couldn't do quite as well as hubble but we did really well compared to hubble and compared to before we had the hubble up there wow so so that's the story of seeing and the twinkling of stars look at that that's that's super cool that's i mean that's really that's really cool i mean except for the fact that you kind of make scientists sound just a little jaded when you say we hate twinkling stars okay okay okay how about this how about this let's just put this to bed once and for all the song twinkle twinkle little star how i wonder what you are up above the sky so bright not this is like the star light star bright no no no sorry i'm getting them confused what's the other one that recitation highlights star bright first star i see tonight and i forget the rest of it i wish i weighed i wish i may i wish i might something something that start right go ahead okay i don't know that's the one i'm talking about not the twinkling star that one the first star you see tonight is generally not a star right it's a planet because the planets are brighter than stars because they're closer and they're reflecting the scenes they're much closer and they reflect and they're not intrinsically brighter but they're like sitting in our own backyard so if you had been making wishes on these first star you see tonight and it hasn't been coming true it's because you were wishing on planets oh that's see that timmy you're really just a dummy timmy if you knew anything about a straw astronomer astronomy you wouldn't be so stupid to wish on a planet is timmy the universal name of a little kid jimmy exactly little timmy sorry timmy you wish your wish can't be you ain't coming to you tonight you're too stupid to know you're wishing on the planet and so one last thing before we gotta land this plane so because if you look through a telescope the planet shows up as a disc you can see saturn's rings you can see weather bands on on on on jupiter you can see the phases that venus goes through it turns out that the blurring the the twinkling is in effect primarily because the dot of light is moving around and sparkling in different spots and you see this all as a as a twinkling spot on the sky with a planet that can happen within the disk of the planet but you're not going to notice the planet changing brightness significantly because it's all happening sort of within the disc itself so this is why you may have heard if it's not twinkling it's probably a planet okay so that's true most of the time so look up at night if it's twinkling and you see something else that's not twinkling put your money on that one as the plan that's the planet okay that's cool man that's that's good to know so that's more than you ever care to know about twinkling stars i don't know i might i might still have a few questions no you don't because there's nothing left yeah right exactly all right we gotta call it quits there chuck all about twinkling stars and i hope you don't have any other questions on this for the rest of your life there you go all right another star talk explainer video neil degrasse tyson keep looking up

Channel: StarTalk

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Keywords: startalk, star talk, startalk radio, neil degrasse tyson, neil tyson, science, space, astrophysics, astronomy, podcast, space podcast, science podcast, astronomy podcast, niel degrasse tyson, physics, chuck nice, why stars twinkle, crm for small business, contact management solution, Salesforce, salesforce essentials, Small business software, what is crm, what is salesforce, customer relationship management

Id: nnBpnv2OH3c

Length: 20min 8sec (1208 seconds)

Published: Tue Oct 13 2020