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Exploring Moons with Atmospheres, Hot Jupiters, and the Mysteries of Black Holes · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Andrew Dunkley: Hello again and thank you for joining us on
• 0:02
  yet another episode of Space Nuts. I don't
• 0:04
  know what we're up to.652.
• 0:07
  Blimey. And we only started yesterday.
• 0:10
  Uh, coming up in this Q and A episode, we
• 0:13
  will be answering questions about, uh, moons
• 0:15
  with atmospheres, secret
• 0:18
  astronomy. This is a fascinating question.
• 0:21
  Uh, we've also got, uh, a question about hot
• 0:24
  Jupiters. We've talked about them before. And
• 0:26
  a very rare, never before
• 0:29
  asked black hole question that's
• 0:32
  coming up in this Q and A edition of space
• 0:34
  nuts. 15 seconds.
• 0:36
  Professor Fred Watson: Guidance is internal. 10,
• 0:39
  9, ignition sequence start. Uh,
• 0:42
  space nuts. 5, 4, 3, 2. 1, 2,
• 0:45
  3, 4, 5, 5, 4, 3, 2, 1.
• 0:48
  Andrew Dunkley: Space nuts.
• 0:49
  Professor Fred Watson: Astronauts report it feels good.
• 0:52
  Andrew Dunkley: Joining us again to resolve all of that is
• 0:54
  Professor Fred Watson Watson, astronomer at
• 0:57
  large. Hi, Fred Watson.
• 0:58
  Professor Fred Watson: Hello, Andrew. How are you? Good to see you
• 1:00
  again.
• 1:00
  Andrew Dunkley: I'm as well as I was the last time you saw
• 1:03
  me.
• 1:05
  Professor Fred Watson: Yes. All those years ago. That's right, yeah.
• 1:08
  Andrew Dunkley: Minutes or seconds, whichever comes first.
• 1:12
  Uh, we've got some good questions today and,
• 1:14
  uh, I thought we might just get straight into
• 1:16
  it if you're, uh, ready to.
• 1:18
  Oh, no, I've got an announcement.
• 1:20
  Professor Fred Watson: Oh, yes, Better do that then.
• 1:23
  Andrew Dunkley: It's a bit of shameless self promotion. I've
• 1:25
  finally released my science fiction trilogy.
• 1:30
  Yes, it's out there. Um, I'm just putting the
• 1:33
  final touches on a few bits and bobs. But the
• 1:35
  ebook is out. Uh, the paperback
• 1:38
  should be out by the time you hear this.
• 1:42
  Um, unless you're watching us live on
• 1:44
  YouTube.
• 1:44
  Professor Fred Watson: Hello.
• 1:45
  Andrew Dunkley: It's called the Human Epoch.
• 1:48
  M which I did look up to see if there are
• 1:51
  any other science fiction books with that
• 1:53
  name, and there are not. So the human
• 1:56
  epoch, parts 1, 2 and 3. I released them all
• 1:58
  at once.
• 1:58
  Andrew Dunkley: Oops.
• 1:59
  Andrew Dunkley: I, uh, nearly released the microphone. Yeah,
• 2:01
  all at once. I thought, I'm gonna write the
• 2:03
  whole thing and release it as a batch rather
• 2:06
  than write one book and then
• 2:08
  release it and then make people wait a year.
• 2:11
  Now the whole bang lot's out there already
• 2:14
  on its way.
• 2:15
  Professor Fred Watson: Seasons one, two and three.
• 2:16
  Andrew Dunkley: Yes, exactly. I hope people enjoy it. Can't
• 2:19
  wait to get the feedback. Good, bad or
• 2:22
  indifferent. So the Human Epoch.
• 2:24
  Professor Fred Watson: Look for it.
• 2:25
  Andrew Dunkley: Uh, and you should be able to order it from
• 2:27
  bookshops. I don't know. I don't know how it
• 2:29
  works. Um, but you know, looking
• 2:32
  at the cost of printing and the
• 2:35
  sharing of spoils, um, if you
• 2:38
  sell a book for 20 bucks these days, you
• 2:40
  might get two or three dollars out of that.
• 2:42
  It's a Tough industry.
• 2:44
  Professor Fred Watson: Very. Yeah.
• 2:46
  Andrew Dunkley: I mean, you've really got to sell
• 2:49
  m tens of thousands of books to even scratch
• 2:51
  the surface. Which I have not done.
• 2:55
  Professor Fred Watson: Yeah, neither have I.
• 2:56
  Andrew Dunkley: No, no. But anyway, I
• 2:59
  thought I'd give it a mention. I've mentioned
• 3:01
  that I was writing it times. I thought I
• 3:03
  might as well people. It's out there. So
• 3:06
  there. That's, um, done.
• 3:07
  Professor Fred Watson: So you're not emulating Douglas Adams with a
• 3:10
  trilogy in four parts?
• 3:13
  Andrew Dunkley: No, but, you know, I
• 3:15
  might. Yeah, I might continue the
• 3:18
  storey because I became very. Isn't.
• 3:21
  Andrew Dunkley: Uh.
• 3:21
  Andrew Dunkley: I don't know if this happens to other
• 3:23
  authors. I'm sure it does.
• 3:24
  Professor Fred Watson: Oh, there you are.
• 3:24
  Andrew Dunkley: It happens to Earth.
• 3:26
  Professor Fred Watson: Yes, it does. He's a bit late.
• 3:27
  Andrew Dunkley: We could have used him in the last episode.
• 3:28
  Professor Fred Watson: We could. That's right. With the dogs.
• 3:31
  Andrew Dunkley: Um, you get a bit attached to some of
• 3:34
  the characters you create.
• 3:35
  Professor Fred Watson: Yes. I believe that happens when you write
• 3:38
  fiction.
• 3:38
  Andrew Dunkley: Um, the main character in this trilogy,
• 3:42
  um, I've come to adore. I really. I love his
• 3:45
  attitude. That's all I say.
• 3:48
  Professor Fred Watson: Okay. All right.
• 3:49
  Andrew Dunkley: Okay. He's
• 3:53
  a different kind of character.
• 3:55
  Professor Fred Watson: Is he based on anybody real?
• 3:57
  Andrew Dunkley: No, I made him up. Um, and I made him
• 4:00
  Canadian. Uh, I don't know why. I just did.
• 4:03
  Professor Fred Watson: I just thought Canadian.
• 4:05
  Andrew Dunkley: Canadians never get much of a mention in
• 4:07
  science fiction novels. So I thought, I'll
• 4:08
  make my hero a Canadian.
• 4:10
  Professor Fred Watson: Good on you. Yeah.
• 4:13
  Andrew Dunkley: All right.
• 4:14
  Professor Fred Watson: Before we do that, I better just go and see
• 4:16
  what's, um. Because I'm home alone at the
• 4:18
  moment. Jordy, I won't be a sec.
• 4:21
  All right?
• 4:22
  Andrew Dunkley: Okay. This doesn't happen very often. He
• 4:25
  could have done that while I was spruiking
• 4:27
  the book, you know, because, um, that would
• 4:29
  have been a nice filler. But now he's
• 4:32
  just left me swinging in the breeze.
• 4:35
  Which, um, happens occasionally.
• 4:39
  This used to happen on radio. I remember
• 4:41
  once, uh, years ago, um, we were
• 4:43
  expecting some guests, so I played an
• 4:45
  appropriate song. I think they were circus
• 4:47
  performers. And I played
• 4:50
  circus by Britney Spears in the hope that
• 4:53
  they would actually arrive while the song was
• 4:54
  on. And, uh, I got lucky. They
• 4:57
  walked in the door just as it was finishing.
• 4:59
  So I got the interview on air in time. It's
• 5:02
  sometimes a bit scary like that. Anyway,
• 5:05
  welcome, uh, back, Fred Watson. Is Jordie
• 5:06
  okay?
• 5:07
  Professor Fred Watson: Yes. I don't know what was causing
• 5:10
  the howling. Uh, ruckus.
• 5:12
  Andrew Dunkley: A butterfly, probably.
• 5:13
  Professor Fred Watson: Could have been. Honestly, it's that level
• 5:15
  that sets him off. You know, a leaf
• 5:18
  moves two, uh, hundred metres away across
• 5:21
  the forest and off he goes. That's right.
• 5:23
  Andrew Dunkley: He could probably use a GPS collar.
• 5:26
  Professor Fred Watson: There were times when he could use a muzzle,
• 5:29
  I think to speak.
• 5:32
  Andrew Dunkley: Um, now let's get into some questions. I
• 5:34
  think that's why we're here.
• 5:35
  Professor Fred Watson: Oh, I suppose it is, yes. Yes.
• 5:37
  Andrew Dunkley: Um, so first question comes from Chris
• 5:40
  in Exmouth in the uk. Just
• 5:42
  wondering, could a moon ever have
• 5:45
  an atmosphere and is it possible for a moon
• 5:48
  to be close enough to a planet to share
• 5:51
  an atmosphere? Really enjoy the show. Thank,
• 5:54
  uh, you Chris for sending that in. Um,
• 5:57
  look, we already know in our solar system
• 6:00
  there are moons with atmospheres and I do
• 6:02
  believe they do share their stuff with their
• 6:05
  home planets, some of them.
• 6:06
  Professor Fred Watson: Uh, correct. That's right. Although
• 6:09
  it's sort of um, probably not quite
• 6:12
  what Chris has, his mind. So yes. Uh, I mean
• 6:15
  the classic example is Saturn's moon Titan,
• 6:18
  that has a very thick atmosphere,
• 6:21
  um, atmospheric pressure I think one and a
• 6:23
  half times that of the Earth. It's a dense
• 6:25
  atmosphere and um, also
• 6:27
  opaque because it's rich in um,
• 6:31
  ah, hydrocarbons. The same
• 6:34
  stuff that makes smog in a city. Uh, is why
• 6:37
  we can't see through Titan's atmosphere. So
• 6:39
  yes, a moon can have an atmosphere, um,
• 6:42
  but you can't have a situation where
• 6:45
  uh, you had a planet and a
• 6:48
  moon which were sort of embedded in a much
• 6:51
  larger dense atmosphere. Uh,
• 6:54
  and that's because the, you basically
• 6:57
  slow down the moon as it orbits the planet,
• 7:00
  uh, and it doesn't last very long. Uh, in
• 7:02
  fact that's what brings satellites down uh,
• 7:04
  from orbit. Low Earth orbit above the Earth.
• 7:08
  They are slowed down by the Earth's
• 7:09
  atmosphere, even though it's very tenuous up
• 7:12
  there. And uh, nevertheless it slows them
• 7:14
  down and they fall deeper into the atmosphere
• 7:16
  and the deceleration continues.
• 7:19
  But the example that you've mentioned is the
• 7:22
  one that came to mind when I read this
• 7:24
  question as well. Uh, which is
• 7:27
  the dwarf planet Pluto, uh,
• 7:30
  which has a large moon. It's uh,
• 7:34
  about half the size of Pluto actually. It's
• 7:35
  called Charon, uh, or Charon, not
• 7:38
  Charon. Some people call it Charon.
• 7:40
  Andrew Dunkley: They do.
• 7:42
  Professor Fred Watson: Charon, Shaz for short.
• 7:45
  Shaza. Yeah, um,
• 7:48
  it's uh, it's a large moon, as
• 7:51
  I said, half the size of Pluto.
• 7:54
  Uh, and so they are in a sense a
• 7:56
  binary dwarf planet system because
• 8:00
  they orbit around a point which
• 8:03
  is outside the body of Pluto, uh,
• 8:06
  which is the kind of definition of a binary
• 8:08
  system, something orbiting around a common
• 8:10
  centre of gravity. Uh, so you've
• 8:13
  got that ah, unusual situation to start
• 8:16
  with, but um,
• 8:19
  it Appears that because of that
• 8:22
  geometry,
• 8:25
  the atmosphere of
• 8:27
  Pluto, which is very, very thin, but it is
• 8:30
  there. I was once helping a project that
• 8:33
  measured the atmosphere of Pluto not from
• 8:35
  space, but by Pluto passing in front of a
• 8:37
  star as observed with the Anglo Australian
• 8:40
  telescope. We could see it dimmed gradually,
• 8:42
  the light of the star rather than just
• 8:44
  switching off as it would have been if
• 8:46
  there'd been no atmosphere. So, uh, that
• 8:48
  atmosphere is mostly nitroge gas,
• 8:51
  uh, or the part that's
• 8:54
  escaping. Uh, and
• 8:56
  apparently it is basically
• 8:59
  captured by Charon. There's
• 9:02
  this flow of the nitrogen
• 9:05
  from Pluto to its dwarf
• 9:08
  planet companion. Um,
• 9:10
  there's probably something similar happens
• 9:13
  with the Earth and Moon, but very, very much
• 9:17
  less intense. Uh, there's probably a
• 9:20
  bit of gas transfer, uh, from
• 9:25
  the Earth, uh, to the Moon. Given that
• 9:28
  the pressure of the Earth's atmosphere
• 9:31
  doesn't just stop suddenly, it falls away
• 9:33
  very gradually. And in fact there are some of
• 9:35
  the molecules of the Earth's atmosphere that
• 9:37
  are out at the distance of the Moon. Uh, so
• 9:40
  they probably do exchange, you
• 9:42
  know, some low levels of gas, but
• 9:45
  not very much. And it is, yes, it's
• 9:48
  a different situation from perhaps what Chris
• 9:50
  had in mind with an atmosphere, with a planet
• 9:52
  and its moon both orbiting within it.
• 9:55
  Andrew Dunkley: Yeah, I understand what he was saying. Uh,
• 9:57
  and as you suggested, um, it
• 10:00
  would be an impossible situation. Although
• 10:03
  we do see, I think around the gas giants,
• 10:06
  some of those planets, particularly the ice
• 10:08
  worlds, do shed some of their
• 10:10
  material, which is picked up by
• 10:13
  um, um, the gas giant, I think.
• 10:17
  Is it Enceladus?
• 10:19
  Professor Fred Watson: Uh, yeah, that forms, um, that's correct.
• 10:22
  So that's solid matter. Actually it's the
• 10:24
  ice crystals that come from Enceladus
• 10:27
  Ocean. They form, uh, Saturn's E
• 10:30
  ring, uh, which is a very, um,
• 10:33
  non dense, very, uh, rarefied ring.
• 10:36
  One. I think it's the outermost ring of
• 10:38
  Saturn. Um, and it's basically,
• 10:41
  uh, the orbit of uh, Enceladus is embedded in
• 10:43
  that. So, yes, that's a sort of similar sort
• 10:46
  of situation. Yeah, that's right.
• 10:47
  Andrew Dunkley: It's not sharing atmosphere, but it's sharing
• 10:50
  material in a way.
• 10:53
  So, uh, the answer to both of your points,
• 10:55
  Chris, is definite. Yes, um,
• 10:59
  but no, in terms of them both sharing the
• 11:01
  same atmosphere. Hold us,
• 11:04
  Bolus. As we say so. Yeah, but great
• 11:07
  question, uh, Christian Exmouth. Where's
• 11:10
  Exmouth, Fred Watson?
• 11:11
  Professor Fred Watson: Uh, down in Devon. It's a lovely part of the
• 11:13
  country. Uh, and um, it's
• 11:16
  uh, not far from Exeter. The River X
• 11:19
  runs through both of them, as you'd expect.
• 11:21
  Andrew Dunkley: Uh, and the River X owned by Elon
• 11:23
  Musk.
• 11:25
  Professor Fred Watson: Probably, yes. It's spelled
• 11:27
  slightly differently from Elon Musk's X, but
• 11:29
  yes, probably still the same thing.
• 11:33
  Andrew Dunkley: Thanks for the question, Chris.
• 11:35
  Next question comes from, uh, somebody
• 11:38
  who's keeping their name a secret. And it's,
• 11:40
  uh, it's about secret astronomy. Oh, hang
• 11:43
  on, That's. I've got to change pages. Here we
• 11:45
  go. Here we go.
• 11:46
  Professor Fred Watson: I have a question about secret
• 11:49
  astronomy. We know that gamma
• 11:51
  ray bursts were first detected by spy
• 11:53
  satellites looking for nuclear testing. We
• 11:56
  know that satellites use star tracking and
• 11:58
  star catalogues for calculating their
• 12:00
  position. And we, uh, know that the Nancy
• 12:03
  Grace Roman launching, hopefully in August,
• 12:06
  uses, um, is built out of a,
• 12:09
  um, spy satellite the National Reconnaissance
• 12:11
  Office, the US Uh spy satellite agency,
• 12:14
  donated to NASA because they weren't going to
• 12:16
  launch it. They donated two and only one is
• 12:19
  being used yet. And we know that the Space
• 12:21
  Force released, um, a bunch of observational
• 12:24
  data around bolides to, um, help with
• 12:26
  planetary defence and asteroid detection
• 12:29
  and understanding. So by their nature, spy
• 12:32
  satellites tend to point at the Earth. Um,
• 12:35
  but obviously they push into a lot of
• 12:37
  astronomy and astronomy adjacent, um, things.
• 12:41
  I just wondered if you could speculate, given
• 12:44
  their budgets and um,
• 12:46
  constantly improving capabilities, where they
• 12:49
  might be ahead of public astronomy or running
• 12:51
  into things that, um. Uh,
• 12:54
  yeah, it might be pretty interesting in a few
• 12:56
  years. Thank you so much.
• 12:59
  Andrew Dunkley: Thank you for the question.
• 13:01
  Professor Fred Watson: Um,
• 13:03
  Andrew Dunkley: yeah, I don't know who that was, but, um.
• 13:05
  That's okay. Happens from time to time. But
• 13:07
  interesting, uh, question, Fred Watson.
• 13:10
  Professor Fred Watson: Really, it's, uh, not just an interesting
• 13:12
  question, but a very well posed one as well.
• 13:14
  Because everything our anonymous questioner
• 13:16
  said is true. Uh, and so we are being
• 13:19
  invited to speculate on what, what else
• 13:22
  might be up and running. Uh, we didn't know
• 13:25
  for a long time that there were two more
• 13:27
  Hubble telescopes, uh, because,
• 13:30
  you know, the company kept their. Built
• 13:33
  it. I think it might have been perkinelmer.
• 13:35
  I'm, um, not sure. But they kept their cards
• 13:38
  very close to their chest, uh, in terms
• 13:40
  of, uh, the existence of the Hubble
• 13:43
  telescope. But it turned out subsequently we
• 13:45
  found out there were two more built for
• 13:48
  surveillance. Um, something else
• 13:51
  that did find its way into astronomy
• 13:54
  that was originally secret was, um,
• 13:56
  President Reagan's Star wars technology,
• 13:59
  uh, which, um, required
• 14:02
  adaptive optics. And those are optical
• 14:05
  surfaces that change in response to, um,
• 14:08
  basically things like, um,
• 14:11
  uh, scintillation in the atmosphere or
• 14:14
  twinkling for a star. So that adaptive
• 14:16
  optics technology is now used very commonly
• 14:19
  in astronomy. Uh, it's not Used
• 14:22
  here in Australia we don't have a
• 14:25
  site that is naturally good enough um,
• 14:28
  to be able to compensate for um,
• 14:31
  this um, atmospheric turbulence. Whereas some
• 14:33
  of the better sites in the world like Mauna
• 14:36
  Kea in Hawaii and Ceropa
• 14:38
  Paranal, uh, in Chile, they do. And
• 14:41
  so they use um, adaptive optics
• 14:44
  very, very uh, commonly for their work.
• 14:47
  Basically allows you to take out the
• 14:49
  twinkling of a star which is something that
• 14:51
  ruins the images as you see them through
• 14:53
  telescopes. Uh and um,
• 14:56
  as I said, came from Star wars technology.
• 14:58
  Uh, that technology by the way, this is uh.
• 15:01
  Not really along the lines of the question
• 15:04
  but uh. It's leapfrogged as well from
• 15:06
  astronomy into um,
• 15:09
  ophthalmology. So uh, people are now using
• 15:12
  adaptive optics to compensate for
• 15:15
  the turbulence inside your eye
• 15:18
  when they're doing sort of retinoscopy and
• 15:21
  things like that. Uh, so that adaptive optics
• 15:23
  technology is now uh, gone from
• 15:27
  defence through astronomy and is
• 15:29
  now um, being developed for uh,
• 15:33
  health reasons, which is very, very good.
• 15:35
  Andrew Dunkley: Don't know if it's quite the same thing but
• 15:37
  my optometrist was telling me they've
• 15:40
  invented a new um, kind of
• 15:42
  um, lens that replaces human
• 15:45
  lens that can now
• 15:49
  do the same thing as a human lens. Like okay,
• 15:52
  when you have a cataract operation they
• 15:54
  replace the human lens. That's all fogged up
• 15:56
  with generally a plastic lens of some
• 15:59
  kind. But it was a fixed lens. It could only
• 16:02
  do one thing. They've now advanced the
• 16:05
  technology to the point where they can put a
• 16:07
  lens in that will be able to
• 16:10
  be controlled by your brain and give you
• 16:13
  various focal lengths.
• 16:15
  Professor Fred Watson: Yeah.
• 16:15
  Andrew Dunkley: Which I think is amazing.
• 16:17
  Professor Fred Watson: It's what you. What your eye naturally does.
• 16:19
  It's called accommodation you that the eye
• 16:21
  accommodates to different distances by
• 16:23
  changing the shape of the lens. Yeah, yeah.
• 16:25
  So um, that's pretty. Yes. Quite remarkable
• 16:28
  and um. Would be a real breakthrough for
• 16:31
  um. You know, for vision, uh, for poor
• 16:34
  vision.
• 16:34
  Anyway, we've strayed off the topic here. We
• 16:36
  have a bit and uh.
• 16:38
  Andrew Dunkley: I do, I'm sure never happens usually.
• 16:43
  Professor Fred Watson: I'm sure that um. Uh. Our uh.
• 16:45
  Listener is on the money suggesting that
• 16:47
  there are technologies that are being used
• 16:51
  in secrets, um.
• 16:53
  Professor Fred Watson: Ah.
• 16:53
  Professor Fred Watson: Or restricted environments.
• 16:56
  Uh, that would be of great
• 16:59
  value for astronomy. I uh.
• 17:02
  Guess the kind of thing that comes to mind is
• 17:05
  quantum detectors and. And things of that
• 17:08
  sort. Um, there is no. I don't think there's
• 17:11
  any equivalent uh, for example in the
• 17:14
  field of gravitational wave astronomy. I
• 17:16
  don't think there's anything that the
• 17:18
  military are doing that could feed into that.
• 17:19
  Although quantum optics are being used in
• 17:21
  that now. So, um, I
• 17:24
  suspect it's in, you know, in relation to the
• 17:26
  tools that are developed for, uh,
• 17:30
  our observations. Um,
• 17:32
  we owe infrared detectors,
• 17:35
  the things that see redder than red light or
• 17:37
  heat radiation. We owe them to the military.
• 17:40
  That's a spin off from military work. Um,
• 17:43
  I do remember, uh, one of the first
• 17:46
  infrared instruments on the Anglo Australian
• 17:48
  telescope. When it was being delivered.
• 17:51
  Uh, I think,
• 17:54
  um, the detector came under armed guard
• 17:56
  almost. It wasn't quite like that. But there
• 17:58
  was a lot of hoops to jump through when this
• 18:01
  detector was delivered. Because it had to be
• 18:03
  certain not to stray into the hands
• 18:06
  of certain foreign nations who the
• 18:09
  Americans who developed this detector didn't
• 18:12
  want, uh, them to get hold of.
• 18:15
  So those technologies do eventually
• 18:19
  kind of sprinkle down to astronomy where the
• 18:21
  poor relations in that regard, uh, although
• 18:24
  we do push the limits perhaps more than
• 18:25
  anybody else, uh, in technology.
• 18:29
  So, um, yes,
• 18:31
  I, I don't have any
• 18:35
  definite, um, speculations, uh,
• 18:38
  except to say that nothing would
• 18:40
  surprise me in that regard
• 18:43
  when it comes.
• 18:45
  Andrew Dunkley: I'm not a conspiracy theorist, but I do
• 18:47
  believe there's a heck of a lot going on up
• 18:50
  there that we do not and probably will
• 18:53
  not know about. Um, and
• 18:56
  I truly believe that the technology
• 18:59
  available today in space and on
• 19:02
  the planet, um, in those
• 19:05
  dark corners of government buildings
• 19:08
  is far, far more advanced than we
• 19:11
  could possibly imagine. I think given what
• 19:14
  we've got access to in a domestic sense in
• 19:16
  the public arena today,
• 19:19
  uh, what's been developed already behind
• 19:22
  closed doors that we're unaware of. And
• 19:25
  it's probably up. They're circling the planet
• 19:27
  as we speak.
• 19:29
  Professor Fred Watson: Yeah, I think it works both ways though,
• 19:31
  because I think, um, we're now
• 19:34
  seeing, uh, the military adopting
• 19:37
  what would have been thought of as commercial
• 19:39
  products before. Uh,
• 19:42
  and that's happened certainly in Ukraine.
• 19:45
  There's been an adaptation of
• 19:48
  all sorts of commercial products for
• 19:51
  military purposes. Um, so
• 19:54
  what I guess I'm saying is that the
• 19:55
  technology that we use every day is not
• 19:58
  as far removed from what the military use
• 20:01
  as it would have been 20 or 30 years ago.
• 20:05
  Uh, I think that's probably fair to say, but
• 20:08
  that's me going out on a limb. And who can
• 20:09
  prove me wrong?
• 20:11
  Andrew Dunkley: Well, that's a good point too. Yeah, it's a,
• 20:14
  uh, really interesting question. Thank you
• 20:16
  for sending it in. This is Space Nuts Andrew
• 20:18
  Dunkley here with Professor Fred Watson
• 20:20
  Watson.
• 20:22
  Professor Fred Watson: I believe that this nation should commit
• 20:25
  itself to achieving the goal
• 20:27
  before this decade is out of landing A man
• 20:30
  on the moon and returning him safely
• 20:33
  Andrew Dunkley: to the Earth face nuts.
• 20:35
  Another audio question from Fred.
• 20:39
  Andrew Dunkley: Hi, this is Fred calling you from St. Paul,
• 20:41
  Minnesota in the US I have a question for
• 20:44
  you regarding the solar systems that contain
• 20:48
  uh, so called hot Jupiter planets, those
• 20:50
  which are very close, ah, around their
• 20:53
  suns. Is it reasonable at all to
• 20:55
  expect that they will have
• 20:58
  smaller planets, rocky planets,
• 21:01
  or are there good reasons that
• 21:04
  come to mind where that should not be the
• 21:06
  case? Um, I'd uh, appreciate hearing
• 21:09
  your theories on this, uh, what the variables
• 21:12
  would be in this and I of course enjoy
• 21:15
  listening to your show. Thank you very much.
• 21:18
  Goodbye.
• 21:19
  Andrew Dunkley: Thank you Fred. Uh, Fred's one of our semi
• 21:22
  regular sender inners and um,
• 21:24
  he's always got a very interesting question
• 21:27
  in mind. Um, so uh, yeah, I'm
• 21:30
  guessing that what he is asking is if you've
• 21:32
  got a solar system with hot Jupiters, uh,
• 21:35
  that are orbiting their parent star in
• 21:38
  close proximity, could those systems
• 21:41
  have rocky planets further out? Now, uh, the
• 21:43
  downside of exoplanet detection is rocky
• 21:45
  planets are very hard to find at a distance.
• 21:47
  You generally find the gas giants
• 21:50
  fast or first. Um,
• 21:53
  we do know there are a lot of hot Jupiters
• 21:55
  out there because we've talked about them.
• 21:58
  Um, but uh, yeah,
• 22:01
  uh, what's the likelihood that that's a
• 22:04
  common thing? Um, not that there's
• 22:06
  anything absolutely common about anything you
• 22:09
  find when you start looking around at other
• 22:12
  solar systems?
• 22:13
  Professor Fred Watson: Yeah, that's exactly right. Our solar
• 22:16
  system is very neat and tidy compared with
• 22:18
  most of the other ones that we've detected.
• 22:20
  But you're absolutely right Andrew. Um, the
• 22:23
  rocky planets are the, the tricky ones to
• 22:25
  observe. And so it might well be that
• 22:28
  what we're seeing is effectively a selection
• 22:31
  effect. We're selecting the easiest ones,
• 22:34
  uh, to discover. Uh, and that's why we see a
• 22:37
  lot of hot Jupiters without any evidence
• 22:40
  of rocky planets in the same solar systems,
• 22:43
  I think, and I haven't looked at this for
• 22:46
  some time but um, one of the ideas
• 22:49
  for why we've got this
• 22:52
  situation with hot Jupiters is basically
• 22:56
  a planetary migration. This is where planets
• 22:59
  change their positions in the solar system.
• 23:02
  Uh, and that might have happened to some
• 23:04
  extent in our solar system, but not
• 23:07
  in um, a really sort
• 23:10
  of existential way. Not in a way that will
• 23:13
  totally alter the shape of the solar system
• 23:16
  because we've got four rocky planets which
• 23:17
  are the innermost ones and they exist within
• 23:20
  a zone where um,
• 23:23
  water exists as a
• 23:26
  gas, whereas beyond the orbit of Mars,
• 23:29
  and we sometimes call that the frost line or
• 23:31
  the ice line water exists
• 23:34
  uh, as ice and that ice is what
• 23:37
  has allowed the gas giants to grow
• 23:40
  to the size that they have because the ice
• 23:43
  basically collects and uh, the
• 23:46
  planets absorb it. So you've got ah,
• 23:50
  not just a massive rock being formed but ice
• 23:52
  as well. And then you end up with a gas
• 23:55
  giant planet. Uh so the four gas giants
• 23:58
  we think are ah, like that because they're
• 24:00
  outside the frost line. Now if you've got
• 24:03
  planetary migration taking place then
• 24:06
  some of those planets could wander in to the
• 24:08
  inner solar system. Uh and
• 24:11
  it may essentially leave your solar
• 24:14
  system looking like some of the ones that we
• 24:16
  see with a hot Jupiter orbiting very close
• 24:19
  to Paris star. But also
• 24:22
  perhaps with some rocky planets lingering
• 24:25
  uh, moaning around or moping around
• 24:28
  uh, where they've been uh, projected
• 24:31
  to by the rearrangement of the planets
• 24:33
  because some of them could be ejected by
• 24:35
  planetary migration. If you've got your gas
• 24:38
  giant wanders too near your little rocky
• 24:40
  planet, it's going to boot it out the solar
• 24:42
  system altogether. Uh but um, I
• 24:45
  suspect that there will be solar systems uh,
• 24:48
  ah that will turn out to have both hot
• 24:50
  Jupiters and rocky planets. And as our
• 24:54
  um, technology improves and allows us to
• 24:56
  detect these things uh, at lower masses, I
• 24:59
  think we'll be finding them as well. So um,
• 25:01
  watch this space phantom. That's the bottom
• 25:03
  line there.
• 25:04
  Andrew Dunkley: Theo was a wandering planet.
• 25:06
  Professor Fred Watson: Yes, that's right. Theo wandered into the
• 25:08
  Earth back in the uh, literally
• 25:11
  late 4,000 B.C. yeah,
• 25:15
  4,000 million BCS. I beg your pardon. Four
• 25:17
  billion. Yeah.
• 25:19
  Andrew Dunkley: I think um, the train of thought these days
• 25:22
  is that uh, in terms of solar systems,
• 25:25
  um, just about every star has at least got
• 25:28
  one planet. Um, that's based
• 25:31
  on an average assumption. But um,
• 25:34
  it also stands to reason that uh,
• 25:37
  solar systems are as many and as varied as
• 25:40
  there are stars in the sky. Ours
• 25:43
  which has the four rocky planets, then the
• 25:45
  gas giants as you move out and then the dwarf
• 25:47
  planets beyond that um, ours
• 25:50
  seems to be quite different
• 25:53
  from most.
• 25:54
  Professor Fred Watson: It does, that's what I meant. It's very neat
• 25:56
  and tidy compared with uh, what we see
• 25:59
  elsewhere. Um, certainly
• 26:02
  if you were on uh, the planet of
• 26:05
  a star 100 light years away, our rocky
• 26:08
  planets would be very difficult to detect.
• 26:10
  And you just think, you'd probably think all
• 26:12
  it had was Jupiter, uh because you'd be
• 26:15
  able to detect Jupiter relatively easily. If
• 26:17
  it passed in front of the sun it would, would
• 26:19
  produce a 1% drop in the um, light
• 26:22
  of the sun. And that's easy to
• 26:25
  measure. So yes. So um,
• 26:28
  uh is the future
• 26:31
  of our solar system, one that does involve
• 26:33
  planetary migration. Um, it doesn't seem
• 26:36
  to be. The planets seem to be in very, very
• 26:38
  stable orbits. And maybe that's just
• 26:40
  something to do with the geometry of the
• 26:42
  solar system itself. But maybe it's something
• 26:44
  to do also with why intelligent
• 26:47
  life has evolved on one of those planets.
• 26:49
  Because we've had this idea long term
• 26:51
  stability over many millions of years,
• 26:54
  which
• 26:54
  Andrew Dunkley: is why it's going to be near impossible to
• 26:56
  find another intelligent, communicative
• 26:59
  civilization. Because, um, the circumstances
• 27:02
  are unique.
• 27:03
  Professor Fred Watson: Could be, probably, yeah, could be almost
• 27:05
  unique. Yes.
• 27:06
  Andrew Dunkley: Thank you, Fred.
• 27:10
  Professor Fred Watson: Roger, you're allowed to clear here.
• 27:11
  Andrew Dunkley: Also space nuts. Our final question
• 27:14
  comes from Ed. Now this is not dissimilar to
• 27:17
  a question we had recently, but it's not
• 27:19
  quite the same either. Uh, we believe
• 27:22
  that nothing can escape from a black hole.
• 27:25
  And yet when two black holes merge, the mass
• 27:27
  of the surviving black hole is significantly
• 27:30
  less than the combined mass of the two
• 27:31
  merging black holes. It would appear this
• 27:34
  missing mass, which I understand is converted
• 27:36
  to gravitational waves, has to come from the
• 27:39
  black holes, hence energy. Matter does
• 27:42
  escape from black holes. Is this
• 27:44
  wrong? Ed asks. Hello, Ed, thanks for the
• 27:47
  question. Uh, black hole questions,
• 27:50
  Fred Watson. It's not. A week goes by we
• 27:52
  don't get a black hole.
• 27:54
  Professor Fred Watson: A great one, though. It's a good question
• 27:56
  that Ed's raised. Um, so it's.
• 27:59
  Yes, the uh, gravitational radiation
• 28:03
  is
• 28:06
  quite different from
• 28:09
  uh, the electromagnetic radiation that's
• 28:12
  coming from a black hole which does get
• 28:14
  trapped. It can't pass the event horizon.
• 28:16
  That's what the event horizon is all about.
• 28:18
  Because gravitation is a property
• 28:22
  not of the black hole, but of
• 28:25
  the universe itself. Ah. It's
• 28:28
  the underlying sort of fabric of space that
• 28:30
  is what carries gravity. Um,
• 28:33
  and so if you've got these colliding
• 28:36
  black holes, they shake the space
• 28:39
  itself rather than emit
• 28:43
  something. So that's the
• 28:45
  difference. The gravitational waves. Uh,
• 28:48
  yes, indeed. They're caused by, uh, the,
• 28:51
  by a loss of mass from the black holes. But
• 28:54
  they're not a property of the black holes. If
• 28:56
  I can put it that way. Yes, it's an
• 28:59
  effect rather than something being emitted.
• 29:02
  So, um, um, Ed's quite right that
• 29:05
  nothing can escape a black hole, but
• 29:07
  gravitational waves apparently do. But
• 29:10
  they're not. Basically what you're seeing is,
• 29:13
  uh, something to do with the universe, not
• 29:15
  the black hole.
• 29:17
  Andrew Dunkley: Okay, yeah, I get it. It's the old pebble in
• 29:20
  the pond trick.
• 29:21
  Professor Fred Watson: Yeah, that's right. Yes it is, yeah.
• 29:24
  The ripples in the pond, uh, don't come
• 29:27
  from the pebble. They come from the fact that
• 29:30
  the pebble has disturbed the underlying
• 29:33
  fabric. Uh, of the water, in fact. Put it
• 29:35
  that way. Yeah, it's a really good analogy.
• 29:39
  Andrew Dunkley: I come up with all sorts.
• 29:41
  Professor Fred Watson: You do, but that's a cracking good one,
• 29:43
  Andrew. Well done. I like that.
• 29:45
  Andrew Dunkley: I think you told it to me once before.
• 29:48
  Maybe.
• 29:49
  Professor Fred Watson: Maybe.
• 29:49
  Andrew Dunkley: Um, so that's the simplicity of it, really.
• 29:52
  There's not much more to tell.
• 29:53
  Professor Fred Watson: No, no, that's right. It's not. You know, it
• 29:55
  doesn't defy the logic of nothing being able
• 29:58
  to escape a black hole. Uh, it's, um,
• 30:01
  because you, um. Yes, Ed's right. Nothing
• 30:04
  can. Nothing solid or,
• 30:07
  um, electromagnetic or particles
• 30:09
  can't either. Uh, but the
• 30:12
  gravitational field is different. It's
• 30:15
  something to do with the underlying universe.
• 30:18
  Andrew Dunkley: Indeed it is. Uh, thanks, Ed. Great question.
• 30:21
  And, um, yeah, answered
• 30:24
  very simply in the end. Which
• 30:27
  doesn't happen often, does it, really?
• 30:29
  Professor Fred Watson: No, usually they're not answered at all.
• 30:32
  Andrew Dunkley: Or just adequately.
• 30:33
  Professor Fred Watson: Yes, adequately. That's right.
• 30:36
  Andrew Dunkley: Thanks, Ed. Uh, thanks to everyone who's sent
• 30:38
  in questions. And if you would like to send a
• 30:39
  question to us, please do go to our website,
• 30:41
  spacenutspodcast.com or spacenuts
• 30:44
  IO and there's a little button, uh, up the
• 30:47
  top top. Uh, or a tab or a link or whatever.
• 30:49
  It's a link. Uh, AMA stands for Ask me
• 30:52
  Anything. And you can send your questions in
• 30:54
  through that particular interface,
• 30:57
  text or audio. Don't forget to tell us who
• 31:00
  you are or where you're from. Although
• 31:01
  sometimes people forget. And you're not going
• 31:03
  to get into trouble for that. We're not that
• 31:06
  kind of people. M
• 31:08
  Nobody there. Have a look around. Visit the
• 31:10
  shop, become a supporter. And don't forget to
• 31:13
  leave, uh, reviews wherever you listen to us.
• 31:15
  Maybe the people listening live right now
• 31:18
  via YouTube could leave reviews. That'd be
• 31:20
  nice. Unless they hated us. Just don't do
• 31:23
  anything. No, I'm just kidding. They've stuck
• 31:26
  around, so we must be doing something right.
• 31:28
  Professor Fred Watson: Yeah.
• 31:28
  Andrew Dunkley: And we're all done, Fred Watson. Thank you
• 31:30
  very much.
• 31:31
  Professor Fred Watson: Thank you, Andrew. Um, we'll talk again soon.
• 31:34
  I, uh, look forward to it.
• 31:35
  Andrew Dunkley: I hope so. Uh, Professor Fred Watson Watson,
• 31:37
  astronomer at large, thanks to Huw in the
• 31:39
  studio, um, who couldn't be with
• 31:42
  us today because, uh, he's got a black
• 31:45
  hole problem. He called a plumber and neither
• 31:48
  of them can get out. And from me, Andrew
• 31:50
  Dunkley. Thanks for your company. I'll catch
• 31:52
  you on the next episode of Space Nuts. Until
• 31:55
  then, bye bye. You've been
• 31:58
  listening to the Space Nuts podcast
• 32:01
  available at Apple Podcasts, Spotify,
• 32:05
  iHeartRadio or your favourite podcast
• 32:07
  player. You can also stream on
• 32:09
  demand@bytes.com um,
• 32:11
  Professor Fred Watson: this has been another quality podcast
• 32:13
  production from bytes.um com.