Speaker 1: The message you often hear about space is that it's
Speaker 1: vast and empty. The Earth and even the Sun are
Speaker 1: these tiny dots and a huge ocean of black space.
Speaker 1: That's all true, but it gives you the wrong idea
Speaker 1: about our cosmic neighborhood. It suggests that the Earth is isolated, alone,
Speaker 1: not affected by our neighbors, not in danger. The truth
Speaker 1: is actually the opposite. Space is vast, but gravity is
Speaker 1: also very patient. There are a lot of big dark
Speaker 1: rocks out there that could get tugged by gravity towards
Speaker 1: the Earth and then dramatically affect our way of life,
Speaker 1: both positively or negatively. They could, of course smash into
Speaker 1: us and cause an extinction event, but then they could
Speaker 1: also create new snazzy bling around our planet. So today
Speaker 1: we're going to dig deep into the history of Earth
Speaker 1: within our cosmic neighborhood, understand the gravitational dance between all
Speaker 1: of these objects, and ask the question about whether there
Speaker 1: was ever a time when the universe put a ring
Speaker 1: on the Earth. So, just in time for Valentine's Day,
Speaker 1: we're getting cosmically romantic and asking did Earth ever have
Speaker 1: a ring? Welcome to Daniel and Kelly's extraordinary universe. Hello.
Speaker 2: I'm Kelly Wienersmith. I'm a parasitologist and I stopped wearing
Speaker 2: rings because I got fish guts stuck in my ring
Speaker 2: too many times and decided it was too gross.
Speaker 1: Oh isn't that romantic though?
Speaker 2: Fish guts in a ring? You got a weird sense
Speaker 2: of romance, Daniel, I'm.
Speaker 1: Trying to resonate with a biology. Hi. I'm Daniel. I'm
Speaker 1: a particle physicist, and I bought my wedding rings for
Speaker 1: two dollars on Telegraph Avenue in Berkeley.
Speaker 2: I was going to ask you, are you and Katrina
Speaker 2: ring people or not ring people?
Speaker 1: We have rings which we feel sentimental about, but we're
Speaker 1: not people who are into expensive fancy stuff. So like
Speaker 1: her engagement ring has a piece of amber in it,
Speaker 1: and I designed the ring myself. There's no like crazy
Speaker 1: diamond in there. And we didn't want to spend a
Speaker 1: lot of money on crazy rings, so we just walked
Speaker 1: down Telegraph Avenue and found a guy who made silver
Speaker 1: rings and bottom for a couple of bucks.
Speaker 2: You designed a ring with amber and got it for
Speaker 2: two bucks.
Speaker 1: Oh no, the engagement ring I had a friend make,
Speaker 1: so that was more than two dollars, but yes, I
Speaker 1: designed it myself. It has a bunch of Danish ruins
Speaker 1: in it and stuff and a piece of amber in
Speaker 1: the middle.
Speaker 2: Oh that's great.
Speaker 1: How about you? What's your guys ring story?
Speaker 2: Can I tell you our engagement story really quick? Oh?
Speaker 1: Yes? Does it involve fish cuts? No?
Speaker 2: No, the rest of our life involves fish cuts, but no,
Speaker 2: our engagement story. So Zach is like not a super
Speaker 2: sentimental guy, and so, like, a couple months earlier, I
Speaker 2: had said to him, like, hey, you know we've been
Speaker 2: together for a year, do you think you could ever
Speaker 2: see yourself marrying me? Because if still, let's keep going.
Speaker 2: But if not, let's like cut our losses and bee
Speaker 2: like this was fun. And so his response, and this
Speaker 2: is amazing. His response was I think you're really nice, wow,
Speaker 2: which I thought was him being like I don't want
Speaker 2: to answer this question because it's going to be uncomfortable,
Speaker 2: but like, that's not what I was looking for, right,
Speaker 2: And so I thought to myself, like, Okay, in a
Speaker 2: couple more months, I'm going to ask him this again,
Speaker 2: and if I don't get a better answer, it's over.
Speaker 2: But so Zach thought, well, you marry the person who
Speaker 2: you think is really nice. So he thought he had
Speaker 2: said like, yeah, I could marry you one day, and
Speaker 2: he thought after that conversation that it was locked in
Speaker 2: and that he didn't even really need to ask.
Speaker 1: That was like the most positive thing he could think
Speaker 1: of saying, I think you're really nice.
Speaker 2: No, he's not a super sentimental side. So it was
Speaker 2: Pie Day, March fourteenth, and he gave me a little
Speaker 2: card with a pie on it that said don't open
Speaker 2: until what are the extended digits of pie? So three
Speaker 2: fourteen is the date, and then it's nine okay, yeah,
Speaker 2: so don't open until one fifty nine. And I thought
Speaker 2: it was going to be a poem about how like
Speaker 2: I eat too much pie he writes like weird poems,
Speaker 2: and I forgot about it, and so later in the day,
Speaker 2: it was like four pm and he was in the
Speaker 2: restroom and I reached into my pocket and I was like, oh,
Speaker 2: I've got this card in my pocket and it's after
Speaker 2: one fifty nine, so I can open it. And it
Speaker 2: said something to the effect of, like, you get frustrated
Speaker 2: because I forgot our anniversary. But if we got engaged
Speaker 2: on Pie Day, that's a date I'd always remember.
Speaker 1: Oh my gosh.
Speaker 2: And so he came out of the bathroom and I
Speaker 2: was like, are you asking me to marry you? And
Speaker 2: so I'll note that he forgot when one fifty nine passed,
Speaker 2: so he wasn't worried about the answer. He knew what
Speaker 2: the answer was gonna be.
Speaker 1: And I love that there's a bathroom visit in the
Speaker 1: middle of this story. That's very Kelly and Zach.
Speaker 2: Exactly, very scatological. And so I was like, wait, so
Speaker 2: are we engaged now? And all he said was, well,
Speaker 2: you weren't supposed to read it while I was on
Speaker 2: the hut. Anyway, he didn't have a ring, he didn't
Speaker 2: have anything. We're not very sentimental. So anyway, we went out.
Speaker 2: We got a ring. I got fish guts in it,
Speaker 2: so I stopped wearing it because while I was doing dissections,
Speaker 2: it kept getting in the way. I got him a ring,
Speaker 2: and when we were walking around Rice University, our daughter
Speaker 2: was playing with it, and I was like, Zach, and
Speaker 2: she was like two as like, Zach, she's gonna drop it.
Speaker 2: You're gonna lose your wedding ring. You probably shouldn't let
Speaker 2: her play with it. And we got back into the
Speaker 2: car and he sat down and he goes, uh oh.
Speaker 2: And anyway, so he lost his ring, and I don't
Speaker 2: wear mine because of fish guts and we are not
Speaker 2: super sentimental. But you know, it's been almost twenty years
Speaker 2: since we've been together, so it's working out.
Speaker 1: So Zach's ring is somewhere on the campus of Rice University, or.
Speaker 2: Some undergrad plays drinking games with it or something. I
Speaker 2: don't know. I don't know where it ended up. We
Speaker 2: never found it.
Speaker 1: All right, Rice students, if you see a ring on campus,
Speaker 1: send it to Kelly.
Speaker 2: Yeah, I'll take all the random rings that get lost
Speaker 2: on campus. All right, Well, I've gotten us off topic.
Speaker 2: Your story was lovely. Mine was hopefully good for a laugh.
Speaker 2: But today we're talking about whether or not Earth ever
Speaker 2: had a ring, which is a fun question to think about.
Speaker 1: It's fun to think about because it makes us think
Speaker 1: about the deep past and how we think of the
Speaker 1: Earth as a certain way and having the moon and
Speaker 1: the sky looks a certain way and the solar systems
Speaker 1: arranged a certain way, and we imagine it's always been
Speaker 1: that way or forzillions of years. But it turns out
Speaker 1: that on a cosmic time scale, the solar system has
Speaker 1: a very chaotic history, and things used to look quite
Speaker 1: a bit different. So it's really fun for me to
Speaker 1: go deep into the past and learn about how the
Speaker 1: Solar system used to be quite different, how life on
Speaker 1: Earth could have been different. You could have looked up
Speaker 1: at the sky and seeing different stuff out there.
Speaker 2: And I got to say, when you sent me this
Speaker 2: idea for a podcast episode topic, it had not been
Speaker 2: on my radar at all that Earth could have ever
Speaker 2: had a ring. So I'm excited about hearing the answer
Speaker 2: to this.
Speaker 1: So I was wondering if folks out there had considered
Speaker 1: the possibility of whether Earth had ever had a ring.
Speaker 1: So I sent this question to our intrepid volunteers. Thank
Speaker 1: you very much to everybody who plays along. If you
Speaker 1: would like to hear your voice answering questions on the podcast,
Speaker 1: please don't be shy. We would love to have you
Speaker 1: as part of the chorus. To us two questions at
Speaker 1: Danielankelly dot org and we will set you up in
Speaker 1: the meantime. Think about it for a minute. Do you
Speaker 1: think Earth could have ever had a ring? Here's what
Speaker 1: our listeners had to say. A big meteorite smashed into
Speaker 1: the Earth all the debris shot up into the into space.
Speaker 1: The Earth did have a ring with the material that
Speaker 1: eventually call us into the Moon.
Speaker 2: Yes, it did have a ring, and it still does.
Speaker 3: Maybe it did, like with all the rocks flying around
Speaker 3: it right at the beginning when it was being formed,
Speaker 3: had like a wriggled rocks around it. And maybe when
Speaker 3: the ice it happens and been a thing of vice
Speaker 3: around it when there was the ice. Say, I don't
Speaker 3: really think that could have happened.
Speaker 2: So, yes, the Earth probably had a ring when the
Speaker 2: Moon was born. As bodies coal started to fall into
Speaker 2: planet olids and eventually planets that would have been rings.
Speaker 1: Earth might have had a ring after the collision with Theata.
Speaker 1: If you're referring to a persistent ring system akin to Saturns,
Speaker 1: then that's more of a complex question open to interpretation.
Speaker 1: The ejecta from that collision temporarily formed a ring.
Speaker 2: There is a chance that's to be some sort of
Speaker 2: ring during its creation.
Speaker 1: It no longer has a ring because it is divorced.
Speaker 1: Middle Earth did and it was a big freaking deal.
Speaker 1: Is that one of the theories or hypotheses behind where
Speaker 1: the Moon came from.
Speaker 2: When a Mars sized object collided with Earth. Do Bear's
Speaker 2: poop in the woods?
Speaker 1: Do taco taste better on Tuesdays?
Speaker 2: Does Tom Cruise will have to sprint like a maniac
Speaker 2: in every one of his movies? Yes, yes, the Earth
Speaker 2: had a ring, but.
Speaker 1: I'll do notize that Liberachi had rings during the formation
Speaker 1: of the Moon.
Speaker 2: No, I mean Saturn offered, but long distance relationships just
Speaker 2: never work out.
Speaker 1: And a protope planet hits it to form the Moon.
Speaker 2: While the moon was being formed.
Speaker 1: I really don't know, but I imagine not since the
Speaker 1: moon has been there.
Speaker 2: That was an amazing mix of like serious good answers
Speaker 2: and some really clever not answers.
Speaker 1: I think Tom Cruise does sprint in every movie he's in.
Speaker 1: I think that's true every.
Speaker 2: Movie I can think of. Did he sprint in Jerry Maguire,
Speaker 2: He must have. There must have been a reason to sprint.
Speaker 2: Somebody check the footage, Okay, let us know.
Speaker 1: And I was a little surprised, though I guess I
Speaker 1: shouldn't have been that most people went to the sort
Speaker 1: of early formation of the Earth, the impact with the
Speaker 1: protoplanet that formed the Moon, and thinking about how that
Speaker 1: might have been a ring as well, and that's a
Speaker 1: totally reasonable answer. That it's not what I was going
Speaker 1: for for today's episode.
Speaker 2: Well, I think probably it would help to know how
Speaker 2: rings are formed in general. So I'm guessing you're going
Speaker 2: to tell us that today, but let's start even earlier. So, like,
Speaker 2: what are rings? I guess I realized, Well, I was
Speaker 2: thinking about this question, like, you know, the moon orbits
Speaker 2: in a ring, but that's not a ring. How continuous
Speaker 2: does the line need to be before you have a
Speaker 2: satellite versus a ring?
Speaker 1: Yeah, so it's astronomy, which means we're going to do
Speaker 1: our best to draw arbitrary dotted lines between the continuous
Speaker 1: concepts that really exist on a spectrum. But you know,
Speaker 1: some things we call moons, some things we call rings.
Speaker 1: What's the difference? How many tiny moons does it take
Speaker 1: before you start calling it a ring? Typically we call
Speaker 1: something a ring if it's composed of solid materials such
Speaker 1: as dust or moonlits, But it's not in one single object.
Speaker 1: So you know, basically there's a spectrum between Like you
Speaker 1: have one single object, you call that a moon. If
Speaker 1: you break that moon up into little rocks, you could
Speaker 1: call those moonlits, Or you could say if they're fine
Speaker 1: enough you could call it a ring.
Speaker 2: But if you had two objects as big as the
Speaker 2: Moon that somehow didn't run into each other, would that
Speaker 2: be a ring. Does Mars have a ring or does
Speaker 2: it just have two moons?
Speaker 1: Mars has two moons, so I think there isn't a
Speaker 1: very crisp distinction. I couldn't find a crisp distinction online.
Speaker 1: I don't think like the astronomers have had a meeting
Speaker 1: arguing about this yet.
Speaker 2: Nature doesn't care about our criteria in our categories.
Speaker 1: But I think one thing that is important for a
Speaker 1: ring is that it's basically in a plane. So, you know,
Speaker 1: a swarm of objects surrounding a planet, you wouldn't call
Speaker 1: that a ring. If it's like in a sphere. If
Speaker 1: it's orbiting in every direction and completely surrounding the planet
Speaker 1: with little rocks, that isn't a ring. When distinguishing feature
Speaker 1: of a ring is that it does orbit in a plane, right, that, like,
Speaker 1: the vertical motion relative to the ring is small compared
Speaker 1: to the motion around the planet.
Speaker 2: Does it happen that you get junk like all around
Speaker 2: a planet or does it always end up in the
Speaker 2: same plane as a ring?
Speaker 1: Yeah? Great question. You can get junk around a planet,
Speaker 1: but that's sort of temporary. That's not a very stable
Speaker 1: situation because gravity will eventually pull it down together into
Speaker 1: a plane. There's a reason that planets have rings and
Speaker 1: not swarms of stuff. And there's a reason that moons
Speaker 1: typically form in a single plane around a planet, which
Speaker 1: aligns with the planet's spin usually, And it's the same
Speaker 1: reason why the planets all spin in the same plane
Speaker 1: as their motion around the Sun, which aligns with the
Speaker 1: rotation of the Sun. And the reason is angular momentum.
Speaker 1: Gravity would like to pull everything down together into a
Speaker 1: little dot. What resists that, Well, sometimes it's like structural
Speaker 1: or integrity. The Earth doesn't collapse into a black hole
Speaker 1: because it's solid, right, and the rocks resist being crushed.
Speaker 1: But there's another factor there, which is the Earth is spinning,
Speaker 1: and the spinning of the Earth sort of fluffs it
Speaker 1: up a little bit and makes it larger. So like
Speaker 1: the Earth's radius from the core to the surface is
Speaker 1: larger at the equator because it's spinning, and if the
Speaker 1: Earth was softer like pizza dough, it would get flatter
Speaker 1: and flatter as that spinning resists gravity. But the spinning
Speaker 1: only resists gravity along the plane. Right, So if you
Speaker 1: have like the Earth spin axis, the spinning helps resist gravity,
Speaker 1: helps keep Earth fluffed out along the plane of that
Speaker 1: spin right, so the axis is perpendicular to the plane,
Speaker 1: but it doesn't prevent things from collapsing to the plane.
Speaker 1: So now I imagine you have a big swarm of
Speaker 1: stuff that's swirling around the Earth. Gravity can pull it
Speaker 1: down into that plane, making a disk, but the spinning
Speaker 1: keeps gravity from pulling it down into the Earth necessarily.
Speaker 1: That's why a big swarm of stuff would collapse into
Speaker 1: a plane. And it's the same reason why the whole
Speaker 1: solar system has collapsed into a plane. The original blob
Speaker 1: of gas and dust that formed our solar system collapse
Speaker 1: due to gravity, but didn't collapse as far along that plane.
Speaker 1: Because everything is spinning, it keeps stuff from falling all
Speaker 1: the way in.
Speaker 2: So if you had a speck around the Earth, not
Speaker 2: around like the plane where you get the ring, would
Speaker 2: it get thrown out or pulled in or either?
Speaker 1: Yeah? So say, for example, Earth has a big ring
Speaker 1: and now you add a rock in a random orientation
Speaker 1: to the Earth. What's going to happen to it? Well,
Speaker 1: it has a lot of al so it's not going
Speaker 1: to fall to the Earth. It's going to be an orbit,
Speaker 1: but it's going to get gravitated towards the ring. The
Speaker 1: ring is going to pull it in, and so while
Speaker 1: it's going to maintain an orbit because of its speed,
Speaker 1: that orbit's going to shift until it joins the ring.
Speaker 1: The ring, because of its gravity, is going to pull
Speaker 1: that new rock into it. So gravity pulls things together,
Speaker 1: but it can't overcome angular momentum.
Speaker 2: Okay, And are rings always at the equator of the
Speaker 2: thing that they're orbiting around, And if the thing is
Speaker 2: at a tilt, that's why it doesn't look like it's
Speaker 2: straight around. So like Saturn, is that a tilt and
Speaker 2: that's why it's rings are kind of tilty.
Speaker 1: Yes, great question, And it depends a little bit on
Speaker 1: the formation. And this is actually a question people have
Speaker 1: about how rings form, Like if the ring formed from
Speaker 1: the original blob of stuff that made the planet. And
Speaker 1: one of the theories for how rings formed is you
Speaker 1: have a big blob of stuff and some of it
Speaker 1: collapses into a planet, and some of it doesn't because
Speaker 1: it's moving too fast and it stays outside and forms
Speaker 1: a ring. Then it all comes from the initial blob
Speaker 1: of stuff that's spin, and then you expect it to
Speaker 1: have the same spin on the same plane and basically
Speaker 1: be around the equator of the planet. But another theory
Speaker 1: is that these rings come from the outside. You have
Speaker 1: a planet that forms, it's already spinning and hard and compact,
Speaker 1: and now some material comes from the outside is captured
Speaker 1: by the planet into a ring that will collapse on
Speaker 1: its own, but its axis doesn't have to align with
Speaker 1: the axis of the planet. Gravity will pull it down
Speaker 1: into a single ring and it will orbit around its
Speaker 1: own spin axis. It doesn't have to align with the planet.
Speaker 1: There's nothing the planet can do to change its spin
Speaker 1: axis because angular momentum is conserved.
Speaker 2: All right, Is there anything else we need to know
Speaker 2: about how rings are formed? Are we all now experts?
Speaker 1: Another thing to think about is the difference between the
Speaker 1: formation of moons and rings, Like, why do some planets
Speaker 1: have rings and some of them have moons and some
Speaker 1: of them have both? You know, why doesn't gravity always
Speaker 1: pull a ring together into a moon? Right? You could
Speaker 1: imagine like a string of little moonlits orbiting together in
Speaker 1: a circle r planet. Why doesn't gravity always pull those together.
Speaker 1: It can do that without violating anyngular momentum. And the
Speaker 1: answer there is tidal forces. Usually when we think about
Speaker 1: the Solar System, we're thinking about gravity as just like
Speaker 1: here you have a rock and there you have a rock,
Speaker 1: and there's gravity between them and they're pulling on each other.
Speaker 1: But gravity is a little bit more complex than that.
Speaker 1: If your rocks are not just points objects. If they're
Speaker 1: just points, then you can just think about the gravity
Speaker 1: on the objects. But if it's big, then you have
Speaker 1: one side that's closer and another side that's further, and
Speaker 1: gravity depends on distance. So gravity is going to pull
Speaker 1: on the closer part harder than it's pulling on the
Speaker 1: further part. And that's true always. So for example, if
Speaker 1: you're an astronaut and you're in space and you're doing
Speaker 1: an ev or whatever, the Earth is pulling on your
Speaker 1: feet harder than it's pulling on your head. You might think,
Speaker 1: no big deal, But those are relative forces. You can
Speaker 1: think of it as pulling on your feet harder than
Speaker 1: your head, or equivalently, you can think the Earth is
Speaker 1: trying to pull your head off of your body, because
Speaker 1: that's really what it's doing, right, It's pulling on one
Speaker 1: side harder than the other side. It's trying to tear
Speaker 1: you apart. And normally your neck is strong enough that
Speaker 1: the Earth's not going to decapitate you. But if you
Speaker 1: are close to a very powerful body like a black hole,
Speaker 1: then those tidle forces are powerful enough to pull you apart.
Speaker 1: That's what spaghetification is. And so planets pull on things.
Speaker 1: The Earth, for example, is tugging on the Moon. It's
Speaker 1: trying to squeeze the Moon into a football. It's trying
Speaker 1: to pull rocks off the surface of the Moon that's
Speaker 1: closer to it.
Speaker 2: I can imagine how that pulling over time would start
Speaker 2: to pull off pieces and result in a ring. So
Speaker 2: does that mean that a lot of the rings around
Speaker 2: planets are moons that just got kind of crushed? And
Speaker 2: then why didn't our moon end up succumbing to that?
Speaker 1: Sure, it depends on distance. It also depends on structural
Speaker 1: integrity what your moon is made out of. But basically,
Speaker 1: if a moon gets too close to a planet, the
Speaker 1: tidle forces will pull it apart. If the moon is
Speaker 1: far enough away, then the structural integrity of the moon
Speaker 1: is more powerful than the tidal forces. It'll stay together.
Speaker 1: So if you look at all the planets in the
Speaker 1: Solar System, you notice that it's usually rings on the
Speaker 1: inside and moons on the outside. And you can calculate
Speaker 1: this sort of dividing line. It's called the Roche limit.
Speaker 1: Things that are closer than the roach limit, the tidal
Speaker 1: forces will probably pull it apart. Things that are further
Speaker 1: things will coalesce into a moon. The self gravity will
Speaker 1: pull it together, and then the structural forces will hold it.
Speaker 2: Is it an interplay between distance and size or is
Speaker 2: it just size or distance? Size and what you're made
Speaker 2: out of, like a chunk of metal, would be harder
Speaker 2: to pull apart than something else.
Speaker 1: It's mostly distance from the planet and what you're made
Speaker 1: out of. So, for example, there's a different roach limit
Speaker 1: for a blob of water than there is for like
Speaker 1: a moon made of diamond, which would be much harder
Speaker 1: to pull apart, but for like a typical rock. You
Speaker 1: can calculate these distances. For the moon, for example, if
Speaker 1: it came within ten thousand kilometers of the surface of
Speaker 1: the Earth, it would be pulled apart. Its orbit is
Speaker 1: safely outside that. It's like three hundred and ninety thousand kilometers,
Speaker 1: so it's well past the Roach limit. And you know,
Speaker 1: the Sun has a roach limit. If a planet gets
Speaker 1: too close to the Sun, it would get pulled apart
Speaker 1: by its tidal forces. So, for example, the Earth came
Speaker 1: within almost a million kilometers of the Sun, it would
Speaker 1: get pulled apart. We're like one hundred and fifty million kilometers,
Speaker 1: so we're in no danger. But this is the distinguishing
Speaker 1: feature between rings and moons, basically how far you are
Speaker 1: from the surface of the planet.
Speaker 2: You know. Now, anytime we discuss something that's named after someone,
Speaker 2: and I'm guessing the roof limit is named after it Roach. Yeah,
Speaker 2: I find myself wanting to have Kathy Johnson back because
Speaker 2: I want to be like, Kathy, did Roche really come
Speaker 2: up with this? Or who was he building on? What
Speaker 2: were people thinking at the time? She should just always
Speaker 2: give us the background on everything, because she's wonderful.
Speaker 1: M m yeah. And science is a human story, which
Speaker 1: means that every time you learn a little bit of knowledge,
Speaker 1: there's a fascinating, probably tortured history for how we figure
Speaker 1: that out and how it is named after this person
Speaker 1: and whether that person was actually a jerk, and if
Speaker 1: their paper was full of mistakes, and whether they deserve
Speaker 1: the credit for that or not. Human history is always fascinating.
Speaker 1: Every time you lift up the rug you find really
Speaker 1: interesting stuff under there.
Speaker 2: I want you check out if you missed it, our
Speaker 2: episode on Maxwell's equation, to hear Kathy's amazing history, and
Speaker 2: also to make you feel better if you're not good at.
Speaker 1: Math, because neither was fair Day or Maxwell. Apparently Maxwell
Speaker 1: was good at math. He just wasn't good at keeping
Speaker 1: track of minus signs. But hey, who is He got.
Speaker 2: Away with a lot of mistakes. Yes, all right, that's true.
Speaker 1: I have fewer published math errors than Max.
Speaker 2: There you go. You should feel good about that. You
Speaker 2: should get a plaque to put over your desk.
Speaker 1: Maybe just a T shirt.
Speaker 2: There you go, that's right here, mistakes than Maxwell. It's
Speaker 2: got to be a pretty niche audience for that T shirt. Okay,
Speaker 2: all right, Well, we're all missing Kathy right now, but
Speaker 2: there's nothing we can do about it at the moment.
Speaker 2: So let's take a break to think about how great
Speaker 2: Kathy is, and when we come back, we'll talk about
Speaker 2: what those rings tend to be made of. All right, So,
Speaker 2: based on our earlier conversation, I'm guessing that a lot
Speaker 2: of rings are made out of you know, like moves
Speaker 2: that got crushed, so probably you know, rocks and metal
Speaker 2: and stuff. What else do we get out there.
Speaker 1: Yeah, so the rings tend to be made out of
Speaker 1: the same stuff that the solar system is made out of.
Speaker 1: So the inner Solar system it's mostly rocky because you
Speaker 1: know the solar system, well, it starts out mostly gas,
Speaker 1: but all that gas gets gobbled up by the Sun
Speaker 1: and any gas left over and the inner Solar system
Speaker 1: got blasted out of it by the Sun's radiation, so
Speaker 1: you don't have a whole lot of gas left in
Speaker 1: the inner Solar system. The rings closer to the Sun
Speaker 1: are going to be rockier. Further out, you're more distant
Speaker 1: from the Sun, so you can have things like water crystals,
Speaker 1: and outpast what we call the frost line, where water
Speaker 1: isn't vaporized by the Sun, you have ice. And so,
Speaker 1: for example, beyond Jupiter, there's a lot of ice in
Speaker 1: those rings.
Speaker 2: So you don't get any ice in rings between the
Speaker 2: Sun and Jupiter, but outwards you can get ice and rings.
Speaker 1: Yeah, exactly right, And so we have some pretty spectacular
Speaker 1: ring systems in the solar system right, and one of
Speaker 1: the first ever to be seen was Saturn's This is
Speaker 1: one of the first things actually that Galileo saw through
Speaker 1: his telescope on those cold Italian nights in the early
Speaker 1: sixteen hundreds are the rings of Saturn, which of you know,
Speaker 1: anybody who's used a telescope in their backyard knows that
Speaker 1: this is an amazing thing to see.
Speaker 2: I can't imagine being the first one to see that
Speaker 2: must have been just absolutely mind blowing right.
Speaker 1: Right to me. It's always exciting when you can resolve
Speaker 1: any feature on these objects in the night sky. Like
Speaker 1: you look at the Moon and you can see things
Speaker 1: on the surface. That's super cool because it's not just
Speaker 1: like a point, and seeing the rings of Saturn is
Speaker 1: the same way. You're like, I'm seeing something that's really
Speaker 1: out there. I don't know about you, but when I
Speaker 1: look at the night sky, it's just too easy to
Speaker 1: think of it as like a screen with dots on it.
Speaker 1: But when you can resolve features on something, then suddenly
Speaker 1: I'm transported to this mode where I understand I'm looking
Speaker 1: across an incredibly vast ocean of nothingness to huge objects
Speaker 1: that are incredibly distant you know, it's so difficult for
Speaker 1: your mind to really put yourself in that vast three
Speaker 1: D space. But on a clear night when you can
Speaker 1: see the rings of Saturn or the moons of Jupiter,
Speaker 1: I feel like it's easier to visualize yourself in this
Speaker 1: vast space rather than thinking of it as a screen.
Speaker 2: Well, part of me feels like this is cheating, but
Speaker 2: I love those apps on my iPhone where you look
Speaker 2: up at the night sky and it tells you like,
Speaker 2: that's Saturn, that's Venus, and like, to me, I get
Speaker 2: all philosophical when I get that extra detail. It makes
Speaker 2: me feel like I'm more of a small speck than
Speaker 2: if I just look out at it. Like you said,
Speaker 2: it's almost like you've got a sheet with little pin
Speaker 2: pricks in it and lights coming through. It's like easy
Speaker 2: to not think about it as a vast expanse out there.
Speaker 2: But anyway, yea for technology, there's an app for that.
Speaker 1: Well. The rings of Saturn are really incredible because they're
Speaker 1: so very There are a bunch of different rings are separated,
Speaker 1: and NASA has given them really creative names. There's the
Speaker 1: A ring, the B ring, the C you know, goes
Speaker 1: out to the G ring and the E ring, which
Speaker 1: are sort of harder to see with your naked eye.
Speaker 1: Some of these things have like a lot of dark
Speaker 1: organic compounds, so they're not as easy to see. The
Speaker 1: inner ones have more ice, like they're just basically a
Speaker 1: bunch of icy particles spread out in these vast, very
Speaker 1: flat rings.
Speaker 2: Who should be naming these right? You know? So NASA
Speaker 2: clearly shouldn't be allowed to name things because they're not
Speaker 2: doing a good job. But you like, if you let
Speaker 2: the Internet name them, it would have been like ringy
Speaker 2: mcring face. What is the right solution here for these
Speaker 2: amazing celestial objects. I think they should be renamed, That's
Speaker 2: what I think.
Speaker 1: Yeah, absolutely, I think they should not be named by scientists.
Speaker 1: Maybe we should have Joge on the podcast to suggest names.
Speaker 1: He was always good at.
Speaker 2: That sounds good.
Speaker 1: But there are these fascinating gaps between the rings, like
Speaker 1: there's the A ring and the B ring, And we've
Speaker 1: known about these gaps forever. It was Cassini, in like
Speaker 1: the latest sixteen hundreds who first saw these gaps. And
Speaker 1: that's why we call that spacecraft that visited Sounder and
Speaker 1: the Cassini spacecraft, because he was the first one and
Speaker 1: see them. And these gaps in the rings come from
Speaker 1: actually the interactions of the ring material with little moons,
Speaker 1: you know. So we talked about how like they are
Speaker 1: only moons out past the rings, but if you're small enough,
Speaker 1: you're gonna avoid those tidal forces. You're like basically a
Speaker 1: big chunk of rock within the ring. Is it really
Speaker 1: part of the ring? Is it a moonlit Now we're
Speaker 1: getting into that murky territory where the dotted lines don't
Speaker 1: make any sense. But these rings sometimes are called shepherd
Speaker 1: rings shepherd moons because they orbit near the edges of
Speaker 1: these rings and they can help keep the material in place.
Speaker 1: There's these fascinating gravitational interactions between the ring and the moon.
Speaker 2: Huh And okay, so the moon is countering Saturn's gravity
Speaker 2: to keep some of the stuff in the ring in
Speaker 2: its place. How is the moon clearing its own orbit?
Speaker 2: Is it's gravity pulling anything else that might have been
Speaker 2: in a ring in that location, It's pulling it into itself.
Speaker 1: Yeah, essentially, it's acting like a little shepherd. It helps
Speaker 1: keep the edge of the ring sharply defined because anything
Speaker 1: that gets too close gets secreted onto the moon, or
Speaker 1: it can make a near miss and can get accelerated
Speaker 1: by the Moon and then deflect it back away from
Speaker 1: the Moon like a slingshot back into the ring. That's
Speaker 1: how it keeps its own like a little lane. That's
Speaker 1: why you get these gaps in the rings. It's really
Speaker 1: fascinating that these rings are really really broad, right, they're
Speaker 1: like seventy thousand kilometers wide, the rings of Saturn, and
Speaker 1: they're only twenty meters thick. That's meters, not kilometers.
Speaker 2: Oh wow.
Speaker 1: Yeah, it's the scale of like if you had a
Speaker 1: sheet of paper, the sheet of paper would be like
Speaker 1: a kilometer wide. Right. It's incredibly thin compared to the
Speaker 1: breadth of it, and that's due to anglar momentum and gravity.
Speaker 1: Gravity has done its work to collapse it down to
Speaker 1: a thin sheet, but it can't do it in the
Speaker 1: sort of plane of rotation because of angular momentum.
Speaker 2: Kind of amazing that we can see anything that thin
Speaker 2: from all the way here.
Speaker 1: It's because it's reflective. It's the icy particles that make
Speaker 1: it possible to see it.
Speaker 2: Oh okay, all right, so then where did Saturn get
Speaker 2: this ring in the first place. Was Jupiter feeling amorous
Speaker 2: at some point.
Speaker 1: You know, the story of Saturn's rings is interesting history.
Speaker 1: It used to be that people thought this is probably
Speaker 1: left over from formation of Saturn because it does orbit
Speaker 1: in the plane of Saturn, and it seemed like, wow,
Speaker 1: this must have been here for a long time. But
Speaker 1: Cassini's visits revealed that the rings are quite low mass.
Speaker 1: You know, there's like less stuff in there than we thought,
Speaker 1: and it's still very sharp and bright, Like the edges
Speaker 1: of these ice crystals are still very sharp, which isn't
Speaker 1: consistent with like being there a long time. You know,
Speaker 1: things tit to get rounded and collisions tend to soften stuff.
Speaker 1: And more recent theory is that some moons of Saturn
Speaker 1: might have collided and left a huge spray of debris
Speaker 1: which basically formed into a ring, which might mean that
Speaker 1: these rings themselves are temporary. It might be the Saturn
Speaker 1: gathers them back together into moons. We don't quite know,
Speaker 1: because the roche limit is a little bit fuzzy, you know,
Speaker 1: the structural integrity. If those rings will be there in
Speaker 1: one hundred million.
Speaker 2: Years, oh man, and we're not gonna be around to know.
Speaker 1: How do you know? Come on, We're gonna have great, great,
Speaker 1: great great great grandkids making non sentimental marriage proposals to
Speaker 1: each other using ice from the rings of Saturn.
Speaker 2: Your grand kids are going to are we getting into
Speaker 2: incestuous to Oh?
Speaker 1: I mean humanity's descendants. I couldn't say enough great great
Speaker 1: grades to get us one hundred million years. But are
Speaker 1: you not optimistic that people will be living in the
Speaker 1: Solar System in one hundred million years? Hi?
Speaker 2: No, I'm optimistic all right.
Speaker 1: Somebody will be here to see the new moons of
Speaker 1: Saturn and to give them a creative name.
Speaker 2: I hope somebody gets on that much sooner. I don't
Speaker 2: want to wait for that to happen.
Speaker 1: And other planets in the Solar System have fascinating histories
Speaker 1: with rings, Like Astronomers think that Mars has gone through
Speaker 1: several cycles of having rings and moons and rings and moons.
Speaker 2: Wait, so does that mean that like Phobos and Demos
Speaker 2: have broken up and come back together multiple times or well,
Speaker 2: we don't.
Speaker 1: Know how long phobos and demos will last, but we
Speaker 1: think that Phobos and Demos formed from a ring that
Speaker 1: was created from a giant impact. So like something hit
Speaker 1: Mars and then ejected a huge amount of stuff like
Speaker 1: ten to the twenty three kilograms of stuff into orbit
Speaker 1: and left this huge debris cloud around Mars, which then
Speaker 1: collapsed into a ring which then got gathered together into
Speaker 1: these small moons.
Speaker 2: So is it possible to look at a moon and
Speaker 2: figure out if it's gathered up ring or not? Like
Speaker 2: that's got to be hard.
Speaker 1: It's not always possible to tell the history, but you
Speaker 1: can get some clues, like, for example, Phobos and Demos
Speaker 1: have very circular orbits, which suggests that you had like
Speaker 1: a lot of stuff which formed a ring and then
Speaker 1: gathered together, rather than being single objects that were like
Speaker 1: captured as they floated near Mars, which would tend to
Speaker 1: be like more elliptical orbits and not necessarily in the
Speaker 1: same plane as Mars, So that suggests that it formed
Speaker 1: from a ring. Also, you can look at the composition
Speaker 1: of the stuff, and Phobos and Demo are made of
Speaker 1: the same stuff as Mars is, which suggests, like our moon,
Speaker 1: that it formed due to a giant impact rather than
Speaker 1: like was captured. Sometimes moons can be captured. Some of
Speaker 1: the moons of Saturn and Jupiter, we think are just
Speaker 1: like big rocks that floated too close and got gobbled
Speaker 1: up into the gravitational system of those planets not yet torn.
Speaker 2: Apart, but hit the cosmic lottery and didn't get pulled
Speaker 2: into the center.
Speaker 1: Exactly. And if these things form moons and then they're
Speaker 1: too close to the planet, like they'll drag, if there's
Speaker 1: an atmosphere there, they'll drag and then eventually just fall
Speaker 1: into the planet and so that you can lose your moon.
Speaker 1: So there's evidence on Mars of several of these cycles,
Speaker 1: like impact forms. A cloud makes a ring, then makes
Speaker 1: a little moon, and that moon gets dragged down into
Speaker 1: the planet and lost and you start again. So Mars
Speaker 1: is like a really kind of checkered history with its moons.
Speaker 1: It's got like a bunch of x's that it's gobbled up.
Speaker 2: Oh man, yet, one more reason and not go to Mars.
Speaker 2: So it sounds like these transitions are very chaotic and
Speaker 2: would be dangerous if humans were living on the surface
Speaker 2: at the time.
Speaker 1: Oh yeah, No, you don't want to be around during
Speaker 1: one of these transitions. And you don't want to be
Speaker 1: around when you have like a huge dust cloud around
Speaker 1: your planet either, because it's going to block a lot
Speaker 1: of light. So you know, the temperature probably plummets on
Speaker 1: the planet when you have a situation like that. In general,
Speaker 1: it's probably really fun to watch from far away, but
Speaker 1: not fun to watch from the surface.
Speaker 2: And the connection with the dust cloud is because when
Speaker 2: something plummets, it kicks up a bunch of dust.
Speaker 1: Is that right, Yeah, a lot of these are formed
Speaker 1: from an impact. So either you have something that comes
Speaker 1: nearby and is torn apart and then you get a
Speaker 1: cloud a debris, or you get actual impact on the
Speaker 1: planet which kicks up huge piles of stuff from the planet,
Speaker 1: which then coalesces into a ring and then a moon.
Speaker 1: And so we used to think that Saturn was the
Speaker 1: only planet in the Solar System that had rings, but
Speaker 1: now we've discovered that rings are much more common. So,
Speaker 1: for example, Jupiter has rings, but we've only known that
Speaker 1: since nineteen seventy nine when Voyager went to visit. These
Speaker 1: things are so faint that you either need to send
Speaker 1: a probe to see them or have a very powerful
Speaker 1: space telescope like Hubble. Can see the rings of Jupiter now,
Speaker 1: but otherwise we couldn't see them from Earth.
Speaker 2: And what are they named? One?
Speaker 1: Two?
Speaker 2: I hope we've done better with Jupiter's rings.
Speaker 1: Maybe alpha beta, gamma delta. Yeah, that's a good question.
Speaker 1: But these rings around Jupiter are very faint because they
Speaker 1: mostly consist of these little dust particles that come from
Speaker 1: like tiny meteors hitting the planet's moons and then being vaporized.
Speaker 1: But this dust also doesn't last very long in the
Speaker 1: Jovian System because Jupiter is crazy. It has really powerful
Speaker 1: magnetic fields, and these basically pull these rings apart and
Speaker 1: shepherd them up to the poles, and so a piece
Speaker 1: of dust can only last in these rings for like
Speaker 1: a few hundred years or a few thousand years, which
Speaker 1: means that like Jupiter's rings are constantly being degraded and replenished,
Speaker 1: like micro ears are hitting the moons, which them to
Speaker 1: get vaporized and then they enjoin the ring. But there's
Speaker 1: also an outflow, so it's not like a constant structure.
Speaker 1: It's more like a river of dust that's moving through
Speaker 1: this sort of like dust cycle around Jupiter.
Speaker 2: It's probably nice to get some new bling from time
Speaker 2: to time, you know, out with the old in with
Speaker 2: the new ring.
Speaker 1: Yeah, maybe you and Zac stually get new rings sometime.
Speaker 2: Yeah. No, he'd just lose them and I would get
Speaker 2: bug guts in them, and it would just not It
Speaker 2: wouldn't work for us. It's all right.
Speaker 1: Yeah, you know. I'm the same way. I lose stuff.
Speaker 1: I put stuff down, I can't remember it, so I've
Speaker 1: always been terrified I was gonna lose my ring. So
Speaker 1: I just never ever ever take it off, Like that's
Speaker 1: my rule. Not in the shower, I never take it
Speaker 1: off because I'm afraid I lose it. Same with my glasses,
Speaker 1: Like I wear glasses all the time. I actually only
Speaker 1: need them for reading. Really, if I ever took them off,
Speaker 1: they would be gone within a day. So I just
Speaker 1: wear them all the time because I can't manage the other.
Speaker 2: I'm just totally blind without mine, So I never take
Speaker 2: mine off. But lately my kids think it's funny to
Speaker 2: try to pull them off, and I do not think
Speaker 2: that's funny at all, So we're working on that.
Speaker 1: They think it's hilarious when mom bumps into stuff in
Speaker 1: the kitchen.
Speaker 2: I mean, yeah, I guess so. But then I remind
Speaker 2: them like, oh, I can't drive you to go get
Speaker 2: ice cream, And then they're like, oh, we found your glasses.
Speaker 2: Like all that was easy.
Speaker 1: Isn't it wonderful? As your kids grow up to be
Speaker 1: real people.
Speaker 2: Yeah, I know they're growing up to be bullies. I'll
Speaker 2: do better, all right. So we've talked about how Mars
Speaker 2: maybe had rings, Jupiter Saturn definitely have rings. How about Urytus,
Speaker 2: She says with glee.
Speaker 1: You're just desperate to talk about rings around Urinus.
Speaker 2: I mean, what would an episode be without it?
Speaker 1: So there are actually Uranian rings. The individual particles in
Speaker 1: these rings are jet black like lumps of coal. And
Speaker 1: we haven't visited close enough or been able to study
Speaker 1: these enough to know exactly what they're made out of,
Speaker 1: but they seem like some kind of carbon or hydrocarbon compounds.
Speaker 1: They're not very well understood because they're so far out,
Speaker 1: and they're so hard to see because they're black. Like, remember,
Speaker 1: we can only see stuff that reflects light unless we
Speaker 1: go and visit, and so jet black stuff out there
Speaker 1: in the deep dark Solar system, it's very hard to study.
Speaker 2: I would have so much fun naming things on a
Speaker 2: Uranus mission rings and all that. Okay, let's take a break.
Speaker 2: You think of what you would name Uranus rings if
Speaker 2: you discovered them, And when we get back, let's talk
Speaker 2: about whether or not Earth ever had a ring. All right,
Speaker 2: So I am going to hope that Earth never has
Speaker 2: another ring because I think that would probably result in
Speaker 2: something catastrophic for the humans living on the planet. And actually,
Speaker 2: have you ever read Seven Eves by I think it's
Speaker 2: Neil Stevenson.
Speaker 1: I have read Seven Eves and greatly enjoy it. It's
Speaker 1: a fun book. I really wanted to know more about
Speaker 1: what blows up the ring in that book. It's not
Speaker 1: a spoiler because it happens in like chapter one, and
Speaker 1: I thought, oh, this book is going to be about
Speaker 1: understanding the mystery of what destroyed the moon, But he
Speaker 1: just basically moves on to like what it's like to
Speaker 1: live in that system, never answers the question like was
Speaker 1: it an alien attack? Was it a random impactor? I
Speaker 1: found that very unsatisfying. I mean, it's a great book. Otherwise,
Speaker 1: I kind.
Speaker 2: Of appreciated that. I felt like, you know, there's just
Speaker 2: a lot of things we don't know the answer to,
Speaker 2: and probably, like in a situation like that where you
Speaker 2: think humanity is in peril, that probably goes to the
Speaker 2: bottom of your to do list, like figuring out the
Speaker 2: answer to that. But I had some questions about the
Speaker 2: evolutionary biology stuff.
Speaker 1: There, No we're science people. We're curious. You can't like
Speaker 1: give us a huge mystery and then leave it unsolved.
Speaker 1: That's the point of these books is to inflame your curiosity,
Speaker 1: itch and then scratch it. You can't just inflame it.
Speaker 1: That's really unfair.
Speaker 2: I mean, there was a lot of other hard science
Speaker 2: in that book.
Speaker 1: No, there definitely was.
Speaker 2: Yeah, if anyone knows mister Stevens said, we would love
Speaker 2: to talk to him all the show let us see.
Speaker 1: Yes, absolutely, please mister Stevenson, come talk to us. We
Speaker 1: will be very nice.
Speaker 2: We'll be huge nerds. All right, So let's hope that
Speaker 2: Earth never has a ring into the future, but let's
Speaker 2: look into our past when might we have had a ring?
Speaker 1: So a lot of the answers from listeners were really insightful.
Speaker 1: They were thinking about the early formation of the moon
Speaker 1: and how that probably got gathered together from a big
Speaker 1: cloud of stuff which probably initially formed into a ring.
Speaker 1: And that's a very insightful answer. I think my only
Speaker 1: quibble with that would be, like, was the Earth really
Speaker 1: formed at that time? You know, we had the proto Earth,
Speaker 1: which then got collided with Fea and formed a huge
Speaker 1: swirling system which coalesced into the Earth and the Moon simultaneously.
Speaker 1: So like, I don't know if that counts as the
Speaker 1: Earth having a ring because the Earth itself was still forming.
Speaker 1: But it's true that the Moon was likely a ring
Speaker 1: of material before it formed a moon.
Speaker 2: Oh interesting, But.
Speaker 1: That was over four billion years ago, very very early
Speaker 1: in the Solar system. There was actually another period much more,
Speaker 1: only four hundred and sixty six million years ago, when
Speaker 1: scientists think the Earth might have temporarily had a ring system.
Speaker 2: Oh man, all right, what catastrophic thing happened to make
Speaker 2: that happen.
Speaker 1: So what we do know and has been well established,
Speaker 1: is that around four hundred and sixty six million years
Speaker 1: ago there was a time of heavy bombardment. It's the
Speaker 1: Ordovician period of the Earth. And we know from fossil
Speaker 1: records and from other crazy pieces of evidence we have
Speaker 1: that there was just a lot of impacts on Earth.
Speaker 1: Like there are these quarries in Sweden where you like
Speaker 1: dig down to get limestone. Each layer is older and older,
Speaker 1: and there's a layer that corresponds to this time period
Speaker 1: with all these fossil meteorites in it. Like they found
Speaker 1: these weird green rocks down there. They're like, what is this,
Speaker 1: and you find them in this one particular strand, and
Speaker 1: they dug into them and discovered these are meteorites. You
Speaker 1: can tell like chemically and also from the shape of
Speaker 1: these things that they are meteorites are not just like
Speaker 1: rocks from Earth. And then they found similar impact sites
Speaker 1: in other places around the Earth. That tells us like, wow,
Speaker 1: there was a period here, like the weather was bad
Speaker 1: on Earth.
Speaker 2: So it's the idea then that there was something that
Speaker 2: got within the roach limit and it got broken up
Speaker 2: into a ring and then it fell all over the planet.
Speaker 2: And that's why there's a lot of it.
Speaker 1: Yes, So the theory used to be that there was
Speaker 1: probably some impact between asteroids out in the asteroid belt
Speaker 1: or near Jupiter or something that created a lot of
Speaker 1: shrapnel and then the Earth basically flew through a cloud
Speaker 1: of this shrapnel. That was the original idea. So we
Speaker 1: know that there was a lot of impacts. You see
Speaker 1: them all over the planet. There's even evidence of like
Speaker 1: enhanced seismic and tsunami activity from all this time ago.
Speaker 1: It's incredible what you can learn from geology from like
Speaker 1: seeing these fragments of rock that got broken up and
Speaker 1: stuck back together. In ways you only get from like
Speaker 1: really cataclysmic tsunamis and seismic events. Anyway, the theory used
Speaker 1: to be, Okay, there's a cloud of stuff that's created
Speaker 1: far from Earth, and the Earth flies through this cloud
Speaker 1: which creates all these impacts. Right. But a recent study
Speaker 1: they analyzed where on the surface these craters were and
Speaker 1: they discovered that there were suspiciously all along the equator.
Speaker 1: That suggests that there was time for this thing to
Speaker 1: form into a ring around the Earth. And probably your
Speaker 1: description was more accurate that some big thing came pretty
Speaker 1: close to the Earth within its roach limit, was then
Speaker 1: torn apart into bits, which orbited for a while formed
Speaker 1: a ring before the atmosphere dragged it down into impacts
Speaker 1: on Earth.
Speaker 2: Oh my gosh, So was there an extinction that happened
Speaker 2: concurrent with this?
Speaker 1: There is a moment called the Great Order Vision biodiversification event,
Speaker 1: and there was definitely a change in the Earth's temperature.
Speaker 1: If you look at the temperature records, they call this
Speaker 1: a global ice house. It's like a big dip in
Speaker 1: the history of the temperature on Earth. And so this
Speaker 1: paper suggests, oh, this could explain that as well, because
Speaker 1: if you have a huge ring that forms over the equator.
Speaker 1: It's going to significantly shade the planet. And this is
Speaker 1: a really hard study to do because if you want
Speaker 1: to think about where these things land on the Earth,
Speaker 1: you have to know where that land was at the time.
Speaker 1: Right continents move, and you might be thinking, hold on,
Speaker 1: didn't Daniel say there were a bunch of fossil meteors
Speaker 1: that landed in Sweden? And Sweden isn't close to the equator. Yeah,
Speaker 1: it isn't today, but four hundred and sixty six million
Speaker 1: years ago it actually was. So what they had to
Speaker 1: do was figure out where are all these craters that
Speaker 1: you can associate with this time period, which isn't always
Speaker 1: easy because sometimes you can date these things very well.
Speaker 1: Sometimes you can't because the layers therein Then they had
Speaker 1: to rewind the history of the Earth to understand where
Speaker 1: were these craters when the impact actually happened. And so
Speaker 1: they computed this amazing word. I love this, the paleo latitude,
Speaker 1: right like, where on the Earth was this when it happened?
Speaker 1: I love that.
Speaker 2: That's a good word. So those people should be in
Speaker 2: charge of naming the rings.
Speaker 1: Yes, exactly. Riot Sometimes you hear words and signs. You're like, Okay,
Speaker 1: that's well done, that's nice, and that's nice. And so
Speaker 1: they did this calculation. They found all these things, but
Speaker 1: you know, we're talking about a handful of things, not
Speaker 1: like millions of examples. They have like a couple of dozen,
Speaker 1: maybe three dozen craters that they can definitively pinpoint are
Speaker 1: from the Ordovician period, and so you might wonder, like, well,
Speaker 1: how do you really know these are within the equator.
Speaker 1: It's not like they all line up perfectly on the equator.
Speaker 1: They're sort of like loosely associated with the equator. Their
Speaker 1: paleo latitude tends to be less than thirty degrees. And
Speaker 1: so they did a pretty robust statistical analysis. I've read
Speaker 1: this paper carefully because honestly, I'm kind of skeptical about
Speaker 1: the ability of lots of folks out there to do
Speaker 1: statistics in a robust way, because not that many people
Speaker 1: really understand statistics. And I've been shocked to read papers
Speaker 1: in other fields, especially biology, and be like, hmm, I'm
Speaker 1: pretty sure that statistical analysis is totally wrong.
Speaker 2: But I'll give you that.
Speaker 1: But I read this paper. I thought they did a
Speaker 1: great job. They thought about, like, what are the chances
Speaker 1: of getting this kind of distribution of paleo latitudes if
Speaker 1: things actually were evenly spread, And they did some good
Speaker 1: calculations and some good simulations. They look, for example, at
Speaker 1: the distribution of modern impacts and show that they're much
Speaker 1: more broadly distributed than these, So they calculate it's very
Speaker 1: unlikely that these things, by random chance just happened to
Speaker 1: fall along the equator, and that suggests that they probably
Speaker 1: were in a ring above the Earth for a while.
Speaker 1: This is four hundred and sixty six million years ago.
Speaker 1: They also looked at some of these rocks, these actual
Speaker 1: fossil metiors, and they can study the chemical composition of
Speaker 1: these things and understand how much space radiation they were
Speaker 1: exposed to. This is super awesome, yeah, because you know,
Speaker 1: there's a lot more radiation out in space than there
Speaker 1: is here on Earth. Because out in space you don't
Speaker 1: have the benefit of our atmosphere protecting you, and so like,
Speaker 1: there are all these high speed particles, cosmic rays and
Speaker 1: solar wind constantly penetrating it, and that changes the chemical
Speaker 1: position of stuff, right. It matches into the rocks, it
Speaker 1: degrades some of those isotopes, so you can basically count
Speaker 1: how long something has been in space by looking at
Speaker 1: the chemical makeup of a rock, and it looks like
Speaker 1: these rocks were not exposed to space for very long,
Speaker 1: only like a few tens of thousands of years, not millions,
Speaker 1: and that means that probably they were like on the
Speaker 1: inside of some large asteroid for many, many, many millions
Speaker 1: or billions of years, basically protected from the radiation of space,
Speaker 1: then torn apart by the Earth's tidal forces into a
Speaker 1: bunch of little rocks which were not protected by the
Speaker 1: radiation of space, but only for a few tens of
Speaker 1: thousands of years before they fell to the surface of
Speaker 1: the Earth and then protected again. So you know they
Speaker 1: were near the surface of an asteroid out in space,
Speaker 1: exposed to radiation for only a few tens of thousands
Speaker 1: of years, So that's also suggestive. None of this is
Speaker 1: completely conclusive, but you know, this is like solving a mystery.
Speaker 1: You have a few clues you're trying to piece together story.
Speaker 1: All this is very circumstantial, but it all points in
Speaker 1: the same direction.
Speaker 2: You mentioned that there was like a shrapnel theory. Wouldn't
Speaker 2: the shrapnel theory also have something big where most of
Speaker 2: it was protected by space radiation, and then it got
Speaker 2: broken into pieces, and those pieces worked both to space
Speaker 2: radiation for a short period of time before Earth hit it.
Speaker 2: How would you tell the difference between those two options?
Speaker 1: Yes, a short period of time, but longer, like if
Speaker 1: there was a collision out on the asteroid belts that
Speaker 1: created all this shrapnel, it would take much longer to
Speaker 1: get to Earth, probably millions of years, not just ten thousand,
Speaker 1: and so that's how they can tell the difference.
Speaker 2: Got it. That's very cool. Who was the first author
Speaker 2: in this study? Let's give them some credit? This sounds
Speaker 2: awesome as scientists who understand statistics.
Speaker 1: Yeah, so this is Andrew Tompkins, Aaron Martin, and Peter
Speaker 1: Kaywood and a paper in Earth and Planetary Studies in
Speaker 1: November twenty twenty four. It's really quite readable, even for
Speaker 1: somebody outside their field. So congrats on the exciting result
Speaker 1: and the nicely written paper.
Speaker 2: And where did you come across this? How did we
Speaker 2: come to talk about this today?
Speaker 1: I think a bunch of listeners might have heard press
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Speaker 1: to explain it. So I put it on my list,
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Speaker 2: So write us at question I always forget our email address.
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Speaker 2: Yes you probably I can be super successful on that one,
Speaker 2: but good luck and we hope to hear.
Speaker 1: From you until next time. Put a ring on it.
Speaker 2: That's right. My daughter would be absolutely appalled if I
Speaker 2: say so. Anyway, Thanks everyone.
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