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Are there comets in the asteroid belt? · Daniel and Kelly’s Extraordinary Universe

0:08
Speaker 1: Hey, Daniel, what's the difference between a physicist and an astronomer?
0:14
Speaker 2: Oh? I feel like this is a trap.
0:17
Speaker 1: It seems like a simple question.
0:19
Speaker 2: It's a constant debate we have in faculty meetings in
0:22
Speaker 2: the Department of Physics and Astronomy. Where do we draw
0:25
Speaker 2: the arbitrary dotted line?
0:27
Speaker 3: Like?
0:28
Speaker 1: Are all astronomers physicists or are some physicists astronomers? How
0:31
Speaker 1: does it work?
0:33
Speaker 2: I feel like any answer I give here is can
0:36
Speaker 2: generate a lot of angry.
0:37
Speaker 1: Emails physicists or astronomers.
0:39
Speaker 2: A lot of astronomers think of themselves as physicists first
0:42
Speaker 2: applied to questions of astronomy, but also a lot of
0:45
Speaker 2: astronomers think of themselves as a very different breed of
0:48
Speaker 2: scientists who tackle problems differently and think about things differently
0:52
Speaker 2: than physicists do.
0:54
Speaker 1: All right, that wasn't so hard.
0:56
Speaker 2: It was my best non answer.
0:58
Speaker 1: All Right? May I actually just ask non questions in
1:00
Speaker 1: the future.
1:01
Speaker 2: Welcome to our non podcast.
1:18
Speaker 1: I am Jorge. I'm a cartoonist and the author of
1:20
Speaker 1: Oliver's Great Big Universe.
1:22
Speaker 2: Hi, I'm Daniel. I'm a particle physicist and a professor
1:24
Speaker 2: at UC Irvine. Though I'm no longer sure what those
1:27
Speaker 2: categories even mean.
1:29
Speaker 1: You don't know what you are? Are you having like
1:30
Speaker 1: an identity crisis?
1:32
Speaker 2: Yes? Yes, and yes. I mean if everything's particles, then
1:37
Speaker 2: isn't everybody a particle physicist?
1:39
Speaker 3: Well?
1:39
Speaker 1: Not everything's a particle, right, then we're.
1:41
Speaker 2: All field physicists.
1:43
Speaker 1: I suppose, like what's dark energy? Dark energy is not
1:46
Speaker 1: necessarily a particle.
1:47
Speaker 2: Yet nobody knows. Maybe dark energy is a particle we
1:50
Speaker 2: don't know.
1:50
Speaker 1: In fact, isn't particles in arbitrary name or term? Like,
1:56
Speaker 1: isn't everything just energy? In the end, maybe you should
1:58
Speaker 1: just all be energiest.
2:00
Speaker 2: Yeah, if you ask ten particle physicists what is a particle?
2:02
Speaker 2: You'll get ten different answers.
2:04
Speaker 1: Well, if you guys can't even agree, then you know
2:06
Speaker 1: what's the point.
2:08
Speaker 2: The point is that names and words are how we communicate,
2:10
Speaker 2: though it's probably best if we do assign meaning to
2:13
Speaker 2: them first.
2:15
Speaker 1: Maybe should just all do science with sign language.
2:18
Speaker 2: Or like charades, Let's just give up on language and
2:22
Speaker 2: use math. Right, that's just so much more crisp.
2:25
Speaker 1: I think charades is not just more fun, but also
2:28
Speaker 1: maybe a little bit easier. You would have a whole
2:31
Speaker 1: conferences where the presentations are just signists getting up there
2:35
Speaker 1: and and miming their papers.
2:38
Speaker 2: Is that supposed to increase clarity or just hilarity?
2:42
Speaker 1: Well, hopefully it'll increase clarity and also hilarity. But anyways,
2:46
Speaker 1: welcome to our podcast, Daniel and Jorge Explain the Universe,
2:49
Speaker 1: a production of iHeartRadio.
2:50
Speaker 2: A podcast that does try to pump both clarity and
2:54
Speaker 2: hilarity into your brain. We hope that the universe is
2:57
Speaker 2: one that we can understand, that we could take it
2:59
Speaker 2: up hard into little bits that follow some fundamental rules.
3:03
Speaker 2: Then we can weave it back together into all the
3:05
Speaker 2: amazing and beautiful emergent phenomena that we enjoy from ourselves,
3:09
Speaker 2: to our planets, to our solar system, to everything beyond,
3:13
Speaker 2: and explain all of it to you with a little
3:14
Speaker 2: bit of Dad Joe hilarity sprinkled on top.
3:17
Speaker 1: Yeah, Because whether you're a physicist and astronomer, a cartoonists
3:20
Speaker 1: and energists, or a dad, we all live in this
3:24
Speaker 1: universe and we all look out there and we wonder
3:26
Speaker 1: how things work, why are things the way they are?
3:29
Speaker 1: And can you cerade math?
3:32
Speaker 2: Nobody wonders that man, Nobody wonders that that's done in
3:36
Speaker 2: the top one thousand questions. Humans ask, how do you know?
3:39
Speaker 1: Nobody wonders that, Daniel, do you have scientific proof or
3:42
Speaker 1: data to back up your claim.
3:44
Speaker 2: I do have some data. Yes, I cannot rule it
3:46
Speaker 2: out entirely. But over the many tens of thousands of
3:50
Speaker 2: questions I get from listeners, I've never gotten that one,
3:53
Speaker 2: which means it's not in the top one thousand questions.
3:56
Speaker 2: I can confidently say that.
3:57
Speaker 1: I see, But you can't say that nobody wonders that.
3:59
Speaker 2: No, right, that was too strong. You wonder that, apparently,
4:03
Speaker 2: and your people, So the exception proves the rule.
4:07
Speaker 1: I'm sure the situation has come up, like somewhere in
4:10
Speaker 1: the history of math, at some point some people needed
4:13
Speaker 1: to communicate some calculation or result and they couldn't talk
4:17
Speaker 1: for some reason.
4:18
Speaker 2: Maybe in Italian universities, you know, hand gestures are much
4:20
Speaker 2: more important in communicating these abstract ideas.
4:24
Speaker 1: Maybe that's why their equations have so much possess.
4:26
Speaker 2: Yes, exactly, whether we're Italian or not, or using charades
4:31
Speaker 2: or symbols or language, we are trying to make sense
4:33
Speaker 2: of the universe, and part of that involves categorizing it,
4:37
Speaker 2: saying this is one kind of thing. This is another
4:39
Speaker 2: kind of thing, whether that means distinguishing between particles and fields,
4:43
Speaker 2: or between living things and not living things, or planets
4:47
Speaker 2: and dwarf planets. Putting things in boxes is just one
4:50
Speaker 2: way the humans make sense of the universe, defining kinds
4:54
Speaker 2: of things and applying those labels.
4:56
Speaker 1: Willy nilly, yeah, And we are trying to make sense
4:58
Speaker 1: of the whole universe, not just the little things that
5:01
Speaker 1: we're made out of, then that things are made out of,
5:03
Speaker 1: but everything, all the huge amazing phenomena that are happening
5:07
Speaker 1: out there, the flying planets, the swirling galaxies, and the
5:11
Speaker 1: ginormous galaxy clusters.
5:13
Speaker 2: And we'd love to study all that in great detail,
5:15
Speaker 2: but most of it is very far away, and so
5:17
Speaker 2: far our technological eyeballs aren't powerful enough to really resolve
5:21
Speaker 2: all the details. So if we want to get down
5:24
Speaker 2: to the astronomical nitty gritty, we're best off studying our
5:27
Speaker 2: own backyard, looking in our solar system to understand how
5:31
Speaker 2: did it form, what's in it, what kinds of stuff
5:33
Speaker 2: are out there swirling around in our neighborhood. And over
5:36
Speaker 2: the last few hundred years, we've come to a pretty
5:38
Speaker 2: good understanding of what's there and where it's going.
5:41
Speaker 1: Yeah, we live in a pretty busy neighborhood full of planets,
5:45
Speaker 1: asteroid comets, raining satellites from failed rockets, and so there's
5:50
Speaker 1: a lot for us to see in our very near vicinity.
5:54
Speaker 2: And while the truth is that the Solar system is
5:56
Speaker 2: fills with a huge spectrum of stuff, from tiny cosmic
5:59
Speaker 2: dust to huge we asked giants to the Sun itself,
6:02
Speaker 2: we do like to impose categories on it. And as
6:04
Speaker 2: the decades and centuries go by, we keep discovering things
6:07
Speaker 2: that lie at the edge of those boundaries that challenge
6:10
Speaker 2: our definitions for what is what, Pluto of course being
6:14
Speaker 2: a famous example. But as our telescopes get more powerful,
6:17
Speaker 2: we keep discovering things in the wrong places or at
6:19
Speaker 2: the edge of these definitions that make us wonder, really,
6:22
Speaker 2: where do we draw these dotted lines?
6:24
Speaker 1: And so to be on the podcast, we will be
6:25
Speaker 1: tackling the question are there comments in the asteroid belt?
6:35
Speaker 4: Now?
6:35
Speaker 1: How many people do you think wonder about this question?
6:39
Speaker 1: Of your tens of thousands of emails, how many have
6:41
Speaker 1: asked this particular question.
6:43
Speaker 2: This particular question in this phrasing.
6:45
Speaker 1: Zero So you're saying the same amount of people that
6:50
Speaker 1: wonder if there are commets in the astert belt. Also
6:52
Speaker 1: probably perhaps wonder if you can cherate.
6:55
Speaker 2: Now if that was your metric. Yes, but there are
6:57
Speaker 2: a lot of questions in the vicinity of this, wondering
7:00
Speaker 2: about like what's the difference between comments and asteroids? Or
7:03
Speaker 2: why do we have comments out there and asteroids over here?
7:06
Speaker 2: And so I think people are curious about, like what's
7:09
Speaker 2: out there in the solar system? Why do we give
7:10
Speaker 2: them these labels? And is it really so neat and crisp?
7:14
Speaker 1: This is an interesting question, and so let's dig into it.
7:16
Speaker 1: And as usually, we were wondering how many out there
7:18
Speaker 1: had thought about this question of whether there are comets
7:21
Speaker 1: in the asteroid belt.
7:22
Speaker 2: Thanks very much to everybody who contributes their voice to
7:24
Speaker 2: this segment of the podcast. Really appreciate your responses. If
7:28
Speaker 2: you'd like to hear yourself on a future episode, please
7:32
Speaker 2: don't be shy or write to me too questions at
7:34
Speaker 2: Danielandjorge dot com.
7:36
Speaker 1: So think about it for a second, cast your mind
7:38
Speaker 1: out there into the far reaches of our solar system
7:41
Speaker 1: and wonder if there are comets in the asteroid belt.
7:44
Speaker 1: Here's what people had to say.
7:46
Speaker 4: I mean, sure, why not. Maybe they also pass through
7:50
Speaker 4: the asteroid belt from time to time. And I always
7:53
Speaker 4: thought asteroid belt was what's mainly in that reage, not
7:57
Speaker 4: what's the only thing in that region.
7:59
Speaker 5: I don't have very good idea of the definition of
8:01
Speaker 5: a comet versus an asteroid, but I think it has
8:04
Speaker 5: to do with amount of ice in the structure. So
8:09
Speaker 5: if that is the definition, I can imagine sure there
8:12
Speaker 5: might be something that falls under that definition in the
8:14
Speaker 5: asteroid belt.
8:14
Speaker 2: No comment in the asteroid belt, just asteroids. Comments are
8:18
Speaker 2: out a lot further.
8:19
Speaker 6: I think another sort of way to distinguish commets from
8:22
Speaker 6: asteroids is that asteroids are well in the asteroid belt,
8:25
Speaker 6: and comets can come from a couple different places. Long
8:28
Speaker 6: period comets come from the Oort Cloud, but then there
8:30
Speaker 6: are shorter period.
8:31
Speaker 2: Comets than that.
8:32
Speaker 6: Now, if we have a dirty snowball in the asteroid belt,
8:36
Speaker 6: which I believe there are. Some of these bodies that
8:38
Speaker 6: have been discovered, are they correctly labeled as comets?
8:41
Speaker 2: Are not commets? I'm always heard made up ice. I
8:44
Speaker 2: think if they were that close, they probably melt.
8:46
Speaker 7: I think comets coming in at a high rate of
8:48
Speaker 7: speed from the Oort cloud are unlikely to get caught
8:52
Speaker 7: up in the asteroid belt.
8:53
Speaker 1: Comments might be more about composition than trajectory. I mean
8:57
Speaker 1: that if it has more ice than rock, it might
9:00
Speaker 1: be a comet.
9:01
Speaker 3: I can never remember the difference between asteroids and comets.
9:04
Speaker 3: I mean, surely there's a good acronym or something out
9:06
Speaker 3: there to remember the difference. But I have to say
9:08
Speaker 3: that there's no comets in the asteroid belt because asteroids
9:10
Speaker 3: become comets after they and through the atmosphere.
9:13
Speaker 8: So there are short period comets, and I think there
9:15
Speaker 8: are some that operate closer to the Sun kind of
9:18
Speaker 8: in that asteroid belt range, but being within the ice
9:21
Speaker 8: line like most of its quote unquote life, I don't
9:25
Speaker 8: really see how they can be long lived.
9:26
Speaker 9: I think comets heavenly bodies which have eccentric orbits around
9:31
Speaker 9: the Sun, so they don't fit in nicely with the
9:33
Speaker 9: other better behaved inhabitants of the Solar System. So although
9:37
Speaker 9: comets may pass through the asteroid belt, I don't think
9:41
Speaker 9: they can remain there permanently.
9:43
Speaker 10: I think that the asteroid belt is far enough out
9:45
Speaker 10: so that comets could remain frozen, and I guess the
9:49
Speaker 10: asteroid belt does have a lot of its own gravity,
9:51
Speaker 10: so it could capture comets if it was lucky.
9:54
Speaker 7: I think there might be a few transient comets in
9:57
Speaker 7: the asteroid belt, but I don't think that there would
10:00
Speaker 7: much chance for comets to persist in that kind of
10:04
Speaker 7: orbit because of exposure to the Solar wind and the
10:08
Speaker 7: interaction of the gravity of Jupiter disrupting either the orbit
10:13
Speaker 7: or the structure of those comets.
10:14
Speaker 8: Guess there could be comets, but yeah, usually commas have
10:17
Speaker 8: a large orbit, a very large orbit in detail.
10:19
Speaker 2: That wouldn't be the case if it was found in
10:21
Speaker 2: the asteroid belt.
10:22
Speaker 1: So yeah, pretty wide range of answers here. I guess
10:25
Speaker 1: there's only two options, yes or no.
10:28
Speaker 2: Or there could be this is a trick question, or
10:30
Speaker 2: let's answer in charades, right.
10:35
Speaker 1: What made you think of this question? Why are there
10:37
Speaker 1: comets in the asteroid belt? Is this something that astromers
10:40
Speaker 1: have been wondering about.
10:41
Speaker 2: I've been thinking about this kind of question for a
10:43
Speaker 2: while because I find the whole labeling of stuff in
10:46
Speaker 2: the Solar System to be kind of ridiculous and arbitrary.
10:50
Speaker 2: You know, we're just humans putting dotted lines on a
10:52
Speaker 2: smooth spectrum of different kind of stuff that's out there.
10:55
Speaker 2: But also it is interesting because when you invent categories,
10:58
Speaker 2: then you can wonder about this in the boundaries or
11:00
Speaker 2: things across the boundaries. And then I read a paper
11:03
Speaker 2: about people who were finding weird stuff in the asteroid
11:06
Speaker 2: belt that didn't belong there.
11:08
Speaker 1: All right, well, let's dig into it, Daniel, I guess
11:11
Speaker 1: the question is, but comets and asteroids, what's the difference
11:14
Speaker 1: between the two?
11:15
Speaker 2: Yes, so these are two human constructed, arbitrary definitions that
11:19
Speaker 2: are mostly historical and don't really represent like our best
11:23
Speaker 2: understanding of what's out there in the Solar System. If
11:25
Speaker 2: you were going to start today, you probably wouldn't come
11:27
Speaker 2: up with the same definitions. But you know, science is
11:30
Speaker 2: a human endeavor, which means we need to understand the
11:32
Speaker 2: words scientists use when they talk to each other, even
11:34
Speaker 2: if it's imprecise or historical or ridiculous. So what do
11:37
Speaker 2: we mean by an asteroid and what do we mean
11:40
Speaker 2: by a comet? So an asteroid is basically like a
11:43
Speaker 2: mini planet. Right, there's this complicated definition of a planet
11:47
Speaker 2: as an object in the Solar System that's orbiting the
11:50
Speaker 2: Sun is big enough to be mostly round and has
11:54
Speaker 2: cleared its own path. An asteroid is like that, except
11:58
Speaker 2: that it's not necessarily big enough to be round, and
12:02
Speaker 2: it hasn't cleared its own path. So it's like a
12:05
Speaker 2: mini chunky, funky shaped planet that doesn't have its own
12:08
Speaker 2: parking space.
12:09
Speaker 1: But is there like a size a range, like can
12:13
Speaker 1: you have an asteroid size of a marble? Or or
12:17
Speaker 1: does that count of something else?
12:19
Speaker 2: Technically there's no minimum size for an asteroid, so like
12:22
Speaker 2: a dust grain, technically is an asteroid. Practically that's very,
12:26
Speaker 2: very difficult to see those things, you know, of course,
12:28
Speaker 2: unless they land on Earth, in which case they're no
12:30
Speaker 2: longer an asteroid. We can't really detect them in the
12:33
Speaker 2: asteroid belt unless they're very shiny or large, or some
12:36
Speaker 2: combination of them. So the range of asteroids that we've discovered,
12:40
Speaker 2: like in the asteroid belt goes from things like down
12:42
Speaker 2: to one meter across all the way up to things
12:45
Speaker 2: like five hundred kilometers across. So there's an incredible range
12:50
Speaker 2: of stuff in the asteroid belt that we call asteroids.
12:53
Speaker 2: We give them all the same name.
12:55
Speaker 1: But I guess there's one common threat, which is that
12:58
Speaker 1: it needs to be some kind of solidial, right, Like
13:01
Speaker 1: a cloud of gas doesn't count as an asteroid, right.
13:04
Speaker 2: Yeah, that's right, needs to hold itself together.
13:07
Speaker 1: So it has to be solid and it has to
13:08
Speaker 1: be in space. Is that about the definition of an asteroid?
13:12
Speaker 1: Something solid floating in space that's not round.
13:14
Speaker 2: And it has to be orbiting the Sun. It's a
13:16
Speaker 2: rocky object that orbits the Sun and doesn't qualify as
13:19
Speaker 2: being a planet or a comet.
13:22
Speaker 1: But I guess why does it need to be orbiting
13:24
Speaker 1: the Sun? Can't you have an asteroid other than space
13:26
Speaker 1: by itself? Like, what do you call those?
13:29
Speaker 2: Well, if it's not orbiting the Sun and it's orbiting
13:31
Speaker 2: like the Earth, then you'd call it a moon. If
13:34
Speaker 2: it's not orbiting the Sun and it's not really orbiting anything,
13:37
Speaker 2: it's just like floating in the galaxy, then it's not
13:40
Speaker 2: an asteroid. It's just a rock.
13:43
Speaker 1: Is that the official astronomy definition? It's just a space rock?
13:47
Speaker 1: Are you sure we don't want to anger any astronomers.
13:51
Speaker 2: Now, it's definitely don't. And you know, I'm in a
13:53
Speaker 2: department of physics and astronomy, and that doesn't make me
13:56
Speaker 2: an astronomer, even though I'm technically a professor of physics
13:59
Speaker 2: and astronomy. And I don't want to speak for the astronomers,
14:03
Speaker 2: but that is my understanding. If it's out there in
14:05
Speaker 2: interstellar space, you could call it an interstellar asteroid. I
14:08
Speaker 2: suppose the problem is we haven't like discovered or seen
14:12
Speaker 2: many of those. You know, we have had a couple
14:13
Speaker 2: of interstellar objects come, but those who think are interstellar
14:17
Speaker 2: comets not interstellar asteroids. So yeah, that's a whole new frontier.
14:22
Speaker 1: Yeah, like like in Star Wars when they run into
14:24
Speaker 1: like an asteroid field, are they takenly not calling it
14:27
Speaker 1: the right thing?
14:28
Speaker 2: Well? I think those are usually near a stars. There
14:31
Speaker 2: probably are orbiting a star.
14:33
Speaker 1: I don't know, they never show the star.
14:36
Speaker 2: That's what I'm always thinking about when they're dodging asteroids.
14:38
Speaker 2: Where's the star that makes us an asteroid and not
14:41
Speaker 2: a rock?
14:42
Speaker 1: Excuse me? Excuse me, I don't see the sun actually,
14:48
Speaker 1: all right, So an asteroid is by definition a rock
14:52
Speaker 1: that's orbiting the sun. Basically, Yeah, that has to be solid, right,
14:56
Speaker 1: or like a solid object that's orbiting the Sun.
14:59
Speaker 2: Yeah, and your point about it being solid as crucial.
15:01
Speaker 2: Asteroids are rocky objects, meaning they're made of rock and
15:05
Speaker 2: metal and this kind of stuff, and that's going to
15:07
Speaker 2: help us distinguish them from their cousin the comet.
15:11
Speaker 1: Gosh, well, how do you define a rock?
15:13
Speaker 2: A rock is something made it mostly out of silica?
15:16
Speaker 2: You know, the chemical composition of these things tells you
15:18
Speaker 2: what it is. If it's a blob of iron, then
15:20
Speaker 2: it's metal, you know, if it's a This is all chemistry. Man,
15:24
Speaker 2: it's well beyond me. Don't ask me to do chemistry.
15:26
Speaker 1: Joined the Department of physic Astronomy and chemistry.
15:29
Speaker 2: No, never, never, My son is into chemistry.
15:33
Speaker 1: Yeah, I guess. I guess all those professors just don't
15:35
Speaker 1: have the chemistry.
15:37
Speaker 2: I don't have chemistry with those professors, that's for sure. No.
15:40
Speaker 2: I respect chemistry, I respect chemists, but I'm not that
15:43
Speaker 2: in the history of asteroids is kind of fascinating because,
15:47
Speaker 2: you know, we use these words, but for a long time,
15:49
Speaker 2: people didn't really distinguish between planets and asteroids, and the
15:53
Speaker 2: word planet was used very broadly, Like the moon was
15:56
Speaker 2: a planet for a while before we invented the concept
15:59
Speaker 2: of a moon. So these things change with time. It's
16:01
Speaker 2: possible to redefine what is a planet or an asteroid
16:04
Speaker 2: maybe in five hundred years astronomers will have totally different
16:07
Speaker 2: words for these things, or use the same words in
16:09
Speaker 2: a different way. Who knows.
16:11
Speaker 1: Yeah, or maybe they'll use the same like charade gesture.
16:15
Speaker 2: That's exactly when we transition fully to charade science.
16:19
Speaker 1: Then we're I wonder if in the future we transition
16:21
Speaker 1: to like telepathy, you know, then you don't need words,
16:25
Speaker 1: you can just transfer thoughts.
16:26
Speaker 2: All right, Well, if we're playing charades and your clue
16:29
Speaker 2: was asteroid, what motions would you use to describe it?
16:33
Speaker 1: Oh, that's totally easy, Dan, I would do this, so
16:38
Speaker 1: he totally conveys what asteroid means.
16:40
Speaker 2: Okay, that's a funny way to duck the question. But seriously,
16:43
Speaker 2: can you describe what an asteroid gesture would be?
16:46
Speaker 1: I just did, all right, but I feel like we're
16:51
Speaker 1: getting a little bit uh deilled.
16:54
Speaker 2: Well, then let's go back to the history of asteroids,
16:57
Speaker 2: because I also think it's fascinating when we knew there
17:00
Speaker 2: were lots of asteroids, Like, as our technology developed to
17:03
Speaker 2: be able to see these things, right, we can see
17:05
Speaker 2: smaller and smaller ones. Then we discovered more, and it's
17:08
Speaker 2: this incredible sort of explosion of discovery.
17:11
Speaker 1: But how do we see them? Like you sort of
17:13
Speaker 1: can't see asteroids with the naked eye, can you? Or
17:16
Speaker 1: sometimes if they catch the sun.
17:18
Speaker 2: Technically, I don't see why you couldn't have photons hit
17:21
Speaker 2: an asteroid and then hit your eye, but enough of
17:24
Speaker 2: them for you to spot it and identify it seems
17:27
Speaker 2: very challenging. So asteroids are usually seen through telescopes just
17:31
Speaker 2: because you know, the aperture is larger and you're gathering
17:34
Speaker 2: more light and so it's basically a bigger eyeball.
17:37
Speaker 1: So is that how they discover them? Like they were
17:39
Speaker 1: looking through a telescope and they saw a bunch of
17:41
Speaker 1: these They probably looked like pinpoint stars, but they were
17:45
Speaker 1: probably moving faster than the regular stars.
17:47
Speaker 2: Exactly the same way that planets move across the field
17:50
Speaker 2: of the stars, which is how you know that they're closer, right,
17:53
Speaker 2: And that's why sort of planets and asteroids were called
17:56
Speaker 2: the same thing for a long time before we distinguished
17:58
Speaker 2: between them somewhat arbitrarly. And you know, until one hundred
18:02
Speaker 2: and fifty years ago, we thought there were six ish planets,
18:04
Speaker 2: and we thought there were about ten asteroids. Like eighteen
18:07
Speaker 2: forty nine, we knew about ten different asteroids, and then
18:11
Speaker 2: as technology improved, that number grew to be one hundred
18:14
Speaker 2: twenty years later to a thousand about one hundred years ago.
18:19
Speaker 2: And now we know about more than a million individual
18:22
Speaker 2: asteroids that can be tracked, and we have these telescopes
18:26
Speaker 2: that look at these things, of course, because we're concerned
18:28
Speaker 2: about whether one of them might eventually hit the Earth.
18:31
Speaker 2: And NASA is tracking all of these things. And as
18:34
Speaker 2: you say, they don't glow, but they do reflect the sun,
18:36
Speaker 2: and so when the conditions line up for like photons
18:40
Speaker 2: from the Sun to hit the asteroid and then reflect
18:42
Speaker 2: back into the telescope aperture, that's when we see it.
18:46
Speaker 2: But a lot of these things are invisible for long
18:48
Speaker 2: fractions of their flight around the Sun.
18:50
Speaker 1: Now, what was the technological advance that it allows us
18:54
Speaker 1: to see so many Like you just we just got
18:56
Speaker 1: bigger telescopes and we're more sensitive. They could see dimmer things,
19:00
Speaker 1: or we could maybe zoom with more presitionion into certain
19:04
Speaker 1: parts of the sky.
19:06
Speaker 2: Yeah, it's a combination of more telescopes and bigger telescopes.
19:10
Speaker 2: So a lot of this is limited by glass technology.
19:14
Speaker 2: Can you make lenses that are big and smooth and
19:16
Speaker 2: free of aberrations and so like Galileo's original telescopes are
19:20
Speaker 2: pretty bad, right, and limited by the size of the
19:23
Speaker 2: telescope you could make, because the glass you could grind
19:26
Speaker 2: and have it to be smooth and not create distortions
19:29
Speaker 2: was pretty small. But then people got a lot better
19:31
Speaker 2: about that about one hundred and fifty years ago, and
19:34
Speaker 2: things exploded from there, and then we also just built
19:37
Speaker 2: more of them, and now of course we have dedicated
19:40
Speaker 2: space telescopes just out there looking for these things.
19:43
Speaker 1: Meli Nastas, that's pretty wild. I mean, if you could
19:46
Speaker 1: see the way these telescopes could see, you would see
19:49
Speaker 1: the night sky basically like shifting all the time, right, moving, swirling, spinning.
19:54
Speaker 2: Yeah, it's much more dynamic than you imagine. There's a
19:57
Speaker 2: lot of stuff out there. There's also inflection point in
20:01
Speaker 2: sort of the history of astronomy in the mid nineties
20:04
Speaker 2: when Jupiter was hit by a comet. Comet shoemaker Levee
20:07
Speaker 2: broke up as it entered the inner Solar system, whipped
20:10
Speaker 2: around the Sun, and then each of the twenty six
20:13
Speaker 2: or so pieces slammed into Jupiter, creating huge fireballs the
20:16
Speaker 2: size of the Earth and that's made people wake up
20:19
Speaker 2: to the idea that like, wow, you know, asteroids of
20:21
Speaker 2: comets really could hit the Earth. This is potentially an
20:24
Speaker 2: existential threat, and NASA has really been investing in tracking
20:28
Speaker 2: near Earth objects ever since that moment comet shoemaker levee.
20:32
Speaker 2: That's one reason why we went from like seeing some
20:35
Speaker 2: of the asteroids to like, let's be serious about this,
20:37
Speaker 2: folks and make a solid catalog of all the biggest ones.
20:42
Speaker 1: Okay, so that's asteroids, and most asteroids are in the
20:45
Speaker 1: asteroid belt, right, or there's a couple of belts around
20:47
Speaker 1: the Solar System.
20:48
Speaker 2: Yeah, asteroids are mostly in the asteroid belt, which is
20:52
Speaker 2: between Mars and Jupiter. And that's not an accident, right.
20:55
Speaker 2: The reason we have asteroids is basically because of Jupiter.
20:59
Speaker 2: Jupiter has a huge, huge fraction of the mass of
21:01
Speaker 2: the Solar System that's not in the Sun. Like the
21:04
Speaker 2: Sun is ninety nine percent of the mass of the
21:06
Speaker 2: Solar System, and Jupiter is almost three times the mass
21:09
Speaker 2: of everything else in the Solar System combined, including like
21:13
Speaker 2: Saturn and Neptune and Urinous. So it's a big massive
21:16
Speaker 2: thing and it's gravity.
21:18
Speaker 1: Wait what so like seventy five percent of the non
21:22
Speaker 1: sun mass in the Solar system is Jupiter.
21:24
Speaker 2: Yeah, Jupiter is a big hog.
21:26
Speaker 1: You know, I'm not sure we should be shaming Jupiter, Daniel.
21:31
Speaker 2: You're taking big hog to be pejorative. I meant it
21:33
Speaker 2: as a compliment, like, hey, good job, Jupiter, congrats.
21:38
Speaker 1: I don't know. I guess it was your tone.
21:40
Speaker 2: Okay, Hey, Jupiter is a big hog. Has that. But
21:45
Speaker 2: you know, this is gravitational runaway effect at work. You
21:48
Speaker 2: have a huge cloud of gas and dust that forms
21:50
Speaker 2: the Solar system. Somewhere in there is an initial density
21:54
Speaker 2: that causes the collapse that's going to turn into the Sun,
21:57
Speaker 2: but it's somewhere else in that nearby cloud also has
22:00
Speaker 2: a little spot of density. Then it can form its
22:03
Speaker 2: own little runaway effect to gobble up some of that
22:06
Speaker 2: gas and dust before it falls into the Sun. And
22:09
Speaker 2: that's what Jupiter did.
22:11
Speaker 1: Now, Jupiter is mostly made out of gas. So I
22:13
Speaker 1: wonder why got so much of the gas in the
22:15
Speaker 1: Solar system, Like, did it some of it just blow
22:18
Speaker 1: away when the Sun ignited or what and it just
22:21
Speaker 1: happened to gather around Jupiter.
22:22
Speaker 2: Yeah, there's a lot of controversy about that where gas
22:25
Speaker 2: giants form. Do they mostly form in the outer Solar
22:28
Speaker 2: System and then transition inward? Do they form in the
22:30
Speaker 2: inner Solar System? We see a lot of gas giants
22:33
Speaker 2: in exoplanet systems that are near their Sun, but we
22:36
Speaker 2: think probably these gas giants form farther away because further
22:40
Speaker 2: away from the Sun. Number one, the gas isn't being
22:43
Speaker 2: blown away by the radiation of the Sun. And number two,
22:47
Speaker 2: there's ice there, which helps these planets to crete more quickly.
22:50
Speaker 2: There's like more stuff to gather. So we think that
22:53
Speaker 2: Jupiter became so big because it's so close to that
22:56
Speaker 2: snow line, you know, where ice and frozen vapor can
22:59
Speaker 2: still exis. It helps these planets accrete quickly. And then
23:03
Speaker 2: we think it's probably a complicated history of Jupiter moving
23:05
Speaker 2: in towards the Sun and then getting pulled back out
23:09
Speaker 2: by a now missing gas giant which was ejected in
23:12
Speaker 2: that interaction. So the whole formation of Jupiter is a
23:15
Speaker 2: really fascinating and complex topic.
23:18
Speaker 1: All right, Well, let's dig into where else in the
23:21
Speaker 1: Solar System you might find asteroids, and then we'll dig
23:23
Speaker 1: into comets and whether there are any in the asteroid belt.
23:27
Speaker 1: So we'll get to that But first, let's take a
23:29
Speaker 1: quick break. All right, we're talking about asteroids, comets and
23:45
Speaker 1: belts and the fact that Jupiter needs a really big
23:47
Speaker 1: built and the question is are there comets in the
23:52
Speaker 1: asteroid belt? So we've been talking about asteroids what they are,
23:55
Speaker 1: and you said they're mostly in the asteroid build but
23:57
Speaker 1: can you find them anywhere else in the Solar System?
24:00
Speaker 2: You can find them also in Jupiter's orbit. So there's
24:03
Speaker 2: a big blob of asteroids ahead of Jupiter in its
24:07
Speaker 2: orbit and another one behind Jupiter in its orbit. They're
24:10
Speaker 2: like bleeding and trailing Jupiter. These are called the Greeks
24:14
Speaker 2: and the Trojans, and these are just like big clumps
24:17
Speaker 2: of rock that are in Jupiter's orbit. So you know, technically,
24:20
Speaker 2: did Jupiter really clear its orbit? Is Jupiter even a planet?
24:25
Speaker 1: Well? I mean is if these things are orbiting Jupiter,
24:27
Speaker 1: then they're not asteroids, right, No, these.
24:29
Speaker 2: Things are orbiting the Sun in the same orbit as Jupiter.
24:33
Speaker 2: Oh yeah, and all of this is just dominated by
24:37
Speaker 2: Jupiter's gravity. Like why don't the rocks in the asteroid
24:40
Speaker 2: belt come together to make another planet the way they
24:43
Speaker 2: did for Earth or for Mercury, or even for Mars.
24:46
Speaker 2: The answer is Jupiter's gravity distorts it. It pulls it apart,
24:50
Speaker 2: it shreds things. These are all tidal forces. Jupiter's gravity
24:54
Speaker 2: is so strong that if you try to pull these
24:55
Speaker 2: things together, It's gravity would tug on one side harder
24:59
Speaker 2: than the tug's on the other side and pull it apart.
25:02
Speaker 2: So it's sort of like mixes it up. It's I
25:03
Speaker 2: got a big spoon, and it keeps stirring up the
25:06
Speaker 2: asteroid belt and keeping it from coalescing into something.
25:09
Speaker 1: Whoa, It just disrupts the formation of any planets in
25:13
Speaker 1: that sort of neighborhood exactly. Do we have any asteroids
25:17
Speaker 1: out there beyond the gas giants?
25:20
Speaker 2: There are definitely rocks further out in the Solar System,
25:23
Speaker 2: because remember any big rocky object that's not a planet
25:26
Speaker 2: or a dwarf planet is technically an asteroid. There's some
25:30
Speaker 2: fuzziness there because past Neptune there's a huge number of
25:34
Speaker 2: these objects were called dwarf planets, which are like sort
25:37
Speaker 2: of larger enough to be called a planet maybe but
25:40
Speaker 2: haven't cleared their own path right like Pluto and Shareon
25:44
Speaker 2: for example. And so the distinction between dwarf planet and
25:47
Speaker 2: asteroid out there, and the edges of the Solar system
25:50
Speaker 2: is pretty fuzzy. You'd have to ask an astronomer.
25:53
Speaker 1: Okay. So then the question was are there commets in
25:56
Speaker 1: the asteroid belt? So now, how do you define what
25:58
Speaker 1: a comet is?
26:00
Speaker 2: So your comment earlier about asteroids that they have to
26:03
Speaker 2: be solid was really on point because one of the
26:06
Speaker 2: crucial ways we define a comet is very similar to
26:10
Speaker 2: the way we define an asteroid. An asteroid is a
26:13
Speaker 2: rocky object that orbits the sun. A comet is an
26:17
Speaker 2: icy and dusty object that orbits the sun.
26:20
Speaker 1: Icy. So it's made out of ice. But isn't ice
26:23
Speaker 1: technically a mineral, which means it's a rock? Right?
26:27
Speaker 2: Yeah, there's a distinction here. Ice is not like a silicate, right,
26:30
Speaker 2: It doesn't have the same chemical composition as these things
26:34
Speaker 2: we call it rocks.
26:35
Speaker 1: Excuse me, Daniel, excuse me. I believe. I believe that
26:39
Speaker 1: the definition of a rock is like a composite of minerals, right,
26:44
Speaker 1: and ice is a mineral. So wouldn't ice be a rock?
26:48
Speaker 1: Or is this something that would be have to be
26:50
Speaker 1: decided in a death match between geologists and astronomer Yeah?
26:53
Speaker 2: And I think some chemistsy to be involved in that conversation.
26:57
Speaker 2: But in terms of the Solar System, we distinguish between
27:00
Speaker 2: ice and other kinds of rock or rocks, depending on
27:03
Speaker 2: whether you're gonna call ice.
27:05
Speaker 1: A rock and so ice. How do you define ice?
27:07
Speaker 1: Does it need to be water or can it be
27:09
Speaker 1: other liquids?
27:09
Speaker 2: There's several categories there. First of all, water ice has
27:13
Speaker 2: lots of different chemical forms, so it's not just the
27:15
Speaker 2: kind of ice that we see on Earth. There's like
27:18
Speaker 2: ice and ice three, and ice seven and ice nine,
27:20
Speaker 2: all sorts of complicated water chemistry to give you solid
27:24
Speaker 2: forms of ice that we don't often see on Earth
27:26
Speaker 2: because it's a very different pressure environment out there in
27:29
Speaker 2: the outer Solar system. But also you know things like methane.
27:33
Speaker 2: If that's frozen, they call that ice. A lot of
27:35
Speaker 2: the ice that's out there is water ice, but there
27:37
Speaker 2: are also other kinds of ices.
27:39
Speaker 1: Gosh, I have so many nitpicky questions, Daniel. I mean, like,
27:44
Speaker 1: if you heat up a rock, it'll melt, so it's liquid.
27:47
Speaker 1: So really a rock is just frozen liquid rock.
27:49
Speaker 2: Yes, a rock is frozen liquid rock, But lots of
27:52
Speaker 2: solids are frozen liquids, right.
27:54
Speaker 1: How do you define what an ice is?
27:56
Speaker 2: There's an arbitrary dotted line, you know, it's just historical
28:00
Speaker 2: crystals we call ices, some crystals we call rocks. And that's, frankly,
28:03
Speaker 2: is my whole problem with chemistry. All of chemistry is
28:06
Speaker 2: like this, just like draw dotted lines between stuff because
28:09
Speaker 2: some dude one hundred and fifty years ago thought that
28:11
Speaker 2: made sense. We're sticking to it.
28:13
Speaker 1: Well, it sounds like it's not just chemistry, it's physics.
28:15
Speaker 1: And it's proud of me too. Why are you trying
28:17
Speaker 1: chemist under the bus.
28:18
Speaker 2: We're definitely guilty of that in physics and in astronomy,
28:21
Speaker 2: and especially in this situation naming things in the Solar system.
28:25
Speaker 2: But and I'm really going to catch a lot of
28:27
Speaker 2: flak from the chemists out there. I feel like all
28:29
Speaker 2: of chemistry is just built on that. Like, if you
28:31
Speaker 2: took that away from chemistry, what do you have left?
28:33
Speaker 9: Man?
28:34
Speaker 2: It's all just exceptions.
28:36
Speaker 1: Oh man, he just lost is a bunch of chemists listeners?
28:40
Speaker 2: No, man, they're all going to write to me and
28:41
Speaker 2: they're gonna listen carefully through all the next episodes to
28:43
Speaker 2: see if I slight chemistry.
28:45
Speaker 1: I see they're gonna hate listen. That's the kind of
28:48
Speaker 1: fan that we want. Look, as long as they sit
28:51
Speaker 1: through the ads, then we don't care why.
28:53
Speaker 2: They're love listen or hate listen.
28:54
Speaker 1: We love you, all right. But so then what does
28:59
Speaker 1: that leave with about the definition of a comet.
29:02
Speaker 2: So, according to the arbitrary distinction between ices and rocks,
29:06
Speaker 2: comets are made out of ice and asteroids are made
29:09
Speaker 2: out of rocks. And one important difference is that if
29:12
Speaker 2: you bring something made out of ice into the Inner
29:14
Speaker 2: Solar System, it tends to vaporize, Like the Sun is
29:18
Speaker 2: capable of turning those ices into vapor, and it's not
29:21
Speaker 2: capable of doing that with rock. So probably there's some
29:24
Speaker 2: distinction there about like the melting point or the vapor
29:26
Speaker 2: point of these substances.
29:28
Speaker 1: Oh, I see, all right, now we're getting somewhere. It's
29:31
Speaker 1: the sort of scientific If it melts under the light
29:34
Speaker 1: of the sun, then you might call it a comet.
29:37
Speaker 1: That's basically the only distinction.
29:38
Speaker 2: That yeah, yeah, And when you bring these things into
29:40
Speaker 2: the inner Solar System, like comets traditionally originate in the
29:45
Speaker 2: Kuiper Belt or in the Oort Cloud, which are kind
29:48
Speaker 2: of like bands of rocks in the more distant parts
29:50
Speaker 2: of the Solar System, much further out than the asteroid belt.
29:54
Speaker 2: When you bring them into the inner Solar System, they
29:56
Speaker 2: develop tails because the Sun is beginning to vaporize them.
30:00
Speaker 2: They get a coma, they have like a little envelope
30:02
Speaker 2: of gas around them, and then as they move in
30:05
Speaker 2: towards the Solar System, they get tails. And so that's
30:08
Speaker 2: really what distinguishes comets from asteroids. Asteroids are just rocks,
30:12
Speaker 2: and comets have these little gas clouds and tails because
30:14
Speaker 2: they're made out of ices.
30:17
Speaker 1: All right, and they mostly hang out on the outside
30:20
Speaker 1: of the Solar System.
30:21
Speaker 2: Right, Yeah, they originate in the Kuiper Belts, which is
30:24
Speaker 2: this big collection of rocks, billions and billions of snowballs
30:29
Speaker 2: in the distant Solar system, and this is probably the
30:31
Speaker 2: origin of short period comets, like you know, years up
30:34
Speaker 2: to tens of years. And then we think there's a
30:36
Speaker 2: collection of them also much much further out in the
30:39
Speaker 2: Ort Cloud, which is like very far out there, much
30:42
Speaker 2: further than Pluto. And it's also technically theoretical because we've
30:47
Speaker 2: never actually seen the Orc Cloud. We've just like deduced
30:50
Speaker 2: its existence from various gravitational calculations and models. And we
30:55
Speaker 2: also think that it's a source of long period comets,
30:58
Speaker 2: comets with periods, you know, again longer than tens or
31:01
Speaker 2: hundreds of years, and they could take a very long
31:03
Speaker 2: time to fall into the inner Solar System. And out
31:06
Speaker 2: there there could be trillions of these snowballs.
31:09
Speaker 1: And that's in the or cloud. So what's the Kuiper belt?
31:12
Speaker 1: Is it asteroids or comets?
31:14
Speaker 2: The Kuiper Belt is snowballs, and when they fall into
31:16
Speaker 2: the Inner Solar System you call them comets. I think
31:19
Speaker 2: you still call them comets when they're in the Kuiper
31:20
Speaker 2: Belt before they've fallen in, because technically they are icy
31:24
Speaker 2: objects out in the Solar System orbiting the Sun.
31:27
Speaker 1: Because they would melt if they got closer to the Sun.
31:30
Speaker 1: But doesn't everything melt if you get close enough to
31:32
Speaker 1: the Sun?
31:32
Speaker 2: Yeah, exactly, And so this distinction between asteroids and comets
31:35
Speaker 2: is also a little bit fuzzy. I found a comet
31:38
Speaker 2: from an astronomer or the University of Arizona who said, quote,
31:41
Speaker 2: everything is a comet. If you brought my couch close
31:44
Speaker 2: enough to the Sun, it would start melting and have
31:46
Speaker 2: a coma. So like it's just a question of how
31:48
Speaker 2: close you get to the Sun. Because you bring an
31:50
Speaker 2: asteroid close enough to the Sun, it's going to get vaporized,
31:53
Speaker 2: even if it's like a hunk of iron.
31:56
Speaker 1: What if it's a hunk of like diamond.
31:58
Speaker 2: If you dropped a huge diamond into the Sun, it
32:00
Speaker 2: would definitely get vaporized.
32:02
Speaker 1: Yeah, into the Sun.
32:04
Speaker 2: If you had a huge diamond and you dropped it
32:05
Speaker 2: from the outer Solar system and it fell in towards
32:08
Speaker 2: the Sun, there at some point at which it would
32:10
Speaker 2: reach its melting point, and you would melt that.
32:12
Speaker 1: Diamond and become a diamond commet.
32:15
Speaker 2: A diamond, commet with a cloud of carbon.
32:17
Speaker 1: And leave a trail of sparkly melted diamonds.
32:21
Speaker 2: Yeah. I think melted diamond is just carbon though, because
32:24
Speaker 2: it's only diamond because of the arrangement of those carbon atoms,
32:27
Speaker 2: and so once you melted it could it's the same
32:29
Speaker 2: as like melted coal. I guess.
32:31
Speaker 1: Oh, man, now we're getting really confusing.
32:33
Speaker 2: Turn chemistry is a mess.
32:36
Speaker 1: Is melted chocolate just carbon?
32:38
Speaker 3: Then?
32:38
Speaker 1: Oh no, amre I just eating coal when I when
32:42
Speaker 1: I'm drinking my hot coco.
32:45
Speaker 2: That's why putting these names on things is such a mess,
32:48
Speaker 2: and we should just use math or charades.
32:50
Speaker 1: That's why would you just use charades or speed up
32:54
Speaker 1: the telepathy idea.
32:57
Speaker 2: And then to make things even more confusing, there's another
32:59
Speaker 2: counter glory of stuff that's sort of like a hybrid,
33:03
Speaker 2: these things that are actually brilliantly named. They call them centaurs.
33:07
Speaker 2: You know, centaurs are like half horse, half human. These
33:10
Speaker 2: things have characteristics of asteroids and characteristics of comets. So
33:16
Speaker 2: they're sort of like a comet because they have long
33:19
Speaker 2: elliptical orbits the way comets do, and some of them
33:22
Speaker 2: have dust comas. But they're kind of like asteroids in
33:26
Speaker 2: that they're really large and they're mostly metallic. But they're
33:29
Speaker 2: not like asteroids because they leave the asteroid belts and
33:32
Speaker 2: they sort of traverse the Solar system the way comets do.
33:36
Speaker 2: So these centaurs are sort of like a weird thing
33:39
Speaker 2: in the Solar system that blurs the line between asteroid and.
33:42
Speaker 1: Comet, meaning like it's a mix of rocks and ice.
33:46
Speaker 2: Yeah, exactly, And it sort of moves like a comet,
33:49
Speaker 2: and it's the size of an asteroid. These things tend
33:51
Speaker 2: to be typically bigger.
33:52
Speaker 1: Wait, what do you mean it moves like a comet?
33:54
Speaker 1: You never said motion was part of the definition.
33:57
Speaker 2: Yeah, it's not technically part of the definition, right, But
34:00
Speaker 2: comets tend to have these longer elliptical orbits just because
34:03
Speaker 2: of where they come from in the Solar System. They
34:05
Speaker 2: come from further out, and so they have these longer
34:08
Speaker 2: orbits that traverse the path of the giant planets, whereas
34:11
Speaker 2: asteroids typically hanging out in the asteroid belt and sometimes
34:14
Speaker 2: fall in and so they don't traverse the giant planets.
34:18
Speaker 2: So if you have like an asteroid like rock that
34:20
Speaker 2: also has a long elliptical orbit, you're like, hmm, it's
34:23
Speaker 2: a little comedy. It's a little asteroid y. You know.
34:26
Speaker 2: It's sort of like chocolate and peanut.
34:27
Speaker 1: Butter, which we all know. If you melt it just
34:30
Speaker 1: becomes carbon.
34:31
Speaker 2: And if you squeeze it hard enough, it becomes a diamond.
34:34
Speaker 1: Yeah, technically a chunky diamond or a smooth diamond.
34:38
Speaker 2: Yeah, maybe a creamy diamond.
34:39
Speaker 1: Yeah, or me a carrot diamond.
34:40
Speaker 2: I like my diamonds nicely salted.
34:42
Speaker 1: So these centers are pretty interesting. How big can they get?
34:45
Speaker 2: Some of them are pretty big, Like the largest one
34:47
Speaker 2: is two hundred and seventy kilometers across and Actually it's
34:52
Speaker 2: so big that it has its own rings, like a
34:55
Speaker 2: little group of dust and tiny rocks orbiting this centaur.
34:59
Speaker 1: Well, and where is that it orbits in.
35:00
Speaker 2: The Solar system out there between Saturn and Urinus. So
35:05
Speaker 2: it's a big blob out there, and it's sort of
35:07
Speaker 2: weird to be that far out. Why isn't it in
35:09
Speaker 2: the asteroid belt? Or if it's that far out, why
35:12
Speaker 2: doesn't that have more ice? You know? You might ask also,
35:15
Speaker 2: well why do all the objects and what we call
35:17
Speaker 2: the asteroid belt, why are they mostly rocks and metal
35:20
Speaker 2: and the stuff out there in what we call the
35:22
Speaker 2: Kuyper belt in the or cloud, why do they have
35:24
Speaker 2: more ices? And that's just distance from the sun. If
35:27
Speaker 2: you're further from the Sun, then the sun is not
35:29
Speaker 2: bright enough, not hot enough to vaporize all that stuff,
35:32
Speaker 2: so you get these ices. And that's why comets when
35:35
Speaker 2: they form out there, are icy and asteroids are not.
35:38
Speaker 2: The way the Earth is not mostly icy, right, and
35:41
Speaker 2: so it's weird to have an object that's out there
35:44
Speaker 2: beyond the snow line that doesn't have as much snow
35:47
Speaker 2: or ice as everything else.
35:50
Speaker 1: And how do we know it's a scenter? Does it
35:52
Speaker 1: have a tail.
35:53
Speaker 2: This one is big enough that it might have its
35:55
Speaker 2: own like little atmosphere, right, things that are boiling off
35:58
Speaker 2: of it. But we don't know the compassation of it
36:00
Speaker 2: that well, it's sort of far enough away that it's
36:02
Speaker 2: difficult to study. But we do see that has its
36:05
Speaker 2: own ring systems, so we have some information about it.
36:08
Speaker 2: But these things are really fascinating because they paint sort
36:11
Speaker 2: of a picture of the history of the solar system.
36:13
Speaker 2: A lot of this stuff is interesting in the context
36:15
Speaker 2: of like, hey, how did we get here? How did
36:17
Speaker 2: our solar system end up the way that it is?
36:20
Speaker 2: All these things are clues that let us like back
36:22
Speaker 2: out that story and figure out how it all got
36:25
Speaker 2: arranged to be this way.
36:28
Speaker 1: So can we tell what it's made out of?
36:30
Speaker 2: With our telescopes, we can tell a little bit because
36:32
Speaker 2: of the color, Like some of these things are a
36:34
Speaker 2: little bluer and some of these things are a little redder.
36:37
Speaker 2: That gives us a clue as to what they are,
36:40
Speaker 2: because what they are determines you know, what they're reflecting
36:43
Speaker 2: and what they're absorbing. So we have some clues about
36:45
Speaker 2: their chemical composition. But that's also sort of a mystery,
36:48
Speaker 2: Like some of these centaurs are bluer, and some of
36:50
Speaker 2: these are redder. Some of them look more like asteroids,
36:53
Speaker 2: some of them look less like asteroids. That's sort of
36:55
Speaker 2: one of the central mysteries of centaurs. But none of
36:58
Speaker 2: these things have been like foot Graft up close. A
37:01
Speaker 2: lot of Solar System objects have been visited by probes,
37:04
Speaker 2: like we recently had up close pictures of Pluto, which
37:07
Speaker 2: is awesome, and most of the moons of Saturn and
37:10
Speaker 2: Jupiter have been visited. But nobody's ever done a close
37:13
Speaker 2: flyby of a centaur to take like crisp photos of
37:17
Speaker 2: its surface and see what it's made out of and
37:19
Speaker 2: what that surface looks like. It'd be really fascinating.
37:22
Speaker 1: But wait, how do we know what they're made out of?
37:24
Speaker 2: Then we don't know for sure. It's just really guesses
37:26
Speaker 2: based on the spectrometry looking at the wavelength of light
37:29
Speaker 2: that bounces off of it. So we have ideas.
37:32
Speaker 1: How do you assume that it has I in it?
37:34
Speaker 2: Because they look different from the asteroids, right, they have
37:36
Speaker 2: different reflections than asteroids do m All.
37:40
Speaker 1: Right, Well, let's get to the question of the episode,
37:42
Speaker 1: which is are there comments in the asteroid belt So
37:46
Speaker 1: let's tackle that. But first let's take another quick break.
38:01
Speaker 1: All right, we're talking about comets, asteroids, and centaurs and
38:07
Speaker 1: also a charades.
38:09
Speaker 2: So in your house, who typically wins the games of charades?
38:12
Speaker 1: We never play charades.
38:14
Speaker 2: What you're such a big proponent on the podcast, but
38:16
Speaker 2: you don't practice that at home.
38:18
Speaker 1: That's what I'm trying to see, Daniel, is bring more
38:20
Speaker 1: charates into everyone's homes. So we're tackling today the question
38:23
Speaker 1: are there comments in the asteroid belt? Now, Daniel? Is
38:27
Speaker 1: the answer yes or no?
38:28
Speaker 2: The answer is that there's some weird stuff in the
38:31
Speaker 2: asteroid belt that we don't understand. In nineteen ninety six,
38:36
Speaker 2: people saw something in the asteroid belt that had a coma,
38:40
Speaker 2: Like it has this gas and envelope in it, so
38:43
Speaker 2: it looks like it's melting in the presence of the sun.
38:45
Speaker 10: Wait.
38:46
Speaker 1: Wait, so that the tail of a comet, you call
38:47
Speaker 1: it a coma.
38:48
Speaker 2: The tail is when it's moving, a coma is like
38:50
Speaker 2: the envelope that surrounds It's sort of like a little atmosphere,
38:53
Speaker 2: but it's not really an atmosphere because it's not holding
38:55
Speaker 2: onto it gravitationally. It's just sort of like off gassing.
38:59
Speaker 2: It's like melting the vapor that's coming off as the
39:01
Speaker 2: sun is melting it.
39:02
Speaker 1: That's the coma, like an ara or like a cloud
39:05
Speaker 1: of a vapor around it.
39:07
Speaker 2: Yeah, exactly. And then if it's in motion, it's going
39:09
Speaker 2: to leave that behind because it's not gravitationally holding on
39:12
Speaker 2: to it and generated a tail. So coma and a
39:15
Speaker 2: tail are characteristic signatures of a comet rather than asteroid.
39:20
Speaker 2: And in nineteen ninety six people were looking at stuff
39:23
Speaker 2: in the asteroid belt and it's like, what's out there,
39:25
Speaker 2: what's weird? And they found this one that had a
39:27
Speaker 2: coma and a tail, and people were like, well, that's weird.
39:30
Speaker 2: But you know, one example is never anything, because you
39:33
Speaker 2: can always find one weird thing just necessarily tell you anything.
39:39
Speaker 2: But then a few years later they did a systematic
39:41
Speaker 2: study this Isaac Newton telescope in the Canary Islands. They
39:45
Speaker 2: were watching five hundred and thirty four asteroids specifically looking
39:49
Speaker 2: for like a gassy shell around them or whether they
39:51
Speaker 2: had a tail, and they found like twenty more of
39:54
Speaker 2: these things in the asteroid belt that have comas and tails.
39:58
Speaker 1: Well, so does that I mean their comments or centaurs.
40:01
Speaker 2: It means we don't know what to name these things,
40:03
Speaker 2: and maybe we're all wrong about these definitions. After all,
40:07
Speaker 2: it means that we don't really understand like how they
40:10
Speaker 2: got there, you know. I think question number one is like,
40:13
Speaker 2: why is there something in the asteroid belt that's still melting?
40:16
Speaker 2: You put something there and it's melting, it's gonna shrink,
40:19
Speaker 2: so it can't last for very long. But we think
40:21
Speaker 2: a lot of these asteroids have been there for like
40:23
Speaker 2: billions of years, and so how long have these things
40:27
Speaker 2: been in the asteroid belt? And if it's only and
40:30
Speaker 2: if it's a recent event, then where do they come from?
40:33
Speaker 2: And if it's not a recent event, then how they
40:35
Speaker 2: lasted so long? So it's weird to see something that
40:37
Speaker 2: you know has got to be short lived. So it's
40:40
Speaker 2: weird to see so many things that you know have
40:42
Speaker 2: to be short lived, because there's got to be some
40:44
Speaker 2: explanation there.
40:46
Speaker 1: You're saying they saw a coma or a shell or
40:49
Speaker 1: a cloud or a tail, because you can see it
40:52
Speaker 1: with the telescope.
40:53
Speaker 2: As it passes in front of the sun, for example,
40:55
Speaker 2: you could see the gas around it affecting the light
40:58
Speaker 2: as it transits, or you can see the way it
41:00
Speaker 2: reflects light differently.
41:01
Speaker 1: These are pretty firmly in the asteroid belt or are
41:04
Speaker 1: they maybe just cruising through the asteroid belt?
41:06
Speaker 2: Oh yeah, great question. Now these are things that are
41:08
Speaker 2: part of the asteroid belt, and as they watch them,
41:10
Speaker 2: they have stable orbits that can make them be part
41:13
Speaker 2: of the asteroid belt. They're not just like happened to
41:15
Speaker 2: be comets that were captured on their way into the
41:17
Speaker 2: inner Solar System. These things are not transients. They're there
41:20
Speaker 2: in the asteroid belt basically to stay. But we don't
41:24
Speaker 2: understand where they came from. And these are deep and
41:27
Speaker 2: important questions because we want to understand, like where is
41:30
Speaker 2: the water in the Solar System? How did it get
41:32
Speaker 2: spread out the way that it did? For example, where
41:36
Speaker 2: did Earth's water come from? We know that all the
41:39
Speaker 2: ice and all the water that originally was involved in
41:42
Speaker 2: the formation of our planet got boiled off by the
41:45
Speaker 2: Sun in the early history of the Solar System, and
41:48
Speaker 2: so it's still an open question of like where did
41:50
Speaker 2: the water that's on the surface of the Earth. Now,
41:52
Speaker 2: Like where did our oceans come from? Did it come
41:55
Speaker 2: from comets hitting the Earth? Did it come from the
41:57
Speaker 2: water that's still trapped inside the Earth. These are important
42:01
Speaker 2: questions and to answer them, we're gonna have to understand
42:03
Speaker 2: like where's the water now and what is it? All
42:05
Speaker 2: of its history. It's a deep question about our origins
42:08
Speaker 2: and the whole history of the Solar System. And so
42:11
Speaker 2: whenever you see something weird.
42:12
Speaker 1: Like wait, are you saying that maybe, like some of
42:14
Speaker 1: these weird objects in the asteroid belt, they came from
42:18
Speaker 1: the outer Solar System and then maybe they crashed into
42:22
Speaker 1: the asteroid belt.
42:23
Speaker 2: It could be absolutely it could be that they were
42:25
Speaker 2: comets and they were coming into the asteroid belt and
42:27
Speaker 2: they like interfered with something. And people think of the
42:30
Speaker 2: asteroid belt the way you described like Star Wars earlier,
42:33
Speaker 2: like oh it's hard, you got to dodge the asteroids,
42:36
Speaker 2: it's very dense. In reality, the asteroid belt is very dilute,
42:39
Speaker 2: Like if you flew through the asteroid belt, it'd be
42:41
Speaker 2: hard to hit an asteroid. So a random comet flying
42:44
Speaker 2: through the asteroid belt is not going to have a
42:46
Speaker 2: problem making it through. But you know, maybe occasionally these
42:49
Speaker 2: things do get disturbed, or they get deflected by Jupiter
42:52
Speaker 2: or captured effectively somehow, And so it could be that
42:55
Speaker 2: these are comets that got waylaid and ended up in
42:58
Speaker 2: the asteroid belt. But then you'd need a continuous stream
43:01
Speaker 2: of them to keep it populated because they're not going
43:04
Speaker 2: to last very long in the asteroid belt, like the
43:06
Speaker 2: Sun is.
43:06
Speaker 1: Going to fry them even with they're that far away.
43:08
Speaker 2: Yeah, I mean, the fact that they have a gassy
43:11
Speaker 2: shell means that they are actively outgassing because they can't
43:14
Speaker 2: hold onto that gas. And if you're actively outgassing, you're
43:18
Speaker 2: literally melting, you're shrinking. That's not going to last very long.
43:21
Speaker 2: They might have like a rocky core and that might
43:24
Speaker 2: be left over when the Sun is done frying all
43:26
Speaker 2: of their ices, but they're definitely not going to look
43:29
Speaker 2: like this for that long. We're talking, you know, millions
43:32
Speaker 2: of years, but in the history of the Solar System,
43:34
Speaker 2: that's just a blink of an eye.
43:37
Speaker 1: I wonder if it could be just like the Earth
43:39
Speaker 1: when the Earth got formed, they had water trapped inside
43:41
Speaker 1: of it in the rock. Could these asteroids also have
43:44
Speaker 1: water inside of them that's maybe sweating out.
43:47
Speaker 2: They certainly might have water inside of them the way
43:49
Speaker 2: the Earth does. And you know, if you think about
43:51
Speaker 2: water inside the Earth, it's not like there's literally an
43:54
Speaker 2: ocean you can go swimming in. It's like the chemical
43:56
Speaker 2: composition of the rock includes a lot of water, and
44:00
Speaker 2: so in a similar way, you might have water infused
44:03
Speaker 2: into the metals and the rocks at the heart of
44:04
Speaker 2: these asteroids. But any water ice that the sun is
44:07
Speaker 2: capable of frying off got fried off a long time ago,
44:10
Speaker 2: because these asteroids have been there for billions of years,
44:14
Speaker 2: and so these guys would have to be new, right,
44:16
Speaker 2: these new, weird things they spotted in the asteroid belt
44:19
Speaker 2: should have arrived fairly recently, if that makes any.
44:21
Speaker 1: Sense, all right, Well, so I guess the answer is
44:25
Speaker 1: maybe are there comets in the asteroid There could be
44:28
Speaker 1: There are definitely things that are comedy, right, or that
44:31
Speaker 1: have ice in them.
44:32
Speaker 2: There's definitely something in the asteroid build that has ice
44:35
Speaker 2: because it's melting. We don't understand what they are, where
44:38
Speaker 2: they came from, or what it means about where our
44:40
Speaker 2: drinking water came from.
44:41
Speaker 1: Or would you say, maybe the answer is that some
44:44
Speaker 1: of the things in the asteroid belt are comets or
44:48
Speaker 1: could be classified as sort of comets.
44:50
Speaker 2: Yeah, by our definition, where comets are things that have
44:52
Speaker 2: ice in them, they're icy and dusty. Then, yeah, there
44:55
Speaker 2: are definitely some icy, dusty things in the asteroid belt.
44:58
Speaker 2: The asteroid belt is not just asteroid anymore where.
45:00
Speaker 1: I guess if you go by your definition of a comment,
45:03
Speaker 1: then everything is a comment.
45:06
Speaker 2: That's right, You're a comment. Right, we tossed you into
45:09
Speaker 2: the sun, you would melt and vaporize as well.
45:11
Speaker 1: So yeah, yeah, yeah, of course I'd be you know,
45:14
Speaker 1: trying to communicate with charades all the way down hoping
45:18
Speaker 1: someone picks me up. Good luck with that, all right? Well,
45:23
Speaker 1: another interesting exploration into our solar system, it's history and
45:28
Speaker 1: the mysteries that are still out there waiting to be discovered.
45:31
Speaker 2: There's so many missing chapters to the history of our
45:34
Speaker 2: solar system, so many things about our own backyard we
45:36
Speaker 2: still don't understand. And every time we look more carefully
45:40
Speaker 2: the things we thought we understood, we find weird things
45:42
Speaker 2: that defy our explanation, that tell us there's a lot
45:45
Speaker 2: more to this story to be revealed.
45:48
Speaker 1: Yeah, to be revealed by astronomers or physicists or both,
45:52
Speaker 1: or perhaps chemists. We're all just people, No, we're all
45:58
Speaker 1: just comments.
45:59
Speaker 2: That's right, what is it? Comed?
46:01
Speaker 1: Yeah? Thank you? We all have tales in Komas. All right, well,
46:04
Speaker 1: we hope you enjoyed that. Thanks for joining us, See
46:07
Speaker 1: you next time.
46:13
Speaker 2: For more science and curiosity, come find us on social media,
46:16
Speaker 2: where we answer questions and post videos. We're on Twitter, Discord, Insta,
46:20
Speaker 2: and now TikTok. Thanks for listening, and remember that Daniel
46:24
Speaker 2: and Jorge Explain the Universe is a production of iHeartRadio.
46:28
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46:33
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