Speaker 1: Pee Katie, help me out with some research for an
Speaker 1: upcoming episode. Alright, as long as you don't put me
Speaker 1: in that collider of yours. Not this time, but you know,
Speaker 1: in general, no promises, so just make sure you always
Speaker 1: read the waiver very carefully. All right, I'll wear a helmet.
Speaker 1: So what are we researching? Well, I'm trying to understand rings,
Speaker 1: all right, and how can I help? Well, you got
Speaker 1: engaged and married recently, didn't you. Yeah, during the pandemic.
Speaker 1: I had a zoom wedding. It was It was really fun.
Speaker 1: And did you get a real ring or a digital
Speaker 1: zoom ring? I got a real ring, not just an
Speaker 1: n f T pointing tour ring. Yes, I have a
Speaker 1: real ring. And tell us a little bit about it.
Speaker 1: Is it made out of icy particles or mostly dust
Speaker 1: and rocks. It was actually grown in a lab lab
Speaker 1: grown diamonds, which is pretty neat to me. Well, I
Speaker 1: wonder if castor and planetary rings have anything in common. Yeah,
Speaker 1: I wonder the same thing. You know. Actually, my husband
Speaker 1: later told me that he had the choice to get
Speaker 1: like a ring made out of a meteorite, So sometimes
Speaker 1: they do converge. While it'd be awesome a little bit
Speaker 1: of space on your finger. Well, we will have to
Speaker 1: invite Saturn on the podcast to ask how it got
Speaker 1: its rings and when it's fiance proposed to it. Saturn's
Speaker 1: got the best bling in the Solar system. Hi, I'm Daniel.
Speaker 1: I'm a physicist at UC Irvine and I do research
Speaker 1: at the Large Hadron Collider. I am Katie Golden. I
Speaker 1: host Creature Feature, a biology podcast, So I'm not actually
Speaker 1: a physicist, but I have used a hula hoop before,
Speaker 1: so I feel fairly confident I can talk about Saturn's
Speaker 1: rings today. Oh. I think that makes you an engineer,
Speaker 1: doesn't it. That's right, Just get me some tape and
Speaker 1: a few paper clips, and boom, I'm an engineer. Well,
Speaker 1: I actually don't wear a whole lot of rings. I
Speaker 1: just have this one wedding ring, which my wife and
Speaker 1: I picked up two days before our wedding on the
Speaker 1: streets of Berkeley for about five bucks. And I think
Speaker 1: at the time we were like, oh, this will work temporarily,
Speaker 1: and here we are twenty years later, I'm still wearing
Speaker 1: the same silver ring. No, that's so sweet. I love
Speaker 1: that story. Yeah, it's a nice memory. It helps me
Speaker 1: understand where I came from. And you know, in the
Speaker 1: same way, we can look up at the night sky
Speaker 1: and study the planets and use their rings to try
Speaker 1: to get an idea of like where they came from,
Speaker 1: what is the history of this planet? How did it
Speaker 1: get that ring? Who gave it to it? And you know,
Speaker 1: what is that wedding going to look like? So you're
Speaker 1: saying because my ring was made in a lab, that
Speaker 1: I two was made in a lab. Maybe your love
Speaker 1: was grown in the lab, you know, which doesn't make
Speaker 1: it any less authentic. I'm a big fan of labs
Speaker 1: and research. It's very romantic test tube romance and welcome
Speaker 1: to the podcast. Daniel and Jorge explain the universe in
Speaker 1: which we try to grow your understanding of the nature
Speaker 1: of this universe that we find ourselves and we cast
Speaker 1: our minds out into the deepest darkness of space and
Speaker 1: try to ring out understanding of everything that's out there
Speaker 1: in the universe, and we zoom on into the tiniest
Speaker 1: little things between our toes and under our fingernails, because
Speaker 1: we want to understand the fundamental nature of the universe,
Speaker 1: the nature of space and time itself, and matter and
Speaker 1: energy and all those tiny little bits which, in their
Speaker 1: two ing and frowing, come together to make the universe
Speaker 1: that we know and love. My friend and co host
Speaker 1: Jorge can't be with us today he is on vacation,
Speaker 1: but we are very pleased to have the be Ringed,
Speaker 1: be Jeweled, be Blinged Kiti two join this today. Well,
Speaker 1: thank you for ringing me up for this episode. Yes,
Speaker 1: I'm very excited. I love science, but that doesn't mean
Speaker 1: I can't appreciate some good old fashioned cosmic jewelry. Well,
Speaker 1: one thing I love about jewelry is that it really
Speaker 1: does tell a story. You know, you talk to somebody
Speaker 1: and you see them with ear rings or with a necklace,
Speaker 1: you know that has a history. You know, maybe somebody
Speaker 1: bought for them, or they got it for some big event,
Speaker 1: or maybe they inherited it from their family, and it
Speaker 1: tells like an even deeper story about where they came
Speaker 1: from and their family history. So it's like everybody who's
Speaker 1: wearing jewelry is walking around telling little stories about themselves. Yeah,
Speaker 1: I love that. Or it bears an ancient curse? Are
Speaker 1: we going to take a deep dark turn on this podcast?
Speaker 1: I don't know. It is Saturn cursed? Is that where
Speaker 1: we're going to discover maybe Aliens visited the Solar System
Speaker 1: and had a war with the Octopi living under the
Speaker 1: oceans of Insulatus, and the rings are just the left
Speaker 1: over remnants that interstellar conflict. That's very spooky, and I
Speaker 1: would love that story for a ring that I had,
Speaker 1: that it was made by some kind of intergalactic war.
Speaker 1: I think it is one of the things about the
Speaker 1: Solar System that really adds a bit of magic to it,
Speaker 1: adds a bit of artistry to it, because of course
Speaker 1: I think all the planets are lovely, but they're all orbs,
Speaker 1: you know, they're they're all these roughly of course, not
Speaker 1: exact precise spears, but you know, roughly spherical. But then
Speaker 1: you have these rings. And it always when I see
Speaker 1: Saturn that gives me a feeling of awe about the
Speaker 1: mystery and artistry of space that I don't necessarily get
Speaker 1: with other planets, absolutely because it's so easy to grab onto,
Speaker 1: you know, it's so visible out there. And it must
Speaker 1: have been an amazing moment in sixteen ten when Galileo
Speaker 1: looked through his telescope and saw the rings of Saturn,
Speaker 1: and how shocking to discover that planets can have these
Speaker 1: incredible dis you know, these things are like ten times
Speaker 1: the size of Saturn. We'll talk later about how Saturday
Speaker 1: might have rings that go out like two hundred times
Speaker 1: the size of its radius. It's an incredible thing. Like
Speaker 1: I have this little tiny ring on my finger. Imagine
Speaker 1: if I was wearing a ring that was like two
Speaker 1: hundred times the size of me. You know, some might
Speaker 1: say that's a little overstated. It would be a statement piece,
Speaker 1: for sure. You know. I was actually just in the
Speaker 1: Galileo Museum in Florence, And when you think of Galileo
Speaker 1: with his telescope, he's often depicted with this small, you know,
Speaker 1: telescope he can hold in his hands. But you look
Speaker 1: at the actual telescopes he used to observe Saturn and
Speaker 1: they were huge. Yeah, he wasn't the inventor of the telescope,
Speaker 1: but he was the first one to really perfect it
Speaker 1: and then to turn it up on the skies, and
Speaker 1: so he got like the biggest first scoop of all
Speaker 1: these discoveries. You know, he saw the moons of Jupiter,
Speaker 1: he saw the rings of Saturn. He's on mountains on
Speaker 1: the Moon on a moment or like really look out
Speaker 1: into the universe. And I think that one of the
Speaker 1: most interesting things for me about it is that they
Speaker 1: do reve yield the history of the Solar System. You know,
Speaker 1: we look out unto the night sky and we want
Speaker 1: to understand not just what's out there, but why it's
Speaker 1: out there and why it looks the way that it does.
Speaker 1: And so anything that's weird or strange or unusual that's
Speaker 1: not just like a ball floating in the sky, Let's
Speaker 1: just ask the question, how did that get there? How
Speaker 1: long can that live? What does that tell us about
Speaker 1: the history of the Solar System? Have those rings just
Speaker 1: been there for the last million years? Have they been
Speaker 1: there since the beginning of the Solar System? Why do
Speaker 1: Saturn have rings and not other planets? Or do they right?
Speaker 1: There's just so many immediate questions that you can ask
Speaker 1: when you see these rings, and then those questions open
Speaker 1: the door to try to understand the formation of the
Speaker 1: Solar System. The other aspect, which is super fascinating for me,
Speaker 1: is just thinking about what physics can do. You know,
Speaker 1: you throw a whole bunch of stuff out into space
Speaker 1: and it forms stars and it forms planets, But not
Speaker 1: just that right, it can also do these other incredible things.
Speaker 1: And it's all these fascinating little wrinkles, these little bits
Speaker 1: of bling that really show us what gravity is capable
Speaker 1: of and the interplay between gravity and all the other forces. So,
Speaker 1: as we'll see on today's episode, these rings will teach
Speaker 1: us a lot about the nature of the Solar System
Speaker 1: and the universe that we live in. And so on
Speaker 1: today's episode we'll be tackling exactly that question. How do
Speaker 1: planets get rings? Okay, I'm gonna stop you right there,
Speaker 1: because I think I have the answer. It is aliens,
Speaker 1: giant aliens doing ring toss with our planets, or maybe
Speaker 1: it's hula hoops from a leftover enormous alien birthday party.
Speaker 1: We're basically their garbage bin. But it's an interesting question
Speaker 1: not just why are there rings, but how do planets
Speaker 1: get rings? Where do they come from? Why do some
Speaker 1: planets have rings and others don't. Why do some planets
Speaker 1: have more moons and fewer rings. What is the connection
Speaker 1: between rings and moons? Can moons have rings? Can rings
Speaker 1: exist on planets in other Solar systems? Is our Solar
Speaker 1: System weird for having this incredible planet with these huge rings,
Speaker 1: or are we weird for not having rings around every
Speaker 1: single planet? These are the kinds of questions we can
Speaker 1: now ask about our solar system because we have looked
Speaker 1: out through our telescopes into even other solar systems around
Speaker 1: other stars to try to get an answer to the
Speaker 1: question of is our solar system strange or is our
Speaker 1: solar system totally vanilla and typical. I find that an
Speaker 1: interesting way to describe if our solar system is similar
Speaker 1: to other solar systems, which is boring and vanilla. Well,
Speaker 1: it's a deep question, right, like are we typical? Are
Speaker 1: we boring? If alien scientists are studying the whole galaxy,
Speaker 1: would they find us an interesting case study or would
Speaker 1: they be like, oh, yeah, another one, just like all
Speaker 1: the other sixty five million systems that I've already studied. Right,
Speaker 1: we'd like to think that we are special in some sense.
Speaker 1: We'd like to imagine that we are at the center
Speaker 1: of the universe. We are unusual, we are sparkling, we
Speaker 1: are exceptional. On the other hand, I'd like to believe
Speaker 1: that we are vanilla, that we are boring, because that
Speaker 1: means it's probably more of us, right, That means it's
Speaker 1: probably life everywhere. One of my favorite things about this
Speaker 1: kind of question, is our solar system typical or not?
Speaker 1: Is that the answer is fascinating either way. Either we're
Speaker 1: incredibly unusual and then we get to ask why, or
Speaker 1: we're not, in which case we got lots of neighbors. Yeah,
Speaker 1: so you would favor us being basic solar system with
Speaker 1: our ugg boots and our Saturn's rings. That is kind
Speaker 1: of an interesting personality quick personality tests, like would you
Speaker 1: prefer our solar system to be unique and special in
Speaker 1: us to be the only planet with life or would
Speaker 1: you prefer us to be run of the mill lots
Speaker 1: of solar systems like ours out there and not feel
Speaker 1: so alone. I agree with you. I hope we're basic
Speaker 1: so that we've got some friends out there. Exactly, We
Speaker 1: can't answer that question directly today because our telescopes are
Speaker 1: not powerful enough to look through the atmospheres of exo planets.
Speaker 1: But we can look in our own backyard and try
Speaker 1: to understand how our solar system formed and if there's
Speaker 1: anything in it that we cannot explained. And it's an
Speaker 1: incredible piece of science to look around you and understand
Speaker 1: how we came together to build a model for the
Speaker 1: processes that could have formed such incredible structures, and to
Speaker 1: think about how long they might have taken. You know,
Speaker 1: we've done something similar here on Earth by looking under
Speaker 1: our feet and asking questions like do we understand how
Speaker 1: the Earth formed? And how the mountains have formed? And
Speaker 1: all the ridges that we see in the layers of rock,
Speaker 1: and those things are clues, the clues that led us
Speaker 1: to understand something really shocking, that the Earth is billions
Speaker 1: of years old, not thousands of years old. Right. We
Speaker 1: have the evidence all around us to reveal the story
Speaker 1: of the formation of the Solar System, but not just
Speaker 1: here on Earth, out there in space, and one of
Speaker 1: the funnest bits is to look at the rings around
Speaker 1: those planets. So that's what we're focusing on today. And
Speaker 1: I was curious whether people understood rings, whether rings were
Speaker 1: still a big source of mystery, or people thought they
Speaker 1: pretty much understood where they came from. So I went
Speaker 1: out there to our cadre of Internet volunteers, who are
Speaker 1: my random questions without a chance to prepare, which gives
Speaker 1: us a sense for what people know, what they think about,
Speaker 1: and what they want to hear about. If you'd like
Speaker 1: to participate for future episodes. Please don't be shy, just
Speaker 1: write to me two questions at Daniel and Jorge dot com.
Speaker 1: Before you hear these answers, think to yourself, do you
Speaker 1: have a good idea of where rings come from on planets?
Speaker 1: Here's what our listeners had to say, UM, and I'm
Speaker 1: pretty sure that I learned about this that UM like
Speaker 1: it's asteroids colliding near the planet itself and the remnants
Speaker 1: of those asteroids going into orbit and creating a sort
Speaker 1: of disc. I think the two classical ways are by
Speaker 1: planets capturing space debris um that's just floating through the
Speaker 1: Solar System, or by recapturing debris caused by an impact.
Speaker 1: But I've also heard of a moon orbiting Saturn. I
Speaker 1: believe that has a geyser and when the guys are
Speaker 1: spits out water um it forms into ice crystals, and
Speaker 1: then that joins the rings of Saturn. So maybe that's
Speaker 1: another option. Well, the rings are kind of like small satellites,
Speaker 1: I would say, like small moons, Like we have the
Speaker 1: most most really tiny moons that get around the planet.
Speaker 1: Each planet has its own way of doing the rings. Well,
Speaker 1: I wanted to say that planets can get rings if
Speaker 1: they collide with big rocky bodies, but I don't know
Speaker 1: how that would work with like gas giants and how
Speaker 1: they got their rings. So I'm going to guess that
Speaker 1: it's just stuff that is left over um from when
Speaker 1: the planet was formed, and it was just stuff that
Speaker 1: was so far away when it was being formed that
Speaker 1: it didn't become part of the planet, but it was
Speaker 1: still close enough to be influenced by the gravity of it.
Speaker 1: I'm almost certain it's got to do with the acreation
Speaker 1: process of when a planets formed and the attraction of
Speaker 1: the stuff towards the planet. Apart from that, I'm not
Speaker 1: really sure actually, because I think planets form when like
Speaker 1: a heavy metal gets caught in orbit around the star,
Speaker 1: so I think something similar happens around the planet. Debris
Speaker 1: and maybe rocks or particles of ice or something um
Speaker 1: gather around a planet in much the same way that
Speaker 1: planets gather around stars. Does all seem like really intelligent answers,
Speaker 1: but I still kind of like my giant alien ring
Speaker 1: toss theory. We'll put it on the list as the
Speaker 1: dark horse theory that might storm out at the end
Speaker 1: if we can't explain it with any of the other theories.
Speaker 1: So it seems like there are so many options for
Speaker 1: what these rings could be made of. How on Earth
Speaker 1: are we, or I should say, how in our Solar
Speaker 1: system are we going to be able to figure out
Speaker 1: what exactly they're made of? If there are so many
Speaker 1: different theories, so many different options for what they could
Speaker 1: be made of. Yeah, it's a great question. I listen
Speaker 1: to these answers and seems to me like they form
Speaker 1: in roughly two categories. There are some folks that say
Speaker 1: that it's basically debris from other stuff that broke up,
Speaker 1: like maybe you had comments or moons that smashed new
Speaker 1: each other and basically just made a big mess, you know.
Speaker 1: But then you have to wonder, like why don't those
Speaker 1: things gather together to make a new moon or to
Speaker 1: make a new comment or something. And the other category
Speaker 1: is like, maybe it's just left over from when the
Speaker 1: planet was formed, the same stuff that formed the planet,
Speaker 1: but some of it didn't get into the planet. So
Speaker 1: it seems like those are two different categories of ideas,
Speaker 1: And you ask a great question, how could we possibly
Speaker 1: ever figure this out? How could we know what the
Speaker 1: history is of the Solar System? And the answer is that.
Speaker 1: Of course, we can't just like watch a video of
Speaker 1: its formation, though we'd love to, but we can just
Speaker 1: look around us for clues. We can try to build
Speaker 1: up models for how rings might form, and then compare
Speaker 1: the details of those models to what we see. So
Speaker 1: the short answer is we need more money and more
Speaker 1: data to measure these rings, to look closely at them,
Speaker 1: to see what they are made out of, how much
Speaker 1: mass they have, what their distribution is. The more detail
Speaker 1: we can get about what they look like and what
Speaker 1: they're made out of, the better we can compare them
Speaker 1: to predictions from our theories about how they were formed.
Speaker 1: I mean, it sounds like a worthy use of funding. However,
Speaker 1: might I suggest an n f T of a farting
Speaker 1: panda instead? I'll put that on the proposed list and
Speaker 1: see where it goes. So when we're talking about rings,
Speaker 1: like what is it? Because you know my wedding ring
Speaker 1: is this solid band that sits around my finger. Hula
Speaker 1: hoop is this very thin tourists that you kind of
Speaker 1: use the motion of your hips to keep moving around
Speaker 1: with its momentum? So what are the rings that are
Speaker 1: around Saturn? Are they spinning around like a hula hoop
Speaker 1: or they just kind of sitting on it, like my
Speaker 1: wedding ring. It's a great question, and when it comes
Speaker 1: to astronomy, you always have to start with the definition,
Speaker 1: which immediately puts you in to a swamp, because nothing
Speaker 1: falls nicely into clean categories out there in space. You know,
Speaker 1: what's a planet, what's a minor planet, what's a centaur.
Speaker 1: A lot of these definitions come from history because we
Speaker 1: didn't really understand what was going on, and we just
Speaker 1: sort of named things randomly, and then we were sort
Speaker 1: of stuck with different categories and so often they could
Speaker 1: be a bit of a mess. Well, we're lucky in
Speaker 1: biology because species is super simple and never has that
Speaker 1: problem exactly. Nature doesn't confine itself to our categories. Was
Speaker 1: out there in the universe is not things that fall
Speaker 1: into crisply defined different boxes. It's a whole spectrum of stuff, right,
Speaker 1: And so we just got to put these arbitrary definitions
Speaker 1: out there so that we can talk to each other
Speaker 1: about it. So one of the most common definitions of
Speaker 1: a ring is a disc or ring composed of solid
Speaker 1: materials such as dust or moonlits. Moonlits. That sounds really cute,
Speaker 1: what's a moonlit moon is like a little moon, you know,
Speaker 1: like a little Moonito, the old baby moon, exactly a
Speaker 1: little my in your moon. Immediately understand, these rings are
Speaker 1: not actually a solid object. It's not like a hulu, right,
Speaker 1: or the rings around Saturn are not huge circles. They're
Speaker 1: actually a bunch of tiny little particles, a bunch of
Speaker 1: chunks that are moving in the same orbit. And so
Speaker 1: from far away it looks like a ring. Of course,
Speaker 1: it looks like a single hula hoop, for example, or
Speaker 1: a wedding ring. But if you zoomed in closely, you
Speaker 1: see it's actually a bunch of individual pieces that are
Speaker 1: not touching each other. So cartoons have lied to me.
Speaker 1: I cannot drive a race car or a skateboard around
Speaker 1: the rings of Saturn. That's right. You can't do Mario
Speaker 1: Kart on the rings of Saturn and you would fall
Speaker 1: right through. It's very disappointing. Cartoons play it real fast
Speaker 1: and loose with physics I'm discovering. And so basically a
Speaker 1: ring is just like a disc of material in a
Speaker 1: single orbit, moving all around. And that makes it a
Speaker 1: little bit unusual because orbits are usually for one object
Speaker 1: you know, like the Moon orbits the Earth and there's
Speaker 1: nothing else in the Moon's orbit. It's not like there's
Speaker 1: something else on the other side, or the Earth disorbiting
Speaker 1: the Sun and there's nothing else in Earth's orbit, right,
Speaker 1: it clears its own path. So it's a bunch of
Speaker 1: individual things sharing a single orbit, kind of like a
Speaker 1: lazy river at a water park exactly so to like
Speaker 1: a lazy river. And once you define it that way,
Speaker 1: you can ask questions like, well, what counts as a ring?
Speaker 1: You know, does it have to be natural? For example,
Speaker 1: like Earth has a bunch of stuff out there in space,
Speaker 1: things we have launched out there, a bunch of satellites
Speaker 1: in the same orbit, you know, zooming all around. Does
Speaker 1: that count as a ring? Have we built our own
Speaker 1: ring system around the Earth because all of the junk
Speaker 1: that we put out there in space. Nobody talks about
Speaker 1: Earth's rings, but technically, you know, it seems like that
Speaker 1: might qualify. There's no like minimum mass requirement for the
Speaker 1: rings as far as I can tell, so we're one
Speaker 1: step closer to Halo am I right, high fibes everyone
Speaker 1: who plays computer games. Another requirement for rings usually is
Speaker 1: that they are pretty flat right, if you have just
Speaker 1: like a swarm of spherical swarm of objects, then your
Speaker 1: planet is just surrounded by junk. A ring is typically
Speaker 1: something which is flattened, right, it's more like a disc.
Speaker 1: And this already shows off what's going on with gravity.
Speaker 1: You know, gravity has pulled the planet together and it's spinning,
Speaker 1: and it's also pulled the ring together. And the reason
Speaker 1: that rings form in disks is the same reason that
Speaker 1: the Solar system is a disc. Right. That most of
Speaker 1: the stuff is spinning in the same direction, along the
Speaker 1: same plane, and that's because of conservation of angular momentum.
Speaker 1: Stuff that spinning keeps spinning, and if gravity pulls it together,
Speaker 1: it keeps spinning. It's harder for gravity to pull together
Speaker 1: towards the spin axis than along the spin axis the
Speaker 1: same way. For example, that like Earth resists falling into
Speaker 1: the Sun because of its speed because of its angular momentum, right,
Speaker 1: But the Earth didn't resist falling into the Sun's plane.
Speaker 1: So gravity is free to compress things down into a
Speaker 1: flat disc. But angular momentum keeps things spinning and keep
Speaker 1: things from falling in That's what gives rings these sort
Speaker 1: of flat structure. So that's another typical thing we expect
Speaker 1: of rings that they're not spherical distributions of stuff. They're
Speaker 1: like these flat disks. Because that's sort of like if
Speaker 1: you pile a bunch of peas on a plate and
Speaker 1: then spin the plate, all the p's are going to
Speaker 1: scatter outwards and get everywhere, but in sort of a
Speaker 1: flat circle. I've never done that experiment, but yes, in
Speaker 1: my mind that that's exactly what you don't do that.
Speaker 1: We call it pea spinning in this household. But in
Speaker 1: our Solar system, of course, there's gravity, and gravity would
Speaker 1: hold those p's in right, so those p's would end
Speaker 1: up in like a circular orbit exactly instead of like
Speaker 1: a bunch of different orbits. And so that's why the
Speaker 1: planets are all roughly in the same plane, because they
Speaker 1: have the same spin from the original blob of gas
Speaker 1: and dust that formed our Solar system. And so that's
Speaker 1: already a clue that tells you something about the origins
Speaker 1: of these rings, because if we're if rings were formed
Speaker 1: with the planet, then you would expect them to have
Speaker 1: roughly the same alignment, the same spin as the planet.
Speaker 1: And if they were not, then they necessarily have to
Speaker 1: have that same spin that came in from like a
Speaker 1: comet that smashed into the planet or broke up a moon,
Speaker 1: it might give you a different kind of distribution. So
Speaker 1: already that's a clue that tells you something about where
Speaker 1: rings might have come from. Oh, that's really interesting. So
Speaker 1: when you have debris from a planet's formation, everything's spinning
Speaker 1: at the same rate, sort of going with the same flow.
Speaker 1: But then if you have something smash into a planet,
Speaker 1: release all these all this debris and it starts orbiting
Speaker 1: the planet, it doesn't need to spin at the same
Speaker 1: rate as the planet spins. Just like our moon. Our
Speaker 1: moon doesn't spin at the same rate as Earth. Right,
Speaker 1: that's right now, it does not, right, So that would
Speaker 1: suggest that the moon was not necessarily formed when the
Speaker 1: Earth was formed, right exactly. And we think that the
Speaker 1: moon is the result of a huge collision, that something
Speaker 1: came and smashed into the Earth and released an enormous
Speaker 1: amount of debris which then coalesced into a moon. Right,
Speaker 1: So that after that collision, Earth may have had a
Speaker 1: very large cloud of debris which then probably coalesced into
Speaker 1: a ring system, which then further gathered into a moon.
Speaker 1: So our moon may have once been a ring. So
Speaker 1: do we know with the rings of Saturn if they
Speaker 1: are moving at the same rate of Saturn where to
Speaker 1: differ rate The rings of Saturn are especially complicated because
Speaker 1: there are so many rings, and some of them are
Speaker 1: moving with Saturn, and some of them may actually be
Speaker 1: rotating the other direction. It's really tricky and complicated, and
Speaker 1: we'll dig into it in a moment when we talk
Speaker 1: about how the rings of planets are formed, the various
Speaker 1: theories and the pieces of evidence for and against the
Speaker 1: first Let's take a quick break. All right, I'm gonna
Speaker 1: try to imagine those rings moving in different directions without
Speaker 1: getting sea sick during the break. All right, we are back.
Speaker 1: I got a little dizzy trying to think about Saturn's rings,
Speaker 1: some moving in one direction, others moving in another. It's
Speaker 1: pretty trippy. But yeah, I still have a lot of
Speaker 1: questions about these rings we're talking about, like how maybe
Speaker 1: they're formed, whether they're formed when the planet forms out
Speaker 1: of basically the same stuff that the planet is formed
Speaker 1: out of, or if it is made out of kind
Speaker 1: of some outside stuff, stuff that wasn't around when the
Speaker 1: planet was formed, like by a collision, Like how maybe
Speaker 1: our moon was formed do we know like what stuff
Speaker 1: is inside of these rings? And how do we know
Speaker 1: what is inside a ring without actually going up there
Speaker 1: and taking a scoop of it. Yeah, that's a good question.
Speaker 1: One thing we can do is we can look at
Speaker 1: it through a telescope and see what kind of light
Speaker 1: it reflects. Is it opaque, is it transparent? Is transparent
Speaker 1: to different kinds of light? Each planet reflects sunlight, but
Speaker 1: or all so emits particles, And so we can see
Speaker 1: whether the rings create shadows in some sort of the
Speaker 1: wind of Jupiter or the wind of Saturn. And we
Speaker 1: have also sent probes out there, and these probes will
Speaker 1: talk about them in a minute have made some really
Speaker 1: startling discoveries by getting very close up to these rings.
Speaker 1: But first I want to talk about sort of the
Speaker 1: general question like talked a minute ago about the Earth's
Speaker 1: moon and how it used to be a ring. And
Speaker 1: you know, in my mind, one of the first question
Speaker 1: is is like why do sometimes things form together into
Speaker 1: a moon and sometimes they don't and they stay as
Speaker 1: rings or is there like a process there where every
Speaker 1: ring eventually turns into a moon. It's really fascinating question,
Speaker 1: and it turns out to be totally dominated by the
Speaker 1: gravity of the planet and how far you are away
Speaker 1: from that planet. So Saturn's rings could conceivably have turned
Speaker 1: into moons if they had been in a different situation. Conceivably. Yeah,
Speaker 1: And it actually turns out the Saturn's rings have little
Speaker 1: moonlits inside them that move around and shepherd them and
Speaker 1: keep them apart. Though really fun. But the crucial thing
Speaker 1: that determines whether something is a moon or a ring,
Speaker 1: whether it gets torn up into little bits, or whether
Speaker 1: it gets clumped together by gravity, is the gravity of
Speaker 1: the host planet. You know, you have a bunch of
Speaker 1: stuff out in the middle of space, gravity will eventually
Speaker 1: gather it together. Gravity is very, very weak, it's the
Speaker 1: weakest force we know. But it's also very patient and
Speaker 1: eventually will pull things together to make a clump. So
Speaker 1: you might expect that all rings would be transient, that
Speaker 1: they would be eventually just gathered together into a moon,
Speaker 1: but that's not necessarily the case because of the gravity
Speaker 1: of the planet. This gravity does more than just pull
Speaker 1: the moon into orbit or keep the rings in orbit.
Speaker 1: You can also pull them apart. This is the concept
Speaker 1: we've talked about on the podcast before, called tidal forces.
Speaker 1: The ideas they have a very strong source of gravity
Speaker 1: like Jupiter or a black hole, or the Sun or
Speaker 1: even the Earth, and it's pulling on you right But
Speaker 1: the strength of its force on you depends on how
Speaker 1: close you are to that object. So if your feet
Speaker 1: are closer to the Sun than your head, then the
Speaker 1: Sun is pulling on your feet harder than it's pulling
Speaker 1: on your head, and effectively it means it's trying to
Speaker 1: pull your head off of your body. Nobody ever said
Speaker 1: the Sun was a nice guy. Okay, oh, I know what.
Speaker 1: I know that right now in July, and that's happening
Speaker 1: right now. If you stand on the surface of the Earth,
Speaker 1: then the Earth is literally trying to pull your head
Speaker 1: off of your body. Now we've evolved with strong enough
Speaker 1: next or is this this and the title forces here
Speaker 1: are not that strong? Yeah, take that Earth. But if
Speaker 1: you're in a situation where the gravitational forces get strong
Speaker 1: very quickly, so the force on your feet is much
Speaker 1: stronger than the force on your head, you can be
Speaker 1: torn apart. And if you're near a black hole for example,
Speaker 1: where this is very dramatic, this is what we call spaghettification,
Speaker 1: you can get pulled apart into tiny little pieces, the
Speaker 1: most delicious way to describe a horrific that exactly. And
Speaker 1: we've seen this happen when comet shoemaker Levy came into
Speaker 1: the Solar System in the nineties. It was headed for
Speaker 1: an impact with Jupiter, but before it hit Jupiter, it
Speaker 1: made a near miss and Jupiter pulled it apart into
Speaker 1: twenty six pieces. So you have this comment coming into
Speaker 1: the Solar System, which got shredded by jupiter gravity. Then
Speaker 1: it went around the Sun and it hit Jupiter twenty
Speaker 1: six different times, which is pretty awesome for everybody to
Speaker 1: look at these huge fireballs the size of the Earth.
Speaker 1: But for our six today, this is just a demonstration
Speaker 1: of tidal forces. So a planet doesn't just pull stuff
Speaker 1: in and keep it in orbit. It can also tear
Speaker 1: it apart if you are close enough, I see so
Speaker 1: because gravity gets weaker the further away you are from something,
Speaker 1: but stronger the closer you are to something. If part
Speaker 1: of you is far enough away that it's pretty weak
Speaker 1: and it's not pulling on you, but the other part
Speaker 1: of you is closer and it's tugging on you more strongly,
Speaker 1: that part of you is going to get kind of
Speaker 1: ripped off of the other part of you. Is that
Speaker 1: what's happening to these poor baby little moonlits, That's what's
Speaker 1: happening to those rings. So if you're a big blob
Speaker 1: of material and you're too close to a planet, you
Speaker 1: cannot form a moon because the planet will just keep
Speaker 1: tearing you apart. If you're far enough away, then you
Speaker 1: can form a moon. So there's a limit there. It's
Speaker 1: called the Roche limit r O. C h E, after
Speaker 1: a scientist who came up with this idea. If you
Speaker 1: are closer than the Roche limit, then you cannot form
Speaker 1: a gravitationally bound object because the gravity of the planet
Speaker 1: is stronger than you're inherent gravity to hold yourself together.
Speaker 1: If you're out past it, then the tidal forces are
Speaker 1: so weak that you can clump the ring together into
Speaker 1: a moon. So past the Roche limit you get moons.
Speaker 1: Closer in than the Roche limit, you get rings. So
Speaker 1: Saturn's rings are too close to Saturn itself to form
Speaker 1: the moon, whereas our moon, which maybe started as a ring,
Speaker 1: was far enough away that it could do its own
Speaker 1: thing without Earth overbearing and deciding its fate for it.
Speaker 1: That's exactly right, and it depends a little bit on
Speaker 1: like what you're made out of. The roche limit itself
Speaker 1: is technically just as me your hell together gravitationally, but
Speaker 1: things can also be held together in different ways. You know,
Speaker 1: if you have a blob of diamond, for example, as
Speaker 1: opposed to a loose bag of golf balls, then the
Speaker 1: diamond is going to be able to hold itself together
Speaker 1: closer to a planet than your bag of golf balls.
Speaker 1: I wish my wedding ring was a bag of golf balls. Now,
Speaker 1: that would be fun. I hope your husband listens to
Speaker 1: this podcast to hear you complaining about his gift to you.
Speaker 1: There's a beautiful gift of love. I wish it was
Speaker 1: a bag of golf balls. Well, in the case of
Speaker 1: our system, for example, you know, the moon holds itself together,
Speaker 1: but if it was closer to the Earth, the Earth
Speaker 1: would shred it. Our moon is about three five thousand
Speaker 1: kilometers away, and the roche limit for the Earth and
Speaker 1: an object the size of the moon is about ten
Speaker 1: thousand kilometers, so the Moon would have to be much
Speaker 1: much closer to the Earth in order for the Earth
Speaker 1: to pull it apart um and make it into a
Speaker 1: ring system. And so that's why the moon is a moon.
Speaker 1: In a similar way. You know, the Sun has a
Speaker 1: tidal force on the Earth, pulling on the part of
Speaker 1: the Earth that's closer to its stronger than it's pulling
Speaker 1: on part of the Earth that's further from it. So
Speaker 1: the Sun is trying to rip the Earth apart, but
Speaker 1: the Earth is too far away, it's too strong. It
Speaker 1: has structural integrity that keeps the Sun from destroying us
Speaker 1: or about a hundred and fifty million kilometers from the Sun.
Speaker 1: If we were just less than a million kilometers, then
Speaker 1: the Earth would get pulled apart and we get torn
Speaker 1: into a ring system around the Sun. Seems like planetary
Speaker 1: bodies are like complicated friendships. You've got to set strong
Speaker 1: boundaries or else you're going to get destroyed exactly. So
Speaker 1: you just you gotta know where you are. You know,
Speaker 1: you've got to have the conversation sometimes to figure this out. Listen, son,
Speaker 1: we love you. You provide us with energy that gives
Speaker 1: us food. But you know, if we're too close to you,
Speaker 1: we all die. So you know how it is. And
Speaker 1: so this is the basic physics of it, right, You
Speaker 1: get too close, you turn into a ring. You stay
Speaker 1: far away, you can be a moon. But that doesn't
Speaker 1: answer the question of like where these things come from,
Speaker 1: because there's still two basic ideas there. One is that
Speaker 1: some of this stuff is from the original formation of
Speaker 1: the Solar System. You know, you have this huge cloud
Speaker 1: of gas and dust. A lot of it formed the Sun.
Speaker 1: Some of the clumps together to form planets. You can
Speaker 1: imagine that some of the stuff is close enough to
Speaker 1: the planet that it gets trapped by the planet's gravity,
Speaker 1: but not so close that it actually gets sucked in.
Speaker 1: It has like too much angular momentum to actually fall
Speaker 1: to the Earth, you know, the same way, like the
Speaker 1: Earth right now has particles that are trapped by its
Speaker 1: gravity and also particles that are not. The Earth's atmosphere
Speaker 1: is boiling away into space. So you can imagine that
Speaker 1: at the edge of the planetary formation, there might have
Speaker 1: been particles there that didn't quite get captured by the gravity,
Speaker 1: but they're too close to clump together into their own moon.
Speaker 1: So that's one theory of how these rings get formed.
Speaker 1: They're like the fastest moving bits of the planet didn't
Speaker 1: quite get captured, but they're not fast enough moving to
Speaker 1: be like out on a further orbit, far enough away
Speaker 1: where they could make their own moon. So the other
Speaker 1: theory has to do with something that wasn't there during
Speaker 1: in the origin of the Solar System coming in and
Speaker 1: creating some debris around Saturn or whatever planet decides to
Speaker 1: make a ring. Yeah, so the first theory that they
Speaker 1: are made with the planet that suggests the rings are old, right,
Speaker 1: that they're as old as the Solar System, like four
Speaker 1: and a half billion years old. The other theories you
Speaker 1: say is that rings could be fairly new. Maybe they're
Speaker 1: sort of transient. Maybe they come from a cataclysmic event,
Speaker 1: like something comes in and smashes into a moon or
Speaker 1: breaks up a moon, and that moon gets shredded into pieces,
Speaker 1: and maybe it will eventually get gathered back together into
Speaker 1: a new moon. Right, So these rings might be short
Speaker 1: lived events in that scenario, like a comet or an
Speaker 1: asteroid or something else might have created this huge mess.
Speaker 1: But the Solar System will eventually clean itself up. But
Speaker 1: if it's in that sweet spot where it's still getting
Speaker 1: shredded by the planet's gravitational force, but it's not so
Speaker 1: close that doesn't get sucked into the planet's going to
Speaker 1: stay a ring, right, it could right, It depends a
Speaker 1: lot on the details. Like you could have a moon
Speaker 1: that was past the roche limit, but then an impact
Speaker 1: creates a huge amount of debris, some of which falls
Speaker 1: into the sort of the ring zone, some of it
Speaker 1: could fall into the planet, or some of it could
Speaker 1: stay out in the sort of moon area and form
Speaker 1: a new moon. So you're right that you could also
Speaker 1: form rings, which then can be fairly stable. If you
Speaker 1: have a collision which creates a lot of mess, and
Speaker 1: some of that mess is stable in the sort of
Speaker 1: ring zone, then you could have a long, living ring.
Speaker 1: That's how I like to describe myself, a stable mess.
Speaker 1: So that seems really difficult to kind of parse out
Speaker 1: those theories, I guess without taking a closer look, because
Speaker 1: stuff that comes crashing into Saturn and stuff that was
Speaker 1: originally there when Saturn was formed may from a distance
Speaker 1: look pretty similar unless we keep investigating right exactly, And
Speaker 1: so to understand where its specific ring comes from, we
Speaker 1: need to look at that ring in detail, and we
Speaker 1: need to think about isn't made out of the same
Speaker 1: stuff as the plan in it or something weird and new?
Speaker 1: Does it look like it's aged a lot, and does
Speaker 1: it look like it's a fairly fresh result of a
Speaker 1: collision or does it look like really weathered from lots
Speaker 1: of Solar system radiation and collisions. We can also understand
Speaker 1: the distribution of the rings, like where the mass is
Speaker 1: in the ring, and build models to see like is
Speaker 1: it stable, could it hold itself together? Could have developed
Speaker 1: into this over time? So for each ring, the crucial
Speaker 1: thing is to get as much information as possible and
Speaker 1: then to build these models to try to explain what
Speaker 1: we see, and that will help us discriminate between various scenarios.
Speaker 1: And a key thing to understand is that it might
Speaker 1: not be one answer for every ring. It might be
Speaker 1: there are some rings that are ancient and other rings
Speaker 1: that are very fresh. What is the difference between what
Speaker 1: we can tell with like a telescope here on Earth
Speaker 1: versus something we send out to get a closer look.
Speaker 1: There's no fundamental difference, right. We can do the same
Speaker 1: things here as we can do getting close. But of
Speaker 1: course the closer you get, the better your data. You
Speaker 1: can resolve these things better just because you're closer up,
Speaker 1: so you don't need like as big a lens. You
Speaker 1: can also bring instruments closer up, you know, things like
Speaker 1: spectrometers to measure these things. There's one thing that you
Speaker 1: can do by sending a satellite that you can't do
Speaker 1: from Earth, which is to try to measure the mass
Speaker 1: of the rings. We'll talk about it when we get
Speaker 1: into Saturn, when we send Cassini out to Saturn and
Speaker 1: actually dove in between the rings and the planets and
Speaker 1: measure the effect of the rings gravity on Cassini itself
Speaker 1: as a way to measure the mass of the rings.
Speaker 1: And that's just not something you can do from Earth.
Speaker 1: That's something that requires perturbing, a gravitationally throwing something out
Speaker 1: there which is going to actually interact with the mass
Speaker 1: of the ring itself to see how much stuff there
Speaker 1: is in there. Is it dangerous for the satellite to
Speaker 1: be in the rings? Like, is it going to get
Speaker 1: hit by a bunch of little little space baby? It
Speaker 1: can be dangerous, But a dove in between in one
Speaker 1: of the gaps to avoid collisions. Yeah, And you know
Speaker 1: these things seem smooth, they seem like, oh, it's a
Speaker 1: continuous blob, but actually there's lots of gaps in between them,
Speaker 1: so you could fly through the rings and survive, though,
Speaker 1: you know, it would be a little bit harrowing. I
Speaker 1: see it, well, brave little satellite, But we don't have
Speaker 1: any satellites that have like a little extendable ice cream
Speaker 1: scoop that scoops up some of the stuff in the rings.
Speaker 1: So how do we know what they're made of? And
Speaker 1: do we know what they're made of? So we can
Speaker 1: so we know a little bit about what they're made
Speaker 1: out of based on our models, you know what's in
Speaker 1: the Solar system, and also based on our studies of
Speaker 1: what light reflects off of them. That's really our best
Speaker 1: way to understand what's in them. Mostly we think that
Speaker 1: the rings are made out of ice and dust, and
Speaker 1: that's also you know what the planets are made out of.
Speaker 1: The Planets when they were forming, were made out of
Speaker 1: the basic ingredients of the Solar system, which was dust
Speaker 1: and ice and gas. Now, most of the gas got
Speaker 1: slurped up by the Sun or by the gas giants themselves,
Speaker 1: and so you're left over with ice and dust. Now,
Speaker 1: in the inner Solar system, a lot of that ice
Speaker 1: is vaporized. But in the outer Solar system, past what
Speaker 1: we call the frost line, it was cold enough for
Speaker 1: that ice to stay solid, and so it helped form
Speaker 1: some of these ice giants, And so the rings are
Speaker 1: made out of that same stuff, mostly ice and dust.
Speaker 1: Beyond the frost line, there's a lot of ice in them.
Speaker 1: Saturn's rings, for example, are mostly icy particles in closes ring.
Speaker 1: You expect more rock and dust in rings. So when
Speaker 1: we're talking about ice, you know, I think of I
Speaker 1: mean especially today because it's so hot, but I think
Speaker 1: of a big chunk of ice that I would put
Speaker 1: in my drink, like in my glass. But is that
Speaker 1: what this ice is? Are they big chunks? Is it
Speaker 1: sort of like ice crystals and a bunch of them?
Speaker 1: What form does this ice take? So when we're talking
Speaker 1: about ice, we do mean water ice. This is like
Speaker 1: h duo. But there's also other kinds of ice, you know,
Speaker 1: ammonia ice and other kinds of things. So when chemists
Speaker 1: say ice, they mean a wide range of stuff, not
Speaker 1: just the stuff you put in your summer cocktails. But
Speaker 1: it does include you know, drinkable water ice, like if
Speaker 1: you are building a colony around Saturn and you need water,
Speaker 1: like the rings are a great source of water the
Speaker 1: humans could actually drink and it comes in chunks. You know.
Speaker 1: Some of these things are as small as a centimeter,
Speaker 1: like cute little ice cubes that would fit in your glass.
Speaker 1: And some of them are like are as big as
Speaker 1: ten meters, so you know, like really pretty big chunks.
Speaker 1: You'd have to be a giant to enjoy that in
Speaker 1: your limited So I couldn't theory right that satellite hold
Speaker 1: out a glass eliminated and get some ice in there.
Speaker 1: As long as I don't get pulverized by a giant
Speaker 1: ice chunk, that's great news. What's the dust made out of?
Speaker 1: So the dust is just you know, silicates, it's like rock,
Speaker 1: the same kind of stuff that the Earth is made
Speaker 1: out of. Like it's just basically dirt, you know, huge
Speaker 1: chunks of rock and dirt. And some of these things
Speaker 1: have organic compounds in them, you know. We wonder about
Speaker 1: like the formation of life whatever. The interesting area of
Speaker 1: research is like where do organic molecules come from the
Speaker 1: basic building blocks of life? Are they only found on
Speaker 1: Earth or are they found all over the universe? So
Speaker 1: looking at the rings helps us understand that kind of thing.
Speaker 1: We also study asteroids and comets and we find is
Speaker 1: that there are organic compounds all over the Solar system.
Speaker 1: These basic building blocks are not rare, They're everywhere. So
Speaker 1: you've got ice, which is, you know, the solid form
Speaker 1: of water, and you've got organic compounds. Is there a
Speaker 1: reason why we wouldn't expect there to be life on Saturn?
Speaker 1: Is it because the ice would be solid? Or is
Speaker 1: it because Saturn's surface is not hospitable to the formation
Speaker 1: of life. I don't know if there's life on Satura.
Speaker 1: And of course, if there is, life on Saturday would
Speaker 1: have to be quite different from life on Earth because
Speaker 1: the environment on Saturday is very different. Right Saturday is
Speaker 1: a gas giant and so it's very high pressure. There's
Speaker 1: a lot of radiation on Saturn, so it would have
Speaker 1: to be quite different. But one of the moons of Saturn, Insulatus,
Speaker 1: which we've talked about, has an icy shell, and underneath
Speaker 1: is a liquid ocean, and that liquid ocean is partially
Speaker 1: kept liquid by those tidal forces. Saturny is squeezing that moon,
Speaker 1: which keeps it from freezing. It's imparting energy to it,
Speaker 1: sort of like by massaging it with its gravity. So
Speaker 1: in the water under the surface of Ensilatus might be
Speaker 1: some life. We just don't know, but the rings are
Speaker 1: mostly frozen. They're mostly just big chunks of ice. And
Speaker 1: you know, there's a fascinating sort of geometrical structure here
Speaker 1: because they are very, very wide. You know, these things
Speaker 1: are like seventy two hundred thousand kilometers wide. We're talking
Speaker 1: about Saturn's rings, but in terms of thickness, they're like
Speaker 1: twenty meters thick. So there are tens of thousands of
Speaker 1: kilometers wide and only tens of meters thick. If you
Speaker 1: had a sheet of paper of this thickness, they would
Speaker 1: have to be like a kilometer wide sheet of paper
Speaker 1: to have the same proportions as Saturn's rings. That's an
Speaker 1: idea for your science project, elementary schoolers, a model of
Speaker 1: Saturn's rings. And you know, you can see Saturn's rings
Speaker 1: from Earth, which is incredible without a really powerful telescope.
Speaker 1: But there's a lot more rings to Saturn than you
Speaker 1: can just see. There's three really bright ring which astronomers
Speaker 1: have cleverly named A, B, and C, of course, but
Speaker 1: there are other rings that go out even further out
Speaker 1: to the G ring and the E ring, and these
Speaker 1: go out like past three to nine times the radius
Speaker 1: of Saturn itself, So like the volume of Saturn is
Speaker 1: dominated by these rings. It's like the biggest thing in
Speaker 1: the Saturn system. That's really interesting. So how many rings
Speaker 1: are there total? Denal, Well, there are rings out to
Speaker 1: G rings and the rings right and so there are
Speaker 1: like dozens of these rings. And it depends a little
Speaker 1: bit on how you count, because each of the rings
Speaker 1: can be subdivided into like sub rings. And some of
Speaker 1: these rings that have there are these gaps between them
Speaker 1: which are maintained by these little shepherd moons. So you
Speaker 1: have these little moonlits which are strong enough to survive
Speaker 1: inside the roche limit. Remember the rocial limit not a
Speaker 1: hard and fast rule, depending on what you're made out of.
Speaker 1: So if you're a small enough moon and you made
Speaker 1: have a really tough stuff and you can survive in
Speaker 1: the ring system and you sort of perturb the rings,
Speaker 1: you can like keep the rings from mixing with each other.
Speaker 1: So a lot of these gaps are because there's a moon.
Speaker 1: They are a little moonlit that's keeping them apart, a
Speaker 1: little hall monitor moon that's adorable exactly, and it keeps
Speaker 1: them having the like really crisply sharply defined edges. It
Speaker 1: seems like there's a bunch of mass and these rings,
Speaker 1: how do we know that, like Saturn's gravity is strong
Speaker 1: enough to keep them in that sort of sweet spot
Speaker 1: of staying rings and not drifting out or forming moons.
Speaker 1: So we didn't know until pretty recently how much mass
Speaker 1: there was. You knew we could see it, but we
Speaker 1: didn't really know like how much stuff is there is
Speaker 1: equivalent to a moon? Is it like thousand times and moons?
Speaker 1: It much less than a moon of Saturn. And so
Speaker 1: it was when Cassini went up there and it passed
Speaker 1: between these rings that it gave us a measurement for
Speaker 1: how much mass there is. And what we discovered was
Speaker 1: that the rings had sort of surprisingly low mass. We
Speaker 1: expected them to have some more mass, to be like
Speaker 1: more substantial, but they're really sort of like light and fluffy.
Speaker 1: The other thing that's really interesting for Cassini is that
Speaker 1: we got these very close up pictures of what these
Speaker 1: rings were made out of, and scientists were surprised to
Speaker 1: see that the components of the rings were still sort
Speaker 1: of sharp, you know, they have like crisp edges to them.
Speaker 1: They're really quite reflective compared to what we expected if
Speaker 1: these rings were ancient. If they've been there for a
Speaker 1: long long time, you would expect them to bump into
Speaker 1: each other. Things eventually get rounded. All the radiation from
Speaker 1: Saturn would have weathered them a little bit. That gives
Speaker 1: people the impression that maybe these things are quite new. Right,
Speaker 1: If you add up all the mass of these rings,
Speaker 1: it's just about the mass of a typical moon of Saturn,
Speaker 1: which is very suggestive. It says maybe this was once
Speaker 1: a moon of Saturn. Maybe one of the moons of
Speaker 1: Saturn got smashed up in a collision, they bounced into
Speaker 1: each other, or something came into the Solar system and
Speaker 1: destroyed a moon of Saturn and created this big mess
Speaker 1: which then fell into the Roche limit and became the
Speaker 1: rings of Saturn. It's a theory. We just don't know,
Speaker 1: but it's one speculation. So if when you're saying these
Speaker 1: are relatively new, what do you mean by that? Because
Speaker 1: I've learned that when you say new in terms of
Speaker 1: the Solar System or the universe, it means very old exactly.
Speaker 1: It means new on a universe time scale. So we're
Speaker 1: talking like maybe in the last hundred million years, whereas
Speaker 1: the Solar system is four and a half billion years
Speaker 1: old if you're forty five, for example, saying you had
Speaker 1: a ring in the last year or so makes it
Speaker 1: feel sort of new, right, Yeah, I mean my ring
Speaker 1: feels still pretty new even though it's about a year old.
Speaker 1: But yes, so that is really interesting. Do you think
Speaker 1: these rings around Saturn are permanent? Well, we don't know
Speaker 1: how long they are going to last. If they're fairly new,
Speaker 1: it suggests that they might not. They might be like
Speaker 1: falling into Saturn. Saturn might be losing its moods as
Speaker 1: its gravity pulls these little bits into it. Or they
Speaker 1: could also be quite stable, right, even if they are new,
Speaker 1: they could still be stable if they ended up in
Speaker 1: the right spot, if they're within the roche limit. So
Speaker 1: in order to understand that whether it's and it's going
Speaker 1: to keep its rings, we need to understand some of
Speaker 1: the process is going on there, like is Saturn gathering
Speaker 1: these things up? Are things falling into Saturn or not.
Speaker 1: We also need to understand like whether there are new
Speaker 1: sources for these rings. That same moon we talked about
Speaker 1: insult Us also has geysers on it, so like cracks
Speaker 1: in those oceans shoot water out into space, constantly, and
Speaker 1: this is new material for rings, as those newly formed
Speaker 1: crystals in space gets sucked in by Saturn's gravity. So
Speaker 1: there's a really far out ring called the E ring,
Speaker 1: which probably is being constantly replenished by geysers from one
Speaker 1: of Saturn's moons. Well, that's interesting. So you've got like
Speaker 1: a sprinkler system that is keeping these rings alive. Well,
Speaker 1: I hope Saturn has a sense of commitment so keeps
Speaker 1: that ring for our benefit because it is so pretty
Speaker 1: to look at. But I'm also curious why Saturn is
Speaker 1: so unique in its rings in the Solar System, or
Speaker 1: whether it is unique. But first I need to take
Speaker 1: a break, and I'm gonna do a little hula hooping
Speaker 1: so I can feel more like I am saturned, so
Speaker 1: I can visualize what it's like to be saturned. And
Speaker 1: we're back after an exhausting five minutes of me hula hooping.
Speaker 1: Remind me never to do that again. But I was
Speaker 1: asking before the break, is Saturn unique in the Solar
Speaker 1: System in terms of its rings and why is it unique?
Speaker 1: Because it seems like it at least has the most
Speaker 1: spectacular rings in the Solar System. It definitely has the
Speaker 1: most spectacular rings and the most obvious from Earth, but
Speaker 1: it turns out it's actually not unique, and that there
Speaker 1: are rings all over the Solar System, and there are
Speaker 1: rings that might be right in our backyard and in
Speaker 1: our future. When you look up at more Cars, which
Speaker 1: is one of our neighboring planets, you don't see rings
Speaker 1: on it. But that might be different in about thirty
Speaker 1: two fifty million years, because Mars is in the process
Speaker 1: of pulling apart its moons and shredding them, so they
Speaker 1: eventually might turn into rings. So physicists out there, I
Speaker 1: want to give you some advice. If you are in
Speaker 1: a relationship and you tell your partner, I see a
Speaker 1: ring in our future, just before warned that they may
Speaker 1: not know you're talking about Mars, and that you've got
Speaker 1: to wait quite a while. You know, we're talking about
Speaker 1: tens of millions of years, and Mars is a really
Speaker 1: fascinating case because it might sort of up end this clear,
Speaker 1: crisp difference between rings and moons a little bit. I
Speaker 1: read a recent paper that suggests that it might be
Speaker 1: in the middle of a ring moon cycle. Then it
Speaker 1: might be forming moons which then get shredded into rings.
Speaker 1: Which then get formed back into moons. So it could
Speaker 1: be like slashing back and forth between ringed and mooned
Speaker 1: and ringed and mooned. That's interesting, I do you know
Speaker 1: some people like that. But so how does it If
Speaker 1: it keeps shifting back and forth, that must mean that
Speaker 1: this roche limit is not always stable. What makes it unstable? Well,
Speaker 1: it depends again on how strong this thing is, the
Speaker 1: structural integrity of the object, and exactly where it is.
Speaker 1: The idea here is you have a giant impact, and
Speaker 1: this giant impact doesn't just create a big spray of
Speaker 1: debris which can form into rings and moons, but it
Speaker 1: can also actually change the gravitational field of the planet itself,
Speaker 1: so like exactly where the roche limit is can change.
Speaker 1: So you can have, for example, the formation of a moon,
Speaker 1: which can last for a little while, but then as
Speaker 1: the planet itself settles back down, you know, part of
Speaker 1: this debris then falls back onto the planet, it can
Speaker 1: change where the roche limit is. So the moon forms
Speaker 1: when the rocial limits in one place, but then as
Speaker 1: the stuff settles in and some of it falls onto
Speaker 1: the planet, the rochial limit shifts, and so the moons
Speaker 1: can then be torn apart. Some of that stuff might
Speaker 1: fall down to the planet, some of it might former ring,
Speaker 1: some of it might like form like a half moon
Speaker 1: which gets pushed out even further. So we're talking about Mars'
Speaker 1: potential future here and potential past. But you also mentioned
Speaker 1: that there are a lot of rings in the Solar
Speaker 1: system currently, right, There are a lot of rings in
Speaker 1: the Solar System exactly. So Jupiter, for example, also has rings.
Speaker 1: These are interesting because they're one of the first ones
Speaker 1: discovered by a satellite. Like it's very hard to see
Speaker 1: Jupiter's rings from Earth, even with a very very powerful telescope,
Speaker 1: and so these were discovered in seventy nine by voyage
Speaker 1: of one And the reason that they're hard to see
Speaker 1: is that they're very faint and it consists mostly of dust,
Speaker 1: and people think that they're probably just constantly created by
Speaker 1: micro meteorites hitting the planets moons. Remember, Jupiter is very
Speaker 1: very massive and it's very strong gravity, so it's likely
Speaker 1: just like suck a lot of this stuff up. But
Speaker 1: they think that there's like a constant replenishment of this
Speaker 1: stuff as things hit the Moon create this like debris
Speaker 1: which forms sort of a temporary ring around Jupiter, which
Speaker 1: eventually falls back into Jupiter. So Jupiter's gravity is so
Speaker 1: strong that doesn't really have a chance to accumulate a
Speaker 1: ring that lasts very long. You mentioned that it's harder
Speaker 1: to see it because it's mainly made out of dust.
Speaker 1: What makes ice more visible? Ice is just shiny or like,
Speaker 1: it's just basic chemistry. You shine a light on a
Speaker 1: piece of ice, it's going to reflect more than a
Speaker 1: rock will. Right, So ice is just brighter and wider.
Speaker 1: I guess that's why we call diamonds ice. That makes fun.
Speaker 1: And Jupiter also, remember, is not just gravitationally powerful. It
Speaker 1: has very strong magnetic fields and radiation, and so the
Speaker 1: electromagnetic forces interact with these dust particles moving around Jupiter,
Speaker 1: and it means that it's hard for these things to
Speaker 1: orbit Jupiter for more than like a hundred or a
Speaker 1: thousand years. And so for Jupiter to have a ring
Speaker 1: system at any point that lasts more than you know,
Speaker 1: a hundred or a thousand years, means it needs a
Speaker 1: constant source of replenishment. That's why this theory that micro
Speaker 1: meteorites are creating dust constantly to sort of feed Jupiter's
Speaker 1: ring system. I see, so Jupiter is just too hungry
Speaker 1: to maintain that ring without having some of those micro
Speaker 1: collisions spewing out more debris. Is Jupiter the only other
Speaker 1: planet that has rings. No Neptune also has rings. These
Speaker 1: are really fascinating, the Air five rings, but they're sort
Speaker 1: of the reverse of Saturn. Instead of being mostly ice,
Speaker 1: they're actually mostly dark particles and they're confined to a
Speaker 1: few little narrow rings, and they're really interesting because they're
Speaker 1: not the same all the way around. It's not like
Speaker 1: Saturn that has this symmetry to have these like bright
Speaker 1: arcs and then these empty gaps between them, so it's
Speaker 1: really kind of weird. So these like broken rings around Saturn, yeah, exactly.
Speaker 1: And people think that maybe there are moons. They're like
Speaker 1: little shepherd moons that are interfering with these rings and
Speaker 1: causing this structure, but we haven't been able to see
Speaker 1: them because our telescopes aren't powerful enough yet. And Urine
Speaker 1: is also has rings. These rings are really strange because
Speaker 1: they're almost totally black. They're like lumps of coal, so
Speaker 1: they think they might be like carbon and hydrocarbon, but
Speaker 1: they're just not sure. So we really need are like
Speaker 1: more exploration of the outer Solar system to understand these
Speaker 1: rings and the role they play in the history of
Speaker 1: these planets. I like that Urineus is going for a
Speaker 1: golf look that is bringing Goth back. I don't know
Speaker 1: if it ever left. So our solar system has a
Speaker 1: good number of rings. But we talked about at the
Speaker 1: beginning whether we are unique as a solar system, whether
Speaker 1: we can find rings outside of our solar system. Is
Speaker 1: there any evidence of rings uh far and wide. So
Speaker 1: scientists think that it's very plausible that other planets might
Speaker 1: have rings, just because they're not that unusual in our
Speaker 1: solar system. As you can hear, they're like basically everywhere
Speaker 1: you know, Saturn, Jupiter, Urinous, Neptune, even Mars might eventually
Speaker 1: have rings. So we suspect that just from that data,
Speaker 1: they should be in other solar systems. But of course
Speaker 1: we want to see it and to know. We don't
Speaker 1: just want to speculate about the nature of the universe.
Speaker 1: And so what we can do is look for rings
Speaker 1: around planet's in much the same way that we look
Speaker 1: for the planets themselves. The way we detect planets around
Speaker 1: other stars, or one way at least, is the transit method.
Speaker 1: The planet passes in front of its star like a
Speaker 1: little mini eclipse and dims the light of that star
Speaker 1: a little bit. That's how we know the planet is there.
Speaker 1: How can we see rings around it? Well? From the
Speaker 1: transit method, we can also get a sense of the
Speaker 1: size of the planet and its mass. So we get
Speaker 1: a sense of the size because of how much light
Speaker 1: is blocked from the star. We get a sense of
Speaker 1: its mass because we can measure its orbit. And so
Speaker 1: if the planet seems to be really really large, there's
Speaker 1: like this extra reduction in the light of the star
Speaker 1: because it has like big fluffy things around it, that
Speaker 1: might be evidence for rings around the planet. If it
Speaker 1: seems like bigger than we would otherwise understand it to be.
Speaker 1: It seems like bigger than we would otherwise expect it
Speaker 1: to be from its mass and from its orbit. I see.
Speaker 1: So if the orbit doesn't match how fluffy it looks,
Speaker 1: how much light it blocks, that may be a sign
Speaker 1: of a ring. Could it be something else instead of
Speaker 1: a ring, like we mentioned, just having a bunch of
Speaker 1: junk kind of floating around the planet in not ring form.
Speaker 1: I mean, it could be like a lot of moons.
Speaker 1: I suppose one candidate is this planet h I p
Speaker 1: S eight F, which looks like it has a really
Speaker 1: really huge radius, like nine times the radius of the Earth.
Speaker 1: So either it's like a big styrofoam planet hardly filled
Speaker 1: with anything, or it's a planet with an extensive ring
Speaker 1: system that's blocking all of that light. And that's really
Speaker 1: the only thing we can really think of. Is another planet,
Speaker 1: Proxima Centauri C, which is a planet orbiting our immediate
Speaker 1: neighbor Proximus Centauri. It has seven times the mass of
Speaker 1: the Earth, but it's sort of weirdly bright and reflective,
Speaker 1: which makes people think like perhaps it's surrounded by icy rings.
Speaker 1: But as you can maybe get a sense for this
Speaker 1: is very uncertain stuff. We're only just recently been able
Speaker 1: to detect exo planets. We're getting better and better at it,
Speaker 1: and soon we'll be doing things like studying the atmosphere
Speaker 1: of exo planets, and this is sort of on that
Speaker 1: list of things we're just beginning to be able to do.
Speaker 1: It's kind of like physicists need to start to catch
Speaker 1: up with jewelers, who can look at rings by using
Speaker 1: a magnifying glass to see things really really tiny, but
Speaker 1: physicists have to investigate their rings by looking at things
Speaker 1: really really far away and blowing them up as much
Speaker 1: as they can. Absolutely, and I expect that some of
Speaker 1: those solar systems may have spectacular ring systems. I suspect
Speaker 1: that when we get really nice images of them, you know,
Speaker 1: if maybe from James Web or from the next generation
Speaker 1: of space telescopes, we'll see things that blow our minds,
Speaker 1: that make scientists say, what, that's impossible. You can't have
Speaker 1: rings like that. That breaks all of our understandings. And
Speaker 1: breaking our understanding is exactly the moment to learn about
Speaker 1: the universe, to say, oh, well, it turns out we
Speaker 1: didn't understand this as well as we thought we did.
Speaker 1: We got to change our models. We have to add
Speaker 1: something new to it, or develop some new idea for
Speaker 1: how these things can form. And that's the exciting thing.
Speaker 1: It's like opening a new book and being surprised by
Speaker 1: what you find in Every one of these solar systems
Speaker 1: will have surprises for us, things that we probably can't
Speaker 1: imagine today. And isn't that the dream of every planetary
Speaker 1: fashionista to wear rings so spectacular it makes scientists scratch
Speaker 1: their heads and throw away all their textbooks. Exactly so
Speaker 1: from Rings down here on Earth, wowing all of your friends,
Speaker 1: two rings around the planets themselves, telling us something about
Speaker 1: how those planets formed, and something about their history and
Speaker 1: something about their future. Rings have a lot to tell
Speaker 1: us about the nature of our lives, all right, Thanks
Speaker 1: very much Katie for joining us on today's episode about Rings.
Speaker 1: Was a lot of fun and we hope you all
Speaker 1: ring in a wonderful day. Thank you very much for
Speaker 1: listening and tune in next time. Hi, thanks for having me,
Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain
Speaker 1: in the Universe is a production of I Heart Radio
Speaker 1: or more podcast from my Heart Radio. Visit the I
Speaker 1: Heart Radio app, Apple Podcasts, or wherever you listen to
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