Space Nuts #472 Q&A Edition: Titan's Mysteries and Cosmic Curiosities
Join Andrew Dunkley and Professor Fred Watson in this intriguing Q&A episode of Space Nuts, where they delve into the mysteries of our solar system and beyond, addressing questions from their curious audience. From the unique atmosphere of Titan to the hypothetical existence of Planet Nine, this episode is filled with captivating discussions and astronomical insights.
Episode Highlights:
- Titan's Atmospheric Enigma : Explore the origins of Titan's thick nitrogen atmosphere and its ability to retain it, unlike Mars. Discover the role of comets and organic chemistry in shaping this unique moon's environment.
- Tidal Locking Explained : Understand the gravitational phenomenon of tidal locking and why proximity and size matter. Learn about the differences in how natural and man-made satellites maintain their orientation.
- Planet Nine Hypothesis : Dive into a speculative theory about Planet Nine and its potential impact on Uranus and Mercury. Discuss the ongoing search for this elusive celestial body.
- Triton's Dwarf Planet Status : Uncover the history of Neptune's moon Triton and its possible past as a dwarf planet. Examine the characteristics that make Triton a fascinating world in its own right.
- Distinguishing Doppler Effects: Differentiate between Doppler shifts caused by relative motion and the redshift due to the universe's expansion. Explore how these phenomena are used to study cosmic objects.
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Stay curious, keep looking up, and join us next time for more stellar insights and cosmic wonders. Until then, clear skies and happy stargazing.
00:00 - This is a Q and A episode and we will be doing some homework
01:17 - How come Titan can retain an atmosphere when Mars cannot
07:23 - Why is tidal locking a function of proximity of bound objects
11:00 - Ash Brisbane proposes that Planet Nine once existed on elliptical orbit
14:43 - Nigel from Brisbane Australia asks hypothetical question about Neptune's Triton
18:59 - Triton may have been formed much further out in the solar system
21:17 - Nigel asks where the word asteroid came from
23:24 - Fred answers question from Robert McCowan about Doppler effect
✍️ Episode References
Kelly Miller
https://www.swri.org
Space.com article
https://www.space.com/
saturn-moon-titan-makes-own-atmosphere.html
3--- Southwest Research Institute
https://www.swri.org
iHeartRadio
https://www.iheart.com
Apple Podcasts
https://www.apple.com/apple-podcasts/
Spotify
https://www.spotify.com
bitesz.com
https://www.bitesz.com
Episode link: https://play.headliner.app/episode/24264457?utm_source=youtube
00:00:00 --> 00:00:02 hello again this is Space Nuts see I
00:00:02 --> 00:00:04 told you I'd be back uh Andrew Dunley
00:00:04 --> 00:00:07 here great to have your company and this
00:00:07 --> 00:00:10 is a Q&A episode and we will be doing
00:00:10 --> 00:00:12 some homework we had a question last
00:00:12 --> 00:00:15 time from Yen about why Titan has an
00:00:15 --> 00:00:17 atmosphere like it does and Fred's done
00:00:17 --> 00:00:19 his homework so we'll tell you all about
00:00:19 --> 00:00:22 it y we're going to look at tidal lock a
00:00:22 --> 00:00:25 new theory about planet planet 9 coming
00:00:25 --> 00:00:27 from one of our audience members and
00:00:27 --> 00:00:28 we're going to talk about something
00:00:28 --> 00:00:31 we've not talked about much but it wrote
00:00:31 --> 00:00:33 to us and said you don't talk about me
00:00:33 --> 00:00:36 so we're going to uh look at Triton
00:00:36 --> 00:00:38 which is uh the moon of
00:00:38 --> 00:00:41 Neptune and the use of Doppler we'll
00:00:41 --> 00:00:43 talk about all of that through questions
00:00:43 --> 00:00:47 on this episode of Space Nuts 15 seconds
00:00:47 --> 00:00:52 guidance is internal 10 9 ignition
00:00:52 --> 00:00:57 sequence start Space Nuts 5 4 3 2 1 2 3
00:00:57 --> 00:01:02 4 5 5 4 3 2 1 space n as report it feels
00:01:02 --> 00:01:05 good and the man on this particular
00:01:05 --> 00:01:07 mission is Professor Fred Watson
00:01:07 --> 00:01:10 astronomer at large hello Fred hello
00:01:10 --> 00:01:13 Andrew it's uh good to join you from a
00:01:13 --> 00:01:15 slightly different location from normal
00:01:15 --> 00:01:17 but that's
00:01:17 --> 00:01:21 fine yes uh let's um get straight into
00:01:21 --> 00:01:22 it because there is a fair bit on the
00:01:22 --> 00:01:24 agenda uh we're going to revisit a
00:01:24 --> 00:01:27 question from last week uh which came
00:01:27 --> 00:01:30 from Sweden yeah uh it was y who was
00:01:30 --> 00:01:33 asking about Titan's atmosphere what we
00:01:33 --> 00:01:36 might do is just play y's question it's
00:01:37 --> 00:01:40 hard to say y's question again uh and
00:01:40 --> 00:01:42 then we can fill in the
00:01:42 --> 00:01:45 blanks hello space nuts this is yans
00:01:45 --> 00:01:48 from The Forest of Doon at Sweden as we
00:01:48 --> 00:01:51 all know Saturn's moon Titan is a very
00:01:51 --> 00:01:54 special place so here is my question how
00:01:54 --> 00:01:57 did titon become so special how did it
00:01:57 --> 00:02:00 accumulate its thick nitrogen atmosphere
00:02:00 --> 00:02:03 and all its methan and ethane there are
00:02:03 --> 00:02:05 dozens of Mo of the outer planets but
00:02:05 --> 00:02:08 only Titan has an atmosphere what is it
00:02:08 --> 00:02:10 about Titan that made it become
00:02:10 --> 00:02:13 different from all the other
00:02:13 --> 00:02:17 Mo and another related question it is
00:02:17 --> 00:02:19 often said that Mars is too small to
00:02:19 --> 00:02:21 retain an atmosphere in the long term
00:02:21 --> 00:02:24 the Titan is even smaller how come Titan
00:02:24 --> 00:02:27 can retain an atmosphere when Mars
00:02:27 --> 00:02:30 cannot thanks for a great show
00:02:31 --> 00:02:34 thanks y we did determine that Mars
00:02:34 --> 00:02:35 probably lost its atmosphere because of
00:02:35 --> 00:02:37 its proximity to the sun and it was all
00:02:37 --> 00:02:40 blown off by the the solar
00:02:40 --> 00:02:43 winds uh but we didn't determine why
00:02:43 --> 00:02:46 Titan might have the unusual atmosphere
00:02:46 --> 00:02:48 that it has and how it uh manages to
00:02:48 --> 00:02:50 retain that well it probably retains it
00:02:50 --> 00:02:53 because it's far enough from the Sun not
00:02:53 --> 00:02:56 to be as significantly affected as as
00:02:56 --> 00:03:00 Mars was but uh how is it that it's got
00:03:00 --> 00:03:02 such a strange atmosphere um that's the
00:03:02 --> 00:03:04 piece of the puzzle we needed to do some
00:03:04 --> 00:03:05 homework on
00:03:05 --> 00:03:08 Fred yeah that's right and uh it's
00:03:08 --> 00:03:12 actually not that hard to to find some
00:03:12 --> 00:03:16 interesting uh theories about why uh T
00:03:16 --> 00:03:21 sorry yes why Titan why Titan has a
00:03:21 --> 00:03:23 thick atmosphere um
00:03:23 --> 00:03:26 and various pieces of work have been
00:03:26 --> 00:03:29 done on this uh the one that I think
00:03:29 --> 00:03:30 really
00:03:30 --> 00:03:32 puts it most cogently is a paper that
00:03:32 --> 00:03:35 was actually published in January
00:03:35 --> 00:03:42 2019 uh and um that was uh written by um
00:03:42 --> 00:03:44 uh a group of scientists led by Kelly
00:03:44 --> 00:03:48 Miller who's at the Southwest Research
00:03:48 --> 00:03:50 Institute in Boulder Colorado one of the
00:03:50 --> 00:03:53 big centers for planetary studies in the
00:03:53 --> 00:03:57 USA um and Kelly says uh and I'm quoting
00:03:57 --> 00:03:59 here a lot of organic chemistry is no
00:03:59 --> 00:04:01 out happening on Titan so it's an
00:04:01 --> 00:04:05 undeniable source of curiosity because
00:04:05 --> 00:04:07 Titan is the only moon in our solar
00:04:07 --> 00:04:09 system with a substantial atmosphere
00:04:09 --> 00:04:11 scientists have wondered for a long time
00:04:11 --> 00:04:14 what its source was the main theory has
00:04:14 --> 00:04:17 been that ammonia ice from comets was
00:04:17 --> 00:04:19 converted by impacts or
00:04:19 --> 00:04:21 photochemistry into nitrogen to form
00:04:21 --> 00:04:24 Titan's atmosphere while that might
00:04:24 --> 00:04:26 still be an important process it
00:04:26 --> 00:04:29 neglects the effects of what we now know
00:04:29 --> 00:04:33 is a very substantial portion of comet's
00:04:33 --> 00:04:37 complex organic material uh so uh what
00:04:37 --> 00:04:40 Kelly is saying there is that uh yes
00:04:40 --> 00:04:44 comets are mostly made of ice uh but
00:04:44 --> 00:04:47 there is a significant proportion of of
00:04:47 --> 00:04:50 them that are the organic chemicals that
00:04:50 --> 00:04:53 we uh we know form the building blocks
00:04:53 --> 00:04:55 of life here on Earth the the carbon
00:04:55 --> 00:04:58 containing chemicals and so the theory
00:04:58 --> 00:05:02 is that those complex
00:05:02 --> 00:05:06 molecules uh have basically landed from
00:05:06 --> 00:05:11 comets uh and interacted with the uh
00:05:11 --> 00:05:13 with the surface of Titan so you you
00:05:13 --> 00:05:16 you've got the the sort of it's a
00:05:16 --> 00:05:17 nitrogen
00:05:17 --> 00:05:21 atmosphere on Titan which also has uh
00:05:21 --> 00:05:24 methane ethane in it as well uh and so
00:05:24 --> 00:05:26 stuff that would land from comets these
00:05:26 --> 00:05:29 complex carbon containing molecules uh B
00:05:29 --> 00:05:32 basically would re would react with the
00:05:32 --> 00:05:34 stuff that's already
00:05:34 --> 00:05:38 there and so uh another Comet comment
00:05:38 --> 00:05:41 from uh Kelly Miller comets and P
00:05:41 --> 00:05:44 primitive bodies in the outer solar
00:05:44 --> 00:05:46 system are really interesting because
00:05:46 --> 00:05:47 they're thought to be leftover building
00:05:47 --> 00:05:50 blocks of the solar system these those
00:05:50 --> 00:05:52 small bodies could be incorporated into
00:05:52 --> 00:05:55 larger bodies like Titan and the dense
00:05:55 --> 00:05:57 organic Rich Rocky material could be
00:05:57 --> 00:06:01 found in its core um and and that if you
00:06:01 --> 00:06:05 have these organic chemicals uh that
00:06:05 --> 00:06:06 have found their way into the core of
00:06:06 --> 00:06:09 Titan that's the the underlying rock
00:06:09 --> 00:06:10 that sits under the ocean that sits
00:06:10 --> 00:06:14 under the ice uh then you've got a
00:06:14 --> 00:06:17 possible um source of the gases that we
00:06:17 --> 00:06:19 see in Titan's atmosphere now so what
00:06:19 --> 00:06:22 we're talking about here is um an
00:06:22 --> 00:06:24 atmosphere that's being that's been
00:06:24 --> 00:06:27 replenished over time which is
00:06:27 --> 00:06:31 essentially uh you know why uh you you
00:06:31 --> 00:06:34 have a body that's got an atmosphere
00:06:35 --> 00:06:38 where you might not expect it to have so
00:06:38 --> 00:06:40 when yens thinks about this a bit more
00:06:40 --> 00:06:43 maybe um have a look at that work Kelly
00:06:43 --> 00:06:46 Miller um from Southwest Research
00:06:46 --> 00:06:49 Institute uh there is actually a a nice
00:06:49 --> 00:06:52 space.com article that reports It Dating
00:06:52 --> 00:06:54 from January 26 2019 Saturn's biggest
00:06:54 --> 00:06:58 moon Titan May bake its own atmosphere H
00:06:58 --> 00:07:00 so it's just like cooking a cake in the
00:07:01 --> 00:07:04 oven everything you put creates a gas
00:07:04 --> 00:07:06 yeah that that's I think that's the
00:07:06 --> 00:07:09 bottom line Andrew yes yeah clever all
00:07:09 --> 00:07:12 right there you go y uh have a look at
00:07:12 --> 00:07:14 that article from space.com if you want
00:07:14 --> 00:07:17 to read more about it but uh that's
00:07:17 --> 00:07:20 basically um the the theory behind
00:07:20 --> 00:07:22 titans's
00:07:22 --> 00:07:24 atmosphere uh now moving on we have got
00:07:24 --> 00:07:28 a question from Ken uh Ken comes from
00:07:28 --> 00:07:30 maridor in Queensland we've got a few
00:07:30 --> 00:07:33 queenslanders uh sent us in questions
00:07:33 --> 00:07:36 for this week uh hi Fred and Andrew why
00:07:36 --> 00:07:39 is tidle locking a function of proximity
00:07:39 --> 00:07:43 of the bound objects uh plus do man uh
00:07:43 --> 00:07:45 man-made satellites that need to point
00:07:45 --> 00:07:48 antennas Etc to Earth automatically tidy
00:07:48 --> 00:07:51 lock or do they need initial and ongoing
00:07:51 --> 00:07:54 manipulation to do so thanks
00:07:54 --> 00:07:57 can uh so double whammy um yeah why is
00:07:57 --> 00:08:01 tidal locking a fun of proximity of
00:08:01 --> 00:08:03 bound
00:08:03 --> 00:08:05 objects
00:08:05 --> 00:08:09 um so it it is uh a
00:08:09 --> 00:08:13 gravitational phenomenon uh but in order
00:08:13 --> 00:08:17 for it to work you've got to have uh you
00:08:17 --> 00:08:20 know a reasonably sizable object so the
00:08:20 --> 00:08:22 whole thing about Tides Andrew is that
00:08:22 --> 00:08:26 they're caused by or what you might call
00:08:26 --> 00:08:28 tidal disruption things that that are
00:08:28 --> 00:08:31 caused by tidal effect the tidal
00:08:31 --> 00:08:35 phenomenon relies on one side of an
00:08:35 --> 00:08:36 object feeling a different amount of
00:08:36 --> 00:08:40 gravity from the other side uh and so
00:08:40 --> 00:08:43 for example in the case of the earth uh
00:08:43 --> 00:08:45 The Far Side of the earth feels less
00:08:45 --> 00:08:48 Gravity from the Moon than the near side
00:08:48 --> 00:08:51 does uh and so that raises the tides on
00:08:51 --> 00:08:57 the earth and that um process uh
00:08:57 --> 00:09:00 essentially involves a breaking
00:09:00 --> 00:09:01 phenomenon because as the Earth's trying
00:09:01 --> 00:09:04 to rotate it's got this tidal pull from
00:09:05 --> 00:09:06 the Moon and that's actually slowing
00:09:07 --> 00:09:08 down the Earth's rotation now the
00:09:08 --> 00:09:11 converse has been true over billions of
00:09:11 --> 00:09:15 years in fact probably not that many in
00:09:15 --> 00:09:17 fact more like millions of years uh the
00:09:17 --> 00:09:18 moon felt the same thing one side of it
00:09:19 --> 00:09:20 was feeling more of the pull from the
00:09:20 --> 00:09:23 earth than the other side uh and so the
00:09:23 --> 00:09:26 the breaking effect was felt uh and uh
00:09:27 --> 00:09:29 the moon's rotation slowed down until it
00:09:29 --> 00:09:31 was at locked to be always facing the
00:09:31 --> 00:09:37 same side to the Earth um now spacecraft
00:09:37 --> 00:09:39 are too small for that phenomenon to
00:09:39 --> 00:09:41 happen I was going to say I'll bet you
00:09:41 --> 00:09:43 that the problem is the the yeah the
00:09:43 --> 00:09:47 size of an object uh would be a major
00:09:47 --> 00:09:50 factor so uh Ken the second part of
00:09:50 --> 00:09:52 Ken's uh question is correct do they
00:09:52 --> 00:09:55 need initial and ongoing manipulation to
00:09:55 --> 00:09:57 point antennas to the earth and the
00:09:57 --> 00:10:01 answer is yes uh they they are directed
00:10:01 --> 00:10:04 uh you know using thrusters to to point
00:10:04 --> 00:10:06 in the direction that they're meant to
00:10:06 --> 00:10:08 it doesn't happen by tial locking it's a
00:10:08 --> 00:10:11 nice idea uh but uh but they're too
00:10:11 --> 00:10:13 small for the tit it would it would
00:10:13 --> 00:10:16 certainly simplify things wouldn't if
00:10:16 --> 00:10:17 that could happen that would make it
00:10:17 --> 00:10:18 easy you just put it up there and it
00:10:18 --> 00:10:20 turns on its own to face the Earth but
00:10:20 --> 00:10:23 that's not it works and now moon is not
00:10:23 --> 00:10:25 the only thing in the solar system
00:10:25 --> 00:10:27 that's totally locked is it there's um
00:10:27 --> 00:10:29 there's other moons that are totally
00:10:29 --> 00:10:31 locked to their respective planets and I
00:10:31 --> 00:10:34 think uh some of is mercury tily locked
00:10:34 --> 00:10:36 to the sun is that it's it's it's
00:10:36 --> 00:10:39 resonant it's it's not exactly lot but
00:10:39 --> 00:10:41 it's a similar process so it's resonant
00:10:41 --> 00:10:47 as is Venus okay St so um yes uh Ken
00:10:47 --> 00:10:51 it's um uh yes it's a it's a a function
00:10:51 --> 00:10:53 of size size Matters apparently when it
00:10:53 --> 00:10:56 comes to Tidal locking good to hear from
00:10:56 --> 00:11:00 you thanks for your question
00:11:00 --> 00:11:03 okay we checked all four systems and go
00:11:03 --> 00:11:07 space Nets our next question comes from
00:11:07 --> 00:11:11 another queenslander his name is
00:11:11 --> 00:11:14 a got a bit of a wh if question for you
00:11:14 --> 00:11:17 to wrap think here I propose that planet
00:11:17 --> 00:11:21 norin once did exist uh out there in the
00:11:21 --> 00:11:23 depths of the solar system on high oal
00:11:23 --> 00:11:26 orbit it came in crossed paths with the
00:11:26 --> 00:11:28 one and only rain giv a smack on the way
00:11:28 --> 00:11:32 past over in the process loses its out
00:11:32 --> 00:11:35 of shell making it size it is now and it
00:11:35 --> 00:11:37 lost a lot of its own momentum making it
00:11:37 --> 00:11:39 drop into the in a solar system and gets
00:11:39 --> 00:11:40 captured by the
00:11:40 --> 00:11:45 Sun and um yeah we now call it recy what
00:11:45 --> 00:11:48 do you think show guys T up good
00:11:48 --> 00:11:51 work thanks a I think there's a bit of
00:11:51 --> 00:11:53 Science Fiction in that one
00:11:53 --> 00:11:57 um only because I suspect that we know
00:11:57 --> 00:11:59 there's something in the far reaches of
00:11:59 --> 00:12:02 the solar system that's still impacting
00:12:02 --> 00:12:05 on um the objects out there and we
00:12:05 --> 00:12:06 haven't yet discovered what it is but
00:12:07 --> 00:12:09 the mathematics says there is something
00:12:09 --> 00:12:12 therefore if it's a planet it's not
00:12:12 --> 00:12:15 Mercury would that be a fair assessment
00:12:15 --> 00:12:17 uh yeah I think you've answered it quite
00:12:17 --> 00:12:21 well the very nicely and Jordy agrees
00:12:21 --> 00:12:22 with you you might have heard him just
00:12:22 --> 00:12:24 yes he does yes yelling in agreement
00:12:24 --> 00:12:28 there um so uh yes it's the the fact
00:12:28 --> 00:12:31 that um that we've got this alignment of
00:12:31 --> 00:12:34 asteroid far distant asteroid trans
00:12:34 --> 00:12:37 neptunian object orbits that makes
00:12:37 --> 00:12:40 people suspect that there is a planetary
00:12:40 --> 00:12:43 body in the depths of the solar system I
00:12:43 --> 00:12:47 think if you um you know if if the
00:12:47 --> 00:12:51 scenario uh and and it's complex but
00:12:51 --> 00:12:55 nicely uh elaborated scenario from Ash
00:12:55 --> 00:12:58 in Brisbane uh if that had happened I
00:12:58 --> 00:13:00 think these orbits would have now
00:13:00 --> 00:13:02 regularized so that the phenomenon would
00:13:02 --> 00:13:04 have disappeared you know if you take
00:13:04 --> 00:13:07 Planet line away and I think the I think
00:13:07 --> 00:13:09 there will be other disruption in the
00:13:09 --> 00:13:11 solar system I do like the the way
00:13:11 --> 00:13:14 though the ash ties in the you know this
00:13:14 --> 00:13:16 peculiar orientation of Uranus which is
00:13:16 --> 00:13:19 on its side uh with the planet Mercury
00:13:19 --> 00:13:21 which is mysterious we think Mercury was
00:13:22 --> 00:13:24 once a bigger object because it's got a
00:13:24 --> 00:13:27 a metal core that is is too big for it
00:13:27 --> 00:13:29 so we do think there might have been an
00:13:29 --> 00:13:32 impa there as well so very nice thinking
00:13:32 --> 00:13:35 um uh let's wait to see whether it
00:13:35 --> 00:13:37 becomes mainstream thinking but I
00:13:37 --> 00:13:41 suspect his chances are pretty small for
00:13:41 --> 00:13:44 that you elucidated we can have a bit of
00:13:44 --> 00:13:46 a smirk about it but he's he's been very
00:13:46 --> 00:13:47 clever in putting a few things together
00:13:47 --> 00:13:51 that we know and coming up coming up
00:13:51 --> 00:13:53 with a theory and theory is where you
00:13:53 --> 00:13:54 start when you're trying to solve these
00:13:54 --> 00:13:56 astronomical puzzles so yeah why not
00:13:56 --> 00:13:58 throw it out there someone might pick up
00:13:58 --> 00:14:01 on it and go hang on a
00:14:01 --> 00:14:03 minute yeah what you've got to do though
00:14:03 --> 00:14:06 is you've absolutely got to do the
00:14:06 --> 00:14:08 mathematical rigor on it all and make
00:14:08 --> 00:14:10 sure that all the equations add up and
00:14:10 --> 00:14:11 that it ties together and it's
00:14:11 --> 00:14:15 physically possible uh and that's um yes
00:14:15 --> 00:14:18 that's where you need um people with
00:14:18 --> 00:14:20 that sort of background um which I don't
00:14:20 --> 00:14:21 actually
00:14:21 --> 00:14:24 have not anym neither does
00:14:24 --> 00:14:26 Ash well you know you never know Ash
00:14:26 --> 00:14:30 might be um oh it might be a closet
00:14:30 --> 00:14:32 planetary dynamicist that we don't know
00:14:32 --> 00:14:34 about who knows yeah yeah may be and I
00:14:34 --> 00:14:36 think we're overdue for a new song Ash
00:14:36 --> 00:14:39 come on who dropping the ball
00:14:39 --> 00:14:42 mate um no but good one I I like his
00:14:42 --> 00:14:44 thinking thanks Ash this is Space Nuts
00:14:44 --> 00:14:50 Andrew Dunley here with Professor Fred
00:14:50 --> 00:14:53 Watson 3
00:14:53 --> 00:14:57 2 Space Nuts uh now our next question
00:14:57 --> 00:15:00 Fred comes from another queenslander
00:15:00 --> 00:15:02 this is Nigel hi Fred and Andrew this is
00:15:02 --> 00:15:05 Nigel from Brisbane Australia I have a
00:15:05 --> 00:15:08 hypothetical question about Neptune's
00:15:08 --> 00:15:09 moon
00:15:09 --> 00:15:13 Triton I believe Triton is said to be
00:15:13 --> 00:15:16 captured by Neptune I hope I got that
00:15:16 --> 00:15:19 right but what if it wasn't captured and
00:15:19 --> 00:15:22 it was still orbiting the Sun out on its
00:15:22 --> 00:15:24 own in the solar
00:15:24 --> 00:15:26 system my question is would it be big
00:15:26 --> 00:15:30 enough to be a minor planet and how do
00:15:30 --> 00:15:33 you describe a minor planet love the
00:15:33 --> 00:15:36 show keep up the good work thank you bye
00:15:36 --> 00:15:39 thanks Nigel I think he'd call it Planet
00:15:39 --> 00:15:41
00:15:41 --> 00:15:45 maybe yeah um how how big is Triton
00:15:45 --> 00:15:47 right uh it's
00:15:47 --> 00:15:51 2 kilometers across so too small to
00:15:51 --> 00:15:54 be officially designated a planet if it
00:15:54 --> 00:15:55 wasn't orbiting
00:15:55 --> 00:15:57 Neptune
00:15:57 --> 00:16:00 um no that wouldn't be what would stop
00:16:00 --> 00:16:04 it being a planet um uh it's so it's
00:16:04 --> 00:16:06 that it's bigger than Pluto in fact if I
00:16:06 --> 00:16:08 remember Pluto's a little bit smaller
00:16:08 --> 00:16:11 than that um got the number Somewhere In
00:16:11 --> 00:16:16 My Head uh 1680 miles or 2710 kilometers
00:16:16 --> 00:16:20 so um it uh it would be without doubt a
00:16:20 --> 00:16:23 dwarf planet uh because it's
00:16:23 --> 00:16:26 sperical uh in you know it's it's it's
00:16:26 --> 00:16:28 big enough for its self-gravity to to
00:16:28 --> 00:16:30 have made its sperical uh and that's
00:16:30 --> 00:16:33 partly the def definition of a planet
00:16:33 --> 00:16:36 but then uh to become a planet it's got
00:16:36 --> 00:16:39 to have cleared its area of the solar
00:16:39 --> 00:16:42 system uh becoming the dominant objects
00:16:42 --> 00:16:45 which it hadn't done um so but but the
00:16:45 --> 00:16:49 thinking is is right um it's uh it would
00:16:50 --> 00:16:52 definitely have been a dwarf planet and
00:16:52 --> 00:16:57 um the um you know uh Nigel's correct in
00:16:57 --> 00:16:59 the uh
00:16:59 --> 00:17:01 in saying that the thinking is that it
00:17:01 --> 00:17:04 has been captured uh that it probably is
00:17:04 --> 00:17:07 a trans neptunian object a dwarf planet
00:17:07 --> 00:17:09 that has been captured by Neptune itself
00:17:09 --> 00:17:11 and the reason why we think that is that
00:17:11 --> 00:17:13 it orbits Neptune the wrong way around
00:17:13 --> 00:17:16 it's in what's called a retrograde orbit
00:17:16 --> 00:17:19 um which is means it's going around in
00:17:19 --> 00:17:22 the opposite direction to the to to
00:17:22 --> 00:17:25 Neptune's rotation and it's actually the
00:17:25 --> 00:17:27 only big moon in the solar system to do
00:17:27 --> 00:17:28 that there are few of the smaller MO
00:17:28 --> 00:17:31 moons of I think Jupiter and Saturn that
00:17:31 --> 00:17:33 have probably captured asteroids that do
00:17:33 --> 00:17:34 that but this is the only big moon and
00:17:34 --> 00:17:37 it is the seventh biggest uh moon in the
00:17:37 --> 00:17:39 solar system so it's quite substantial
00:17:39 --> 00:17:43 in size um so it would have been a dwarf
00:17:43 --> 00:17:48 planet now uh um the the term that Nigel
00:17:48 --> 00:17:50 uses minor planets that's really an
00:17:50 --> 00:17:53 old-fashioned word or an oldfashioned
00:17:53 --> 00:17:57 term for what we now call asteroids um
00:17:57 --> 00:18:00 minor planets were the sort of the Posh
00:18:00 --> 00:18:03 term for asteroids asteroid was always
00:18:03 --> 00:18:05 and I'm going back 60 years now or so
00:18:05 --> 00:18:08 asteroid was thought to be a rather you
00:18:08 --> 00:18:11 know sort of common rather commonplace
00:18:11 --> 00:18:14 term that wasn't proper uh and so if you
00:18:14 --> 00:18:16 were a scientist and you were working on
00:18:16 --> 00:18:19 asteroids you would have called them
00:18:19 --> 00:18:21 minor planets and in fact the title of
00:18:21 --> 00:18:23 my Master's thesis is practical
00:18:23 --> 00:18:25 techniques for the determination of
00:18:25 --> 00:18:27 minor planet orbits because we didn't
00:18:27 --> 00:18:29 call them asteroids
00:18:29 --> 00:18:32 uh and that was a set of Suite of um uh
00:18:32 --> 00:18:35 software to to using these new Final
00:18:35 --> 00:18:36 things called computers to work out the
00:18:36 --> 00:18:39 orbits of asteroids uh so minor planet
00:18:39 --> 00:18:42 is a term that we we don't now use I I
00:18:42 --> 00:18:45 suspect um uh what um Nigel's thinking
00:18:45 --> 00:18:47 of is is dwarf planets so it would have
00:18:47 --> 00:18:49 definitely would have been categorized
00:18:49 --> 00:18:50 as a dwarf
00:18:50 --> 00:18:55 planet aha okay so um yes U well that
00:18:55 --> 00:18:57 doesn't surprise me at all really um
00:18:57 --> 00:18:59 it's not one we've talked about very
00:18:59 --> 00:19:02 often what what kind of um moon is
00:19:02 --> 00:19:04 Triton and it must keep quiet because
00:19:04 --> 00:19:06 it's it's really embarrassed that it it
00:19:06 --> 00:19:08 was a dwarf planet but now it's been
00:19:08 --> 00:19:10 demoted to
00:19:10 --> 00:19:12 Moon I mean it can't get worse it can't
00:19:12 --> 00:19:14 get much
00:19:14 --> 00:19:17 worse it's um it's a once again it's an
00:19:17 --> 00:19:22 ice world we think um a a crust of ice a
00:19:22 --> 00:19:26 top of probably subsurface ocean and
00:19:26 --> 00:19:28 then you know a rocky core in the middle
00:19:28 --> 00:19:33 middle um it is geologically active uh
00:19:33 --> 00:19:35 and the reason why that's thought to be
00:19:35 --> 00:19:40 the case is that its surface is pretty
00:19:40 --> 00:19:44 smooth uh without much in the way of of
00:19:44 --> 00:19:47 craters uh the estimated average surface
00:19:47 --> 00:19:50 age is less than 100 million years and
00:19:50 --> 00:19:53 that now that sounds like a long time
00:19:53 --> 00:19:56 but uh you know for example our moon
00:19:56 --> 00:19:58 bears the scars of the light heavy
00:19:58 --> 00:20:01 bombardment 3.8 billion years ago so
00:20:01 --> 00:20:04 that's an old surface so Triton has a
00:20:04 --> 00:20:07 young surface and that there's probably
00:20:07 --> 00:20:13 evidence of um maybe some evidence of uh
00:20:13 --> 00:20:16 there being um geysers you know ice
00:20:16 --> 00:20:17 geysers of the kind that we see on
00:20:17 --> 00:20:21 Enceladus and Europa so it is a very
00:20:21 --> 00:20:23 very interesting world uh especially
00:20:23 --> 00:20:26 being a being a captured possibly
00:20:26 --> 00:20:27 captured dwarf planet so it may have
00:20:27 --> 00:20:29 been formed much further out in the
00:20:29 --> 00:20:32 solar system it's uh yeah there's a
00:20:32 --> 00:20:34 number of things about Triton that make
00:20:34 --> 00:20:35 it very interesting including its orbit
00:20:35 --> 00:20:39 it's a very very circular orbit uh and
00:20:39 --> 00:20:42 um and uh you know it's thought that
00:20:42 --> 00:20:45 that might have happened over the of the
00:20:45 --> 00:20:49 Millennia uh and because of um usually
00:20:49 --> 00:20:51 if you've got a circular orbit there's
00:20:51 --> 00:20:54 not much of a a squashing and squeezing
00:20:54 --> 00:20:56 effect like we see on eio Jupiter's moon
00:20:56 --> 00:20:58 eio which is in a an orbit that carries
00:20:58 --> 00:21:01 it nearer and further from Jupiter and
00:21:01 --> 00:21:02 that squashing and squeezing is what
00:21:02 --> 00:21:04 makes it very volcanically active uh
00:21:04 --> 00:21:06 tritons is circular but there is
00:21:06 --> 00:21:08 thinking that there still it still might
00:21:08 --> 00:21:11 have a warm interior from tidal heating
00:21:11 --> 00:21:14 that squashing and squeezing uh that
00:21:14 --> 00:21:16 that happens at a much lower
00:21:16 --> 00:21:19 level I just uh thought while you were
00:21:19 --> 00:21:21 talking it prompted a question in my
00:21:21 --> 00:21:24 brain about where the word asteroid came
00:21:24 --> 00:21:26 from if they were previously known as
00:21:26 --> 00:21:28 minor planets and it actually came from
00:21:28 --> 00:21:30 the fact that William
00:21:30 --> 00:21:33 hersel uh saw them and and couldn't
00:21:33 --> 00:21:35 understand them he was completely
00:21:35 --> 00:21:36 baffled according to this article I've
00:21:36 --> 00:21:41 read so he turned to a another fellow uh
00:21:41 --> 00:21:45 who happened to be a poet uh to come up
00:21:45 --> 00:21:48 with um a name for them uh and I'll just
00:21:48 --> 00:21:49 quote this so the Sunday before the
00:21:49 --> 00:21:52 Royal Society meeting herel appealed to
00:21:52 --> 00:21:55 Charles Bernie senior a poet with whom
00:21:55 --> 00:21:58 he was collaborating on an educational
00:21:58 --> 00:22:01 about the cosmos Bernie considered the
00:22:01 --> 00:22:02 question and that night by candlelight
00:22:02 --> 00:22:05 penned a letter to his son Greek expert
00:22:05 --> 00:22:08 Charles Bernie Jr the Elder Bernie
00:22:08 --> 00:22:13 suggested the word asteros or stellula
00:22:13 --> 00:22:16 to describe the new celestial objects
00:22:16 --> 00:22:18 and they came up with the term asteroid
00:22:18 --> 00:22:20 as a consequence it didn't take off
00:22:20 --> 00:22:21 until the
00:22:21 --> 00:22:24 1850s they didn't yeah obviously the um
00:22:24 --> 00:22:27 astronaut the people the big names in
00:22:27 --> 00:22:29 astronomy at the time went not not using
00:22:29 --> 00:22:32 that but eventually it C on well they
00:22:32 --> 00:22:34 were still doing they were still saying
00:22:34 --> 00:22:36 that when I was a young astronomer oh
00:22:36 --> 00:22:38 were they asteroids yeah absolutely it's
00:22:38 --> 00:22:41 a minor that was the uh the proper term
00:22:41 --> 00:22:44 for it anything else was vaguely common
00:22:44 --> 00:22:46 place you know got z sing that we talk
00:22:46 --> 00:22:49 about but yes um I do remember reading
00:22:49 --> 00:22:51 that actually and it could have you know
00:22:51 --> 00:22:53 it could have had a very odd name
00:22:53 --> 00:22:55 asteroids a lot nicer than some of the
00:22:55 --> 00:22:57 things that were being were being Su
00:22:57 --> 00:22:59 yeah well what was the the other want
00:22:59 --> 00:23:03 stellus stellus stelli yeah
00:23:03 --> 00:23:07 stellus interesting um thank you Nigel
00:23:07 --> 00:23:08 good to have a chat about Triton we
00:23:08 --> 00:23:10 haven't done that very much I'm not sure
00:23:11 --> 00:23:13 we ever raised it before to be honest
00:23:13 --> 00:23:15 but um yeah it's out there it's doing
00:23:15 --> 00:23:17 its thing it's um feeling fairly full on
00:23:17 --> 00:23:19 being demoted
00:23:19 --> 00:23:22 from um dwarf planet to Moon it got
00:23:22 --> 00:23:25 itself caught that's why it happened uh
00:23:25 --> 00:23:27 one more question before we wrap up um
00:23:27 --> 00:23:29 this is a bit of a a one that comes from
00:23:29 --> 00:23:32 Robert Macau whereabouts unknown I said
00:23:32 --> 00:23:33 that because he didn't tell us where
00:23:33 --> 00:23:35 he's from but that's okay uh thanks
00:23:35 --> 00:23:39 Robert um when a radar station measures
00:23:39 --> 00:23:41 the motion of an airplane or weather
00:23:41 --> 00:23:43 that uses Doppler radar to tell if the
00:23:43 --> 00:23:45 target is moving toward or away from the
00:23:45 --> 00:23:48 radar by frequency shift in other words
00:23:48 --> 00:23:50 it measures the frequency change of
00:23:50 --> 00:23:53 waves or photons of the emitted signal
00:23:53 --> 00:23:56 when we measure the signals from
00:23:56 --> 00:23:58 cosmologically distant objects like
00:23:58 --> 00:24:01 quazars and galaxies we observe that
00:24:01 --> 00:24:04 they receive them at relativistic
00:24:04 --> 00:24:07 velocities in this context how is the
00:24:07 --> 00:24:10 difference of um the Doppler effect
00:24:10 --> 00:24:13 observed on Earth and in the local
00:24:13 --> 00:24:15 Universe different from the loss of
00:24:15 --> 00:24:17 energy of photons from the distant
00:24:17 --> 00:24:19 Universe due to the expansion of
00:24:19 --> 00:24:23 SpaceTime based on Dark Energy expansion
00:24:23 --> 00:24:26 wow uh is this an example of the change
00:24:26 --> 00:24:29 in the symmetry of translation explained
00:24:29 --> 00:24:30 by Emma
00:24:30 --> 00:24:33 NOA um and that's come from Robert
00:24:33 --> 00:24:38 maowen uh no NOA I think that's right
00:24:38 --> 00:24:41 Emmy Emy no not Emy
00:24:41 --> 00:24:42 not
00:24:43 --> 00:24:46 um yeah actually I think so so Roberts
00:24:46 --> 00:24:50 kind of answered it himself um
00:24:50 --> 00:24:53 because yeah we do differentiate
00:24:53 --> 00:24:56 between uh the Doppler effect caused by
00:24:56 --> 00:24:59 motion relative motion
00:24:59 --> 00:25:03 uh and the cosmological red shift caused
00:25:03 --> 00:25:05 by the expansion of the universe exactly
00:25:05 --> 00:25:09 as as he says uh so they are different
00:25:09 --> 00:25:11 that they're different things
00:25:11 --> 00:25:14 they uh
00:25:14 --> 00:25:17 they're the the sort of how can I put
00:25:17 --> 00:25:20 this the the the physical way in which
00:25:20 --> 00:25:23 they manifest themselves is the same
00:25:23 --> 00:25:26 it's a shift of the wavelength of light
00:25:26 --> 00:25:28 towards the red end of the spectrum but
00:25:28 --> 00:25:31 one's caused by a relative motion
00:25:31 --> 00:25:34 between objects and the other is caused
00:25:34 --> 00:25:38 simply by the stretching of of uh light
00:25:38 --> 00:25:40 uh caused by the expansion of the
00:25:40 --> 00:25:43 universe and in fact we can we can
00:25:43 --> 00:25:45 sometimes work uh on these two things
00:25:45 --> 00:25:47 together in fact I've been involved with
00:25:47 --> 00:25:50 this because uh in the early 2000s uh
00:25:50 --> 00:25:54 the UK schmit telescope did a survey of
00:25:54 --> 00:25:55 about
00:25:55 --> 00:25:59 136 galaxies where we were looking
00:25:59 --> 00:26:04 at their red shift in other words the
00:26:04 --> 00:26:07 the um the expand the the the shift
00:26:07 --> 00:26:08 towards the red of their light caused by
00:26:08 --> 00:26:10 the expansion of the universe the fact
00:26:10 --> 00:26:12 that the light was being stretched we
00:26:12 --> 00:26:15 could differenti we could measure that
00:26:15 --> 00:26:18 but also we could work out what are
00:26:18 --> 00:26:20 called their peculiar velocities and
00:26:20 --> 00:26:23 that is the independent motion of a
00:26:23 --> 00:26:27 galaxy uh when it's superimposed if I if
00:26:27 --> 00:26:28 I put it this way on what we call the
00:26:28 --> 00:26:30 Hubble flow the Hubble flow is the
00:26:30 --> 00:26:32 motion of galaxies as they're carried
00:26:32 --> 00:26:34 Along by the expansion of the universe
00:26:34 --> 00:26:35 but they've sometimes got their own
00:26:35 --> 00:26:38 individual motions on top of that uh the
00:26:38 --> 00:26:41 usual analog that we give is it's a bit
00:26:41 --> 00:26:44 like imagine somebody imagine somebody
00:26:44 --> 00:26:47 in a boat on a flowing river and that
00:26:47 --> 00:26:48 flow of the river is what's carrying
00:26:48 --> 00:26:50 them along but they can move the boat
00:26:50 --> 00:26:52 around within that flow so they've got
00:26:52 --> 00:26:54 their own peculiar motion we do the same
00:26:54 --> 00:26:58 with galaxies and the way you do that is
00:26:58 --> 00:26:59 actually actually quite clever you can
00:26:59 --> 00:27:02 measure properties of galaxies that give
00:27:02 --> 00:27:06 you a um a basically an estimate of
00:27:06 --> 00:27:09 their intrinsic Luminosity how bright
00:27:09 --> 00:27:11 they are and then you can use that as a
00:27:11 --> 00:27:14 distance measure and com combine compare
00:27:14 --> 00:27:17 that with the measure you get from the
00:27:17 --> 00:27:19 Hubble flow and if they're different
00:27:19 --> 00:27:21 that's due to The Peculiar motion of the
00:27:21 --> 00:27:23 Galaxy I've not explain that very well
00:27:23 --> 00:27:26 but that's how it works so yes uh so um
00:27:26 --> 00:27:28 the answer to the question is is
00:27:28 --> 00:27:32 basically yes thank you very much right
00:27:32 --> 00:27:34 excellent well done Robert and thanks
00:27:34 --> 00:27:36 for sending in your question and uh
00:27:36 --> 00:27:38 don't forget if you have a question for
00:27:38 --> 00:27:40 us you can do uh that or send it to us
00:27:40 --> 00:27:43 via our website SPAC nuts podcast.com or
00:27:43 --> 00:27:44 SPAC
00:27:44 --> 00:27:47 nuts. and click on the AMA Link at the
00:27:47 --> 00:27:49 top now we did have a question from
00:27:49 --> 00:27:51 somebody asking uh if there would be a
00:27:51 --> 00:27:55 better way of labeling the AMA link and
00:27:55 --> 00:27:57 uh yes that's a good question and I've
00:27:57 --> 00:28:00 referred that one to Hugh who's looking
00:28:00 --> 00:28:02 into it but yeah it is a bit of an
00:28:02 --> 00:28:05 obscure Target when it comes to finding
00:28:05 --> 00:28:07 a way of sending us questions but um
00:28:07 --> 00:28:08 we're getting plenty of them so I think
00:28:08 --> 00:28:10 most people are aware of it but yeah if
00:28:10 --> 00:28:12 we can relabel it we will I'm not I'm
00:28:12 --> 00:28:16 not sure what the process entails but um
00:28:16 --> 00:28:20 uh yeah it's it's a work in progress um
00:28:20 --> 00:28:21 thanks Robert thanks to everybody who
00:28:21 --> 00:28:24 sent in questions and thanks to you Fred
00:28:24 --> 00:28:25 for answering them we really appreciate
00:28:26 --> 00:28:28 it
00:28:28 --> 00:28:31 that's a pleasure um I um I I always
00:28:31 --> 00:28:34 enjoy having my brain stretched by Space
00:28:34 --> 00:28:37 Nuts listener questions it's good
00:28:37 --> 00:28:39 stuff yes which can be measured using
00:28:39 --> 00:28:43 the Doppler effect uh yes indeed uh
00:28:43 --> 00:28:47 thanks Fred we'll see you
00:28:47 --> 00:28:50 soon uh and uh thanks to H in the studio
00:28:50 --> 00:28:52 who we won't see soon but he's out there
00:28:52 --> 00:28:53 somewhere and for me Andrew Dunley
00:28:54 --> 00:28:55 thanks for your company looking forward
00:28:55 --> 00:28:58 to joining you again soon uh my be on
00:28:58 --> 00:29:01 the next episode of Space Nuts bye-bye
00:29:01 --> 00:29:03 Space Nuts you'll been listening to the
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