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Where do comets come from? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Jorgey, what's your favorite Solar System object? I'm gonna
0:12
Speaker 1: have to go with the Earth because you know, it's
0:14
Speaker 1: the only one I've been to, so you're not a
0:17
Speaker 1: gas giant kind of person. Depends how many tacas I
0:20
Speaker 1: had for munch. But what if I do? You do
0:22
Speaker 1: you have a favorite? I'm a big fan of the
0:24
Speaker 1: Sun and everything it does for us here on Earth,
0:27
Speaker 1: But my favorite thing in the Solar System is actually comets.
0:31
Speaker 1: Comments what have commets done for us? Well, they're like
0:34
Speaker 1: cosmic snowballs, and actually most of Earth's water turns out
0:38
Speaker 1: to be melted comets. I guess water is pretty useful
0:42
Speaker 1: to have. But wait, are you saying the Solar System
0:44
Speaker 1: is having a snowball fight. Yeah, it's more like deadly
0:48
Speaker 1: planetary dodgeball. Hi am more Hammon, cartoonists and the creator
1:07
Speaker 1: of PhD Comics. Hi. I'm Daniel. I'm a particle physicist,
1:11
Speaker 1: but I have strong opinions about various Solar System objects.
1:15
Speaker 1: And Welcome to our podcast, Daniel and Jorge Explain the Universe,
1:18
Speaker 1: a production of I Heart Radio in which we talk
1:20
Speaker 1: about everything that we know about the universe and everything
1:23
Speaker 1: that we don't know about the universe, everything that makes
1:25
Speaker 1: us wonder and everything that makes us go huh. And
1:28
Speaker 1: we explain all of it to you because we think
1:31
Speaker 1: that your curiosity is as valuable as the curiosity of
1:35
Speaker 1: scientists working on the front line. Yeah, and there's a
1:38
Speaker 1: lot to be curious about. The universe is full of
1:41
Speaker 1: amazing and incredible things and a lot of mysteries, a
1:44
Speaker 1: lot of things that we don't know where they come from,
1:48
Speaker 1: or what makes them what they are, or why they're there. Yeah,
1:51
Speaker 1: And a lot of great scientific discoveries begin with pretty
1:55
Speaker 1: simple questions, you know, like why is that thing there?
1:58
Speaker 1: Or why are those common? It's flying through space and
2:01
Speaker 1: where do they come from? Is one of them going
2:03
Speaker 1: to hit us and wipe us out? Great scientific discoveries
2:06
Speaker 1: come from really simple questions that everybody wants to know
2:09
Speaker 1: the answers to. Yeah, because we have questions even about
2:12
Speaker 1: our own backyard. Our solar system is still full of
2:16
Speaker 1: things that we don't quite fully understand. People like to
2:20
Speaker 1: talk about things in the distant universe that are still
2:23
Speaker 1: a mystery. We don't know how big it is or
2:25
Speaker 1: what's going on out there in the depths of the universe.
2:28
Speaker 1: But you're absolutely right, there's still a lot to be
2:30
Speaker 1: discovered right in our own neighborhood, big questions about what's
2:34
Speaker 1: going on in our own household that we still don't
2:38
Speaker 1: know the answers to. So they know you have a
2:39
Speaker 1: strong opinions about things in our Solar System? Are they
2:42
Speaker 1: all positive or are some of them negative? Is there
2:45
Speaker 1: someone you don't like here in system? Now? They're all positive.
2:49
Speaker 1: I love everything in the Solar System, from ice giants
2:52
Speaker 1: to planetism als, to space centaurs, to deadly comments to
2:57
Speaker 1: enormous burning balls of gas. I just think it's all
3:01
Speaker 1: pretty awesome. I can't imagine having a negative opinion about anything.
3:04
Speaker 1: Do you include in that all the people on Earth too? Yes?
3:09
Speaker 1: I love everybody. No, it's incredible when you look out
3:12
Speaker 1: there in space that you see so many beautiful, amazing things.
3:16
Speaker 1: Like when was the last time you looked at something
3:18
Speaker 1: out in space and you thought that's just kind of
3:21
Speaker 1: you know, it's all just sort of like incredible and beautiful.
3:23
Speaker 1: You know, whoever the universe's visual artist is, they're doing
3:26
Speaker 1: a good job. Although you know, we live in California,
3:29
Speaker 1: so right now, when I look up at the sky,
3:31
Speaker 1: it's mostly smoke. Well, then take a journey through the
3:34
Speaker 1: Solar System with your mind's eye. Yeah, there are a
3:36
Speaker 1: lot of big questions about the Solar System and how
3:38
Speaker 1: we got to where we are. And one of those
3:40
Speaker 1: big questions about our Solar system is where do comets
3:44
Speaker 1: come from? We don't know a comet factory here in
3:48
Speaker 1: our Solar system, do we We don't know of a
3:50
Speaker 1: comet factory. It could be that there are aliens out
3:52
Speaker 1: there in the outskirts of the Solar System packing up
3:55
Speaker 1: ice balls and shooting them at Earth. Or it could
3:58
Speaker 1: be that they come from something else, something deep out
4:01
Speaker 1: there in the Solar System. That's basically a huge reservoir
4:05
Speaker 1: of comets ready to fall in, screaming towards the Sun
4:09
Speaker 1: and boiling. And this is a big question because some
4:11
Speaker 1: people think that most of the water on Earth came
4:14
Speaker 1: from comets. That's right, Commets are mostly ice. You know,
4:18
Speaker 1: something a lot of people don't understand about the universe
4:21
Speaker 1: is that water is not rare. We talk about liquid
4:25
Speaker 1: water being something we're looking for in the surface of
4:27
Speaker 1: planets to see if there's alien life, but water as
4:30
Speaker 1: a chemical, there's tons of it out there. There's like
4:32
Speaker 1: planet size blobs of it. So most comets are icy
4:37
Speaker 1: planetism alls. They're just big balls of ice, and some
4:40
Speaker 1: of them fell towards the Earth in the early days
4:43
Speaker 1: and landed and melted and formed our oceans. Thank goodness,
4:47
Speaker 1: because that's where life came from. Right, we had them
4:50
Speaker 1: in for those snowballs, and we wouldn't be here, that's right.
4:53
Speaker 1: So next time you put your lips to a glass
4:55
Speaker 1: of melted comet, remember you're drinking. The outer Solar System
5:00
Speaker 1: are melted common Right, next time you go somewhere in
5:04
Speaker 1: order a drink, order sparkling melted comment and see what
5:07
Speaker 1: they do. Yeah, So a big question is where they
5:09
Speaker 1: come from, and so scientists have a potential answer to
5:12
Speaker 1: that question, right, Daniel, that's right. They don't know for sure.
5:15
Speaker 1: Nobody's ever actually seen it, but we've given it a name.
5:18
Speaker 1: So today on the podcast, we will be asking the question,
5:25
Speaker 1: what is now Daniel? Is that pronounced or or or
5:29
Speaker 1: because it's spelled O r T. It's a great question,
5:33
Speaker 1: and it's a Dutch name. It comes from a Dutch
5:35
Speaker 1: astronomer who first thought it up. And so I reached
5:38
Speaker 1: out to my Dutch speaking brother to ask him for
5:42
Speaker 1: his preferred pronunciation because I didn't know is it ort
5:45
Speaker 1: ort ort or something like weird Dutch vowel that we
5:48
Speaker 1: don't even have in English that can never be replicated?
5:51
Speaker 1: Keep going, keep going? Well, you know there are vowels
5:54
Speaker 1: in Danish that you know you can only replicate. You
5:56
Speaker 1: get like punched in the gut in exactly the right way,
5:59
Speaker 1: like you Dango speakers out there know what I'm talking about.
6:04
Speaker 1: But it turns out that or its spelled o o
6:07
Speaker 1: rt is pronounced like port. All right, So it's a
6:11
Speaker 1: cloud apparently of some sort, and it's I'm guessing it's
6:13
Speaker 1: out in space, and so the big question is how
6:16
Speaker 1: many people out there know what it is and what
6:18
Speaker 1: its significance is. That's right? So I pulled our listeners
6:22
Speaker 1: who have volunteered to answer random questions over the Internet
6:26
Speaker 1: from a businessist they've never met. If you'd like to
6:29
Speaker 1: participate in such absurd commentary on our physical universe, please
6:34
Speaker 1: write to me two questions at Daniel and Jorge dot com.
6:37
Speaker 1: And thanks to everybody who shared your speculations. Think about
6:40
Speaker 1: it for a second. If someone asked you what the
6:42
Speaker 1: orc cloud is, what would you answer. Here's what people
6:46
Speaker 1: had to say, The or Cloud is one of the
6:50
Speaker 1: outermost regions of the Solar System, comprised of we think
6:55
Speaker 1: a bunch of remnants of the early Solar system. The
6:59
Speaker 1: Orc Cloud is a group of like dust and rocks
7:05
Speaker 1: and asteroids and just material that's way outside are encircles
7:11
Speaker 1: our whole Solar system. I think in a giant sphere,
7:16
Speaker 1: or maybe just a circle. The art Cloud is a
7:20
Speaker 1: vast array of comets and other such I see debris
7:26
Speaker 1: forwarding around the Sun, very far away from the rest
7:28
Speaker 1: of the planetary systems. I know that the Sun, it's
7:33
Speaker 1: the middle of it, and it passes our solar systems,
7:38
Speaker 1: so passes Pluto. Is it the big cloud of dust
7:41
Speaker 1: that I'm spewing out the top and the bottom of
7:43
Speaker 1: the Milky Way? I have anything to do with equippable?
7:46
Speaker 1: Probably close to the Solar system. I think the art
7:49
Speaker 1: Cloud is like an area outside the Solar system where
7:53
Speaker 1: there are some icy objects. I'm not sure what, probably
7:59
Speaker 1: comets and things like that. All right, some pretty good answers.
8:02
Speaker 1: Most people seem to know it's something related to our
8:05
Speaker 1: Solar system, and that it's a cloud, and that maybe
8:08
Speaker 1: there's ice involved. Yeah, exactly, it's something big and fuzzy
8:12
Speaker 1: and out there and cool. Cool. And my favorite thing
8:16
Speaker 1: about the Orc cloud is at the acronym the O
8:18
Speaker 1: C is the same as the place I live, Orange County,
8:23
Speaker 1: except it's a little warmer, I think, a little warmer,
8:26
Speaker 1: but it's also still very very cool. That's the first
8:29
Speaker 1: time I've heard you give a compliment to the Orange
8:32
Speaker 1: County there. I love Orange County. Best place in the
8:36
Speaker 1: world to live. Seriously, what could you complain about? But
8:39
Speaker 1: that's not the topic of today's podcast. We're talking about
8:42
Speaker 1: the cosmic o C, the solar systems O C, not
8:46
Speaker 1: calibornias o C and to uh, it's apparently something out
8:49
Speaker 1: in space and so Daniel, let's step people through it.
8:52
Speaker 1: So what is the orc Cloud? The orc cloud is
8:54
Speaker 1: super awesome. It is a theoretical cloud of icy planetisml's
9:01
Speaker 1: or many planets planetismal. Did you just make that up
9:04
Speaker 1: or is that the actual science terms? Oh? Man, I
9:07
Speaker 1: wish I could have made that word of there's something
9:08
Speaker 1: wonderful about just saying that word planetismal. Right, but no,
9:13
Speaker 1: planetismal is a mini planet and it's smaller than a
9:16
Speaker 1: dwarf planet. Right, You've got planet dwarf planet, and then
9:19
Speaker 1: planet Tismal. They couldn't just say mini planet. Well it's
9:23
Speaker 1: sort of like Planetino, you know, that's what you do
9:25
Speaker 1: with English planet Tito. And so it's a bunch of
9:28
Speaker 1: these and they're really really far out there. Like if
9:33
Speaker 1: you have the Solar system, you know, the Earth is
9:35
Speaker 1: at one AU call an astronomical unit, and you go
9:38
Speaker 1: really far out you get out to like Neptune and Pluto.
9:42
Speaker 1: You have to go much, much, much further before you
9:45
Speaker 1: get to the arch cloud. Is it even considered our
9:48
Speaker 1: Solar system or is it technically outside of our Solar system? Yeah,
9:51
Speaker 1: it's a great question. Most people consider the end of
9:54
Speaker 1: our Solar system to be just under about a hundred
9:57
Speaker 1: a U, where the sun radiation becomes dominated by the
10:02
Speaker 1: galactic radiation. How you think of space is sort of
10:05
Speaker 1: like empty, right, but actually it's filled with streaming particles.
10:08
Speaker 1: The Sun is pumping out particles, not just photons, but
10:11
Speaker 1: protons and electrons and all sorts of crazy stuff, and
10:14
Speaker 1: it dominates the region around it with all of its
10:17
Speaker 1: pulsating radiation. But the rest of the galaxy also has
10:20
Speaker 1: a wind that's coming from all the other stars in
10:23
Speaker 1: the central black hole. And all that crazy stuff. So
10:26
Speaker 1: we define the edge of the Solar system it's called
10:28
Speaker 1: the helio pause, as the place where the Sun's radiation
10:33
Speaker 1: stops dominating the local environment and you're taken over by
10:36
Speaker 1: the galactic wind. And that's like a hundred or so A.
10:40
Speaker 1: It's like when our Sun becomes just another star kind
10:42
Speaker 1: of yeah, exactly, and the wind from the rest of
10:45
Speaker 1: the galaxy takes over the Sun's wind. And here again
10:49
Speaker 1: wind we don't mean air, We just mean the particles
10:51
Speaker 1: that it's shooting out. But the rac cloud starts like
10:54
Speaker 1: ten times further out than that, like at a thousand
10:58
Speaker 1: a U. Now it's just still sort of like bound
11:02
Speaker 1: by the gravity of the Sun, or is it pretty
11:05
Speaker 1: much like an independent thing from our solar system. It's
11:08
Speaker 1: definitely bound by the gravity of the Sun. So if
11:11
Speaker 1: you define the edge of the Solar system by the radiation,
11:14
Speaker 1: it's like a hundred a U. But stuff that's further
11:17
Speaker 1: out is still gravitationally bound to the Sun, but it's
11:20
Speaker 1: a little bit loose. It's like a little fuzzy. It's
11:23
Speaker 1: so far out from the Sun that it's not that
11:26
Speaker 1: hard to knock something off and have an escape into
11:29
Speaker 1: interstellar space, so it's not orbiting around us. It's sort
11:33
Speaker 1: of like we're tugging them and it's tugging us. It's
11:36
Speaker 1: definitely orbiting around us. Think of it like a huge
11:39
Speaker 1: shell surrounding the Solar System. The other fascinating thing about
11:42
Speaker 1: it is that it's not a disk, right, Most of
11:45
Speaker 1: the stuff in the Solar System is a big disc,
11:47
Speaker 1: it's flat. But the Orc Cloud, we think, is a sphere.
11:50
Speaker 1: It's like totally surrounding the Solar System, and it goes
11:53
Speaker 1: out really really far out to like a light year
11:56
Speaker 1: maybe two light years of just this like cloud of
12:00
Speaker 1: little frozen objects, and there could be like trillions of
12:03
Speaker 1: the planetismal, trillions of planetism many planets I'm sorry, yeah,
12:08
Speaker 1: planet titos. And it's sort of like calculus. You know,
12:10
Speaker 1: in calculus, you sum over infinitismals and you get like
12:13
Speaker 1: an actual quantity. In the same way, if you sum
12:16
Speaker 1: over all the planetism als in the ord cloud, you
12:19
Speaker 1: get a combined mass of stuff that's like five times
12:22
Speaker 1: the mass of the Earth, but then again spread out
12:25
Speaker 1: into like trillions of objects. It spread out not just
12:28
Speaker 1: like wide but tall to like it's it's pretty diffuse
12:31
Speaker 1: it's very diffuse, Like it's not like flying the millennium
12:34
Speaker 1: falcon through an asteroid field. You gonna like dodge and
12:36
Speaker 1: weave right, it's like, could we see something, like is
12:39
Speaker 1: there one there? It's so far out there, it's mostly empty.
12:43
Speaker 1: But again, they are gravitationally bound to the Sun and
12:46
Speaker 1: they are orbiting the Sun. That's why they are in
12:48
Speaker 1: a cloud around the Sun. It's not like just the
12:51
Speaker 1: whole interstellar medium is filled with these objects. It's a
12:54
Speaker 1: cloud of them. We think. Again, we think we don't
12:56
Speaker 1: know for sure. We haven't seen them because they're so
12:58
Speaker 1: small and far away, but we think that they're there
13:02
Speaker 1: in this big blob around the size see, and it's
13:04
Speaker 1: made up of like giant literally like giant balls of ice,
13:07
Speaker 1: basically snowballs. How big, Well, each one could be like
13:11
Speaker 1: bigger than a kilometer in size, So we think that
13:14
Speaker 1: they're like trillions of them that are more than a
13:16
Speaker 1: kilometer and maybe only billions that are twenty kilometers are larger.
13:20
Speaker 1: But if you wanted to have a cosmic snowball fight,
13:23
Speaker 1: that's like where your arsenal is, that's the best place
13:25
Speaker 1: to go for the stockpile. Wow, So that's like, let
13:28
Speaker 1: me see, that's like a snowball about the size of
13:30
Speaker 1: Los Angeles right kilometers. Yeah, there are billions of frozen
13:35
Speaker 1: Los Angeles is out there in the o C because
13:39
Speaker 1: they are pretty cool, icy cool. They are pretty cool,
13:43
Speaker 1: and if they weren't gravitationally bound to the Sun, they
13:45
Speaker 1: would just sort of float away into space. But they
13:49
Speaker 1: are bound there. They're floating around, but you know, it's
13:51
Speaker 1: sort of loose, and so sometimes the thought is sometimes
13:55
Speaker 1: something perturbs them and then they can get knocked out
13:58
Speaker 1: of their very loose orbit and plummet towards the inner
14:01
Speaker 1: Solar System because they're in a stable orbit. Is that
14:04
Speaker 1: the idea is that they're like happily going around our
14:07
Speaker 1: Sun in this huge, wide orbit, but sometimes they can
14:11
Speaker 1: fall in. Yeah, we think it's probably stable and if
14:14
Speaker 1: nothing perturbed them, they would just happily hang out there
14:17
Speaker 1: really far away, staying frozen. But you know, we are
14:21
Speaker 1: in a little neighborhood, and since it's sort of loosely
14:24
Speaker 1: held by the Sun, it's not that hard to perturb them.
14:27
Speaker 1: And you can have things like galactic tides that squeeze
14:31
Speaker 1: the orac cloud and knock some of them out of orbit.
14:33
Speaker 1: You mean from the center of the galaxy. Yeah, just
14:35
Speaker 1: the way the Moon has a gravitational effect on the
14:38
Speaker 1: water of the Earth. So as the Moon goes around
14:41
Speaker 1: the Earth, it tugs on the oceans and causes tides.
14:44
Speaker 1: We have a gravitational pull towards the center of the galaxy,
14:47
Speaker 1: and that tends to tug on one part of the
14:49
Speaker 1: Orc Cloud that's closer to it more than the rest
14:52
Speaker 1: of the Orc clouds, so sort of extends it. And
14:54
Speaker 1: then as we move around the center of the galaxy
14:57
Speaker 1: very slowly, you know, hundreds of millions of years, the
15:00
Speaker 1: direction of that tug changes, so it's a dynamic. So
15:04
Speaker 1: as we move around the center of the galaxy, the
15:06
Speaker 1: tides change, the galactic tides change. So are we right
15:09
Speaker 1: now and high tide or lord tide. Well, we're at
15:17
Speaker 1: the center of it right so we wouldn't feel it
15:20
Speaker 1: at all. But there's a blob of the Orc cloud
15:22
Speaker 1: that's always pointed towards the center of the galaxy that
15:25
Speaker 1: would be at high tide. There's more objects in that
15:27
Speaker 1: part of it, so we're sort of at the very
15:30
Speaker 1: center of it, so we can't tell, but it can
15:33
Speaker 1: be galactic tides. It can also be like nearby stars.
15:36
Speaker 1: If a nearby star happens to come somewhere close to
15:39
Speaker 1: us as we all swish around the Milky Way, it
15:42
Speaker 1: can perturb the orc cloud and send comets falling in
15:45
Speaker 1: towards the center of the Solar system, right or steal them,
15:48
Speaker 1: possibly steal them, or steal them absolutely, and we'll talk
15:51
Speaker 1: about where these came from. It's not clear that all
15:53
Speaker 1: of them actually came from our Solar system. And I
15:57
Speaker 1: guess the thing is that we've never actually seen the cloud, right, Like,
16:00
Speaker 1: we don't have pictures of it or even like radar
16:03
Speaker 1: of it or evidence of it. That's right. It's so
16:06
Speaker 1: far out there that it's still theoretical. There have been
16:08
Speaker 1: some glimpses of one or two objects that people debate
16:12
Speaker 1: might be like part of the Inner Inner Inner or cloud.
16:15
Speaker 1: But these things are really small and really really far away,
16:19
Speaker 1: Like it's hard to see Pluto, right, and Pluto is
16:22
Speaker 1: really close compared to these things, and nothing that we
16:26
Speaker 1: have out there in the Solar System has gotten anywhere
16:29
Speaker 1: close to them, Like the thing that we have sent
16:31
Speaker 1: out into space, that's the furthest object the humans have
16:34
Speaker 1: ever built, that's Voyager one. The fastest human spaceship ever. Right,
16:40
Speaker 1: that thing won't get to the beginning of the Orc
16:42
Speaker 1: Cloud for another three hundred years. Well, Daniel, I don't
16:46
Speaker 1: know if I believe in this thing or not, but
16:49
Speaker 1: let's get into how we know it's actually there and
16:52
Speaker 1: why we think it's important for our origin as a
16:55
Speaker 1: planet and as a human species. But first, let's take
16:59
Speaker 1: a quick break. All right, we're talking about the or Cloud,
17:14
Speaker 1: which is uh. I guess Daniel, you would describe it
17:17
Speaker 1: as like a giant shell of city size snowballs floating
17:22
Speaker 1: out hundreds of light years away from the Sun. That's right,
17:27
Speaker 1: And snowballs makes it sound quaint and fun and like
17:30
Speaker 1: if you get hit by one, you can just go
17:32
Speaker 1: inside and warm up with a cup of hot cocoa. Right,
17:35
Speaker 1: But these things are massive ice balls, and if one
17:38
Speaker 1: of them hit the Earth, we might be toasted. So
17:40
Speaker 1: we'll talk about the danger these things later on, but
17:43
Speaker 1: I want to make sure people are aware that these
17:45
Speaker 1: are basically massive space bullets waiting to hit the Earth.
17:48
Speaker 1: It's like a real snowball. If they pack enough ice
17:50
Speaker 1: into that slush ball, it can really hurt. Yeah, alright,
17:53
Speaker 1: so how do we know that it's actually there. Then
17:55
Speaker 1: what makes us think that there is this giant cloud
17:57
Speaker 1: of snowballs in space? Well, it comes um sort of
18:00
Speaker 1: a paradox. In the last hundred years, we've established that
18:03
Speaker 1: there are lots of comets, but the Solar system is
18:06
Speaker 1: not very young, and so people have been wondering, like,
18:08
Speaker 1: where do all these comets come from? Because comets are
18:12
Speaker 1: not stable. Like, once a comet starts falling in towards
18:15
Speaker 1: the Sun, it loses a lot of its mass as
18:17
Speaker 1: the Sun boils it away. So a comet can't like
18:21
Speaker 1: zip around the Sun for billions of years. It only
18:24
Speaker 1: gets like, you know, fifty or a hundred, maybe two
18:27
Speaker 1: hundred times around before it gets boiled away. Right, So
18:30
Speaker 1: if that's the case, if comets don't last very long,
18:33
Speaker 1: why are we still seeing commets? Like you lived in Arizona,
18:36
Speaker 1: and every once in a while somebody throws a snowball
18:38
Speaker 1: at your house, You're like, this is recent, Like somebody
18:41
Speaker 1: just made this. Yeah, Or you know, if you're walking
18:44
Speaker 1: around your neighborhood and everybody's eating ice cream, you're like,
18:46
Speaker 1: where's the ice cream? Chuck? It must have just come by.
18:49
Speaker 1: And so exactly, they thought there must be some sort
18:51
Speaker 1: of source of these things. The other clue was that
18:55
Speaker 1: there's sort of two types of comets. There are short
18:58
Speaker 1: period comets. Com is to have an orbit around the
19:01
Speaker 1: Sun that's like less than ten a U, and these
19:04
Speaker 1: are mostly aligned with the Solar System. It seems like
19:06
Speaker 1: they're like basically Solar System objects, just blobs of ice
19:09
Speaker 1: somewhere in the outer reaches of the Solar System. But
19:12
Speaker 1: then there's a second group of commets. They're called long
19:15
Speaker 1: period comets. These are ones that have an orbit that's
19:18
Speaker 1: like a thousand a U or more, and they take
19:21
Speaker 1: a long time to go around the Sun, and they
19:23
Speaker 1: don't follow the plane of the Solar system. So these
19:26
Speaker 1: were really the mystery. They're like, where are these long
19:29
Speaker 1: period comets coming from? They couldn't explain it. They shouldn't
19:32
Speaker 1: stick around. And so to explain where the new ones
19:36
Speaker 1: were coming from, they said, maybe there's a huge blob
19:38
Speaker 1: of them somewhere out there beyond where we can see. Oh,
19:41
Speaker 1: I see, you're saying these long period comments. They're sort
19:44
Speaker 1: of coming out of left field. Doesn't look like they're
19:46
Speaker 1: hanging out with us, or have been hanging out with
19:48
Speaker 1: us for a long time. It's like they're coming from
19:52
Speaker 1: somewhere else. Yeah, because they can't last for very long. Like,
19:55
Speaker 1: once you see a comet, you're seeing it in the
19:57
Speaker 1: end of its life cycle. It could have been out
20:00
Speaker 1: happily for billions of years deep out there in the
20:02
Speaker 1: Solar System. But once you see it, that means it's
20:05
Speaker 1: falling towards the Sun and it's going to get boiled
20:07
Speaker 1: away as it goes around the Sun, and it can't
20:10
Speaker 1: survive for very long. And even if it does make
20:13
Speaker 1: it a hundred or two hundred orbits, it's got a
20:15
Speaker 1: high chance of getting kicked out of the Solar System
20:18
Speaker 1: being perturbed by the gravity of one of the outer planets.
20:21
Speaker 1: So once you see a comet, it means it's in
20:24
Speaker 1: its last chapter of its life in the Solar System.
20:26
Speaker 1: So we're still seeing comets four and a half billion
20:29
Speaker 1: years into the story of the Solar System. There has
20:31
Speaker 1: to be some fresh resupply every once in a while.
20:34
Speaker 1: I guess if you're seeing a comment, that means it's
20:36
Speaker 1: getting hit by the rays of the Sun, which is
20:38
Speaker 1: probably melting it. It's definitely melting it, and that's where
20:42
Speaker 1: the comets tail is. Right. People like to imagine the
20:44
Speaker 1: commets tails like little action lines in a cartoon that
20:48
Speaker 1: show you where it's moving. But the commets tail is
20:50
Speaker 1: not actually pointed away from the direction of the comets motion.
20:54
Speaker 1: It's pointed away from the sun because the tail comes
20:57
Speaker 1: from the sun boiling away all the stuff on the comet. Yeah,
21:02
Speaker 1: that's the signature tale of of comets. That's what it is.
21:04
Speaker 1: It's not really a tail. It's more like a haircut.
21:07
Speaker 1: Is that what you're saying, Yeah, precisely. And comets can
21:12
Speaker 1: actually have multiple tales. They can have tales going in
21:15
Speaker 1: different directions based on like the stuff that's in there
21:18
Speaker 1: that's good and getting boiled away different compositions. So it's
21:21
Speaker 1: pretty fascinating look at the tales of comets. It's pretty awesome. Okay.
21:24
Speaker 1: So then someone named Yon Ord in the fifties said, hey,
21:28
Speaker 1: maybe all of these weird long period comets are coming
21:32
Speaker 1: from a very specific place. And so he came up
21:35
Speaker 1: with this idea of the Ord cloud. Yeah, and he
21:37
Speaker 1: looked at the orbits of these comets and he said,
21:39
Speaker 1: how far out does it have to be to generate
21:42
Speaker 1: comets with this length or but these long period comets,
21:46
Speaker 1: And so that's how he estimated. He made a very
21:48
Speaker 1: rough estimate for you know, how far away should be.
21:51
Speaker 1: And since then we have much better data, better telescopes.
21:54
Speaker 1: We can see the orbit of these comets much more clearly.
21:57
Speaker 1: We have more telescopes, we have hubble and so be
22:00
Speaker 1: can track all this stuff, and we have better estimates
22:02
Speaker 1: for what's out there and how big it is. But
22:05
Speaker 1: the basic idea came from this guy, yawned Ort in
22:08
Speaker 1: nineteen fifty. And you know, it's pretty awesome to get
22:10
Speaker 1: to put your name on the biggest thing in the
22:13
Speaker 1: Solar system, Like this thing just dwarfs the rest of
22:16
Speaker 1: the Solar system. Did he call it that the the
22:18
Speaker 1: ord cloud or was it named after him? That's a
22:20
Speaker 1: great question. I should read his original paper to see
22:23
Speaker 1: if he put his own name on it or if
22:25
Speaker 1: he was humble. Yeah, when he called the cloud of
22:27
Speaker 1: Testimal and let somebody said that's a ridiculous name. We'll
22:31
Speaker 1: go with orc. Yeah. And it's fascinating and it's cool
22:34
Speaker 1: because it answers a question, right, It tells you, oh,
22:36
Speaker 1: that must be where these comets are coming from. But
22:39
Speaker 1: like everything in science, when you answer a question, it
22:41
Speaker 1: opens up more questions, like all right, Well, where did
22:44
Speaker 1: this ort cloud come from? Why is it there? Why
22:47
Speaker 1: aren't they just closer into the rest of the Solar System.
22:50
Speaker 1: And that's an active area of research right now. So
22:52
Speaker 1: we actually haven't seen this cloud. We're just sort of
22:55
Speaker 1: tracking where comets come from, and we think they come
22:59
Speaker 1: from the cloud. Yeah, we have not seen this. We
23:02
Speaker 1: don't have telescopes that are powerful enough to spot it,
23:05
Speaker 1: none of our probes are anywhere near it. But it's
23:08
Speaker 1: sort of the best explanation and we have for the
23:11
Speaker 1: source of comets. So it's pretty well accepted in the
23:14
Speaker 1: astronomical community that it exists. Like we always like to
23:18
Speaker 1: see direct evidence of something before we conclude that it exists,
23:22
Speaker 1: like there was evidence for Pluto before we spotted it
23:25
Speaker 1: in a telescope. But you don't really claim discovery of
23:28
Speaker 1: it until you actually see it, right, It's like finding
23:31
Speaker 1: the body in a murder mystery. But sometimes it's the
23:34
Speaker 1: best you can do for a while, so we can
23:36
Speaker 1: talk later about like plans people have for how to
23:39
Speaker 1: spot the Orc cloud and to study it, but for
23:41
Speaker 1: now we have no direct evidence of it. I guess
23:43
Speaker 1: it's not a thick enough cloud that it like makes
23:45
Speaker 1: your view hazy, or you can see some of the
23:48
Speaker 1: like the light getting filtered through it. It's not that thick, No,
23:52
Speaker 1: it's not that thick. These things are very small and
23:54
Speaker 1: very far away, so thick is definitely not how you
23:57
Speaker 1: describe it. There's enormous that empty spaces between every object
24:02
Speaker 1: in the orc cloud. Even though there are trillions and
24:05
Speaker 1: trillions of objects. The space we're talking about is incredibly vast, Right,
24:10
Speaker 1: We're talking about a sphere that's basically a light year
24:13
Speaker 1: in radius, and so there's a lot of space in
24:16
Speaker 1: there to distribute the trillion objects and still have lots
24:20
Speaker 1: of room in between them. All Right, Well, I guess,
24:21
Speaker 1: like you said, a big question is where did this
24:23
Speaker 1: orc cloud come from? Like why is there all this
24:26
Speaker 1: water deposited in one spot out there in the Solar system?
24:29
Speaker 1: Beyond the Solar system. Well, as usual, we have a
24:32
Speaker 1: few theories. We have sort of like the most boring
24:34
Speaker 1: theory and then the most exciting theory, and the most
24:37
Speaker 1: boring theory is sort of a story of the formation
24:40
Speaker 1: of our Solar system. Like we start from a big
24:43
Speaker 1: cloud of molecular gas and dust and stuff that collapses
24:47
Speaker 1: and you get the Sun and you have a disc
24:49
Speaker 1: of stuff that has too much angular momentum to collapse
24:52
Speaker 1: into the Sun, so it spins around the Sun without
24:54
Speaker 1: forming part of the star. And that's the protoplanetary disc, right.
24:59
Speaker 1: And there you have of ice and gas and dust
25:01
Speaker 1: and all kinds of stuff that starts to form planets
25:04
Speaker 1: and clump together and form all sorts of stuff. The
25:07
Speaker 1: idea is that not everything clumps together to form a planet,
25:11
Speaker 1: like you have asteroids for example, of smaller things. Gravity
25:14
Speaker 1: doesn't succeed in clumping everything together. But you do get
25:19
Speaker 1: big gas giants out there, like Neptune and Urineus and
25:22
Speaker 1: Saturn and Jupiter. They start to be sort of like
25:25
Speaker 1: heavyweights of their own gravitationally, and they can perturb the
25:29
Speaker 1: other stuff. And so there was a bit of a
25:31
Speaker 1: dance in the early Solar System as these big planets
25:35
Speaker 1: we're finding their place, and as they move around, they
25:38
Speaker 1: affected everything else. So the short version of the story
25:41
Speaker 1: is that we think that they were essentially tossed out
25:43
Speaker 1: of the Solar System by some of these gas giants
25:46
Speaker 1: as they were being born. These planets sort of like
25:49
Speaker 1: muscled their way around the craziness of the Solar System. Yeah,
25:52
Speaker 1: and one of the definitions of planets, if you believe
25:54
Speaker 1: in you know, silly astronomical categories, is that it's cleared
25:58
Speaker 1: its own path around the Sun. And so that's just
26:00
Speaker 1: sort of like the job of growing up and being
26:02
Speaker 1: a modern planet is that you have to like toss
26:05
Speaker 1: the little bits out of the way, or you know,
26:07
Speaker 1: slave them and make them into your moons. But in
26:09
Speaker 1: this case, most of the stuff we think was tossed
26:12
Speaker 1: out sort of in the early days of the Solar
26:15
Speaker 1: System formation. And it also it had a reverse effect.
26:18
Speaker 1: Remember gravity is always two directions. So we think that
26:21
Speaker 1: one of the reasons that Neptune is as far out
26:23
Speaker 1: as it is is that it got tugged out by
26:26
Speaker 1: these objects as they were leaving the Solar System. I guess.
26:29
Speaker 1: One question is if a planet is kind of plowing
26:32
Speaker 1: through and sending things out into space, wouldn't it send
26:35
Speaker 1: all kinds of things like asteroids and rocks and gas.
26:38
Speaker 1: How did all this ice come together so purely, I guess,
26:43
Speaker 1: And like, you know, why isn't it a mix of
26:45
Speaker 1: all other things? Yeah, that's a great question. It is
26:47
Speaker 1: mostly a mix, right, These things are not pure water.
26:50
Speaker 1: It's like you go out there and you find these
26:52
Speaker 1: pristine cubes of ice that you're ready to chisel out
26:55
Speaker 1: and put onto your space cocktails. These things are dirty.
26:59
Speaker 1: It's definitely still rocks in there. But remember that a
27:02
Speaker 1: large fraction of the stuff in the outer Solar system
27:05
Speaker 1: is ice, like you call uranus and neptune. They are
27:08
Speaker 1: called ice giants, and so it's something of a matter
27:11
Speaker 1: of how these chemicals are distributed through the solar system,
27:14
Speaker 1: like where water ends up and ends up freezing and
27:17
Speaker 1: gathering together. But a lot of the stuff in the
27:20
Speaker 1: outer Solar system, and non significant fraction of all the
27:23
Speaker 1: mass in the outer Solar system is water. I guess
27:26
Speaker 1: out there most of it is ice and liquid, because
27:29
Speaker 1: if it was closer, it would evaporate and maybe blow
27:32
Speaker 1: out exactly. Some complicated arguments about where stuff in the
27:35
Speaker 1: solar system collapses and what falls in and what doesn't.
27:39
Speaker 1: But you end up with a lot of ice in
27:40
Speaker 1: the outer Solar system. But these things are not pure water. Again,
27:44
Speaker 1: they're definitely bits of rock. I would not recommend drinking
27:47
Speaker 1: an or object if you found one, unless you like rocks,
27:52
Speaker 1: unless they like your cocktails dirty. I guess they're dirty
27:54
Speaker 1: snowballs all right, So that's one theory about how it forms,
27:58
Speaker 1: just like you know, byproduct of the dynamics of the
28:00
Speaker 1: solar system. What are the more interesting theories? The more
28:03
Speaker 1: interesting theories are the interstellar theories. One idea is that
28:07
Speaker 1: our son, when it formed, wasn't on its own. But
28:10
Speaker 1: you know, we've discovered barely recently that a lot of
28:13
Speaker 1: stars it was a twin. Yes, we're born as twins.
28:16
Speaker 1: That binary star systems are much more common than we imagined.
28:20
Speaker 1: So it could have been that our son had a
28:22
Speaker 1: twin and that this collapsing cloud of stuff formed two
28:26
Speaker 1: stars instead of one. But then these two sort of
28:28
Speaker 1: drifted apart, as you know siblings sometimes do, and there's
28:33
Speaker 1: a lot of material exchanged, and that gives you an
28:35
Speaker 1: opportunity to sort of pull material further away from the
28:39
Speaker 1: Sun because you have this big, heavy object, the other star,
28:42
Speaker 1: tugging on your solar system. What so, what happened to
28:46
Speaker 1: this other star, sister star. It's the subject of a
28:49
Speaker 1: Netflix documentary, you know, where they're going to reunite the
28:51
Speaker 1: stars for a dramatic conclusion at the end of the universe,
28:54
Speaker 1: or a hit podcast mini series. That's right, not true crime,
28:59
Speaker 1: but true physics. No, we don't know. It's just hypothetical.
29:02
Speaker 1: We don't know that the Sun had a twin star
29:05
Speaker 1: at its birth. It's just an idea. But if it did,
29:08
Speaker 1: it could have been pulled off and gone in any direction.
29:11
Speaker 1: It's been a long time, it's been billions of years,
29:13
Speaker 1: and so it's hard to trace. It's not like the
29:16
Speaker 1: nearest star is necessarily a category for our lost twin.
29:20
Speaker 1: This thing would have been moving for a long time.
29:22
Speaker 1: It could be anywhere at this point. And so the
29:24
Speaker 1: idea is that the sister star pulled some things from
29:27
Speaker 1: the Sun and then left it out there and where
29:30
Speaker 1: the orc tod would be. Yeah, just like we were
29:32
Speaker 1: talking about the gas giants tossing stuff out of the
29:35
Speaker 1: Solar system, Now you have a much bigger object, a
29:38
Speaker 1: heavier object, another star even further out. It's going to
29:41
Speaker 1: tug out some of these stuff in our solar system
29:44
Speaker 1: to have a very large radius. And then as the
29:46
Speaker 1: to sort of separate. I'm imagining, like you know, sell
29:49
Speaker 1: mitoses here two stars are pulling apart from each other
29:52
Speaker 1: and it's sort of like threads in between them, and
29:55
Speaker 1: then as they get far enough away, they stop affecting
29:57
Speaker 1: each other gravitationally and things settle into place. But you
30:01
Speaker 1: have stuff out at a pretty far radius because the
30:04
Speaker 1: gravitational pull of the other star interesting. So it was
30:07
Speaker 1: like the leftover from the divorce or something I just
30:10
Speaker 1: got dropped there in the middle of space. That's right,
30:13
Speaker 1: the poor abandoned objects in the stellar o c so
30:17
Speaker 1: many seems appropriate. All right, let's get into our last
30:23
Speaker 1: theory about where this orc cloud came from and what
30:26
Speaker 1: it all means. The first let's take another quick break.
30:41
Speaker 1: All right, Daniel, there's a giant cloud of snowballs out
30:46
Speaker 1: in space about three light years away from the Sun,
30:50
Speaker 1: and we think that's where comments come from. But the
30:51
Speaker 1: question is where did this cloud come from? And so
30:54
Speaker 1: you have one more theory for us about that, and
30:57
Speaker 1: I'm going to guess it involves eight It involves alien stars,
31:02
Speaker 1: though we don't know if there are aliens enough living
31:04
Speaker 1: around those stars. The problem is that if you do
31:06
Speaker 1: the calculations, and you have your theory of the Solar
31:09
Speaker 1: system and you predict how many things there should be
31:12
Speaker 1: in the or cloud, you get a number that's way
31:15
Speaker 1: too small. You get a number like six billion objects.
31:18
Speaker 1: But we know the number is much much bigger than that.
31:21
Speaker 1: So the idea is like, well, where do these things
31:23
Speaker 1: come from? So wait, how do we know how big
31:26
Speaker 1: it should be? If we don't, we've never seen it
31:28
Speaker 1: and it's all theoretical. Is it just from like the
31:30
Speaker 1: frequency of comments that we get exactly to explain the
31:33
Speaker 1: number of comments that we see, and they're radius and stuff,
31:36
Speaker 1: there should be a certain number of objects in the
31:39
Speaker 1: Orc cloud, otherwise we would see fewer and fewer comments.
31:42
Speaker 1: But if we try to predict how many things are
31:44
Speaker 1: in the Orc cloud from sort of first principles formation,
31:47
Speaker 1: like how many things should have been tossed out there
31:49
Speaker 1: by Neptune and Saturn Uranus, then we get a much
31:52
Speaker 1: smaller number. So there's a discrepancy there. We know there
31:55
Speaker 1: are objects out there, we can't explain how they got there.
31:58
Speaker 1: So one idea is as well, when our star was forming,
32:01
Speaker 1: what was going on nearby? We talked about how maybe
32:04
Speaker 1: there was a sister star formed with us. But another
32:07
Speaker 1: idea is that maybe our stellar cloud that collapsed was
32:11
Speaker 1: near some other objects and it stole some material from
32:15
Speaker 1: those objects. That basically the Orc cloud is like a
32:19
Speaker 1: lot of stuff from other solar systems that was stolen
32:22
Speaker 1: by our sun when it formed. What it could be stolen? Good? Yeah,
32:28
Speaker 1: the water we're drinking could have been stolen from another
32:31
Speaker 1: solar system. Is that what you're saying? You should feel
32:33
Speaker 1: guilty every time you have a drink. It's elicit. But
32:36
Speaker 1: it could basically be all a muamua, right, Remember Mumua
32:39
Speaker 1: was this interstellar comment, this frozen object that passed through
32:43
Speaker 1: our solar system coming from some other solar system. And
32:47
Speaker 1: it could be that the Orc Cloud is basically just
32:50
Speaker 1: a bunch of these. Oh I see, is that a
32:52
Speaker 1: theory that Oma came from the Orc Cloud? No, mum
32:55
Speaker 1: It definitely did not come from the Orc Cloud. Its
32:57
Speaker 1: trajectory is totally inconsistent with that. We know that it
33:00
Speaker 1: came from another solar system. But it could be think
33:03
Speaker 1: the Orc Cloud is the product of stealing a bunch
33:06
Speaker 1: of Omumua like objects much much earlier, a long time ago,
33:10
Speaker 1: as our solar systems forming. So you know, possession is
33:14
Speaker 1: nine tenths of the law. Then you know we've had
33:16
Speaker 1: these for billions of years. They're basically ours now, but
33:19
Speaker 1: there's a bit of original sin there and having stolen
33:22
Speaker 1: them from another solar system a long time ago. Well, yeah,
33:24
Speaker 1: I guess, because you know, I think the closest stars
33:27
Speaker 1: to us our solar system are about what is it
33:30
Speaker 1: like five light years away, right, yeah, three and a
33:33
Speaker 1: half light years away to proximates Centauri. Yeah, so this
33:36
Speaker 1: orc cloud is about where those other stars are. Yeah,
33:39
Speaker 1: it's the right order of magnitude, right, it's that big.
33:42
Speaker 1: It's so big that it gets you part way to
33:44
Speaker 1: other stars. And those other stars probably have their own clouds,
33:48
Speaker 1: and these stars tugging each other, and one of the
33:50
Speaker 1: ways to perturb our or cloud is to have other
33:53
Speaker 1: stars come nearby and give it like a little gravitational tug,
33:56
Speaker 1: which results in comets falling towards the Earth. Also, an
34:00
Speaker 1: orac cloud is not necessarily like a good thing. We
34:02
Speaker 1: talked about stealing this, but like it's a bunch of
34:05
Speaker 1: bullets hanging over our head where at the bottom of
34:08
Speaker 1: this gravity, well, any of them roll down, they could
34:11
Speaker 1: totally wipe us out, like deadly hail or something. You
34:13
Speaker 1: don't You don't necessarily want that, it won't create a
34:16
Speaker 1: winter wonder lamp. You want it early on, so we
34:18
Speaker 1: can give you oceans, but then you basically want to
34:21
Speaker 1: give them away. To your neighbor, so you don't have
34:23
Speaker 1: them anymore. Wow. Alright, so it is kind of like
34:25
Speaker 1: a giant interplanetary snowball fight almost or tug of war. Yeah,
34:31
Speaker 1: and that's where we think most commets come from. And
34:33
Speaker 1: you know, every time you see a comet that's come
34:35
Speaker 1: from the outer Solar System, it's been out there for
34:38
Speaker 1: billions of years, happily orbiting, not being close to anybody,
34:42
Speaker 1: being an introvert. And now it's screaming towards the center
34:45
Speaker 1: of the Solar System, maybe hitting a planet, maybe hitting
34:48
Speaker 1: the Sun, maybe just whipping around and going back out right.
34:51
Speaker 1: It's kind of dangerous. It's actually quite dangerous. You know.
34:54
Speaker 1: People talk about asteroids hitting the Earth and worrying about
34:58
Speaker 1: big rocks and planet killers and all kinds of stuff,
35:01
Speaker 1: But the truth is NASA has most of those figured out.
35:04
Speaker 1: Like most of the asteroids, the things in our Solar System,
35:07
Speaker 1: we could see them because they're pretty close, certainly anything
35:10
Speaker 1: that's big enough to cause us any danger. And NASA
35:13
Speaker 1: has a great team of planetary protectors tracking these things
35:17
Speaker 1: and predicting where they're gonna be and letting us know
35:19
Speaker 1: if they're gonna be anywhere nearby, and often one of
35:22
Speaker 1: them slips through and we don't see it until it
35:23
Speaker 1: hits us. But that's because it's small. So a really
35:27
Speaker 1: big object that would actually cause any damage. NASA is
35:30
Speaker 1: pretty sure we're safe from those for a couple hundred
35:32
Speaker 1: years because they're hanging out in the Solar System, so
35:34
Speaker 1: we can kind of see them, but we can see them.
35:36
Speaker 1: But if it's coming from outside the Solar System, then
35:39
Speaker 1: it can surprise us. Yeah, if it comes from left field,
35:42
Speaker 1: it could be a real surprise. These things could have
35:44
Speaker 1: orbits that are hundreds or thousands of years, and so
35:48
Speaker 1: the first time we see one might be the last
35:51
Speaker 1: time we see one because it could be headed for Earth.
35:55
Speaker 1: And so these things could fall into the Solar System
35:57
Speaker 1: and smack right into a planet and you know, cause
36:00
Speaker 1: a lot of destruction. Because they also they move really
36:03
Speaker 1: really fast. They've been accelerating for a long time falling
36:07
Speaker 1: in towards the Sun, and so they have a huge
36:09
Speaker 1: amount of kinetic energy. This is not a gently tossed snowball.
36:13
Speaker 1: This is like a rocket. It's like a rocket propelled
36:16
Speaker 1: missile launched snowball. Yeah, you give like a really hard
36:19
Speaker 1: block of ice to a major League pitcher and stand
36:22
Speaker 1: right in front of the mess. He throws it at
36:23
Speaker 1: your face. That's about how terrifying this is. Just like
36:26
Speaker 1: when they threw those frozen turkeys at airplane to see
36:29
Speaker 1: if the airplanes would break. Is that a real experiment
36:32
Speaker 1: used to make that up? That's a real thing. They
36:35
Speaker 1: shot frozen turkeys at an airplanes to see what would happen.
36:39
Speaker 1: And it's happened before, right, Like our Solar system has
36:41
Speaker 1: gone pelted by giant snowballs, and some of them even
36:44
Speaker 1: hit some planets. Yeah, exactly. If you think, oh, that's
36:47
Speaker 1: not likely to happen, or it might only happen every
36:49
Speaker 1: thousand or million years, we don't know how often it happens,
36:53
Speaker 1: but we do know that it happened recently. It was
36:56
Speaker 1: in the nineties that a big comet hit Jupiter commt
37:00
Speaker 1: Maker Levy. It broke up into a bunch of pieces
37:02
Speaker 1: and each one pelted Jupiter, and even after it broke
37:06
Speaker 1: up and made fireballs that were larger than Earth when
37:10
Speaker 1: each one hit. So these are very dramatic planetary events,
37:13
Speaker 1: not the kind of thing we want to have happened
37:15
Speaker 1: to Earth. Yeah, that would be bad, It would be bad.
37:18
Speaker 1: And now, Daniel, I have a note here in the
37:20
Speaker 1: document you send me here, and I'm trying to figure
37:22
Speaker 1: out it says also space centaurs, And that's it. What
37:29
Speaker 1: does that even mean? Space centers are so much fun.
37:33
Speaker 1: I decided to make it a whole other episode for
37:35
Speaker 1: a few weeks from now. But there is this thing
37:37
Speaker 1: in the Solar System called a space center. Seriously, it's
37:42
Speaker 1: a thing. Scientists found the thing and called them space centers.
37:46
Speaker 1: But they're not like you might imagine, maybe like you know,
37:49
Speaker 1: asteroids that happened to look like the fusion between man
37:52
Speaker 1: and horse. No, they're just the name that you give
37:56
Speaker 1: small objects between Jupiter and Neptune that sort of cross
38:00
Speaker 1: back and forth between the orbits of these gas giants,
38:03
Speaker 1: sort of like transitional objects. So they're like we could
38:05
Speaker 1: call them space unicorns or space griffins. That would be
38:09
Speaker 1: too crazy, but we'll go with space centers. I don't
38:12
Speaker 1: know what kind of bananas they were smoking the day
38:14
Speaker 1: they came up with that name, but it did tickle
38:16
Speaker 1: my sense of humor. But they think that maybe space
38:19
Speaker 1: centers also have come from the orc cloud. They've essentially
38:23
Speaker 1: fallen in and then into these more stable orbits somewhere
38:27
Speaker 1: in the outer solar systems thing. Well, then I vote
38:29
Speaker 1: we rename comments to space unicorns. I second your motion,
38:34
Speaker 1: but I don't think we have any jurisdiction here. All right, Well,
38:39
Speaker 1: it sounds like comments are pretty cool. They might be
38:41
Speaker 1: coming from the Orc cloud, this theoretical cloud out there
38:45
Speaker 1: in space which gave us water, which is a good thing,
38:47
Speaker 1: but which may kill us in the future. And so
38:50
Speaker 1: we're we're studying this cloud. Now we're studying comments more.
38:53
Speaker 1: What are we doing about it? Well, we're doing everything
38:55
Speaker 1: we can. It's pretty hard to spot these things right there,
38:58
Speaker 1: so small, they're so far away. People have one really
39:01
Speaker 1: fun idea for how to visualize these things, and essentially
39:05
Speaker 1: it's to look for star eclipses. Like if we are
39:09
Speaker 1: surrounded by this huge cloud of these little objects there
39:12
Speaker 1: essentially black, they're so far away they don't reflect enough sunlight,
39:16
Speaker 1: but occasionally they should pass in front of stars, causing
39:20
Speaker 1: these little transitions where the star basically blinks out momentarily.
39:25
Speaker 1: So you can look at all the stars and watch
39:27
Speaker 1: them and wait to see if you see one of
39:30
Speaker 1: these eclipses, and if you do, then you can use
39:33
Speaker 1: that to measure like how many things there are out there,
39:36
Speaker 1: but based on the rate at which you see these things,
39:38
Speaker 1: And if you don't, then you can set a limit
39:41
Speaker 1: and say, well, there can't be that many, otherwise I
39:43
Speaker 1: would have seen them. You're looking at Like how the
39:46
Speaker 1: stars are twinkling, Yeah, because they might be twinkling because
39:49
Speaker 1: of a giant comment heading towards us, Yeah, or just
39:52
Speaker 1: a giant, silent, frozen comment passing between us and that star.
39:57
Speaker 1: And you know it has to line up just right.
39:59
Speaker 1: You have to draw a line between the Earth and
40:01
Speaker 1: that star super far away, and then the orc cloud
40:04
Speaker 1: object has to basically break that line in order for
40:08
Speaker 1: there to be this eclipse. So it's not that likely,
40:11
Speaker 1: but there are a lot of stars out there and
40:13
Speaker 1: maybe a lot of orc cloud objects, so if you
40:15
Speaker 1: get enough telescope time, you might be able to spot it.
40:18
Speaker 1: And unicorns are pretty magical, so you never know what
40:20
Speaker 1: they're gonna do. What if they're all turned out to
40:23
Speaker 1: be rainbow colored, that would be amazing. And it could
40:27
Speaker 1: also be that if we pass nearby another star, that
40:30
Speaker 1: that star could like pass through our or cloud, causing
40:34
Speaker 1: like a new bombardment of comets, and that would be
40:37
Speaker 1: sort of a confirmation because we'd see a lot of
40:39
Speaker 1: these things rushing towards the inner Solar system. Well, clearly
40:42
Speaker 1: we need to build like an ice Ford Daniel around
40:45
Speaker 1: the Earth. That um, yeah, I think it's called Neptune.
40:49
Speaker 1: That's an ice giant, and hopefully it captures these things
40:53
Speaker 1: as they come into the inner Solar system. You know,
40:55
Speaker 1: we actually do have the gas giants to thank for
40:58
Speaker 1: protecting us from a lot of these things. They tend
41:01
Speaker 1: to pull them in and they also tend to clean
41:02
Speaker 1: them up. So without those big planets out there protecting
41:06
Speaker 1: us from the o C bullies throwing snowballs, we would
41:10
Speaker 1: have had a rougher time of it. And then, to
41:11
Speaker 1: be ironic, if there was a like a giant comment
41:14
Speaker 1: heading towards us, but then at the last minute Pluto
41:16
Speaker 1: gets in the way and blocks it. That sounds like
41:20
Speaker 1: the plot of our movie. That sounds like a good
41:22
Speaker 1: slow motion scene at the end and flat and everyone's like, oh, Pluto,
41:29
Speaker 1: we took you for granted, but now you see it
41:31
Speaker 1: is all it's too late, but now we value your contribution,
41:35
Speaker 1: all right. Well, the next time you look out into
41:38
Speaker 1: the night, Skuy, we hope you think about what's out
41:40
Speaker 1: there and what could possibly be out there, and also
41:44
Speaker 1: think of ice unicorns floating out there in space. And
41:47
Speaker 1: remember that there's a lot of things out there that
41:49
Speaker 1: we still don't understand, sources of mystery, sources of wonder,
41:52
Speaker 1: and sources of danger. So we better get on it
41:56
Speaker 1: and figure this stuff out before it wipes us out,
41:59
Speaker 1: or it might be too late. We're ready or not.
42:01
Speaker 1: All right, Well, we hope you enjoyed that. Thanks for
42:03
Speaker 1: joining us, See you next time. Thanks for listening, and
42:14
Speaker 1: remember that Daniel and Jorge Explain the Universe is a
42:17
Speaker 1: production of I Heart Radio or more podcast For my
42:20
Speaker 1: heart Radio, visit the I heart Radio app, Apple Podcasts,
42:24
Speaker 1: or wherever you listen to your favorite shows.