Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / Strange Spins and Cosmic Rings: Exploring NGC 4698 and Chariklo's Secrets

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Strange Spins and Cosmic Rings: Exploring NGC 4698 and Chariklo's Secrets · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hi there. Thanks for joining us on yet
• 0:01
  another edition of the Space Nuts
• 0:04
  podcast. My name is Andrew Dunkley, your host
• 0:06
  and it's good to have your company as we look
• 0:09
  into these, uh, issues, you call them issues
• 0:12
  stories. Uh, there's a really weird
• 0:15
  galaxy out there. It's got a really
• 0:17
  odd rotational pattern, uh, and
• 0:20
  one wonders why.
• 0:21
  I have a theory, but it's probably wrong. Uh,
• 0:24
  we're also going to look at the changing
• 0:27
  rings of Chariklo. What is
• 0:30
  that? It's a weird thing in a weird
• 0:32
  place I think is the best way to describe it.
• 0:35
  And we don't need to talk about it anymore.
• 0:37
  And we've got a juicy story from ESA as well.
• 0:40
  That's all coming up on this episode of
• 0:43
  Space Nuts.
• 0:44
  Professor Fred Watson: 15 seconds. Guidance within channel
• 0:47
  N9. Ignition
• 0:49
  sequence star.
• 0:50
  Professor Fred Watson: Uh, SpaceNets.
• 0:51
  Professor Fred Watson: 5, 4, 3, 2, 1. 3, 3, 4,
• 0:54
  5, 5, 4, 3, 2', 1. Space
• 0:57
  Nuts astronauts reported. Neil.
• 0:59
  Good.
• 1:01
  Andrew Dunkley: Actually, we've got a couple of stories from
• 1:02
  ESA today. Joining us to explain all
• 1:05
  of that mystery that I just unveiled is
• 1:08
  Professor Fred Watson Watson, astronomer at
• 1:10
  large. Hello Fred Watson.
• 1:11
  Professor Fred Watson: Good morning. Uh, uh, what's your name again?
• 1:13
  Andrew. Yeah, that's it, sorry. Dave.
• 1:16
  Andrew Dunkley: Dave. I've copped that many times. I still
• 1:19
  get that now. That was years ago that
• 1:21
  somebody accidentally calls me Dave. And
• 1:24
  it's still going.
• 1:25
  Professor Fred Watson: Part of Space Nuts legend is that
• 1:28
  Andrew Dunkley: my best friend's name is Dave. So I'm not
• 1:31
  offended.
• 1:31
  Professor Fred Watson: Uh, could be, actually. Um, I've got several
• 1:34
  really close friends who are Dave's as well,
• 1:35
  so must be what it is.
• 1:39
  Anyway, Dave, it's nice to talk to you again.
• 1:41
  Andrew Dunkley: Thank you, Fred Watson.
• 1:43
  Professor Fred Watson: Um,
• 1:45
  Professor Fred Watson: I usually get Frank.
• 1:47
  Andrew Dunkley: Do you?
• 1:47
  Professor Fred Watson: Uh, sometimes I get Greg. Yeah. When people
• 1:50
  m. Mishear the consonants.
• 1:53
  Okay, so it's when you, you know
• 1:56
  when you go and order a coffee and they say
• 1:58
  what's your name? So they can yell out your
• 2:00
  name when your coffee's ready. Yeah.
• 2:01
  And um, so I expect Greg or
• 2:05
  you know, Ted or anything that's got
• 2:07
  different consonants. And occasionally I get
• 2:09
  Frank as well.
• 2:10
  Andrew Dunkley: Well, my elder, I've got a better one than
• 2:12
  that. Uh, my eldest son's name is Kyle. K
• 2:15
  Y L E. And uh,
• 2:18
  this turned into a Facebook, um,
• 2:20
  epidemic, uh, at one stage where
• 2:23
  he'd go and order a coffee down in Sydney
• 2:25
  somewhere and then they'd call out Kylie,
• 2:29
  Kylie. And they'd even
• 2:32
  written Kylie on the car.
• 2:33
  Professor Fred Watson: Ah, yeah, yeah.
• 2:34
  Andrew Dunkley: And every time it happened he'd take a photo
• 2:36
  and go put it on Facebook and go what the
• 2:39
  bleep? And it still
• 2:41
  happens. To him. But he's been down there
• 2:44
  for, I don't know, 15 years now. And, um,
• 2:47
  he still gets called Kylie.
• 2:50
  Professor Fred Watson: I don't understand. Could be there.
• 2:52
  Andrew Dunkley: Anyway, he hates us because we named him, so.
• 2:55
  Anyway.
• 2:55
  Professor Fred Watson: Yeah, yeah.
• 2:56
  Professor Fred Watson: Why did he call him Kyle?
• 2:58
  Andrew Dunkley: Uh, that's a funny story too, because, uh,
• 3:01
  when Judy fell pregnant and I'm
• 3:04
  still trying to find the man that did it.
• 3:05
  Anyway, um, when
• 3:08
  Judy fell pregnant, we were sitting in the
• 3:10
  lounge room saying, what are we going to call
• 3:12
  him? And we were watching the movie the
• 3:15
  Terminator. And the original one, the
• 3:18
  very first one, and the. And the, um,
• 3:20
  hero's name in that was Kyle. I said, that's
• 3:23
  a nice name. And Judy said, yeah, yeah, let's
• 3:25
  go with that.
• 3:26
  So it's from the mo Movie the Terminator.
• 3:28
  There's. There's no family connection
• 3:31
  whatsoever with the name. We just liked it
• 3:34
  from the film.
• 3:37
  Professor Fred Watson: I thought you might. There might be a link
• 3:39
  with Scotland there. Uh, no, Kyle is
• 3:42
  an estuary. Oh, is it kind of
• 3:45
  local? Of Sutherland. Yeah. So he's an
• 3:47
  estuary. That's his name.
• 3:49
  Andrew Dunkley: I mean, there's a bit of Scottish heritage in
• 3:51
  our family, so that probably works.
• 3:53
  Professor Fred Watson: That'll.
• 3:53
  Andrew Dunkley: That'll do.
• 3:54
  Professor Fred Watson: Yeah.
• 3:55
  Professor Fred Watson: Yeah.
• 3:56
  Andrew Dunkley: And our other two, we. We picked Morgan for a
• 3:58
  girl and never had a girl.
• 3:59
  So when we had our second boy, we went, well,
• 4:01
  let's just use that just in case.
• 4:04
  And then the third one came along and we
• 4:06
  were. We were still devoid of names. And I
• 4:08
  said, well, why not Lachlan? You know, we're
• 4:11
  not far from the Lachlan River. Let's just
• 4:13
  stick with Lachlan. So that's how that
• 4:15
  happened as well.
• 4:17
  Professor Fred Watson: Yeah.
• 4:18
  Andrew Dunkley: Yeah, it is. It is, yeah.
• 4:20
  Professor Fred Watson: There you go.
• 4:21
  Andrew Dunkley: Hmm. Yeah. I hadn't thought about
• 4:24
  how we named our kids, and I haven't thought
• 4:26
  about it for years. And they never asked, so
• 4:29
  I. We don't go there.
• 4:32
  Professor Fred Watson: We'll do another episode, uh, down the track
• 4:35
  and I'll tell you how, uh, we. Why we
• 4:37
  named our kids. All right. Yeah,
• 4:40
  no, we won't do it now. We won't do it now.
• 4:42
  Andrew Dunkley: We'll do it in the next episode.
• 4:43
  Professor Fred Watson: Do it in the next episode.
• 4:45
  Andrew Dunkley: We should do some stories, though. Um, now
• 4:48
  this.
• 4:48
  This one's really weird and it's
• 4:51
  all to do with observ of a
• 4:54
  very strange, uh, galaxy,
• 4:57
  uh, that's behaving badly. Or is it just
• 5:00
  behaving strangely? Has it had too much to
• 5:02
  drink? Fred Watson?
• 5:03
  Professor Fred Watson: It could be. Certainly. It probably is a
• 5:06
  digestive issue, uh, for the galaxy.
• 5:08
  Andrew Dunkley: I was gonna Say that that was my theory. I
• 5:10
  bet this is a result of a galaxy merger.
• 5:13
  Professor Fred Watson: Yeah, I think that's right. That's the
• 5:15
  general view of it. So the galaxy we're
• 5:17
  talking about, it's actually not. It's a
• 5:19
  nearby galaxy. It's um, 55
• 5:22
  million light years away. That's very
• 5:24
  much uh, our uh, local backyard. So the
• 5:26
  images that we see of it are very, very
• 5:28
  detailed. There's a beautiful image, uh,
• 5:31
  which I think is on both the ESA and NASA
• 5:33
  website because it's a Hubble telescope
• 5:36
  image. And of course the Hubble telescope is
• 5:39
  um, um, funded by both and uh,
• 5:41
  operated by both. Um. Uh,
• 5:44
  it's a spiral galaxy, uh, in
• 5:47
  the constellation Virgo. As I said, 55
• 5:49
  million light years away. Uh, it's one
• 5:52
  member of the Virgo Cluster, which
• 5:55
  is one of the biggest nearby galaxy clusters
• 5:58
  that we can see. Um, there's something like a
• 6:00
  thousand galaxies in it. Um, there are a
• 6:03
  few really big ones, the Coma Cluster, uh,
• 6:06
  Virgo Cluster, a few in our locality. And
• 6:09
  they're big, they're big, um, galaxy
• 6:11
  clusters.
• 6:12
  So um, when you look at
• 6:15
  this, there's a lovely Hubble telescope image
• 6:18
  that I guess is the centre of uh,
• 6:21
  attention on this story. Um,
• 6:24
  beautiful image of this galaxy, spiral
• 6:27
  arms, which unlike
• 6:30
  the spiral arms of our Milky Way
• 6:32
  galaxy, we think they are at their
• 6:35
  inner edge firmly pinned down to the
• 6:39
  um, central bar of the galaxy. That
• 6:41
  means when you look at it, and we clearly
• 6:44
  can't look at our own galaxy in a photograph
• 6:47
  because we're right inside it. Uh, we can't
• 6:49
  look at the whole thing but we can map it
• 6:51
  through infrared and radio astronomy. And um,
• 6:54
  the evidence seems to be that there is a bar,
• 6:57
  uh, at the centre. Now that's not a bar you
• 6:59
  lean against. It's an elongated distribution
• 7:02
  of stars, uh, and
• 7:04
  um, with some really interesting dynamics,
• 7:06
  really interesting movement in it. Uh, but
• 7:09
  our spiral arms, uh, are uh, sort of
• 7:12
  fixed to the end of the bar. That's where
• 7:14
  they seem to originate from. Um,
• 7:16
  whereas with ah, this particular galaxy, and
• 7:19
  I haven't given it its name, it is NGC
• 7:22
  4698. A uh, lovely,
• 7:24
  um, meaningless name. Um,
• 7:28
  uh, NGC stands for New General Catalogue
• 7:30
  which if I remember rightly was published in
• 7:32
  1888. Uh, so it's still pretty new
• 7:35
  really. NGC
• 7:37
  4698. Uh, the point
• 7:40
  about this galaxy is when you look at it you
• 7:42
  can see spiral arms, but they're sort of
• 7:44
  only in the outer, I guess the
• 7:47
  outer third of the galaxy.
• 7:49
  And in the middle there's no sign of
• 7:52
  spiral arms. So that straight away
• 7:55
  tells you that there's something different
• 7:57
  about this object. Um, the
• 7:59
  other thing, and the thing that is, I guess,
• 8:02
  really remarkable is what we
• 8:05
  slightly unflatteringly refer to as the bulge
• 8:07
  of the galaxy. Um, our galaxy has a bulge.
• 8:10
  Uh, it's, uh, what is often known as a
• 8:13
  peanut bulge because it's kind of vaguely
• 8:16
  peanut shaped. And that probably comes about
• 8:18
  because of the, the bar in the centre of our
• 8:20
  galaxy. Uh, we see it from our vantage point
• 8:23
  here in the solar system. We see it in the
• 8:26
  constellation of Sagittarius. And,
• 8:28
  um, if you look on winter nights
• 8:31
  at the Milky Way, when it's nearly overhead,
• 8:34
  that's where it is at its widest. There is a
• 8:37
  sort of big swath of stars there
• 8:40
  and that's the bulge of our own galaxy. So
• 8:42
  you can kind of see it with the naked eye.
• 8:45
  Uh, this one has a bulge as well, which is
• 8:48
  elongated a bit like ours, but
• 8:51
  it's elongated in the wrong direction.
• 8:54
  It stretches out
• 8:56
  perpendicular to the disc of the
• 8:58
  galaxy. And that is a rarity.
• 9:01
  I don't think it's unique, but I think it's
• 9:04
  pretty rare. Uh, and
• 9:07
  so what, um, is
• 9:10
  perhaps the smoking
• 9:13
  gun about how this originated
• 9:16
  is that when you look at the movement of
• 9:19
  stars within that perpendicular bulge,
• 9:22
  um, you find that the motion of the stars is
• 9:25
  perpendicular to the rest of the galaxy as
• 9:27
  well. So it's not just that it looks as
• 9:29
  though it's at right angles, it really is
• 9:31
  because the stars are moving in that
• 9:34
  direction, uh, up and down through the centre
• 9:37
  of the galaxy, rather than, uh,
• 9:40
  swirling around in the same plane as the disc
• 9:43
  of the galaxy.
• 9:44
  Andrew Dunkley: Yeah, I don't, you know,
• 9:47
  is that possibly a rarity or is
• 9:50
  this most likely more common than we think
• 9:52
  we've just happened to find? The first one
• 9:55
  that looks this way.
• 9:56
  Professor Fred Watson: Uh, yeah, that's a good question.
• 9:57
  Is it, um, you know, is it a selection effect
• 10:00
  that we normally don't see that. But I
• 10:03
  think it is more likely that this is
• 10:06
  quite rare because, um, certainly the
• 10:09
  imagery of this object, uh, is
• 10:12
  very striking. When you look at it, you can
• 10:14
  see straight away that its bulge is
• 10:17
  different from, uh, normal
• 10:20
  galaxies, that it's got this, uh,
• 10:23
  sprinkling of stars which are well above the
• 10:26
  plane of the galaxy and that's not what you
• 10:27
  expect from, uh, the bulge.
• 10:30
  Andrew Dunkley: So you can see it in the image. It's a
• 10:32
  beautiful image, by the way, isn't it?
• 10:34
  Professor Fred Watson: Isn't it lovely? Um, there's other
• 10:37
  fainter galaxies in the background, which,
• 10:39
  um, are always nice to see, it looks as
• 10:41
  though, um, uh,
• 10:44
  the dust is showing up very clearly, uh,
• 10:48
  reddish in this image. And that's
• 10:51
  probably a true colour as well. So it looks
• 10:53
  like the dust looks like gravy swirling
• 10:55
  around, uh, the spiral arms at the outer side
• 10:57
  of the galaxy. But, um, yes, it's a
• 11:00
  very, very, uh, attractive image.
• 11:04
  So, um, the reason
• 11:06
  possibly is that
• 11:09
  maybe there was a collision.
• 11:12
  Uh, and we know that galaxies
• 11:15
  have grown by sort of gobbling up smaller
• 11:18
  galaxies. And if this collision
• 11:21
  took place at, uh, this high angle,
• 11:23
  uh, so that you've got a dwarf galaxy perhaps
• 11:26
  being absorbed by, uh, uh,
• 11:29
  NGC 4698, um,
• 11:32
  then you might very well get
• 11:35
  these velocities which are perpendicular to
• 11:37
  the disc of the galaxy. Um, we've
• 11:40
  got a similar situation in our own
• 11:43
  galaxy with the Two Magellanic Clouds,
• 11:46
  the dwarf galaxies. They're quite big for
• 11:49
  dwarf galaxies, actually. Uh, but they still
• 11:52
  count as that. Uh, they are visible in our
• 11:54
  southern hemisphere sky. They are being
• 11:57
  absorbed by our own galaxy. And there's a
• 11:59
  sort of something called the Magellanic, uh,
• 12:01
  stream, which is a stream of stars between
• 12:04
  them and connecting with the disc of our
• 12:06
  galaxy. And they're at a relatively high
• 12:08
  angle. So maybe in a few
• 12:12
  hundred million years, when space nuts will
• 12:14
  still be going, uh, we might have a
• 12:17
  similar phenomenon in our own galaxy. A bulge
• 12:20
  that's modified, that sticks up. Uh, although
• 12:22
  we've got a bar as well in the middle, which
• 12:24
  is a fairly robust feature. I think as
• 12:27
  the galaxy evolves, that will stay pretty
• 12:30
  solidly there. So we might end up with two
• 12:32
  bulges.
• 12:32
  Who knows?
• 12:33
  Andrew Dunkley: You never know. Yeah, so this one's, uh,
• 12:36
  quite, quite amazing. And, uh, uh, you
• 12:39
  can read all about it on the
• 12:41
  European Space agency website. That's
• 12:44
  ESA.int and just do
• 12:47
  a search for, uh, NGC
• 12:49
  4698, I think, would be probably the easiest
• 12:52
  thing to do, Fred Watson.
• 12:53
  Professor Fred Watson: Yeah, Or, I mean, the title of their press
• 12:56
  release is lovely. A Galaxy Spinning out of
• 12:59
  Sink. I like that.
• 13:00
  Andrew Dunkley: Yes.
• 13:01
  Professor Fred Watson: Yeah.
• 13:01
  Andrew Dunkley: Or it fell down a sink or something.
• 13:04
  Those tend to spiral as well.
• 13:06
  Professor Fred Watson: Yes, well, they do. That's right. Yeah.
• 13:08
  Andrew Dunkley: Indeed.
• 13:09
  Professor Fred Watson: Two different sinks.
• 13:11
  Andrew Dunkley: Have a look for it. Uh, this is Space Nuts
• 13:13
  with Andrew Dunkley and Professor Fred Watson
• 13:15
  Watson. Okay, we've had a problem here.
• 13:18
  Professor Fred Watson: This is Houston. Say again, please.
• 13:20
  Professor Fred Watson: We've had a problem.
• 13:21
  Professor Fred Watson: We've had a B pup on a vault.
• 13:24
  So we're looking at it.
• 13:26
  Andrew Dunkley: Space Muffs. And I've got to say
• 13:29
  hello to a couple of our live viewers.
• 13:31
  Uh, Emily is, uh, watching us from a
• 13:34
  taxi in Perth at the moment on her way to a
• 13:37
  conference or a training course, I think.
• 13:40
  And, uh, yeah, so, um, yeah, the
• 13:42
  places we tune in from, I guess we're all
• 13:45
  nuts. She says, hi
• 13:47
  Emily.
• 13:48
  And, uh, Sophie's listening to us, uh, from,
• 13:51
  uh. Now, where did she say? Doesn't, uh,
• 13:54
  say where she's from, but she does ask if
• 13:56
  we'd heard about the potential closure of the
• 13:59
  Jodrell bank facility. Oh, she's in
• 14:01
  Somerset in the uk. Hi, Sophie. Yes, we, we
• 14:04
  were very much aware of that. That's been
• 14:06
  brought to our attention by a couple of
• 14:07
  listeners recently. Yes, and very
• 14:10
  sad news. Very sad news indeed.
• 14:13
  Professor Fred Watson: Except that we think it's been the, the, the
• 14:16
  prime. The Prime Minister mentioned it in
• 14:17
  Parliament about two weeks ago, saying that,
• 14:21
  uh, every school kid of his generation
• 14:23
  went to visit Jodrell bank and there's no way
• 14:25
  he was going to see it being closed in his
• 14:27
  watch.
• 14:28
  Andrew Dunkley: That's good news. There you go, Sophie. So,
• 14:30
  um, it may well be saved. Yeah, that
• 14:33
  would be wonderful.
• 14:35
  Um, lovely to have a live audience. It's
• 14:37
  becoming a new trend for us.
• 14:38
  Professor Fred Watson: Isn't it great? Yeah, it's absolutely
• 14:40
  fantastic.
• 14:41
  Andrew Dunkley: Terrific. Let's go to our next story,
• 14:44
  and this one's a little bit weird,
• 14:47
  and I'll try and pronounce this correctly,
• 14:49
  but we're talking about an object named
• 14:52
  Carricklo. Uh, now, um,
• 14:55
  the story is about the rings around
• 14:58
  Chariklo that are. That are changing. But
• 15:01
  we better firstly explain what this
• 15:03
  object actually is.
• 15:06
  Professor Fred Watson: Uh, yes, that's a, uh, nice way to
• 15:09
  introduce the story because, um, Chariklo is
• 15:11
  not one that we talk about very much.
• 15:13
  Uh, its full name is one zero one. Um, nine.
• 15:16
  Nine Chariklo. And the fact that it's
• 15:18
  preceded by a number tells you that it's an
• 15:20
  asteroid. Uh, uh,
• 15:22
  every asteroid, uh, has a number as well as a
• 15:25
  name like 5691. Fred Watson Watson.
• 15:28
  Sorry, couldn't resist it. So
• 15:31
  10199 curriculo. Um, but
• 15:33
  it's not, uh, an asteroid. Ah, Fred Watson
• 15:36
  Watson, by the way, is probably the single
• 15:38
  most boring object in the solar system.
• 15:41
  It is in the main asteroid belt. It never
• 15:44
  does anything, uh, just sort of circulates
• 15:46
  around the sun. Um, there's not really
• 15:48
  anything to, you know, to make it stand out
• 15:50
  and it definitely won't hit the Earth anytime
• 15:53
  soon. Uh,
• 15:55
  Cariklo, on the other hand.
• 15:57
  Andrew Dunkley: Wouldn't it be ironic though if it hit Earth
• 15:59
  and hit your house?
• 16:03
  Professor Fred Watson: I probably told you this story before when
• 16:06
  more than 20 years ago now, when it was
• 16:08
  announced that the IAU was naming an
• 16:11
  asteroid after me. I went home from the
• 16:13
  observatory, told my two young sons that
• 16:16
  that was what had happened. They said, dad,
• 16:18
  that was terrible. If it hits the Earth,
• 16:20
  it'll be your fault. Um, and, um.
• 16:23
  So, yes, I've had that hanging over my head,
• 16:25
  uh, ever since. It will never, ever hit the
• 16:27
  Earth. The dynamics of the solar system are
• 16:29
  such that it will remain, as I said, probably
• 16:32
  the single most boring object in the entire
• 16:34
  solar system. Unlike Curriculo, um,
• 16:36
  which, uh, is, uh. Actually,
• 16:39
  it's called a centaur.
• 16:41
  That's a class of asteroids and this
• 16:44
  is the biggest of them. Curriculo. It's
• 16:45
  probably 250 kilometres across itself. A
• 16:48
  large ish asteroid. Um, and they
• 16:51
  orbit, uh, between the orbits of Saturn
• 16:54
  and Uranus. Uh, ah,
• 16:56
  that's the centaurs. Uh, this particular one,
• 16:59
  Chariklo, has an orbital period of
• 17:02
  62 and a half years. That's how long it takes
• 17:04
  to go around. Once actually discovered back
• 17:07
  in the 1990s at Kitt Peak National
• 17:09
  Observatory in Arizona. Uh, it's
• 17:12
  got a, uh, dark reddish surface.
• 17:15
  Um, uh, uh, this brief
• 17:19
  update comes from Wikipedia just
• 17:21
  so I can get all the facts in there. It's got
• 17:24
  water, ice, silicate minerals, amorphous
• 17:26
  carbon and various complex organic
• 17:29
  compounds known as solins. Actually, uh, so
• 17:32
  these are the things that make
• 17:35
  many of those very distant trans. Neptunian
• 17:38
  objects, like, um,
• 17:40
  our old friend Arrokoth, the most distant
• 17:42
  object that's yet been visited by a
• 17:44
  spacecraft. Quite a, uh, reddish reddy
• 17:47
  brown surface.
• 17:49
  Andrew Dunkley: Yeah, SEDNA is like that too, apparently.
• 17:52
  Professor Fred Watson: That's right, yeah. It's common. It
• 17:55
  comes about because of the, uh,
• 17:58
  um, bombardment by
• 18:01
  subatomic particles from the sun and also
• 18:04
  cosmic rays, which come from outside the
• 18:06
  solar system, uh, over, uh, many billions
• 18:09
  of years. Like the four billion year history
• 18:11
  of the solar system. A four and a half
• 18:13
  billion year history. Um, and that modifies
• 18:16
  these chemicals to give you this brownish
• 18:18
  colour. So, um,
• 18:21
  there are, uh, uh, rings around
• 18:24
  Curriculo. I think it may have a
• 18:26
  moon. Um, I have that
• 18:29
  wrong, but it certainly has
• 18:33
  rings.
• 18:34
  Uh, maybe it doesn't have a moon. Sorry, M. I
• 18:37
  don't want to mislead anybody.
• 18:38
  Andrew Dunkley: Um, I'll tell you in a second. No,
• 18:42
  it does not have a confirmed moon yet,
• 18:45
  is the answer.
• 18:46
  Professor Fred Watson: Yeah, well, that's right. It's a long way
• 18:48
  away. It's beyond the orbit of Saturn.
• 18:51
  An object only a couple of hundred kilometres
• 18:53
  across, uh, smallish object.
• 18:56
  Um, uh, but it's got
• 18:59
  rings. And uh, how do we know that?
• 19:02
  By this marvellous technique, uh, that I
• 19:05
  always think is a great way to find solar
• 19:07
  system objects and measure them. Sometimes
• 19:10
  what we call occultations. When,
• 19:12
  uh, a solar system object passes in front
• 19:15
  of uh, a distant star and
• 19:18
  so its light is blocked, the light of the
• 19:20
  star is blocked. And if you have enough
• 19:22
  people observing the occultation, you spread
• 19:25
  them out across, well, sometimes across a
• 19:27
  nation like Australia, uh,
• 19:30
  you can essentially uh,
• 19:33
  see the dip in light, uh,
• 19:36
  and map it. Map m whatever it is that's uh,
• 19:39
  obscuring over uh, this area
• 19:42
  of the land where you've got observers.
• 19:45
  So you get all the observers to
• 19:48
  time when the background star
• 19:51
  seems to disappear and reappear. And by
• 19:53
  doing that, by plotting all those timings
• 19:56
  on a map, you can actually get the shape of
• 19:59
  whatever it is that's occulting or blocking
• 20:01
  out the light of the star. And back in
• 20:04
  2013, uh, Kuriklo,
• 20:06
  uh occulted a star and it
• 20:09
  was seen that there were
• 20:12
  sort of symmetric occultations on either side
• 20:15
  of the main object which tell you that you've
• 20:18
  got rings. So
• 20:21
  that's the backstory. Uh, the front
• 20:24
  story is that uh,
• 20:26
  curricula has now been observed or
• 20:29
  occultations have now been
• 20:31
  observed by the James Webb Telescope, which
• 20:34
  of course is a very powerful instrument.
• 20:36
  And so you get very, very sensitive light
• 20:38
  curves or very detailed light curves. And
• 20:41
  what they're finding is, uh, that its
• 20:44
  rings have changed.
• 20:47
  They've changed significantly since that
• 20:50
  um, 2013 discovery.
• 20:54
  Uh, um, it
• 20:57
  basically uh, is a very nice
• 20:59
  occultation because it misses the
• 21:02
  curricula itself. Curricula, uh, didn't dim
• 21:05
  the star, uh, because the
• 21:08
  line of sight to the star from the James Webb
• 21:10
  telescope was uh, about seven kilometres
• 21:13
  above the Curriculo's surface. We're talking
• 21:15
  in very small distances here. So that the
• 21:18
  rings of Curriculo, and I didn't mention that
• 21:21
  there are two, not just one, there are two,
• 21:23
  uh, which crossed, uh, passed in
• 21:26
  front of the star, uh, and uh, were
• 21:29
  able to be measured um, by
• 21:32
  the James Webb Space Telescope. Some very
• 21:34
  nice observations, uh, of that. And
• 21:38
  uh, what we now know, uh, is
• 21:41
  that the rings have changed, as I said, since
• 21:44
  20. Um, and so what
• 21:47
  we've got is a darkening of
• 21:50
  the inner ring, uh
• 21:53
  m sort of more so than would be
• 21:56
  expected. Uh, there have been other
• 21:58
  observations since 2013, uh, in 2014
• 22:01
  and 2017. Um, so
• 22:04
  these, you know, uh, the observations allow
• 22:07
  uh, us to see the way things uh,
• 22:10
  change. The astronomers who've done
• 22:13
  this work do make the comment though
• 22:16
  that maybe these rings are unequal in
• 22:19
  density. Uh, so if you've got, you know, the
• 22:22
  rings are made of material, just
• 22:24
  dusty material, uh, in orbit around the
• 22:27
  parent star. Uh, but there can be regions
• 22:30
  where there's more dust than there is further
• 22:32
  along the ring. And so it may be
• 22:35
  that uh, we've, you know, that
• 22:39
  they, that's what they've seen, a more dense
• 22:41
  region. Uh, but um, doing a
• 22:44
  statistical um, analysis of that
• 22:47
  suggests that that's probably not the case.
• 22:49
  That it probably is a real effect
• 22:52
  that the rings are actually
• 22:55
  um, that you know, the rings themselves are
• 22:58
  changing in structure.
• 22:59
  Andrew Dunkley: Yeah. Interestingly Fred Watson, we
• 23:02
  mentioned um, earlier about whether or not it
• 23:05
  had a moon. There is a hidden moon
• 23:07
  hypothesis, uh. Ah, yes, attached to this
• 23:10
  uh, object. And um, uh, some
• 23:13
  astronomers believe a tiny moon about two
• 23:15
  miles across, three kilometres, ish,
• 23:19
  uh, is orbiting inside or near the
• 23:21
  rings. And its gravity acts like
• 23:24
  a sheepdog, cosmic sheepdog they say,
• 23:27
  containing the icy particles so the rings
• 23:29
  stay intact. That's one theory,
• 23:32
  yes.
• 23:33
  Professor Fred Watson: Uh, and
• 23:36
  um,
• 23:39
  certainly um, this research
• 23:42
  uh, mentions that partly because
• 23:45
  um, there are resonances here and we've
• 23:48
  talked about resonances before. When you've
• 23:50
  got one thing that orbits, for
• 23:53
  example, um.
• 23:54
  Well, if you've got moons orbiting like
• 23:57
  Saturn as resonances, one moon will
• 23:59
  orbit uh, twice for
• 24:02
  another moon going around three times. These
• 24:04
  are uh, what we call resonances. And
• 24:09
  apparently uh, one of the rings is a uh, one
• 24:12
  to three resonance with curricula itself.
• 24:15
  So you've got a ring particle going around
• 24:17
  once for every three rotations of
• 24:20
  curricula. And that could shape the
• 24:23
  structure of the rings. Um, but
• 24:25
  that in itself might be caused, exactly as
• 24:28
  you've just said, by what they call a
• 24:30
  shepherd satellite. An unseen moon
• 24:33
  could perhaps uh, help to keep the
• 24:35
  ring intact. Uh, exactly as we
• 24:38
  see in some of the tiny moons of Saturn,
• 24:41
  which are almost embedded in Saturn's ring
• 24:43
  system. So yeah, this is um,
• 24:46
  really interesting stuff. Uh, if you're an
• 24:49
  asteroid fanatic, uh, um,
• 24:52
  with these possibilities, um, imagine what
• 24:54
  something like that would look like if you
• 24:56
  could stand close to it. Because curricula
• 24:58
  itself is probably a fairly irregular object.
• 25:00
  It is big enough to be more or less
• 25:02
  spherical, but um, we don't know its true
• 25:05
  shape. That's something else that can be
• 25:07
  gained by the way, by occultation
• 25:08
  measurements.
• 25:10
  Professor Fred Watson: Mhm.
• 25:10
  Andrew Dunkley: The other interesting thing is um,
• 25:13
  the belief is those rings will disperse
• 25:16
  eventually.
• 25:18
  Professor Fred Watson: Yeah, exactly as we think with Saturn. Ah,
• 25:21
  but I think these might have a relatively
• 25:24
  short timescale. I can't remember what sort
• 25:25
  of timescale.
• 25:27
  Andrew Dunkley: Uh, a few million years
• 25:30
  Is the, the theory.
• 25:32
  Professor Fred Watson: Relatively short. Saturn's rings are expected
• 25:35
  to disperse within the next hundred million
• 25:38
  years or so. It's in the diary. I've got it
• 25:40
  in my diary. I hope you have too.
• 25:42
  Andrew Dunkley: Uh, yes, I have, yes. Um, when they say
• 25:45
  disperse, what does that mean? They're just
• 25:46
  going to go drifting off into space.
• 25:48
  Professor Fred Watson: And probably in um, maybe,
• 25:51
  I suspect in both cases it will be a question
• 25:54
  of them collapsing onto the, gradually
• 25:56
  collapsing onto the surface of the body
• 25:59
  itself. We know that um, the inner edge
• 26:02
  of Saturn's rings are uh, basically raining
• 26:05
  down into Saturn. We saw that with the
• 26:07
  Cassini spacecraft. Direct evidence of that.
• 26:10
  A kind of rainfall of ice
• 26:13
  from the inner edge of the rings, uh,
• 26:16
  heading down towards the planet. And I
• 26:18
  suspect that's what will happen with
• 26:20
  Curriculo. Uh, the rings will end up on the
• 26:22
  surface. We think, and you and I have covered
• 26:24
  this on space knots, there might be evidence
• 26:27
  that the same thing happened on Earth
• 26:29
  billions of years ago.
• 26:31
  Andrew Dunkley: Interesting. If you'd like to read all about
• 26:34
  it, you can find out about uh,
• 26:36
  Curriculo's rings on the
• 26:38
  Brighterside News website.
• 26:42
  This is Space Nuts. Andrew Dunkley here,
• 26:45
  Fred Watson Watson there.
• 26:49
  Professor Fred Watson: Amen.
• 26:50
  Professor Fred Watson: Space Nuts.
• 26:52
  Andrew Dunkley: Now Fred Watson, we turn our attention to the
• 26:55
  JUICE mission. This is an ESA mission to
• 26:58
  Jupiter, uh, to look at its uh,
• 27:01
  it's moons and uh, it's about
• 27:04
  to do something. By the time this podcast is
• 27:07
  out, um, Juice will have done the, something
• 27:09
  that we're talking about doing.
• 27:11
  Professor Fred Watson: Right? It will, it'll have
• 27:13
  done it, it'll have done its thing and uh,
• 27:16
  uh, successfully, we hope so. Juice, uh,
• 27:18
  it's a really juicy topic of course. We can't
• 27:21
  resist, uh, that. I uh, had a nice glass of
• 27:23
  orange juice a couple of hours ago as well,
• 27:25
  which was good.
• 27:26
  Anyway, um, it's um, uh, it is
• 27:29
  the European Space Agency's Jupiter
• 27:31
  Icy Moons Explorer. That's where the name
• 27:34
  comes from. Uh, and uh, it's heading for
• 27:37
  Jupiter. Uh, if I remember rightly, it
• 27:39
  will orbit the planet itself, making
• 27:42
  frequent flybys. Um,
• 27:46
  uh, there is NASA's probe which is also
• 27:50
  uh, looking at the ice moons. Uh,
• 27:54
  that is Europa Clipper, that's called.
• 27:56
  Andrew Dunkley: That's right, yeah.
• 27:57
  Professor Fred Watson: That will also be in orbit around
• 28:00
  Jupiter. Anyway, Juice, um, is
• 28:03
  heading out to Jupiter but it's been on its
• 28:06
  way there for three and a half years. Uh,
• 28:08
  and um, given that it was
• 28:11
  launched in April 2023, uh, in
• 28:14
  French Guiana. That's where, uh, the
• 28:17
  ESA Space Port is. And
• 28:20
  what it's done in the time since
• 28:22
  then. Uh, first of all, it did,
• 28:26
  uh, a lunar Earth flyby. Um,
• 28:29
  in other words, kind of taking
• 28:31
  the gravitational pull of both the Moon and
• 28:34
  the Earth into account. Uh, then
• 28:37
  it did a Venus flyby and you think, wait a
• 28:39
  minute, Venus isn't on the way to Jupiter.
• 28:42
  It's the other way.
• 28:43
  Andrew Dunkley: Here we go again.
• 28:44
  Professor Fred Watson: Yeah, here we go again. But that's how you do
• 28:46
  these gravitational assists, uh, that um,
• 28:49
  actually increased its speed. Uh,
• 28:52
  and I think I'm right in saying as we stand
• 28:54
  here now, there are two more flybys of Earth.
• 28:57
  Uh, one on the 28th of September,
• 29:01
  um, which is as we're speaking now in the
• 29:03
  future, but perhaps won't be by the time our
• 29:05
  listeners hear this, except for our live
• 29:07
  audience who are hearing it now. Um, and
• 29:09
  welcome again.
• 29:11
  Andrew Dunkley: By the time this one goes out, this episode
• 29:14
  goes out, what we're talking about will have
• 29:15
  happened last week.
• 29:17
  Professor Fred Watson: Okay, so last week there was another flyby
• 29:20
  of the Earth, um, coming
• 29:23
  within, uh, actually less than 9,000
• 29:26
  kilometres of the Earth's surface. That is
• 29:28
  very close. Uh, and that sets it
• 29:31
  up for a, uh, gravitational.
• 29:34
  Final gravitational assist in January
• 29:37
  2029. A, uh, couple of
• 29:40
  years down the track, three years down the
• 29:42
  track, um, or two and a half. Um,
• 29:45
  and that will put Juice on its,
• 29:48
  uh, sort of, um. I guess the
• 29:51
  best way to describe it is on the
• 29:53
  fastest part of its journey because it will
• 29:55
  then head off towards Jupiter, uh, and
• 29:58
  intercepting the orbit of Jupiter in July
• 30:01
  2031. Uh, so a long
• 30:04
  and complicated journey. Still simple
• 30:06
  compared with BepiColombo, uh, which is now
• 30:09
  in the region of Mercury after I think. Was
• 30:11
  it eight or nine gravitational assists?
• 30:13
  Andrew Dunkley: It was nine. Yeah.
• 30:14
  Professor Fred Watson: Nine. Yeah. Um, so, uh,
• 30:18
  it's actually um, one of these things
• 30:21
  that uh, uh, we almost
• 30:24
  certainly won't notice it. Uh, but
• 30:26
  at that height, uh, it's uh,
• 30:29
  possible that people who know
• 30:32
  how to find the trajectory in the sky
• 30:36
  using, uh, telescopes or even binoculars
• 30:39
  might be able to track it. And there is a
• 30:41
  link on the European Space
• 30:43
  Agency's, uh, media
• 30:46
  brief on this, a link to tell you how to find
• 30:49
  the trajectory. So, uh, head
• 30:52
  to, uh, the page called Juice to fly past
• 30:54
  Earth for a third gravity assist. Uh,
• 30:58
  which might have been revised to Juice flew
• 31:01
  past Earth for a third gravity assist.
• 31:03
  Andrew Dunkley: It might.
• 31:05
  Professor Fred Watson: In which case you don't need to know where
• 31:07
  its trajectory is. But anybody who's
• 31:09
  listening live now can find that trajectory
• 31:11
  data on that website.
• 31:12
  I think there's at least two people who are
• 31:13
  listening.
• 31:15
  Andrew Dunkley: It's a very exciting mission.
• 31:16
  Professor Fred Watson: Can't wait. It is, isn't it? Yeah.
• 31:19
  Andrew Dunkley: And, and such a complicated way to get
• 31:21
  somewhere. But, uh, probably no more
• 31:23
  complicated than catching suburban trains.
• 31:26
  So, um, you know, sometimes you have to
• 31:29
  go out there to get back there, but.
• 31:31
  Professor Fred Watson: Yeah, that's right. Yeah, indeed.
• 31:33
  Andrew Dunkley: But, yeah, yes, uh, it's on the ESA website
• 31:35
  if you want to check it out. The Juice
• 31:38
  mission. Um, yeah. Uh, and who
• 31:41
  knows what it will reveal? We just gotta be a
• 31:43
  bit patient.
• 31:43
  We've got a few more years to wait yet. That,
• 31:46
  uh, brings us to the end. Fred Watson, thank
• 31:48
  you very much.
• 31:50
  Professor Fred Watson: Uh, you're welcome, Andrew. It's been a joy
• 31:52
  to talk to you again and to our, uh,
• 31:54
  listeners and to the audience who will
• 31:56
  eventually see this, uh, long after Juice has
• 31:59
  come and gone.
• 32:00
  Andrew Dunkley: Yes, indeed, professor, um, Fred Watson
• 32:03
  Watson, astronomer at large, part of the team
• 32:05
  here at Space Nuts. Don't forget to visit our
• 32:07
  website. Uh, in the meantime, you can send us
• 32:10
  a message on the Ask me Anything link at the
• 32:12
  top that's labelled ama. Uh, you can check
• 32:15
  out the shop. Uh, you can, um,
• 32:18
  subscribe to the Astronomy newsletter
• 32:21
  or, or. And, uh, you can, um,
• 32:24
  do something else that I've completely
• 32:25
  forgotten about. Hate it
• 32:28
  when that happens. Anyway,
• 32:31
  and thanks to Huw in the studio who couldn't
• 32:33
  be with us today. He, um, he
• 32:36
  grabbed some juice and now he's
• 32:38
  156.7 million kilometres away.
• 32:41
  He'll be back next week and from me, Dunkley,
• 32:44
  thanks for your company.
• 32:45
  We'll see you on the next episode of Space
• 32:47
  Nuts.
• 32:47
  Professor Fred Watson: Bye.
• 32:48
  Andrew Dunkley: Bye.