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Why do stars twinkle? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Or Hey, do you know the song Twinkle Twinkle Little Star?
0:11
Speaker 1: I do? Yeah? Are we taking song requests now on
0:14
Speaker 1: the podcast? Now? I'm just trying to see something. How
0:17
Speaker 1: about the alphabet song? Is that something you heard as
0:19
Speaker 1: a kid. I've heard of the alphabet? Yeah? Do you
0:23
Speaker 1: want me to get my guitar? Um? Do you also
0:25
Speaker 1: know Bob Bob black Sheep? That one I'm not super
0:28
Speaker 1: familiar with, but it's another kid song? Right? Well? Did
0:32
Speaker 1: you ever realize these all have exactly the same music?
0:36
Speaker 1: What you just blew my mind? Are they all called
0:40
Speaker 1: the same like Twinkle Twinkle, Little Alphabet Black Sheep? Yeah?
0:44
Speaker 1: They all end with three bags full of twinkling a
0:46
Speaker 1: BCS and a bunch of lawsuits, maybe apparently for copyright infringement.
1:07
Speaker 1: Hi am r Handy cartoonists and the creator of PhD comics. Hi.
1:10
Speaker 1: I'm Daniel. I'm a particle physicist and a professor at
1:13
Speaker 1: UC Irvine, And like every other professor, I also play
1:16
Speaker 1: the guitar. Is that a requirement for professors? I don't know,
1:21
Speaker 1: but I live in a neighborhood of professors, and I
1:23
Speaker 1: feel like every single house I go into has a
1:25
Speaker 1: guitar on the wall. I don't know if they play
1:27
Speaker 1: it or if it's just like a demonstration object, but
1:30
Speaker 1: there's lots of guitars in this neighborhood. It's like when
1:32
Speaker 1: they were visiting some foreign country. They picked up a
1:35
Speaker 1: guitar or something on a field trip or a conference,
1:38
Speaker 1: or maybe it's just a conversation piece. Nobody actually plays.
1:42
Speaker 1: Are you supposed to play guitar? You just have one
1:44
Speaker 1: on your wall right to look cool? You could ask
1:47
Speaker 1: something to look cool. I guess if you're a professor.
1:49
Speaker 1: But you're quite an accomplished guitar player, aren't you. I
1:51
Speaker 1: don't know if I would say accomplished. But I am
1:54
Speaker 1: in a band now. Is there anyone else in your band?
1:57
Speaker 1: Not a one man band. I'm in a rock band
2:01
Speaker 1: with some friends. Oh wow, awesome. Yeah, a bunch of
2:03
Speaker 1: middle aged men having a middle age crisis. I've never
2:06
Speaker 1: heard of that happening before. That's amazing. We're called the
2:10
Speaker 1: Grateful Dad's, so shout out to my band members. But
2:13
Speaker 1: I don't think they listen to this podcast. But anyways,
2:15
Speaker 1: welcome to our podcast. Daniel and Jorge explained the university
2:18
Speaker 1: production of I Heart Radio, in which these two dads
2:21
Speaker 1: are grateful for our ability to understand anything out there
2:25
Speaker 1: in the universe and dive deep into all of the mysteries,
2:28
Speaker 1: the crazy, bonkers weirdness of our universe, the amazing quantum
2:32
Speaker 1: frothing foam, the incredible cosmic conundrums, all of the stuff
2:37
Speaker 1: that you want to know, the answers to the things
2:39
Speaker 1: that frame our existence, that tell us how we got
2:41
Speaker 1: here and where the universe is going. We explore all
2:44
Speaker 1: of these questions and more. Yeah, because it is a
2:47
Speaker 1: pretty amazing and incredible universe, full of exciting and crazy
2:51
Speaker 1: things happening, all at the same time as a lot
2:53
Speaker 1: of sleepy things happening, a lot of interesting tunes to
2:56
Speaker 1: putudiou sleep. I was wondering what you were talking about there,
3:00
Speaker 1: sleepy things happening. It was like a rhel We're losing him.
3:02
Speaker 1: Is he falling asleep over there? I don't think Twinkle Twinkle,
3:05
Speaker 1: Little Star is supposed to put anybody to sleep? Is it?
3:07
Speaker 1: It's in it a bedtime song? Oh maybe not. Maybe
3:10
Speaker 1: I didn't grow up here, so these were not songs
3:13
Speaker 1: that I was sunk to. I think it's more of
3:14
Speaker 1: a campfire song. You're sitting there out in nature, looking
3:17
Speaker 1: up at the stars and wondering, you know, what they are.
3:20
Speaker 1: It's one of the oldest questions humans have been asking
3:23
Speaker 1: about the nature of the cosmos. What is out there?
3:26
Speaker 1: What is sending us those beams of light? Yeah, it's
3:28
Speaker 1: pretty incredible to think that, you know, the earliest humans
3:32
Speaker 1: were looking up at the same sky we were, and
3:34
Speaker 1: they were probably asking themselves the same questions, like what
3:37
Speaker 1: is that Chinese little dought there? And how far away
3:39
Speaker 1: is it exactly? And how many quarks are inside the
3:42
Speaker 1: heart of a neutron star. I think that's the question
3:44
Speaker 1: people have been asking for thousands of years, right if
3:47
Speaker 1: they were pretty smart. Cavement, I guess Warren Cavement the
3:50
Speaker 1: original particle colliders getting rocks together exactly me makes smaller rocks.
3:55
Speaker 1: But it's true, it's an age old question, and there's
3:57
Speaker 1: a grand cosmic scale to these questions, because those photons
4:01
Speaker 1: departed those stars millions of years or billions of years
4:05
Speaker 1: before even cavemen evolved. Yeah, definitely, starts have been around
4:09
Speaker 1: for billions, maybe trillions of years, way before people were
4:13
Speaker 1: looking at them, and they've been sending their light to
4:15
Speaker 1: us for all that time. And some of that light
4:17
Speaker 1: is just now getting to us right now, And it's
4:19
Speaker 1: incredible to think about how that light actually arrives here.
4:23
Speaker 1: A tiny little photon emitted by a star billions and
4:26
Speaker 1: billions of miles away, has to fly through an incredible
4:30
Speaker 1: amount of universe, dodging all sorts of kinds of stuff
4:34
Speaker 1: just to land in your eyeball. It's an incredible journey,
4:37
Speaker 1: and frankly, it's amazing to me that any of the
4:39
Speaker 1: photons survive it. Yeah, I mean, who knows what that
4:42
Speaker 1: photon has been through, right Like it could have maybe
4:44
Speaker 1: gone around a black hole or barely dodged an asteroid
4:48
Speaker 1: or a comment, you know, made it through an atmosphere,
4:50
Speaker 1: dodge all those bolly kills of air in our atmosphere,
4:53
Speaker 1: and just to go into your eyeball, or just to
4:55
Speaker 1: hit a rock, and nobody even observes it. That's the
4:58
Speaker 1: thing that frustrates me. How many photons carrying tiny little
5:01
Speaker 1: clues about the universe just go totally unobserved. They fade
5:05
Speaker 1: away like an old rock star. They're like little presents
5:08
Speaker 1: that nobody unwraps. You know, each one has a clue
5:11
Speaker 1: about the kind of star that it came from, the
5:13
Speaker 1: history of that star what was going on in that
5:15
Speaker 1: star at that moment, and then just boom, nobody gathers
5:18
Speaker 1: and it just goes like splat on the sidewalk. Yeah,
5:21
Speaker 1: it's pretty cool to think that every star you see,
5:23
Speaker 1: I mean it was generated by a whole sun, right,
5:26
Speaker 1: basically a giant ball of of fusion powered fire that
5:30
Speaker 1: was shooting photons in every direction, and some of them
5:33
Speaker 1: make it out to here. It gives you a sense
5:35
Speaker 1: for the incredible size and brightness of these stars that
5:38
Speaker 1: you can see them from so far away. Imagine if
5:41
Speaker 1: your friend in Los Angeles had a flashlight that you
5:44
Speaker 1: could see in New York, you would think, oh my gosh,
5:47
Speaker 1: that must be a crazy, crazy bright flashlight. Right. Well,
5:50
Speaker 1: these stars are so much further away, and yet you
5:53
Speaker 1: can see them with your naked eyes. It's incredible that
5:57
Speaker 1: these photons make it over this distance. I feel like
5:59
Speaker 1: something I realized only recently was the fact that the
6:02
Speaker 1: reason why stars looked like little pin points in the sky.
6:05
Speaker 1: It's not that they are pinpoints, or it's not that
6:08
Speaker 1: the sun is so far away that the sun keeps
6:10
Speaker 1: getting smaller as it goes away. It's it's it's literally
6:12
Speaker 1: just like one photo receptor in my eyeball getting activated
6:16
Speaker 1: by one photon. You're saying that stars are like single
6:19
Speaker 1: eye pixels in your mind basically, right, Yeah, they're just well,
6:24
Speaker 1: what I think of as a star, or what I
6:25
Speaker 1: see as a star is really just one eye pixel,
6:27
Speaker 1: right like, Like it doesn't really tell me anything about
6:30
Speaker 1: its shape or size. Yeah, it's fascinating to think about
6:32
Speaker 1: how photons spread out from that star and then sort
6:35
Speaker 1: of get more and more distant from their neighbors. And
6:37
Speaker 1: to see a star that's really far away, you only
6:39
Speaker 1: really just need one photon, And even if that photon
6:43
Speaker 1: was created with billions of other photons really near it,
6:45
Speaker 1: they all shoot out at slightly different angles, and so
6:48
Speaker 1: by the time they arrives on Earth, it's basically alone.
6:51
Speaker 1: It's the only photon that came from that star. Of course,
6:54
Speaker 1: there are more coming behind it, but that's why the
6:56
Speaker 1: stars seem much dimmer, of course, the further way they are,
6:59
Speaker 1: because the photons are now spread out over a much
7:02
Speaker 1: larger area, and so only a single cone in your
7:05
Speaker 1: eye might register a photon from that star. Yeah, it
7:07
Speaker 1: kind of makes you wonder like if we had bigger
7:09
Speaker 1: photo receptors in our eyeballs, you know, like if our
7:12
Speaker 1: pixels were bigger, the stars would look bigger, right, And
7:15
Speaker 1: if they were smaller they would look like smaller pinpoints.
7:17
Speaker 1: I suppose if they were smaller, eventually we could even
7:20
Speaker 1: resolve the size and the shape of the stars. You think,
7:23
Speaker 1: so eventually eventually, right, because there is that information there.
7:26
Speaker 1: I mean, if you have a large enough telescope for
7:28
Speaker 1: close enough stars, you can definitely resolve the size of
7:31
Speaker 1: the star. You think, maybe like a hawk can see
7:33
Speaker 1: the somehow, the contours of Alpha Centauri or something, or
7:36
Speaker 1: the Sagittarius. We shouldn't be inviting eagles to astronomy conferences
7:40
Speaker 1: for sure, Yeah, or at least on the podcast. I
7:42
Speaker 1: have questions for them. I want to interview the first
7:44
Speaker 1: hawks astronomer. Now I hear they're just a bunch of
7:48
Speaker 1: ye astronomy is for the birds. But I hear that
7:50
Speaker 1: have a lot of feathers in their publishing caps. But anyways,
7:53
Speaker 1: it's just it is interesting to look at a star
7:55
Speaker 1: in the night sky and see it twinkle, right. It
7:58
Speaker 1: kind of makes you wonder, like, why is it twink
8:01
Speaker 1: wiz it actually twinkling? Or is it does it just
8:03
Speaker 1: look like it's twinkling. Yeah, And this is a question
8:05
Speaker 1: that people have been asking for a long long time,
8:08
Speaker 1: not just what are the stars, but what is the
8:10
Speaker 1: fact that they're twinkling? Tell us about them? Why do
8:13
Speaker 1: different stars seem to twinkle different amounts? And it's a
8:16
Speaker 1: question with lots of different layers of answers, because it
8:19
Speaker 1: turns out there's lots of different reasons that stars can twinkle. Yeah,
8:22
Speaker 1: And it's a question that apparently inspired a song a
8:24
Speaker 1: long time ago. Three different songs. M have you dug
8:28
Speaker 1: into it? Which one came first, Twinkle Twinkle, Little Star
8:30
Speaker 1: or the ABC song. Yeah. Actually, turns out the song
8:33
Speaker 1: for Twinkle Twinkle is derived from something composed by Mozart,
8:38
Speaker 1: which is inspired by something even earlier, And then later
8:42
Speaker 1: an American music publisher adapted the tune to fit the
8:45
Speaker 1: alphabet song. So Twinkle Twinkle came first, and then the
8:47
Speaker 1: alphabet Interesting, but even Twinkle Twinkle was based on something else.
8:50
Speaker 1: All music, of course, is inspired by previous music. Right,
8:53
Speaker 1: It's all derivative, right, right, We're all made out of
8:56
Speaker 1: start us, even the songs about stars. Does your band
8:58
Speaker 1: play original music or only cover? So far we're only covers.
9:02
Speaker 1: Yet I say, you got twinkle twinkle, you've got Bob Bob,
9:05
Speaker 1: black Sheep, you've got the alphabet song. A huge variety,
9:08
Speaker 1: that's right. We cover everything from back to Pink Floyd.
9:12
Speaker 1: But anyways, this is an interesting question, and so today
9:14
Speaker 1: on the podcast, we'll be asking what makes a star twinkle? Twinkle? Right,
9:24
Speaker 1: not tinkle. It's not that kind of podcast. We don't
9:27
Speaker 1: ask stars about their personal habits, about their bodily functions.
9:32
Speaker 1: We do sort of ask a lot about how the
9:35
Speaker 1: insights of stars all right, and and the gases that
9:38
Speaker 1: erupt from it. And that's true when you talk about
9:40
Speaker 1: the waste products of stars and how they can be
9:43
Speaker 1: the compost that nourishes the formation of a future solar system.
9:46
Speaker 1: They're all part of the life cycle. Yeah, yeah, it's
9:48
Speaker 1: all physics. And so maybe next time we should ask
9:51
Speaker 1: what makes its start tinkle? Welcome to our spinoff podcast,
9:56
Speaker 1: Inappropriate Physics. But it's a fascinating question. I think a
9:59
Speaker 1: lot of people i'd have some sense of the common
10:02
Speaker 1: answer to this question, but if you dig deeper, it
10:04
Speaker 1: turns out there's lots of different fascinating physics that might
10:07
Speaker 1: make stars twinkle. Yeah, it turns out. There's not just
10:10
Speaker 1: one reason stars twinkle. There are several reasons. But the
10:14
Speaker 1: basic effect is that when you look at the star
10:15
Speaker 1: in the night sky, it's sort of doesn't look like
10:18
Speaker 1: a constant dot, right, or a constant dots shining. It
10:22
Speaker 1: looks sort of like it's blinking on and off a
10:24
Speaker 1: little bit. Yeah, exactly, stars look a little bit like
10:27
Speaker 1: they blink like they're not just like a laser focused
10:30
Speaker 1: at your eyeball. Yeah, it's it's it's almost like something
10:33
Speaker 1: is turning it on and off a little bit, or
10:35
Speaker 1: something is interfering with it, something is getting between you
10:38
Speaker 1: and the star. All right, So we'll dig into this
10:41
Speaker 1: question what makes its start twinkle? But first we were
10:44
Speaker 1: wondering how many people either there have thought about this
10:45
Speaker 1: question when they were singing the song or otherwise, And
10:49
Speaker 1: so Daniel went out there into the did you go
10:51
Speaker 1: into the internet or to the u c I campus
10:54
Speaker 1: this time? These are answers from the internet. So thank
10:56
Speaker 1: you to everybody who participated. And if you like to
10:59
Speaker 1: put your mind to the test for future episodes and
11:02
Speaker 1: let people hear what you think about hard physics problems,
11:05
Speaker 1: please don't be shy right to us, do questions, add
11:08
Speaker 1: Daniel and Jorge dot com. That's right, and you can
11:10
Speaker 1: also go visit Daniel. Do you see Irvine right and
11:14
Speaker 1: hope to run into him in the middle of campus.
11:16
Speaker 1: That's right. I'm on canvas at Easy Irvine. I have
11:19
Speaker 1: office hours, so come on stop by to think about
11:21
Speaker 1: it for a second. Why do you think stars twinkle?
11:24
Speaker 1: Here's what people had say. I don't think stars twinkle.
11:28
Speaker 1: I think their photons are disrupted by temperature and pressure
11:31
Speaker 1: differentials in our atmosphere, giving us the appearance of twinkling.
11:35
Speaker 1: I imagine it's the same phenomenon that one witnesses looking
11:38
Speaker 1: over hot asphalt and seeing the horizon winkle. And I
11:40
Speaker 1: venture to guess that they don't twinkle when observed from
11:43
Speaker 1: the International Space Station. Well, I guess it depends what
11:46
Speaker 1: we mean by blink. The first thing that comes to
11:49
Speaker 1: mind is if we're observing a star and something moves
11:54
Speaker 1: between us and the star, like a planet, it's gonna
11:58
Speaker 1: appear to have blink, I guess. But the star itself
12:01
Speaker 1: isn't actually doing anything. It's just something's moved in front
12:04
Speaker 1: of it, so it looks like something's happened to it.
12:07
Speaker 1: I think that might be what the blink is. In general,
12:11
Speaker 1: I don't think stars actually blink, but I can envision
12:18
Speaker 1: dust clouds were particularly large planets moving between us and
12:24
Speaker 1: that star, making them appear to blink or dim significantly.
12:32
Speaker 1: It makes us star blink when the stars about to explode,
12:35
Speaker 1: that is one. That is one reason the atmosphere makes
12:39
Speaker 1: the start blank to right h And then a lot
12:44
Speaker 1: of stars are binary pairs actually, and some of them
12:47
Speaker 1: I think can be uh rotating around really quick, and
12:52
Speaker 1: that would make the star appear like it's blinking. Well,
12:55
Speaker 1: I know, the blinking that we see from here on Earth,
12:57
Speaker 1: like the twinkling star, that's more to do with our
13:01
Speaker 1: atmosphere than the star itself. But I do know that
13:04
Speaker 1: stars also blink over the course of weeks and months.
13:09
Speaker 1: I know Bill just did recently. I'm not sure what
13:12
Speaker 1: the cause was, though, so if I had to guess,
13:14
Speaker 1: I would think it would be maybe gas clouds, um
13:17
Speaker 1: or even transitting planets. I don't know. I think that
13:21
Speaker 1: what makes us start blink maybe some kind of intern
13:26
Speaker 1: interference with any object objects that may cross in the
13:32
Speaker 1: path between the star and the person who observes the blinking.
13:38
Speaker 1: I would say that What makes us star blink is
13:41
Speaker 1: the disturbances in the atmosphere, similar to what we see
13:47
Speaker 1: when looking at distant street lights. There are um, you know,
13:52
Speaker 1: small air currents, pockets of warm and cold air that
13:56
Speaker 1: are constantly moving that through refraction, cause distant, tiny light
14:00
Speaker 1: sources such as stars to blink when viewed. Although that
14:04
Speaker 1: just might be my view as an amateur astronomer. All right,
14:08
Speaker 1: people seem to have pretty strong opinions here. I mean
14:11
Speaker 1: a few people didn't know, but a lot of people
14:13
Speaker 1: seem to think what was going on. Yeah, there's a
14:15
Speaker 1: strong vein here of people thinking that stars are interfered
14:18
Speaker 1: with by our atmosphere. Yeah. A lot of people said
14:21
Speaker 1: that it's not that the stars actually blinked, like at
14:23
Speaker 1: the source, like the star itself. It's just that it
14:26
Speaker 1: just looks like it's blinking. And that's a fascinating answer
14:28
Speaker 1: because it suggests that the photons are like uninterrupted for
14:32
Speaker 1: billions and billions of years and then just like micro
14:36
Speaker 1: seconds before they hit your eyeball, that's when they get twinkled. Yeah,
14:39
Speaker 1: that's what we tell people who come listen to our band.
14:41
Speaker 1: That's thought that we sound bad. It's just said you
14:44
Speaker 1: know our perfect sounds. Somebody guests distorted it on the
14:46
Speaker 1: way to your ear. That's right. That's why you have
14:48
Speaker 1: forced them to plug indirectly to your instruments, right, so
14:50
Speaker 1: they can hear the adulterated intended version of your music.
14:54
Speaker 1: That's right. Yes, the direct neural download. That's the next step. Actually,
14:58
Speaker 1: I know somebody with hearing loss and have a new
15:00
Speaker 1: kind of hearing aid that allows for a Bluetooth connection
15:04
Speaker 1: so that the sound doesn't have to go through the air.
15:06
Speaker 1: They can just hear the original unadulterated sound. Wow, that's
15:10
Speaker 1: really interesting. I wonder if it sounds better or different. Oh,
15:13
Speaker 1: it's much clearer. They can go to presentations, they can
15:15
Speaker 1: hear in church. Now, it's much better than just amplifying
15:18
Speaker 1: the sound through the air. Sounds great, And that means
15:20
Speaker 1: you can also hit the mute button, I imagine at
15:23
Speaker 1: church or at a professor lecture, that's right. It probably
15:26
Speaker 1: also means that you can hack them and you can
15:28
Speaker 1: like pipe in the Grateful Dads or something else. Yeah,
15:31
Speaker 1: much better than a professor lecture for sure, especially if
15:33
Speaker 1: you're getting it at the source. But anyways, it's there's
15:36
Speaker 1: some interesting ideas here. A lot of people say, it's
15:38
Speaker 1: not the stars that are actually blinking, it's somehow like
15:41
Speaker 1: the atmosphere that's making them blink or somehow making them
15:44
Speaker 1: look like they're blinking. So Daniel, maybe step us through.
15:47
Speaker 1: What are some of the actual reasons why stars sprinkle? Well,
15:50
Speaker 1: our atmosphere is the number one reason. And this is
15:52
Speaker 1: basically why we have space telescopes, because it's not a
15:56
Speaker 1: very nice to look at distant stars through the atmosphere
16:00
Speaker 1: because while the air seems clear to you, it actually
16:03
Speaker 1: can make light zig and zag a little bit because
16:06
Speaker 1: it's a slightly different temperatures and slightly different densities. And
16:09
Speaker 1: that's sort of like looking through glass with impurities in it.
16:13
Speaker 1: That's interesting. But I guess like if I look at
16:15
Speaker 1: something through a glass or like a hazy glass, it
16:19
Speaker 1: doesn't make the light source twinkle, It just makes it
16:21
Speaker 1: look dimmer. Well, what a glass does It bends the light, right,
16:24
Speaker 1: That's how a lens works. And so if you have
16:26
Speaker 1: glass that has like varying densities and varying temperatures in it,
16:30
Speaker 1: for example, then it will change the path of that light.
16:32
Speaker 1: And so what happens to the photons is they hit
16:34
Speaker 1: the atmosphere. Is not that they're like destroyed, is that
16:37
Speaker 1: they're just change direction. And so for you to see
16:40
Speaker 1: a star, you need like a direct line of sight
16:42
Speaker 1: between you and the star. But if some photons are deflected,
16:45
Speaker 1: then you don't see them. Those photons might land to
16:47
Speaker 1: your left or to your right or somewhere else. They
16:49
Speaker 1: still hit the earth, but they're not hitting your eye anymore.
16:52
Speaker 1: So to your eye it looks like the star is
16:55
Speaker 1: twinkling because the stream of photons is interrupted. Right. But
16:58
Speaker 1: but I guess what I mean is that the difference
16:59
Speaker 1: between like a glass and the atmosphere is that the
17:02
Speaker 1: atmosphere is sort of like always changing. Right, there's wind,
17:06
Speaker 1: and there's you know, variations and clouds, and so it's
17:09
Speaker 1: it makes the starts twinkle because the air is sort
17:12
Speaker 1: of like moving and waving around in front of you,
17:15
Speaker 1: whereas it like a glass doesn't. Right, Like a glass
17:17
Speaker 1: doesn't make a start twinkle. That's right, a glass wouldn't
17:19
Speaker 1: make a start twinkle. It might deflect the path, but
17:21
Speaker 1: if you find the right location, you could see a
17:23
Speaker 1: constant stream of light flowing through the glass. But as
17:26
Speaker 1: you say, air is constantly changing, right, The wind. The
17:29
Speaker 1: atmospheric conditions are constantly changing, and so the path of
17:32
Speaker 1: a photon through the air is not constant. So if
17:35
Speaker 1: you're just standing there with your eyeball in one location,
17:37
Speaker 1: you're not going to get all the photons that come
17:40
Speaker 1: from that star. Well, it's kind of interesting because the
17:42
Speaker 1: atmosphere makes the stars twinkle like it makes the photons
17:45
Speaker 1: sometimes reach your eyeball and sometimes not. But you're saying
17:48
Speaker 1: that it can also bend the photons, But it doesn't
17:50
Speaker 1: make the stars kind of wavy? Does it? Right? In principle,
17:53
Speaker 1: it does if you could capture all of those photons,
17:56
Speaker 1: like if you had a huge collection device, then you
17:58
Speaker 1: would still see the star because as the deflected photons
18:01
Speaker 1: would land in your collection device, and then you would
18:03
Speaker 1: think the star came from a different place. And so
18:06
Speaker 1: because you have a small collection device, just your eyeball,
18:08
Speaker 1: you're missing some of those photons, so it looks like
18:10
Speaker 1: the star twinkles rather than dances. There's actually another really
18:14
Speaker 1: interesting effect called stellar aberration, which means that the stars
18:17
Speaker 1: are not actually where they look like they are because
18:20
Speaker 1: they have relative velocity to the Earth. So by the
18:22
Speaker 1: time the light gets here, the stars have sort of
18:25
Speaker 1: moved away from where they appear to be. But that's
18:28
Speaker 1: a different thing. It doesn't cause the stars to twinkle,
18:30
Speaker 1: just causes them to be somewhere other than where they
18:32
Speaker 1: appear to be. I see, that's a different song altogether.
18:36
Speaker 1: That's more like a Baba Black stellar aberration. Yeah. Historically
18:39
Speaker 1: it is actually really important because it's one clue that
18:41
Speaker 1: we use against the either hypothesis. People are trying to
18:44
Speaker 1: understand how light propagated through the universe, and they thought
18:47
Speaker 1: maybe there's ether, but then Michaelson and Morley showed that
18:50
Speaker 1: there couldn't be either. Some people thought, oh, well, maybe
18:52
Speaker 1: we are stuck in a blob of ether that travels
18:54
Speaker 1: with the Earth, but then we wouldn't have stellar aberration.
18:57
Speaker 1: But anyway, back to twinkling stars. Yeah, I think you're
19:00
Speaker 1: saying is that the Start is shooting this train of
19:02
Speaker 1: photons add us and they're all coming sort of in
19:04
Speaker 1: a street line to our eyeballs. But some of them,
19:07
Speaker 1: like hit a pocket of hot air and get deflected,
19:10
Speaker 1: or they happen to hit a molecule of nitrogen in
19:13
Speaker 1: the atmosphere and it doesn't make it out to us.
19:15
Speaker 1: And so this train of photons is interrupted, and that
19:19
Speaker 1: is making it look like it's turning on and off
19:21
Speaker 1: to our eyeballs. That's exactly right. And then if you
19:23
Speaker 1: look at something slightly bigger, like a planet, which is closer,
19:27
Speaker 1: you're getting multiple streams of photons from that planet. It's
19:30
Speaker 1: not so far away that it just looks like a
19:31
Speaker 1: point source. It's like a little disc in the sky.
19:34
Speaker 1: And so while some of those photons may get scattered
19:37
Speaker 1: from one stream, you're pretty much always getting them from
19:39
Speaker 1: another stream. And so a planet looks like a little
19:42
Speaker 1: hazy because the atmosphere or its edges might wiggle a
19:45
Speaker 1: little bit. But a planet doesn't twinkle because it doesn't
19:47
Speaker 1: get like all of its streams interrupted at once, unless
19:51
Speaker 1: it's maybe like a super cloudy day, right or you know,
19:55
Speaker 1: particularly kind of hazy night. Yeah, it could be, you know,
19:57
Speaker 1: if something passes between you and the planet, like an
20:00
Speaker 1: eagle or something, it can block the view, or if
20:02
Speaker 1: it's like a huge blob of gas hot gas somewhere
20:05
Speaker 1: in the atmosphere, it could distort it. But twinkling is
20:07
Speaker 1: not something you're going to see regularly from a planet
20:09
Speaker 1: because it appears larger in the sky, and so it's
20:12
Speaker 1: not as often actually interrupted. All right, Well, that's one
20:14
Speaker 1: source of twinkling of the stars, and there are others,
20:17
Speaker 1: and there's are things we can do to correct that twinkling,
20:20
Speaker 1: so we can actually study stars. But let's get into
20:23
Speaker 1: that after we take a quick break. All right, we're
20:38
Speaker 1: talking about twinkle twinkle, little stars or big stars. I
20:41
Speaker 1: guess yeah, technically stars are not little. Some stars are little,
20:46
Speaker 1: you know, Neutron stars are only like ten kilometers across.
20:49
Speaker 1: That's pretty little by star standards, and some of them
20:52
Speaker 1: are enormous. We have an episode about the biggest stars
20:55
Speaker 1: in the universe, and some of them are bigger than
20:58
Speaker 1: our solar systems. So maybe should be more like twinkle
21:00
Speaker 1: twinkle gigantic star. You say it that way, it sounds flattering, like, wow,
21:04
Speaker 1: you're swoll star. You've been working out Twinkle twinkle rip star.
21:10
Speaker 1: Stars always skip leg day. So we were talking about
21:13
Speaker 1: how the twinkling, most of the twinkling, or a lot
21:16
Speaker 1: of the twinkling we see of the stars is due
21:17
Speaker 1: to our atmosphere, Like we have this kind of hazy
21:21
Speaker 1: layer of air and gas around the Earth which is
21:23
Speaker 1: constantly moving, maybe has pockets of hot air cold air,
21:27
Speaker 1: different you know, clouds and things like that, and so
21:29
Speaker 1: that is what a lot of what makes stars twinkle
21:32
Speaker 1: because they kind of obscure or interrupt the train of
21:35
Speaker 1: photons coming to our eyes from the stars. Yeah, and
21:39
Speaker 1: that's a big challenge for ground based astronomy because we
21:42
Speaker 1: want to study the star and we want to get
21:43
Speaker 1: great resolution. You know, this fuzzes out one star that
21:46
Speaker 1: might be next to another one. It makes it harder
21:48
Speaker 1: to observe things in space and get really really crisp images. Yeah,
21:53
Speaker 1: I guess you know, the way astronomy started is that
21:55
Speaker 1: it was pretty good for like basic stuff of of
21:58
Speaker 1: star observing. But then as we want to get more
22:00
Speaker 1: detailed or you know, look further out than the atmosphere,
22:03
Speaker 1: and the twinkling became a problem. Yeah. Well, until recently,
22:06
Speaker 1: we couldn't do anything about it. We couldn't avoid the atmosphere. Now,
22:09
Speaker 1: of course we have things like space based telescopes, which
22:12
Speaker 1: are awesome and it can avoid atmospheric effects. But there
22:15
Speaker 1: are limitations on space telescopes, right, They're expensive, they're hard
22:18
Speaker 1: to fix, they have to fit within a rocket. Sometimes
22:21
Speaker 1: they blow up, and so there's sort of two very
22:24
Speaker 1: complementary paths for astronomy, one space based where you get crisp,
22:27
Speaker 1: clear pictures, and the other ground based astronomy, where they've
22:31
Speaker 1: come up with some really really clever techniques to try
22:34
Speaker 1: to overcome some of the atmospheric limitations. Yeah, this is
22:37
Speaker 1: called adaptive optics. Like they actually constantly move the mirrors
22:41
Speaker 1: to correct for the twinkling. It's totally bonkers and it
22:43
Speaker 1: sounds like it would never work, but you're right. They
22:46
Speaker 1: have these mirrors that are deformable, meaning you can change
22:49
Speaker 1: the shape of the mirror so when the light hits it,
22:51
Speaker 1: it bounces off at a different angle. And if you
22:54
Speaker 1: know the effect of the atmosphere on your light source,
22:58
Speaker 1: then you can calculate in real time how to deform
23:01
Speaker 1: your mirror, to undo it, to like enhance, to defog it,
23:05
Speaker 1: to de fuzz it. And so they do these on
23:07
Speaker 1: really fancy telescopes on like the millisecond time scale. It's
23:11
Speaker 1: like constantly varying in small amounts the shape of the mirrors.
23:16
Speaker 1: But I guess I'm a little confused now because earlier
23:18
Speaker 1: we said that, you know, the twinkling is sort of
23:20
Speaker 1: not it's not making the star wavy or fuzzy. It's
23:24
Speaker 1: actually just kind of interrupting the stream of photons. So
23:28
Speaker 1: how can moving the mirrors correct for photons that didn't
23:31
Speaker 1: get to me? Well, it doesn't get to you if
23:33
Speaker 1: you have a tiny little collection device like an eyeball.
23:35
Speaker 1: But if you have, you know, like a thirty meter telescope,
23:38
Speaker 1: then it's more likely that you are going to get
23:40
Speaker 1: that photon. And the photon has just been deflected a
23:42
Speaker 1: little bit in one direction. And now if you have
23:44
Speaker 1: a few objects near each other, then when the atmosphere changes,
23:48
Speaker 1: it's changing the path of all those photons, and those
23:50
Speaker 1: objects get fussed together instead of getting a clear crisp image.
23:54
Speaker 1: So if you change in the shape of your mirror,
23:56
Speaker 1: you can sort of undo that and send the photons
23:58
Speaker 1: back as if the atmosphere had happened. Oh, I see
24:01
Speaker 1: this is for a different song. I guess right, this
24:03
Speaker 1: would be for like fuzzy fuzzy Little Star. Yeah, exactly.
24:08
Speaker 1: But it's a hard problem to solve, Like, to do this,
24:10
Speaker 1: you have to know what the atmosphere has done to
24:13
Speaker 1: your photons, and you might wonder like, well, how could
24:15
Speaker 1: you possibly know? You're trying to get a crisp image?
24:18
Speaker 1: You don't know what the true image should look like,
24:20
Speaker 1: so how can you like invert the atmosphere. It's a
24:23
Speaker 1: really hard problem. Yeah, and I hear they use lasers
24:26
Speaker 1: for that, right, Sometimes they use lasers. What you need,
24:29
Speaker 1: ideally is some point source near the thing you're looking
24:32
Speaker 1: at where you know what it should look like, like
24:34
Speaker 1: something else nearby in the sky, where you know exactly
24:38
Speaker 1: how it should look, and that lets you calculate what
24:40
Speaker 1: the atmosphere has done to it. You don't always have that,
24:42
Speaker 1: because you don't have like something we have a hubble
24:45
Speaker 1: image of it nearby your star. So sometimes they use
24:48
Speaker 1: lasers and they create these artificial guide stars, Like we
24:52
Speaker 1: know what it should look like when you shoot a
24:53
Speaker 1: laser into the upper atmosphere to like excite the gases
24:57
Speaker 1: and create some emission. We know what that should look like,
25:00
Speaker 1: so we can sort of calculate what the atmosphere has
25:02
Speaker 1: done to that light and then undo that to the
25:04
Speaker 1: light from the stars. I see used the laser or
25:08
Speaker 1: the reference like a control and it actually sort of
25:10
Speaker 1: tells you what the atmosphere is doing. Out's distorting your image, Yeah,
25:13
Speaker 1: it's probing the atmosphere. That's why sometimes you see these
25:16
Speaker 1: telescopes with these lasers shooting out at it. It's not
25:18
Speaker 1: like we're defending the Earth from aliens or sending messages
25:22
Speaker 1: or zapping eagles or anything like that. We're just creating
25:25
Speaker 1: a reference image. So we know what the atmosphere has
25:27
Speaker 1: done to our star light. All right, Well, that's kind
25:29
Speaker 1: of the what the atmosphere is doing. It's doing a
25:32
Speaker 1: lot of the twinkling So does that mean that like
25:34
Speaker 1: a space telescope like the Hubble or the New James
25:37
Speaker 1: Web that's out there in space doesn't get twinkling stars.
25:40
Speaker 1: It doesn't get twinkling stars for that reason, right, there's
25:42
Speaker 1: no atmosphere up there in space to interfere with the Hubble,
25:45
Speaker 1: and that's one reason why it's pictures can be so
25:48
Speaker 1: awesome and crisp and clear. So it's definitely an advantage
25:51
Speaker 1: of space based telescopes. But when the Hubble looks out
25:53
Speaker 1: of stars, it's still sometimes sees their life getting interrupted interesting.
25:58
Speaker 1: It still sees twinkling stars, still sees twinkling stars. And
26:02
Speaker 1: because we can remove the atmosphere from the explanation, that
26:05
Speaker 1: means there must be something else interfering with these stars
26:08
Speaker 1: or something else going on at the actual star itself. WHOA,
26:13
Speaker 1: So there are other sources of twinkling for a star,
26:16
Speaker 1: like even if you get out of the atmosphere, you
26:18
Speaker 1: might still see some twinkling. Yeah, and it's totally fascinating.
26:21
Speaker 1: There were a lot of articles a few years ago
26:23
Speaker 1: about this star called Tabby Star wearing two thousand fifteen.
26:26
Speaker 1: Some citizen scientists saw this dimming of this star that
26:29
Speaker 1: nobody could explain. And you might remember there were a
26:31
Speaker 1: lot of articles written about how like it might be
26:33
Speaker 1: an alien dicen sphere, some huge megastructure built to gather
26:37
Speaker 1: all of the energy from the star that might be
26:39
Speaker 1: explaining why it seemed to be eclipsed. Who did you say?
26:42
Speaker 1: A Tabby star like a cat. It's called Tabby's Star.
26:48
Speaker 1: I'm not sure if it's named after a person named
26:50
Speaker 1: Tabby or a person's cat named Tabby. It's called Tabby Star.
26:53
Speaker 1: I feel like if you had the whole zoo here
26:56
Speaker 1: talked about black sheep and hawks and now cats. It's
27:00
Speaker 1: also sometimes called w t F star, though I won't
27:03
Speaker 1: speculate on what that stands for White toroid formation. Yes,
27:09
Speaker 1: I'm sure that's what they meant or what the physics
27:14
Speaker 1: in Spanish. But it turns out, of course, that it's
27:17
Speaker 1: likely not a Dicens swarm. A dicenswarm would block light
27:20
Speaker 1: at all wavelengths because it would basically be opaque. But
27:23
Speaker 1: the light that's coming from Tabby Star has been interfered
27:26
Speaker 1: with in some way that's not consistent across the spectrum,
27:30
Speaker 1: like some frequencies of light can penetrate still from Tabby
27:33
Speaker 1: Star and other frequencies can't. But we don't have a
27:36
Speaker 1: great idea for what it is that's interfering with the light.
27:39
Speaker 1: People thought maybe it's a planet that blew up and
27:41
Speaker 1: created a big ring of dust, but that's also not
27:44
Speaker 1: creating the amount of infrared glowing people would see. It's
27:47
Speaker 1: so it's really fascinating when a star twinkles when it dims,
27:50
Speaker 1: because it lets us understand what might be going on
27:53
Speaker 1: in that star's system. Right. It tells us a little
27:55
Speaker 1: bit about its internal body bound movements. Breath. I like
28:00
Speaker 1: to think about it. It's like telling us about its neighborhood. Hey,
28:03
Speaker 1: what's going on over there, Tabby Star? Who are your friends?
28:06
Speaker 1: Who are you hanging out with? Did you blow up
28:07
Speaker 1: a planet? All? Right? So you're saying, that's kind of
28:11
Speaker 1: one example of of us seeing a star out in
28:14
Speaker 1: space sort of changing its brightness, but not due to
28:17
Speaker 1: the atmosphere. And people who are interested in exo planets,
28:20
Speaker 1: of course, know that seeing the stars light dim by
28:22
Speaker 1: a tiny little bit is an excellent way to observe
28:25
Speaker 1: exo planets in that star. Right When we get like
28:28
Speaker 1: eclipsed by planet that passes in front of the star,
28:31
Speaker 1: it can cause a very slight dimming, and if you
28:34
Speaker 1: observe that carefully, you can deduce the presence of that
28:37
Speaker 1: exo planet. I wouldn't call that exactly twinkling, but it's
28:40
Speaker 1: an example of a star getting a small eclipse from
28:43
Speaker 1: an exo planet, right, Because these planets, they don't come
28:46
Speaker 1: in front of the sun that often, right, like maybe
28:49
Speaker 1: every couple of most like a couple of hours, right,
28:51
Speaker 1: it could be a slow twinkle, slow twinkle like a twinkle,
28:56
Speaker 1: And of course it depends on the exo planet and
28:58
Speaker 1: what its orbit is. Sometimes it's once in a hundred
29:01
Speaker 1: years it passes around, or maybe it's every few hours.
29:03
Speaker 1: If it's zooming around really close to the star, really
29:06
Speaker 1: limits our ability to discover this kind of thing. But
29:08
Speaker 1: sometimes we see stars with much more dramatic dimming than
29:12
Speaker 1: we could ever explain with exoplanets or even dust swarms. Interesting.
29:16
Speaker 1: I guess my question is like, how common are these
29:19
Speaker 1: other phenomenon? Like if I was out in space in
29:21
Speaker 1: my space suit and I looked at the stars, would
29:23
Speaker 1: I see the stars twinkling? Or they would they look
29:26
Speaker 1: pretty overall, pretty constant to my eyeball, this is pretty unusual.
29:29
Speaker 1: Most of the stars are pretty constant. Sometimes there are
29:32
Speaker 1: things that interfere with the star light, and that's fascinating
29:35
Speaker 1: for astronomers, and there's like a short list of these objects.
29:38
Speaker 1: But most of the stars would look pretty bright and
29:40
Speaker 1: pretty even if I was out in space. If you're
29:42
Speaker 1: out in space, yeah, so if you're observing from the
29:44
Speaker 1: I S S or you're living on the Moon, if
29:46
Speaker 1: you're flying in Elon Musk's roadster, for example, then the
29:49
Speaker 1: stars are going to look pretty clear. Interesting. So the
29:52
Speaker 1: song Twinkle Twinkle Little Star kind of doesn't apply in space. Yeah,
29:56
Speaker 1: nobody's gonna be selling the galactic rights to that song.
29:58
Speaker 1: It's really just the Earth territories or any planet with
30:02
Speaker 1: an atmosphere, right, or maybe like if you're in the
30:06
Speaker 1: middle of a nebula maybe like a space cloud maybe.
30:09
Speaker 1: But there is one star that's really interesting that astronomer
30:12
Speaker 1: has been struggling to understand for like ten years. Now.
30:15
Speaker 1: What is it. It's a star called vvv w I
30:19
Speaker 1: T zero eight and it's in the Sagittarius constellation about
30:23
Speaker 1: twenty five thousand light years away. This is a giant star.
30:26
Speaker 1: It's like a hundred times the size of the Sun.
30:30
Speaker 1: And about ten years ago it seemed to be eclipsed
30:34
Speaker 1: and not just slightly dimmed. Its light was reduced by
30:36
Speaker 1: nine seven percent. Whoa it like it almost turned off completely.
30:41
Speaker 1: It almost turned off exactly. And they've been observing this
30:44
Speaker 1: star for like seventeen years since it is the only
30:46
Speaker 1: time it ever happened. And it dimmed by nine percent
30:50
Speaker 1: for a few hundred days and then came back up
30:52
Speaker 1: to full brightness. Wait what in like the space of
30:55
Speaker 1: like a few months. Yeah, they watched this star for
30:58
Speaker 1: years and nothing happens, and then all of a sudden, boom,
31:01
Speaker 1: it's knocked down by a factor of thirty and then
31:04
Speaker 1: it stays pretty dark for a few months, and then
31:06
Speaker 1: it goes back up to full brightness like all of
31:10
Speaker 1: a sudden or was this a gradual thing? It happened
31:13
Speaker 1: very quickly once it began, and then it stayed dark
31:16
Speaker 1: for months. Right, And so this is fascinating because this
31:19
Speaker 1: is a huge star, right, this is not an eclipse
31:21
Speaker 1: from a small object. No planet passing in front of
31:24
Speaker 1: this giant star could reduce its light by Yeah, that's
31:29
Speaker 1: a big twinkle. I guess it's one big twink. Really,
31:33
Speaker 1: you know, it made all this torontomer twinkle observing it.
31:38
Speaker 1: They were so excited, exactly. And so people are wondering
31:41
Speaker 1: what could this thing be and they've done some calculations.
31:44
Speaker 1: You know, if this thing is going to eclipse such
31:46
Speaker 1: a big star, it has to be huge. It has
31:48
Speaker 1: to be. The minimum size of this thing would be
31:51
Speaker 1: point to five a U, like a quarter of the
31:54
Speaker 1: distance between the Earth and the Sun. We're talking about
31:57
Speaker 1: a single object that size with the thing that blocked
32:01
Speaker 1: the star. Because you're saying the star is so big,
32:04
Speaker 1: it would have to be that something really big to
32:06
Speaker 1: block it. But that's only if we assume that the
32:08
Speaker 1: thing that blocked it is close to the star, Like
32:10
Speaker 1: it could have maybe been something closer that blocked it. Yeah,
32:13
Speaker 1: it could have been something in between us and the star, right,
32:15
Speaker 1: because you can block an entire star with the tip
32:17
Speaker 1: of your finger, which is not a quarter a U
32:20
Speaker 1: wide if your finger is really close. But that would
32:22
Speaker 1: require like a bunch of just dark objects floating through
32:25
Speaker 1: the universe passing between us and these stars. And they
32:27
Speaker 1: did a calculation to see, like how many of those
32:30
Speaker 1: dark objects would have to be randomly floating around the
32:32
Speaker 1: galaxy in order to block stars like this, and it
32:34
Speaker 1: would be a huge number. So that's an explanation, but
32:38
Speaker 1: it's less likely than some huge object closer to the star,
32:41
Speaker 1: some remnant of the stellar formation. But this doesn't happen
32:45
Speaker 1: that often, right, does it? This does not happen that often,
32:48
Speaker 1: But for it to ever happen, space would basically have
32:51
Speaker 1: to be filled with these big dark objects because it's
32:54
Speaker 1: very hard to cross the line of side between a
32:57
Speaker 1: star and us unless you have a lot of stuff
32:59
Speaker 1: out there in space, because space is really, really really big. Interesting,
33:04
Speaker 1: So they think it's maybe something in the orbit of
33:06
Speaker 1: the star and it's something huge, yeah, but they don't
33:09
Speaker 1: really understand it because we don't have models for solar
33:11
Speaker 1: system formation that include stuff like this, Like what could
33:14
Speaker 1: it be? We have ideas of planets and maybe even
33:17
Speaker 1: rings around stars. People have this theory that maybe it's
33:20
Speaker 1: like a huge ring with a big blob in it
33:23
Speaker 1: that got exploded or torn apart by tidal forces, something
33:26
Speaker 1: like a circumstellar disc with a huge object in it,
33:29
Speaker 1: but it's much bigger than any model can predict. Interesting,
33:32
Speaker 1: Could it be like a giant cloud of something like
33:35
Speaker 1: an asteroid cloud? Maybe you certainly could be. And perhaps
33:37
Speaker 1: for example, another solar system passed by and lost some
33:41
Speaker 1: of its stuff to this solar system, So it could
33:43
Speaker 1: be something that happened fairly recently, because these things wouldn't
33:46
Speaker 1: last for very long. If you have like a huge
33:49
Speaker 1: cloud of stuff in your solar system, eventually gravity is
33:52
Speaker 1: going to pull it together after a few million years
33:54
Speaker 1: and form it into like a planet or into something else.
33:58
Speaker 1: And so like huge clouds of gas and dust around
34:00
Speaker 1: the star and to be short lived objects on astronomical
34:03
Speaker 1: time scales. WHOA, alright, so that's one, I guess twinkling
34:08
Speaker 1: That puzzled scientist. It's it's like a big twinkle that
34:12
Speaker 1: caused this one start to twinkle. What are some other
34:15
Speaker 1: famous examples of twinkling stars? Yeah, so we have a
34:17
Speaker 1: short list of them. There's another one called Epsilon R
34:21
Speaker 1: e J, and this one is eclipped every twenty seven
34:25
Speaker 1: years by some giant dust cloud which orbits it, and
34:29
Speaker 1: it's eclipsed by fifty percent whoa meaning like we see
34:32
Speaker 1: the star called Epsilon R J, and it it dims
34:35
Speaker 1: every twenty seven years. We've been looking at it that
34:38
Speaker 1: long to note to notice this pattern. Yeah, it was
34:40
Speaker 1: first observed in eighteen twenty one, so we've been looking
34:43
Speaker 1: at this thing for like hundreds of years, which is
34:46
Speaker 1: why we have a handle on like a twenty seven
34:48
Speaker 1: year cycle. So it's like a twinkle, but in atar
34:51
Speaker 1: scale kind of exactly if you fast forward at the universe,
34:55
Speaker 1: this one would seem to twinkle. It's like a very
34:58
Speaker 1: slow motion tween. You have to play the song one
35:02
Speaker 1: note per year exactly, and the dimming here lasts for
35:05
Speaker 1: like two years and then it happens every twenty seven years.
35:09
Speaker 1: So it's like a giant, slow moving dust cloud. And
35:12
Speaker 1: this one we do know what causes. How do we
35:14
Speaker 1: know what causes this eclipse? Mostly we can study these
35:16
Speaker 1: things by looking at the spectrum, Like we can study
35:19
Speaker 1: the kind of light that can penetrate, and that tells
35:22
Speaker 1: us why this thing is transparent and why this thing
35:24
Speaker 1: is opaque, because remember every object is either transparent or
35:28
Speaker 1: opaque to light at different frequencies depending on what it is,
35:31
Speaker 1: because the atoms that make things up can only absorb
35:35
Speaker 1: photons as specific frequencies. And so by looking at the
35:38
Speaker 1: light that passes through, for example, a cloud of gas,
35:41
Speaker 1: you can tell, oh, there hydrogen, or there's helium, or
35:43
Speaker 1: there's sodium, or it's gas or its dust or whatever.
35:46
Speaker 1: You can tell by seeing which frequencies of light are
35:49
Speaker 1: filtered out by that object. And so by studying it
35:53
Speaker 1: we can tell, oh, this is probably a big cloud
35:55
Speaker 1: of dust, and I see like the shade of the
35:57
Speaker 1: light that comes through tells you kind of what it
36:00
Speaker 1: went through exactly, just like you know, you can throw
36:02
Speaker 1: things into flames and they make different colors. That's because
36:05
Speaker 1: different elements emit at different frequencies. They also absorb at
36:09
Speaker 1: those same frequencies. And so if you shine white light
36:12
Speaker 1: through a cloud of random gas, and astronomer can tell
36:15
Speaker 1: you what was in that gas based on whether green
36:18
Speaker 1: was removed or red was removed, or the infrared was
36:21
Speaker 1: removed or something. It's like a fingerprint. All right, that's
36:24
Speaker 1: another twinkling star in space. What are some other examples,
36:28
Speaker 1: So this is a short list of them. V four
36:31
Speaker 1: hundred Centauri, which is also called Mama Jets object is
36:34
Speaker 1: also eclipsed by something we don't really understand, but astronomers
36:38
Speaker 1: suspect that it's something that's point for a U wide,
36:41
Speaker 1: it's an object that's like forty million miles wide. Well,
36:44
Speaker 1: it's it's not maybe one objecting it's at that scale.
36:47
Speaker 1: It's probably like a cloud of something or a cluster
36:49
Speaker 1: of something. Right, Yeah, it's probably like a big cloud
36:52
Speaker 1: of gas or dust or a huge rain of rocks. Right,
36:54
Speaker 1: it's probably not a single solid object that would big
36:57
Speaker 1: because it's like a huge block of iron that big
37:00
Speaker 1: and gravitationally will probably collapse into a black hole. All right. Well,
37:03
Speaker 1: those are different things that can make a star twinkle
37:06
Speaker 1: out in space that is not our atmosphere. But it
37:08
Speaker 1: turns out there are other reasons why a star might twinkle,
37:11
Speaker 1: and it might have to do with their inner bowel movement.
37:14
Speaker 1: So let's get into that. But first let's take another
37:16
Speaker 1: quick break. All right, we're talking about twinkling and twinkling stars.
37:32
Speaker 1: Both big and little and also bad bla black cheeps
37:36
Speaker 1: that might be eclipsing stars out there in space. So
37:40
Speaker 1: then we talked about how, like most of the stars
37:42
Speaker 1: we see twinkle here on Earth, it's it's because of
37:44
Speaker 1: the atmosphere. It's the air around us is making the
37:47
Speaker 1: light kind of dim on and off. But you can
37:49
Speaker 1: also see a about twinkling in space because there are
37:52
Speaker 1: other things in space that might be blocking our view.
37:54
Speaker 1: But it turns out that even if you are sort
37:55
Speaker 1: of standing next to the star, you might even then
37:59
Speaker 1: see a twinkle. This is one of my favorite explanations
38:01
Speaker 1: for twinkling stars because it really goes to the heart
38:04
Speaker 1: of like your original idea. When you're looking up at
38:07
Speaker 1: the night sky and you're looking at the star and
38:09
Speaker 1: it's twinkling, you're wondering, like, is it getting brighter and
38:12
Speaker 1: dimmer or is the light getting blocked. Well, it turns
38:14
Speaker 1: out that stars can actually get brighter and dimmer. That's
38:18
Speaker 1: something that a bunch of stars can do. And I
38:20
Speaker 1: was surprised to learn that the Sun does this as well.
38:23
Speaker 1: The Sun varies its brightness. It's not just like a
38:26
Speaker 1: constant stream of photons every year. Wait, what like our sun,
38:30
Speaker 1: that the one that provides are daylight is not constant.
38:33
Speaker 1: It's twinkling. Also, Yeah, it turns out all stars are variable.
38:37
Speaker 1: Some of them are much more variable than others, and
38:39
Speaker 1: we'll talk about those, but every single star has some
38:42
Speaker 1: variability to it. You know, our sun has like an
38:44
Speaker 1: eleven year cycle where something mysterious is going on at
38:47
Speaker 1: the heart of this swirling, crazy plasmas with these enormous
38:52
Speaker 1: tubes and magnetic fields that flip every eleven years, and
38:55
Speaker 1: so the brightness of our sun varies, but only a
38:57
Speaker 1: small amount. It's like zero point one percent over the
39:01
Speaker 1: eleven year cycle. Well, I meaning like if you took
39:04
Speaker 1: a film of the Sun and you fast forward at it,
39:07
Speaker 1: you would see it kind of like twinkle, right, you'd
39:09
Speaker 1: see it kind of blinking on and off about point
39:11
Speaker 1: one percent, but still you might notice it. Yeah, you
39:14
Speaker 1: have a good camera, you could definitely detect that, and
39:16
Speaker 1: people have and people who study the sun see this
39:18
Speaker 1: kind of cycle. You know, there's another longer term trend,
39:21
Speaker 1: which is the sun is overall getting brighter and brighter
39:24
Speaker 1: as it gets older, and over like a billion years,
39:26
Speaker 1: it's going to get maybe ten percent brighter. That's not
39:29
Speaker 1: something we can observe with our telescope today. But this
39:31
Speaker 1: kind of gentle twinkling is something that the Sun does.
39:36
Speaker 1: And then I guess that's because the Sun. I mean,
39:38
Speaker 1: it's not like a machine, right, It's like a process.
39:41
Speaker 1: It's like a giant nuclear chemical reaction, right, Like there's
39:44
Speaker 1: stuff going on inside of it that maybe causes it
39:47
Speaker 1: to kind of grow brighter or dimmer. Sometimes you're suggesting
39:51
Speaker 1: that if it was a machine, like designed by a
39:52
Speaker 1: stellar engineer or something, it would be more reliable. Well,
39:56
Speaker 1: all engineers are stars, Daniel. All engineers are stellar. We're
40:00
Speaker 1: all stellar engineers. I mean, the Sun has been burning
40:03
Speaker 1: for five billion years without a breakdown, so you know,
40:06
Speaker 1: I think it's pretty effective. Well, I guess what I
40:08
Speaker 1: mean is it's it's a it's kind of like it's
40:10
Speaker 1: an organic process, right, Like, it's not perfectly imbalanced. Maybe
40:14
Speaker 1: sometimes it gets a little over excited and sometimes a
40:16
Speaker 1: little under excited. Yeah, it's a different process than combustion.
40:20
Speaker 1: But it's sort of like a fire. You know, it
40:21
Speaker 1: has fuel, it keeps burning and that flame fluctuates and
40:25
Speaker 1: so it's not like designed or orchestrated in order to
40:27
Speaker 1: provide a certain amount of light. It's just a thing
40:29
Speaker 1: that is there and does what it's doing, and that
40:32
Speaker 1: means that it has cycles because of the internal workings
40:35
Speaker 1: of the sun very and it's incredible that it's so
40:38
Speaker 1: regular too. It's not something that we understand the source
40:41
Speaker 1: of this eleven year cycle for the sun. Well, so
40:44
Speaker 1: I wonder, like, if we're a different species of animal
40:47
Speaker 1: and we had like a thought process that was a
40:49
Speaker 1: lot slower like to us, maybe the sun would look
40:51
Speaker 1: like a stroke light almost if we thought about things
40:54
Speaker 1: in the scale of like centuries, it would look like
40:56
Speaker 1: it was blinking on and off kind of. Yeah, that's
40:58
Speaker 1: fun to think about. Or another idea is what if
41:01
Speaker 1: we were species that was extraordinarily sensitive is the abount
41:04
Speaker 1: of sunlight, so that we could like observe and notice
41:07
Speaker 1: this eleven year cycle and it affected our evolution the
41:10
Speaker 1: way like the day night cycle and the winters have
41:13
Speaker 1: affected the evolution of light on Earth. I'd be interesting
41:15
Speaker 1: if you had species that were sensitive to these eleven
41:17
Speaker 1: year cycles. Whoa, like, maybe you're sleepier for eleven years
41:21
Speaker 1: and then you're less sleepy. Maybe that's why I've been
41:25
Speaker 1: late this past eleven years. Yeah, all right, well, then
41:28
Speaker 1: how do you explained the previous eleven years? I was
41:31
Speaker 1: a lot more on time eleven years ago. Man, I
41:33
Speaker 1: believe that I've known you for more than eleven years,
41:35
Speaker 1: so I can contest that data. Well, you just don't
41:38
Speaker 1: have enough data points. Then you need at least what's
41:41
Speaker 1: the mic was frequency that you need at least twice
41:44
Speaker 1: the periosity. All right, I'll get back to you intend Yeah, wait,
41:48
Speaker 1: wait or other thirty years and then we'll talk about
41:51
Speaker 1: my peakers. All right, I'm putting it on my calendar
41:53
Speaker 1: series schedule appointment for thirty years from today. But anyways,
41:58
Speaker 1: I think what you're saying is that, like, maybe I
42:00
Speaker 1: wonder if there are things on Earth that are sensitive
42:02
Speaker 1: to that cycle, right, Like, maybe it might affect our
42:05
Speaker 1: atmosphere too, Right, every eleven years, maybe things get a
42:07
Speaker 1: little bit warmer or colder. Yeah, well, the brightness of
42:10
Speaker 1: the sun definitely affects the atmosphere and the climate here
42:12
Speaker 1: on Earth, but there are larger effects. The Earth goes
42:15
Speaker 1: through these cycles that affect like the ice ages and
42:17
Speaker 1: glaciation because the Earth's orbit changes a little bit, and
42:21
Speaker 1: the tilt changes a little bit. Is it's tweaked by
42:23
Speaker 1: like Jupiter. So I think those effects are larger than
42:26
Speaker 1: the variability of the Sun itself. So the Sun is
42:28
Speaker 1: a twinkling star. It's pretty interesting. But then and then
42:31
Speaker 1: there are other ways in which a star can change to. Yeah,
42:34
Speaker 1: so all stars vary, and some of them vary a lot.
42:38
Speaker 1: They are these stars that are called pulsating stars, and
42:41
Speaker 1: they get brighter and dimmer and brighter and dimmer, sometimes
42:44
Speaker 1: by huge amount. A classic example of these are the sefids.
42:47
Speaker 1: These are the ones that Hubble used to discover that
42:49
Speaker 1: the universe is expanding. These aren't like pulsars, which shoot
42:52
Speaker 1: out a beam of light which spins around and sweeps
42:54
Speaker 1: over the Earth. These are like radially shrinking and growing.
42:58
Speaker 1: They get bigger and bright, eater, and then smaller and dimmer. Whoa,
43:02
Speaker 1: they're They're like a beating heart, almost like the star
43:05
Speaker 1: is growing and shrinking. Yeah, they pulse with a regular frequency.
43:08
Speaker 1: Well what kind of frequency we're talking about. There's a
43:10
Speaker 1: big range in the periods, but it's on the order
43:13
Speaker 1: of days. Some of these things have a period of
43:15
Speaker 1: like ten days or eighty days or ninety days. So
43:19
Speaker 1: this is not like a pulsar that can be spinning
43:22
Speaker 1: at like millisecond frequencies or something that's more like on
43:24
Speaker 1: the order of days. But sometimes they have like multiple frequencies.
43:28
Speaker 1: They can have like a major frequency, and then they
43:30
Speaker 1: have like another cycle that's going on inside of that
43:33
Speaker 1: that I can constructively or destructively interfere. But even a
43:37
Speaker 1: period of days seems a lot, right, Like can you
43:40
Speaker 1: imagine the start changing that quickly, like a start size
43:43
Speaker 1: of our sun changing that quickly every couple of days,
43:46
Speaker 1: that that would be pretty dramatic. It would be crazy
43:48
Speaker 1: to be in a system like that where things got
43:50
Speaker 1: a lot brighter and then a lot dimmer, and also
43:52
Speaker 1: the star itself is getting bigger, right, This is like
43:55
Speaker 1: an astrophysical thing you can observe, like the star is
43:58
Speaker 1: expanding and now it's shrinking. It has to do with
44:00
Speaker 1: what's going on inside the star, you know, like is
44:03
Speaker 1: the star opaque to its own energy, so that there's
44:07
Speaker 1: all this pressure from the radiation being generated the core
44:10
Speaker 1: that's pushing out the outer layers or it is a
44:12
Speaker 1: cool down and then become like transparent to that energy
44:15
Speaker 1: and it can collapse a little bit. So this this
44:17
Speaker 1: cycle that's going on inside every star, but in some
44:20
Speaker 1: stars it's very dramatic, right, because stars, as we talked
44:23
Speaker 1: about it, are kind of a balance between gravity squishing
44:26
Speaker 1: everything in and effusion exploding everything out. And like our
44:30
Speaker 1: star is pretty steady, Like it's pretty well balanced, but
44:32
Speaker 1: maybe there are stars out there that are not as
44:34
Speaker 1: well balanced, and so they kind of swing back and
44:36
Speaker 1: forth more wildly between squishing and exploding, you know. And
44:39
Speaker 1: it's something we're still trying to understand in detail. People
44:42
Speaker 1: are building models to try to explain this kind of thing,
44:45
Speaker 1: and it's a great way to probe what's going on
44:47
Speaker 1: inside the star. Also because the sefids, at least, there's
44:51
Speaker 1: this close connection between the period, how long it takes
44:55
Speaker 1: to go from bright to dim and bright to dim,
44:57
Speaker 1: and how bright it is at its brightest point, which
45:00
Speaker 1: of course is super helpful if you want to understand
45:02
Speaker 1: how far away the star is, but also helpful if
45:05
Speaker 1: you want to understand what's going on inside the star,
45:08
Speaker 1: what crazy processes are driving these things. Uh, it's got
45:12
Speaker 1: like a lot of turmoil inside of it, but predictable
45:15
Speaker 1: turmoil on this yeah, precisely, okay, cool. And then there
45:19
Speaker 1: are also erupting stars or farting stars. There are some
45:22
Speaker 1: stars that are even more dramatic than these pulsating stars.
45:25
Speaker 1: They are called erupting stars. These stars like blowout material.
45:31
Speaker 1: They're like puff away material and then they lose it.
45:34
Speaker 1: You know, it's like gone out into space. These are
45:36
Speaker 1: not like explosive events. It's not like, you know, the
45:39
Speaker 1: star has exploded. It's not like a supernova. It's more
45:42
Speaker 1: just like the star has very rapidly grown and then
45:45
Speaker 1: loses some of its material. It's not like a gas pocket.
45:48
Speaker 1: It's more like it has one of these flow ups
45:50
Speaker 1: and in the process that shoots out a big bunch
45:53
Speaker 1: of stuff. It shoots out a big bunch of stuff,
45:55
Speaker 1: and it can also a creed a big bunch of stuff.
45:57
Speaker 1: Like sometimes they're near a source and so they're gathering
46:00
Speaker 1: more fuel and that can make the star brighter. In
46:03
Speaker 1: extreme cases, it can be really dramatic. One example is
46:06
Speaker 1: called a flare star. These kind of stars can grow
46:09
Speaker 1: in brightness by a factor of six and then fade
46:12
Speaker 1: back down. And this whole thing happens in like half
46:15
Speaker 1: an hour. That's huge, but it's not is it constant
46:18
Speaker 1: or is it just happens every once in a while.
46:20
Speaker 1: These things are not regular the way like pulsating stars are,
46:23
Speaker 1: and it's not something that we understand, you know, we
46:26
Speaker 1: don't even understand it as well as we understand like
46:29
Speaker 1: solar flares on the surface of our sun, which have
46:31
Speaker 1: to do with like magnetic field lines snapping and reconnecting.
46:34
Speaker 1: So it's something we observe by, something we still don't
46:36
Speaker 1: understand the process of. Oh, I see, it's more like
46:39
Speaker 1: one twinkle like it twinkles ones sometimes you know, it's
46:43
Speaker 1: regular and it's unpredictable. Um, but it does seem to
46:46
Speaker 1: happen much more often to red dwarfs, like these dim
46:49
Speaker 1: red dwarfs that are all over the galaxy one of
46:52
Speaker 1: the most common types of star. These are the ones
46:54
Speaker 1: that turn into flare stars. Interesting, regular and unpredictable. I
46:59
Speaker 1: feel like it's a good description of myself as well.
47:03
Speaker 1: Maybe I should have said not uncommon and unpredictable. It's
47:07
Speaker 1: sort of cool because the galaxy is filled with these unassuming,
47:10
Speaker 1: sort of generic dim red dwarfs. But occasionally one of
47:13
Speaker 1: them becomes like ridiculously bright for just like a half
47:16
Speaker 1: an hour and then goes back to being a boring star.
47:18
Speaker 1: So these are examples of stars kind of twinkling by themselves.
47:23
Speaker 1: Like you said, like, it's not something that's blocking it.
47:25
Speaker 1: It's not the atmosphere that's the story. It's like the
47:27
Speaker 1: star it self kind of twinkles, even if it's on
47:29
Speaker 1: a pretty big time scale exactly, and it's sort of
47:32
Speaker 1: across the whole spectrum, you know, the whole star lights
47:35
Speaker 1: up in many different frequencies, and so it's pretty cool
47:38
Speaker 1: because that means that the twinkling you're seeing is not
47:40
Speaker 1: just something local, not just your atmosphere, but it's actually
47:43
Speaker 1: information about what's going on inside the star. So it's
47:47
Speaker 1: like there's science there. It's like it's sending you a message. Interesting,
47:50
Speaker 1: it's like there's yeah, there's a there's hidden mechanics going
47:54
Speaker 1: on that you can maybe figure out if you could
47:55
Speaker 1: study this, this twinkling. Yeah, and I think about this
47:58
Speaker 1: kind of thing every time I'm out in nature enjoying
48:00
Speaker 1: a dark sky night, which you know is harder and
48:02
Speaker 1: harder to get these days. Right, But you go camping
48:05
Speaker 1: a lot, right, is that when you look at stars mostly, Yeah,
48:08
Speaker 1: when you go camping is when you're far away from
48:10
Speaker 1: the city and all the light pollution, and hopefully you
48:12
Speaker 1: don't see too many clouds. That's when you break out
48:14
Speaker 1: the guitar and you start lecturing. Do your kids about
48:18
Speaker 1: the stars in music? I try not to force them
48:22
Speaker 1: to listen to it, but you know, by the way,
48:24
Speaker 1: we got a comment from a listener about something you
48:26
Speaker 1: said about the weather in Spokane, Washington and how likely
48:30
Speaker 1: they are to have clear skies. Wait, what what happened?
48:32
Speaker 1: What did I say? And what did they say? Apparently
48:34
Speaker 1: you said that it rains eleven months per year in Spokane, Washington,
48:38
Speaker 1: and this listener, Jeremy wrote in and said, I just
48:40
Speaker 1: want you to know that Spokane is basically a desert
48:43
Speaker 1: and it's pronounced Spokane. So thanks Jeremy for the fact checking.
48:47
Speaker 1: So I was wrong and many many counts. Yeah, and
48:50
Speaker 1: actually I looked it up and it rains seventeen inches
48:52
Speaker 1: a year in Spokane and twenty inches a year in
48:55
Speaker 1: your hometown of Pasadena. So it's even drier and Spokane
48:59
Speaker 1: than it is where you live. Interesting. Wow, Well I
49:02
Speaker 1: was wrong, but it means that observing the night sky
49:04
Speaker 1: in Pasadena and in Spokane, you won't get blocked by
49:07
Speaker 1: a lot of clouds. I am wrong. Every eleven years
49:10
Speaker 1: it does happen due to the sun variations. You know,
49:13
Speaker 1: it's not something I can help. That's right. Every star
49:15
Speaker 1: has their variability, and this is yours. That's right. Every
49:19
Speaker 1: stellar engineer has a cycle. All right. Well, it's interesting that,
49:23
Speaker 1: you know, something as simple as a kids song like
49:25
Speaker 1: Twinkle Twinkle Little Star has so much science behind it.
49:28
Speaker 1: You know, it tells us it's inspired by, you know,
49:32
Speaker 1: the effects of our atmosphere that we have, how it
49:34
Speaker 1: blocks our view of the universe. And it also maybe
49:37
Speaker 1: has something to do with the mechanics of stellar you know,
49:40
Speaker 1: fusion and processes inside of these incredible exploding machines. Yeah,
49:45
Speaker 1: it's really an outstanding way to think about the universe
49:48
Speaker 1: and the journey that these lotons make across it, from
49:51
Speaker 1: when they're born in this hot ball of plasma billions
49:53
Speaker 1: and billions of miles away to finally landing on your eyeball.
49:57
Speaker 1: The fact that they get there tells you something about
49:59
Speaker 1: the union verse between here and there, and the fact
50:02
Speaker 1: that some of their brothers and sisters didn't get there
50:04
Speaker 1: also tells you something about what's between us and that star. Yeah.
50:09
Speaker 1: Only the lucky ones make it too spoken. The unlucky
50:13
Speaker 1: ones make it to Pasadena or Irvine is the lucky
50:17
Speaker 1: ones get here and they have to listen to my
50:18
Speaker 1: band plan. I'm gonna file a noise complain the universe
50:24
Speaker 1: already did it all right? Well, the next time you
50:27
Speaker 1: listen to this song, think about the stars and think
50:29
Speaker 1: about how our view of the universe still not completely clear.
50:34
Speaker 1: We hope you enjoyed that. Thanks for joining us, See
50:36
Speaker 1: you next time. Thanks for listening, and remember that Daniel
50:46
Speaker 1: and Jorge Explain the Universe is a production of I
50:49
Speaker 1: Heart Radio. For more podcast for my heart Radio, visit
50:53
Speaker 1: the i heart Radio app, Apple Podcasts, or wherever you
50:56
Speaker 1: listen to your favorite shows. No