Latest / Space Nuts: Astronomy Insights & Cosmic Discoveries / #472: Titan's Unique Atmosphere, Tidal Locking Insights & Triton's Cosmic Journey

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#472: Titan's Unique Atmosphere, Tidal Locking Insights & Triton's Cosmic Journey · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Speaker 1: Hello again. This is Space Nuts.
• 0:02
  Speaker 2: See I told you I'll be back.
• 0:03
  Speaker 1: Andrew Dunkley here, great, they have your company, and this
• 0:07
  Speaker 1: is a Q and A episode and we will be
• 0:10
  Speaker 1: doing some homework. We had a question last time from
• 0:12
  Speaker 1: Yenst about why Titan has an atmosphere like it does,
• 0:17
  Speaker 1: and Fred's done his homework.
• 0:18
  Speaker 2: So we'll tell you all about it. Yenst.
• 0:20
  Speaker 1: We're going to look at tidal Locke, a new theory
• 0:23
  Speaker 1: about planet planet nine coming from one of our audience members,
• 0:27
  Speaker 1: and we're going to talk about something we've not talked
• 0:29
  Speaker 1: about much, but it wrote to us and said, you
• 0:32
  Speaker 1: don't talk about me. So we're going to look at Triton,
• 0:36
  Speaker 1: which is the moon of Neptune, and the use of Doppler.
• 0:41
  Speaker 1: We'll talk about all of that through questions on this
• 0:44
  Speaker 1: episode of Space.
• 0:46
  Speaker 3: Nuts fifteen second Channel ten nine ignition Space Nuts or
• 0:55
  Speaker 3: three two Space and I reported Neil Good and the
• 1:04
  Speaker 3: man on this particular mission is Professor Fred Watson, astronomer
• 1:08
  Speaker 3: at LA tellofred Illo.
• 1:10
  Speaker 2: Andrew, it's good to join.
• 1:12
  Speaker 4: You from a slightly different location from normal, but that's fine.
• 1:17
  Speaker 1: Yes, let's get straight into it because there is a
• 1:21
  Speaker 1: fair bit on the agenda. We're going to revisit a
• 1:24
  Speaker 1: question from last week which came from Sweden. Yeah, it
• 1:29
  Speaker 1: was YenS To who was asking about Titan's atmosphere. What
• 1:33
  Speaker 1: we might do is just play yenst question. I gets
• 1:37
  Speaker 1: how to say yenst question again and then we can
• 1:41
  Speaker 1: fill in the blanks.
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  Speaker 5: Hello, space nuts, This is YenS from the Forest of
• 1:46
  Speaker 5: Dulston at Sweden. As we all know, Saturn's moon Titan
• 1:50
  Speaker 5: is a very special place. So here's my question. How
• 1:54
  Speaker 5: did Titan become so special? How did it accumulate this
• 1:58
  Speaker 5: sick night to Jenna atmosphere and not it's meeting and eating.
• 2:02
  Speaker 5: There are dozens of months of auto planets, only Titan
• 2:06
  Speaker 5: has an atmosphere. What is it about Titan that made
• 2:10
  Speaker 5: it become different from all the other moons? And another
• 2:15
  Speaker 5: related question. It is often said that Mars is too
• 2:18
  Speaker 5: small to retain an atmosphere in the long term. The
• 2:22
  Speaker 5: Titan is even smaller. How came Titan carry ten an
• 2:25
  Speaker 5: atmosphere when Mars cannot? Thanks very great show.
• 2:31
  Speaker 1: Thanks to Angst. We did determine that Mars probably lost
• 2:34
  Speaker 1: its atmosphere because of its proximity to the Sun, and
• 2:37
  Speaker 1: it was all blown off by the solar winds, But
• 2:41
  Speaker 1: we didn't determine why Titan might have the unusual atmosphere
• 2:46
  Speaker 1: that it has and how it manages to retain that. Well,
• 2:49
  Speaker 1: it probably retains it because it's far enough from the
• 2:52
  Speaker 1: Sun not to be as significantly affected as Mars was.
• 2:58
  Speaker 1: But how is it that it's got such a strange atmosphere.
• 3:02
  Speaker 1: That's the pace of the puzzle we needed to do
• 3:04
  Speaker 1: some homework on for it.
• 3:06
  Speaker 4: Yeah, that's right, and it's actually not that hard to
• 3:10
  Speaker 4: find some interesting theories about why sorry, yes, why Titan?
• 3:19
  Speaker 4: Why Titan has a thick atmosphere? And various pieces of
• 3:26
  Speaker 4: work have been done on this. The one that I
• 3:28
  Speaker 4: think really puts it most cogently is a paper that
• 3:32
  Speaker 4: was actually published in January twenty nineteen, and that was
• 3:39
  Speaker 4: written by.
• 3:42
  Speaker 2: A group of.
• 3:43
  Speaker 4: Scientists led by Kelly Miller, who's at the Southwest Research
• 3:48
  Speaker 4: Institute in Boulder, Colorado, one of the big centers for planetary.
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  Speaker 2: Studies in the USA.
• 3:55
  Speaker 4: And Kelly says, and I'm quoting here, a lot of
• 3:58
  Speaker 4: organic chemistry is no doubt happening on Titan. So it's
• 4:01
  Speaker 4: an undeniable source of curiosity because Titan is the only
• 4:06
  Speaker 4: moon in our Solar system with a substantial atmosphere. Scientists
• 4:10
  Speaker 4: have wandered for a long time what its source was.
• 4:13
  Speaker 4: The main theory has been that ammonia ice from comets
• 4:16
  Speaker 4: was converted by impacts or photochemistry into nitrogen to form
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  Speaker 4: Titan's atmosphere. While that might still be an important process,
• 4:26
  Speaker 4: it neglects the effects of what we now know is
• 4:29
  Speaker 4: a very substantial portion of comets complex organic material. So
• 4:37
  Speaker 4: what Kelly is saying there is that, yes, comets are
• 4:41
  Speaker 4: mostly made of ice, but there is a significant proportion
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  Speaker 4: of them that are the organic chemicals that we form
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  Speaker 4: the building blocks of life here on Earth, the carbon
• 4:55
  Speaker 4: containing chemicals. And so the theory is that those complex
• 5:01
  Speaker 4: molecules have basically landed from comets and interacted with the
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  Speaker 4: with the surface of Titan. So you've got the sort
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  Speaker 4: of nitrogen atmosphere on Titan, which also has methane ethane
• 5:22
  Speaker 4: in it as well. And so stuff that would land
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  Speaker 4: from comets, these complex carbon containing molecules basically would would
• 5:30
  Speaker 4: react with the stuff that's already there. And so another
• 5:37
  Speaker 4: comet comment from Kelly Miller comets and primitive bodies in
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  Speaker 4: the outer Solar System are really interesting because they're thought
• 5:46
  Speaker 4: to be left over building blocks of the Solar System.
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  Speaker 4: These those small bodies could be incorporated into larger bodies
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  Speaker 4: like Titan, and the dense, organic, rich rocky material could
• 5:57
  Speaker 4: be found in its core. And that if you have
• 6:02
  Speaker 4: these organic chemicals that have found their way into the
• 6:06
  Speaker 4: core of Titan, that's the underlying rock that sits under
• 6:09
  Speaker 4: the ocean, that sits under the ice, then you've got
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  Speaker 4: a possible source of the gases that we see in
• 6:18
  Speaker 4: Titan's atmosphere. Now, so what we're talking about here is
• 6:22
  Speaker 4: an atmosphere that's been replenished over time.
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  Speaker 2: Which is essentially.
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  Speaker 4: You know why you have a body that's got an
• 6:33
  Speaker 4: atmosphere where you might not expect it to have. So
• 6:38
  Speaker 4: when YenS thinks about this a bit more, maybe have
• 6:41
  Speaker 4: a look at that work. Kelly Miller from Southwest Research Institute.
• 6:47
  Speaker 4: There is actually a nice space dot Com article that
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  Speaker 4: reports it dating from January twenty six to twenty nineteen.
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  Speaker 4: Saturn's biggest moon, Titan, may bake its own atmosphere.
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  Speaker 1: So it's just like cooking a cake in the oven.
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  Speaker 1: Everything else creates a gas that.
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  Speaker 2: I think that's the bottom line Andrew.
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  Speaker 1: Yes clever, all right, they go against Have a look
• 7:12
  Speaker 1: at that article from space dot Com if you want
• 7:15
  Speaker 1: to read more about it. But that's basically the theory
• 7:20
  Speaker 1: behind Titan's atmosphere. Now moving on, we have got a
• 7:25
  Speaker 1: question from Ken. Ken comes from Maruci door in Queensland.
• 7:30
  Speaker 1: I've got a few Queenslanders sent us in questions for
• 7:33
  Speaker 1: this week. Hi Fred and Andrew. Why is title locking
• 7:37
  Speaker 1: a function of proximity of the bound objects? Plus do
• 7:43
  Speaker 1: man made satellites that need to point antennas, et cetera
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  Speaker 1: to Earth automatically tidally lock or do they need initial
• 7:50
  Speaker 1: and ongoing manipulation to do so? Thanks Ken, so double whammy.
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  Speaker 1: Why is title locking a function of proximity of bound objects?
• 8:06
  Speaker 4: So it is a gravitational phenomenon, but in order for
• 8:13
  Speaker 4: it to work, you've got to have a reasonably sizeable object.
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  Speaker 4: So the whole thing about tides, Andrew, is that they're
• 8:23
  Speaker 4: caused by or what you might call tidal disruption, things
• 8:27
  Speaker 4: that are caused by a tidal effect. The tidal phenomenon
• 8:32
  Speaker 4: relies on one side of an object feeling a different
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  Speaker 4: amount of gravity from the other side, and so, for example,
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  Speaker 4: in the case.
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  Speaker 2: Of the Earth.
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  Speaker 4: The far side of the Earth feels less gravity from
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  Speaker 4: the Moon than the near side does, and so that
• 8:50
  Speaker 4: raises the tides on the Earth. And that process essentially
• 8:58
  Speaker 4: involves a breaking phenomenon, because as the Earth trying to rotate,
• 9:02
  Speaker 4: it's got this tidal pull from the Moon, and that's
• 9:06
  Speaker 4: actually slowing down the Earth's rotation. Now, the converse has
• 9:09
  Speaker 4: been true over billions of years. In fact, probably not
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  Speaker 4: that many. In fact, more like millions of years. The
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  Speaker 4: Moon felt the same thing.
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  Speaker 2: One side of it was.
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  Speaker 4: Feeling more of the pool from the Earth than the
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  Speaker 4: other side, and so the breaking effect was felt and
• 9:27
  Speaker 4: the moon's rotation slowed down until it was actually locked
• 9:30
  Speaker 4: to be always facing the same side to the Earth. Now,
• 9:36
  Speaker 4: spacecraft are too small for that phenomenon, you're.
• 9:39
  Speaker 1: Going to say, I'll bet you that the problem is
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  Speaker 1: the size of an object would be a major ef factor.
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  Speaker 4: So Ken the second part of Ken's question is correct,
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  Speaker 4: Do they need initial and ongoing manipulation to point antennas
• 9:56
  Speaker 4: to the Earth, And the answer is yes, they are directed,
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  Speaker 4: you know, using thrusters to point in the direction that
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  Speaker 4: they're meant to. It doesn't happen by tidal locking. It's
• 10:08
  Speaker 4: a nice idea, but but they're too small for the
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  Speaker 4: It would.
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  Speaker 1: It would certainly simplify things, wouldn't then if that could happen,
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  Speaker 1: it wouldn't make it easier.
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  Speaker 4: You just put it up there and it turns on
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  Speaker 4: its own to face the Earth. But that's not it works.
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  Speaker 1: And now moon is not the only thing in the
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  Speaker 1: Solar System that's tidally locked, is it. There's there's other
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  Speaker 1: moons that are tidally locked their air respective planets, and
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  Speaker 1: I think some of it is mercury tidally locked to
• 10:34
  Speaker 1: the Sun.
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  Speaker 4: It's it's it's it's resonant. It's it's not exactly a lock,
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  Speaker 4: but it's a similar process. So it's resonant, as is venus.
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  Speaker 1: Okay, Steve, so yes, Ken, It's yes, it's a it's
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  Speaker 1: a function of size. Size matters apparently when it comes
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  Speaker 1: to tidal locking.
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  Speaker 2: Good to hear from you.
• 10:56
  Speaker 1: Thanks to your question. Okay, we've tacked all for crystal
• 11:03
  Speaker 1: space nuts. Our next question comes from another Queenslander.
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  Speaker 5: His name is Ants.
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  Speaker 1: Got a bit of a what if question for you
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  Speaker 1: to wrap thinking here around.
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  Speaker 5: I'll propose that planet.
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  Speaker 6: Nourrin once did exist out there in the depth of
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  Speaker 6: the Solar System on Tyler olypical all but it came
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  Speaker 6: in and crossed paths. But the one and only ran Us,
• 11:27
  Speaker 6: giving us smack on the way past delment Over in
• 11:30
  Speaker 6: the process loses it's out of shell, making its size
• 11:33
  Speaker 6: it is now and it lost a lot of its
• 11:35
  Speaker 6: own momentum, making it drop into the inner Solar System
• 11:38
  Speaker 6: and gets captured by the Sun. And yeah, we now
• 11:43
  Speaker 6: call it planet Mercury. What do you think?
• 11:46
  Speaker 5: All right, so guys step up to work.
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  Speaker 1: Yeah, thinks that I think there's a bit of science
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  Speaker 1: fiction in that one, only because I suspect that we
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  Speaker 1: know this something in the far reaches of the Solar
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  Speaker 1: System that's still impacting on the objects out there, and
• 12:05
  Speaker 1: we haven't yet discovered what it is. But the mathematics
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  Speaker 1: says there is something. Therefore, if it's a planet, it's
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  Speaker 1: not Mercury. Would that be a fair assessment.
• 12:15
  Speaker 4: Yeah, I think you've answered it quite well. I'm very nicely,
• 12:20
  Speaker 4: and Jordie agrees with you. You might have heard him
• 12:22
  Speaker 4: just yelling in the groove there. So yes, it's the
• 12:27
  Speaker 4: the fact that that we've got this alignment of asteroid
• 12:32
  Speaker 4: far distant asteroid Transnaptunian object orbits that makes people suspect
• 12:38
  Speaker 4: that there is a planetary body in the.
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  Speaker 2: Depths of the Solar System.
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  Speaker 4: I think if you you know, if if the scenario
• 12:48
  Speaker 4: and it's a complex but nicely elaborated scenario from Ash
• 12:55
  Speaker 4: in Brisbane, if that had happened, I think these orbits
• 12:59
  Speaker 4: were have now regularized so that the phenomenon would have disappeared.
• 13:03
  Speaker 4: You know, if you take play Kine away and I
• 13:07
  Speaker 4: think there will be other disruption in the Solar System.
• 13:10
  Speaker 4: But I do like the way though the Ash ties
• 13:12
  Speaker 4: in the you know, this peculiar orientation of Uranus which
• 13:16
  Speaker 4: is on its side with the planet Mercury, which is mysterious.
• 13:20
  Speaker 4: We think Mercury was once a bigger object because it's
• 13:23
  Speaker 4: got a metal core that is too big for it.
• 13:27
  Speaker 4: So we do think there might have been an impact
• 13:29
  Speaker 4: there as well. So very nice thinking. Let's wait to
• 13:34
  Speaker 4: see whether it becomes mainstream thinking, but I suspect its
• 13:38
  Speaker 4: chances are pretty small, and for that you elucidated.
• 13:43
  Speaker 1: We can have a bit of a smirk about it.
• 13:45
  Speaker 1: But he's been very clever in putting a few things
• 13:47
  Speaker 1: together that we know and coming up coming up with
• 13:51
  Speaker 1: a theory, and theory is where you start when you're
• 13:53
  Speaker 1: trying to solve these astronomical puzzles. So yeah, why not
• 13:57
  Speaker 1: throw it out there. Someone might pick up on it
• 13:58
  Speaker 1: and go, hang on minute.
• 14:02
  Speaker 4: Yeah. What you've got to do, though, is you've absolutely
• 14:05
  Speaker 4: got to do the mathematical rigor on it all and
• 14:08
  Speaker 4: make sure that all the equations add up and that
• 14:10
  Speaker 4: it ties together and it's physically possible. And that's Yes,
• 14:15
  Speaker 4: that's where you need people with that sort of background,
• 14:20
  Speaker 4: which I don't actually have.
• 14:23
  Speaker 2: Not neither is Ash.
• 14:25
  Speaker 5: Well, you know, you never know.
• 14:26
  Speaker 2: Ash might be.
• 14:27
  Speaker 4: Oh, it might be a closet planet to your dynamicis
• 14:31
  Speaker 4: that we don't know about.
• 14:32
  Speaker 1: Who goes, Yeah, it may be. And I think we're
• 14:35
  Speaker 1: overdue for a new song, Ash, come on, we're dropping
• 14:38
  Speaker 1: the ball mate, No, a big good one. I like
• 14:42
  Speaker 1: he's thinking, thanks Ash. This is Space Nuts Andrew Dunkley
• 14:45
  Speaker 1: here with Professor Fred Watson.
• 14:54
  Speaker 2: Space Nuts.
• 14:55
  Speaker 1: Now. Our next question, Fred comes from another queen's.
• 15:00
  Speaker 5: This is Nigel.
• 15:01
  Speaker 7: Oh, friend and Andrew. This is Nigel from Brisbane, Australia.
• 15:04
  Speaker 7: I have a hypothetical question about Neptune's moon Triton. I
• 15:11
  Speaker 7: believe Triton is said to be captured by Neptune. I
• 15:15
  Speaker 7: hope I got that right. But what if it wasn't
• 15:18
  Speaker 7: captured and it was still orbiting the Sun out on
• 15:22
  Speaker 7: its own in the Solar System? My question is would
• 15:26
  Speaker 7: it be big enough to be a minor planet? And
• 15:30
  Speaker 7: how do you describe a minor planet? Love the show,
• 15:33
  Speaker 7: keep up the good work, Thank you, bye.
• 15:36
  Speaker 1: Thanks Nigel. I think you'd call it planet ten. How
• 15:43
  Speaker 1: big is Triton?
• 15:45
  Speaker 5: Right?
• 15:46
  Speaker 4: It's two seven hundred and ten kilometers across.
• 15:50
  Speaker 1: So it's too small to be official who designated a planet?
• 15:54
  Speaker 1: If it wasn't orbiting Neptune, No.
• 15:59
  Speaker 4: That wouldn't be what would stop it being a planet?
• 16:03
  Speaker 4: It's so it's that it's bigger than Pluto. In fact,
• 16:06
  Speaker 4: if I remember our Pluto is a little bit smaller
• 16:08
  Speaker 4: than that.
• 16:10
  Speaker 2: Got the number somewhere in my.
• 16:11
  Speaker 4: Head sixteen hundred and eighty miles or twenty seven hundred
• 16:15
  Speaker 4: and ten kilometers, So it it would be, without doubt
• 16:20
  Speaker 4: a dwarf planet because it'spherical in you know, it's it's
• 16:26
  Speaker 4: it's big enough for itsself gravity to have made its
• 16:28
  Speaker 4: fairy coal. And that's partly the definition of a planet.
• 16:33
  Speaker 4: But then to become a planet, it's got to have
• 16:36
  Speaker 4: cleared its area of the Solar System become heredominant projects,
• 16:42
  Speaker 4: which it hadn't done. So, but the thinking is is right,
• 16:48
  Speaker 4: it's it would definitely have.
• 16:50
  Speaker 2: Been a dwarf planet.
• 16:51
  Speaker 4: And the you know, Nigel's correct in the in s
• 17:00
  Speaker 4: that the thinking is that it has been captured, that
• 17:03
  Speaker 4: it probably is a trans Neptunian object to dwarf planet
• 17:07
  Speaker 4: that has been captured by Neptune itself. And the reason
• 17:10
  Speaker 4: why we think that is that it orbits Neptune the
• 17:12
  Speaker 4: wrong way around. It's in what's called retrograde orbit, which
• 17:17
  Speaker 4: means it's going around in the opposite direction to Neptune's rotation.
• 17:24
  Speaker 4: And it's actually the only big moon in the Solar
• 17:26
  Speaker 4: System to do that. There are a few of the
• 17:28
  Speaker 4: smaller moons of I think Jupiter and Saturn that are
• 17:31
  Speaker 4: probably captured asteroids that do that, but this is the
• 17:34
  Speaker 4: only big moon, and it is the seventh biggest moon
• 17:37
  Speaker 4: in the Solar System, so it's quite substantial in size.
• 17:41
  Speaker 4: So it would have been a dwarf planet. Now, the
• 17:47
  Speaker 4: term that Nigel uses minor planets, that's really an old
• 17:51
  Speaker 4: fashioned word or an old fashion term for what we
• 17:54
  Speaker 4: now call asteroids. Minor planets were the sort of the
• 18:00
  Speaker 4: posh term for astroids. Asteroid was always and I'm going
• 18:04
  Speaker 4: back sixty years now or so, asteroid was thought to
• 18:07
  Speaker 4: be a rather you know, sort of common a rather
• 18:10
  Speaker 4: commonplace term that wasn't proper, And so if you were
• 18:15
  Speaker 4: a scientist and you were working on asteroids, you would
• 18:18
  Speaker 4: have called them minor planets. And in fact, the title
• 18:21
  Speaker 4: of my master's thesis is Practical Techniques for the Determination
• 18:25
  Speaker 4: of Minor planet orbits, because we didn't call them asteroids.
• 18:29
  Speaker 4: And that was a set of a suite of software
• 18:33
  Speaker 4: to using these new phonal things called computers to work
• 18:36
  Speaker 4: out the orbits of asteroids. So minor planet is a
• 18:39
  Speaker 4: term that we don't now use. I suspect what Nigel
• 18:45
  Speaker 4: thinking of is dwarf planets. So it would have definitely
• 18:48
  Speaker 4: would have been categorized as a dwarf planet.
• 18:51
  Speaker 1: Ah okay, so yes, well that doesn't surprise me at all. Really,
• 18:57
  Speaker 1: it's not one we've talked about very often. What kind
• 19:00
  Speaker 1: of moon is triedent and it must keep quiet because
• 19:04
  Speaker 1: it's it's really embarrassed that it was a dwarf planet.
• 19:07
  Speaker 2: But now it's been demoted to Moon.
• 19:11
  Speaker 5: I mean, if you.
• 19:11
  Speaker 1: Can't get worse, it can't get much worse.
• 19:15
  Speaker 4: It's it's a once again, it's a nice world. We
• 19:19
  Speaker 4: think like a cross device atop a probable subsurface ocean
• 19:26
  Speaker 4: and then you know a rocky core in the middle.
• 19:30
  Speaker 4: It is geologically active, and the reason why that's thought
• 19:35
  Speaker 4: with the case is that its surface is pretty smooth,
• 19:41
  Speaker 4: without much in the way of craters. The estimated average
• 19:47
  Speaker 4: surface age is less than one hundred million years and
• 19:50
  Speaker 4: that now that sounds like a long time, but you know,
• 19:55
  Speaker 4: for example, our Moon bears the scars of the late
• 19:58
  Speaker 4: Heavy bombardment three point eight billion years ago, so that's
• 20:02
  Speaker 4: an old surface. So Triton has a young surface, and
• 20:06
  Speaker 4: that there's probably evidence of maybe some evidence of there
• 20:13
  Speaker 4: being geysers, you know, nice geysers of the kind that
• 20:17
  Speaker 4: we see on Enceladus and Europa. And so it is
• 20:20
  Speaker 4: a very very interesting world, especially being a captured possibly
• 20:26
  Speaker 4: captured dwarf planet, so it may have been formed much
• 20:28
  Speaker 4: further out in the Solar System. It's yeah, there's a
• 20:32
  Speaker 4: number of things about Triton that make it very interesting,
• 20:35
  Speaker 4: including its orbit. It's a very very circular orbit and
• 20:41
  Speaker 4: you know, it's thought that that might have happened over
• 20:44
  Speaker 4: the millennia, and because of usually if you've got a
• 20:50
  Speaker 4: circular orbit, there's not much of a squashing and squeezing
• 20:54
  Speaker 4: effect like we see on he O, Jupiter's moon Eo,
• 20:56
  Speaker 4: which is in an orbit that carries it near and
• 20:59
  Speaker 4: further from Jupiter, and squashing and squeezing is what makes
• 21:02
  Speaker 4: it very volcanically active. Triton's is circular, but there is
• 21:06
  Speaker 4: thinking that it still might have a warm interior from
• 21:10
  Speaker 4: tidal heating. That squashing and squeezing that happens at a
• 21:15
  Speaker 4: much lower level.
• 21:17
  Speaker 1: I just thought while you were talking, it prompted a
• 21:20
  Speaker 1: question in my brain about where the word asteroid came
• 21:24
  Speaker 1: from if they were previously known as minor planets, And
• 21:27
  Speaker 1: it actually came from the fact that William Herschel saw
• 21:32
  Speaker 1: them and couldn't understand that. He was completely baffled, according
• 21:36
  Speaker 1: to this article I've read, so he turned to another
• 21:39
  Speaker 1: fellow who happened to be a poet to come up
• 21:45
  Speaker 1: with a name for them. And I'll just quote this.
• 21:48
  Speaker 1: So the Sunday before the Royal Society meeting, Herschel appealed
• 21:52
  Speaker 1: to Charles Bernie, a poet with whom he was collaborating
• 21:56
  Speaker 1: on an educational poem about the cosmos. Bernie considered the
• 22:01
  Speaker 1: question and that night, by candlelight, penned a letter to
• 22:04
  Speaker 1: his son, Greek expert Charles Bernie Jr. The Elder Bernie
• 22:08
  Speaker 1: suggested that word asta ricos or stellular to describe the
• 22:14
  Speaker 1: new celestial objects, and they came up with the term
• 22:18
  Speaker 1: asteroid as a consequence. It didn't take off until the
• 22:21
  Speaker 1: eighteen fifties. They didn't. Yeah, obviously the astronomy and the people,
• 22:26
  Speaker 1: the big names in astronomy at the time went not
• 22:29
  Speaker 1: using that, but eventually it caught on.
• 22:32
  Speaker 4: Well, there was still doing They were still saying that
• 22:34
  Speaker 4: when I was a young astronomer.
• 22:36
  Speaker 2: Oh were they asteroids?
• 22:37
  Speaker 5: Yeah?
• 22:37
  Speaker 4: Absolutely, it's a minor plant. That was the proper term
• 22:42
  Speaker 4: for anything else was vaguely commonplace, you know, not ze
• 22:46
  Speaker 4: sing that we talked about, But yes, I do remember
• 22:48
  Speaker 4: reading that. Actually it could have you know, it could
• 22:51
  Speaker 4: have had a very old name asteroids, a lot nicer
• 22:54
  Speaker 4: than some of the things that were being were being.
• 22:57
  Speaker 1: Yeah, well what was the now they want stellulus stellular?
• 23:01
  Speaker 2: Yeah, wus interesting.
• 23:06
  Speaker 1: Thank you, Nigel. Good to have a chat about Triton.
• 23:08
  Speaker 1: We haven't done that very much. I'm not sure we
• 23:11
  Speaker 1: ever raised it before, to be honest, but yeah, it's
• 23:14
  Speaker 1: out there. It's doing its thing. It's feeling fairly forlorn
• 23:17
  Speaker 1: being demoted from dwarf planet to moon. It got itself caught.
• 23:23
  Speaker 1: That's why it happened. One more question before we wrap up.
• 23:27
  Speaker 1: This is a bit of a long one that comes
• 23:29
  Speaker 1: from Robert McCown. Whereabouts unknown. I said that because he
• 23:32
  Speaker 1: didn't tell us where he's strong. But that's okay, thanks Robert.
• 23:37
  Speaker 1: When a radar station measures the motion of an airplane
• 23:40
  Speaker 1: or weather that uses Doppler radar to tell if the
• 23:43
  Speaker 1: target is moving toward or away from the radar by
• 23:46
  Speaker 1: frequency shift. In other words, it measures the frequency change
• 23:50
  Speaker 1: of waves or photons of the emitted signal. When we
• 23:54
  Speaker 1: measure the signals from cosmologically distant objects like quasars and galaxies,
• 24:00
  Speaker 1: we observe that they receive them at relativistic velocities. In
• 24:05
  Speaker 1: this context, how is the difference of the Doppler effect
• 24:10
  Speaker 1: observed on Earth and in the local universe different from
• 24:14
  Speaker 1: the loss of energy of photons from the distant universe
• 24:18
  Speaker 1: due to the expansion of space time based on dark
• 24:21
  Speaker 1: and it expanded.
• 24:22
  Speaker 7: Wow.
• 24:24
  Speaker 1: Is this an example of the change in the symmetry
• 24:27
  Speaker 1: of translation explained by Emma Noa And that's come from
• 24:33
  Speaker 1: Robert McCowen notha.
• 24:36
  Speaker 5: I think that's right.
• 24:39
  Speaker 1: Noah, Yeah, Actually I think so.
• 24:46
  Speaker 4: Roberts kind of answered it himself, because we do differentiate
• 24:52
  Speaker 4: between the Doppler effect caused by motion relative motion, and
• 25:00
  Speaker 4: the cosmological red shift caused by the expansion of the
• 25:04
  Speaker 4: universe exactly as he says. So they are different, they're
• 25:10
  Speaker 4: different things the sort of how can I put this?
• 25:17
  Speaker 4: The physical way in which they manifest themselves is the same.
• 25:23
  Speaker 4: It's a shift of the wavelength of light towards the
• 25:26
  Speaker 4: red end of the spectrum, but one's caused by a
• 25:30
  Speaker 4: relative motion between objects, and the other is caused simply
• 25:34
  Speaker 4: by the stretching of light caused by the expansion of
• 25:40
  Speaker 4: the universe. And in fact, we can sometimes work on
• 25:44
  Speaker 4: these two things together. In fact, I've been involved with
• 25:47
  Speaker 4: this because in the early two thousands, the UK Schmidt
• 25:51
  Speaker 4: Telescope did a survey of about one hundred and thirty
• 25:55
  Speaker 4: six thousand galaxies where we were looking at their red
• 26:01
  Speaker 4: shift in other words, they expand, they shift towards the
• 26:07
  Speaker 4: red of their light caused by the expansion of the universe.
• 26:10
  Speaker 4: The fact that the light was being stretched, we could differentiate,
• 26:13
  Speaker 4: We could measure that, but also we could work out
• 26:17
  Speaker 4: what are called their peculiar velocities, and that is the
• 26:21
  Speaker 4: independent motion of a galaxy when it's superimposed.
• 26:27
  Speaker 2: If I put it this way on what we call
• 26:28
  Speaker 2: the hubble flow.
• 26:29
  Speaker 4: The hubble flow is the motion of galaxies as they're
• 26:32
  Speaker 4: carried along by the expansion of the universe, but they've
• 26:35
  Speaker 4: sometimes got their own individual motions on top of that.
• 26:38
  Speaker 4: The usual analogue that we give is it's a bit
• 26:41
  Speaker 4: like imagine somebody. Imagine somebody in a boat on a
• 26:45
  Speaker 4: flowing river, and that flow of the river is what's
• 26:48
  Speaker 4: carrying them along, but they can move the boat around
• 26:51
  Speaker 4: within that flow, so they've got their own peculiar motion.
• 26:54
  Speaker 4: We do the same with galaxies, and the way you
• 26:57
  Speaker 4: do that is actually quite clever. You can measure proper
• 27:00
  Speaker 4: of galaxies that give you basically an estimate of their
• 27:07
  Speaker 4: intrinsic luminosity, how bright they are, and then you can
• 27:10
  Speaker 4: use that as a distance measure and combine compare that
• 27:15
  Speaker 4: with the measure you get from the hubble flow and
• 27:17
  Speaker 4: if they're different, that's due to the peculiar motion of
• 27:21
  Speaker 4: the galaxy.
• 27:21
  Speaker 2: I've not explained that very well, but that's how it works.
• 27:24
  Speaker 4: So yes, So the answer to the question is is
• 27:28
  Speaker 4: basically yes, and thank you very much.
• 27:31
  Speaker 1: Correct, excellent, Well Dan, Robert, and thanks for sending in
• 27:35
  Speaker 1: your question, and don't forget if you have a question
• 27:37
  Speaker 1: for us, you can do that or send it to
• 27:40
  Speaker 1: us via our website, space nets podcast dot com or
• 27:43
  Speaker 1: spacenats dot io and click on the AMA link at
• 27:47
  Speaker 1: the top. Now, we did have a question from somebody
• 27:49
  Speaker 1: asking if there would be a better way of labeling
• 27:53
  Speaker 1: the AMA link, and yes, that's a good question, and
• 27:57
  Speaker 1: I've referred that one to Hugh who is looking into it.
• 28:01
  Speaker 2: But yeah, it is a.
• 28:01
  Speaker 1: Bit of an obscure target when it comes to finding
• 28:05
  Speaker 1: a way of sending us questions, but we're getting plenty
• 28:07
  Speaker 1: of them, so I think most people are aware of it.
• 28:10
  Speaker 2: But yeah, if we can relabel it, we will.
• 28:12
  Speaker 1: I'm not sure what the process entails, but yeah, it's
• 28:18
  Speaker 1: a work in progress. Thanks Robert, thanks to everybody who's
• 28:21
  Speaker 1: sent in questions, and thanks to you Fred for answering them.
• 28:25
  Speaker 1: We really appreciate it.
• 28:28
  Speaker 2: That's a pleasure.
• 28:30
  Speaker 4: I always enjoy having my bread stretched by space, not
• 28:35
  Speaker 4: as listener questions.
• 28:36
  Speaker 1: It's good stuff, yes, which can be measured using the
• 28:39
  Speaker 1: Doppler effect. Yes, indeed.
• 28:43
  Speaker 5: Thanks Fred, We'll see you, sir.
• 28:48
  Speaker 1: And thanks to here in the studio who we won't
• 28:50
  Speaker 1: see soon but he's out there somewhere. And from me
• 28:53
  Speaker 1: Andrew Dunkley, thanks for your company. Looking forward to joining
• 28:56
  Speaker 1: you again soon might be on the next episode of
• 28:59
  Speaker 1: Space Bye Bye.
• 29:02
  Speaker 8: You'll be listening to the Space Nuts podcast, available at
• 29:07
  Speaker 8: Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player.
• 29:12
  Speaker 1: You can also stream on demand at bites dot com.
• 29:16
  Speaker 8: This has been another quality podcast production from nights dot com.