# From Dark Matter to Dormant Comets: Your Astronomy Questions Answered

An episode of [Space Nuts: Astronomy Insights & Cosmic Discoveries](https://invisiblenetwork.ai/podcast/1080090608), 4 Aug 2026, 33 min.

Audio: https://dts.podtrac.com/redirect.mp3/pscrb.fm/rss/p/op3.dev/e/api.spreaker.com/download/episode/73423055/from_dark_matter_to_dormant_comets_your_astronomy_questions_answered.mp3

In this enlightening Q&A episode of Space Nuts, join host Andrew Dunkley and astronomer Fred Watson Watson as they field a range of intriguing questions from listeners. From the hypothetical concept of dark matter stars to the mysteries of dormant comets and the mechanics of gravitational slingshots, this episode is packed with engaging discussions that spark curiosity in the cosmos. In this episode: - An exploration of dark matter stars: What are they, and how could they hypothetically shine without fusion? - Understanding dormant comets: What defines them, and how can we identify these ancient celestial bodies? - The mechanics behind gravitational slingshots: How do spacecraft gain speed from planetary gravity, and what role does the planet's rotation play? - The rise of smart telescopes: Are these automated devices a boon for budding astronomers, or do they undermine traditional astrophotography? - Personal experiences with smart telescopes and their impact on learning and engagement in astronomy. Resources & Links: - \[Dark Matter and Dark Energy Overview\](NASA) - Insights into these elusive components of the universe. - \[NASA's Comet Research\](NASA Comet Missions) - Discoveries and ongoing studies of comets in our solar system. - \[Gravitational Slingshots Explained\](NASA's Gravitational Assist) - How spacecraft use gravity to navigate the solar system efficiently. Join Andrew and Fred Watson as they unravel the complexities of space science, encouraging listeners to explore the universe and engage with the wonders of astronomy. Don't forget to submit your questions for future episodes! Become a supporter of this podcast: https://www.spreaker.com/podcast/space-nuts-astronomy-insights-cosmic-discoveries--2631155/support. (00:00) This is Space Nuts and we've got questions from our audience (01:57) Frederick: Greens Goddess started following me some time ago (02:47) Casey from Colorado says dark matter stars could be incredibly bright (09:13) Our next question comes from Michael about dark matter (10:27) What's a dormant comet and how do you detect them (16:28) Just wondering if you could explain the orbital mechanics behind Slingshots (22:32) Smart telescopes allow beginners to dive straight into astrophotography (28:56) Jason: Is there a privacy infringement there? Maybe, yeah (30:03) Astronomer Fred Watson answers your Space Nuts questions (32:16) Space Nick Nuts podcast available at Apple Podcasts and Spotify

## Transcript

[0:00] Professor Fred Watson: Hi there.
[0:01] Andrew Dunkley: Thank you for joining us. This is Space Nuts
[0:03] and it's a Q and A edition. My name is Andrew
[0:06] Dunkley. What's Q and A stand for? I don't
[0:09] know, but we've got questions, uh, from our
[0:11] audience, which we will answer.
[0:13] Qa. Oh, there it is.
[0:15] Um, Casey wants to know about dark matter
[0:18] stars even though they don't exist. And we
[0:20] can't answer the question.
[0:21] Professor Fred Watson: Uh, Michael.
[0:23] Andrew Dunkley: Um, he's sent one in about dormant
[0:26] comets, uh, which, uh, I found most
[0:28] intriguing. So it'd be interesting to
[0:30] discover what that's about. Uh, Derek is
[0:33] asking about gravitational slingshots,
[0:36] and Jason is asking what
[0:38] Fred Watson thinks of the new wave of
[0:41] smart telescopes. Ooh.
[0:44] Uh, we'll talk about all of that on this
[0:46] episode of space nuts.
[0:48] Andrew Dunkley: 15 seconds. Guidance is internal.
[0:51] 10, 9.
[0:53] Professor Fred Watson: Ignition sequence start. Space nuts.
[0:55] Andrew Dunkley: 5, 4, 3, 2. 1, 2, 3, 4,
[0:58] 5, 5, 4, 3, 2, 1.
[1:01] Andrew Dunkley: Space nuts. Astronauts report at mill.
[1:03] Andrew Dunkley: Good.
[1:04] Andrew Dunkley: And he's, uh, back again to try and sort all
[1:07] that out. It's Professor Fred Watson Watson,
[1:09] astronomer at large. Hello, Fred Watson.
[1:11] Professor Fred Watson: Hello, Andrew. Very good to see you again.
[1:13] Andrew Dunkley: And you too. It's been minutes.
[1:16] Professor Fred Watson: It has. Um, uh, I might add a postscript
[1:19] to, um, when we recorded the last session.
[1:22] Yeah, I just, uh, got back from the annual
[1:25] science meeting of the Astronomical Society
[1:27] of Australia. And I meant to mention that,
[1:30] um, an old friend of Space Nuts was
[1:33] there and I had dinner with him, um,
[1:36] on the first night. And that is Peter
[1:37] Verwein, who is our contact in
[1:40] the world of mond. Uh, modified Newtonian
[1:43] dynamics. Yeah. So, uh,
[1:45] terrific. Nice to do. He's still
[1:48] monding, although, um, I think
[1:51] he's had some hurdles to overcome. So
[1:53] we might have to do an update on that down
[1:56] the track.
[1:57] Andrew Dunkley: Well, while we're sending shout outs, I'll
[1:59] send a shout out to an Instagram, um,
[2:02] presence person named the Greens
[2:05] Goddess, Uh, a female golfer who,
[2:08] uh, started following me, I don't know, some
[2:11] time ago. And I thought, I'll do the honour
[2:12] of following her back. And, uh, she posted a
[2:15] video of her swing the other day and I noted
[2:17] a couple of issues with it. So
[2:20] I sent her a note and said, look, you got a
[2:23] bit of a reverse pivot going there.
[2:26] Try this drill to sort it out.
[2:29] Anyway, she sent a note back and said, oh,
[2:30] that's very helpful. By the way, big fan of
[2:33] Space Nuts.
[2:34] Professor Fred Watson: Okay, that's nice.
[2:36] Andrew Dunkley: Might have been why she followed me in the
[2:38] first place.
[2:38] Professor Fred Watson: But anyway, good on the Green Goddess.
[2:40] Andrew Dunkley: Yeah, good for her. All right,
[2:43] um, shall we answer Some questions,
[2:45] Fred Watson.
[2:46] Professor Fred Watson: Yes, we might as well might.
[2:47] We know we're here.
[2:48] Andrew Dunkley: Let's get into our first one. And it comes
[2:50] from one of our regular contributors. This is
[2:53] Casey.
[2:54] Andrew Dunkley: Hello, Fred Watson, Andrew and Huw. This is
[2:56] Casey from Colorado. I know
[2:59] that dark matter stars are completely
[3:01] hypothetical at this point. I've read
[3:04] before that they would be some of the
[3:06] brightest objects in the sky. If they do
[3:08] exist though, I was wondering if you could
[3:11] please explain why that is and also how they
[3:13] can get so hot without any fusion.
[3:16] Hope you're both well and thanks for the
[3:18] podcast.
[3:20] Andrew Dunkley: Thank you, Casey. I just knocked everything
[3:21] over on my desk, but, um, it'll wash out,
[3:25] um, dark matter stars.
[3:28] I think somebody's brought these up once
[3:30] before, if I'm correct in my thinking.
[3:33] But, um, maybe we should start by
[3:36] trying to explain what they're supposed to
[3:38] be.
[3:39] Professor Fred Watson: Yes, well, that's right. Uh, um,
[3:42] uh, first of all, Dark matter
[3:45] is still hypothesised, really,
[3:47] notwithstanding, uh, what we're just saying
[3:49] about, um, Peter Verweil. And that is an
[3:52] alternative theory to try and account for
[3:55] the, uh, low, um,
[3:58] the way, uh, the galaxies tell
[4:01] us that there is something there that we
[4:03] can't see. Uh, um, his
[4:06] uh, version of that is something called
[4:08] modified Newtonian dynamics that suggests
[4:10] that accelerations, uh, do not follow the
[4:13] normal Newtonian rules at very low levels.
[4:16] I think that's going into doubt though now.
[4:19] So I think, I suspect that dark matter
[4:22] is, um, basically
[4:26] consolidating, uh, its position as the
[4:29] number, um, one theory for why galaxies don't
[4:31] just fly apart because they've got all this
[4:33] stuff in them that we called out matter. So I
[4:35] think it's true to say, um, that
[4:38] despite a few people looking in other
[4:40] directions, most of the scientific community
[4:43] believes that we are in a universe
[4:46] whose matter content is dominated by
[4:48] something that we see sort of outweighs
[4:51] normal matter by five to one. Yeah, uh, and
[4:54] it's probably some sort of subatomic particle
[4:56] that we just have not, uh, come to grips with
[4:59] yet. Now, once you accept
[5:02] the idea of new
[5:04] species of subatomic particles that only
[5:07] interact with, uh,
[5:10] everything else through gravity, they don't
[5:12] interact through electromagnetic radiation or
[5:15] any other kind of, uh, particle physics.
[5:17] It's only gravity that lets us know that
[5:20] these things, uh, these dark matter
[5:23] particles are there, hypothesised still, but
[5:26] likely to be there. Uh, and it's their own
[5:28] gravitational attraction that stops galaxies
[5:30] falling apart or flying apart because they're
[5:32] rotating too quickly. So that's what dark
[5:35] matter is now, um,
[5:38] on that bare
[5:41] framework or foundation. Scientists have
[5:44] built up some models of what dark matter
[5:46] particles might be. And
[5:49] um, in particular there is an
[5:52] idea that if dark matter
[5:54] particles come together, then
[5:57] a bit like matter and antimatter,
[6:00] they would annihilate and
[6:03] basically produce radiation.
[6:07] And that's the idea of a dark matter star
[6:09] that you've got a, uh, hypothetical object,
[6:12] um, bigger than your average solar system.
[6:15] So they're very large.
[6:17] Andrew Dunkley: Wow.
[6:17] Professor Fred Watson: Uh, made of dark matter. Uh, but
[6:20] what makes them shine is the dark matter
[6:23] particles self annihilating.
[6:27] Uh, and there are some
[6:29] pundits who believe
[6:33] that the very first stars that
[6:35] formed when the universe was in its infancy
[6:38] were actually dark matter stars. Uh,
[6:41] were these ones that are super
[6:43] bright in the sense that they emit a
[6:46] large amount of radiation, but not,
[6:49] not super bright in a way that you
[6:52] might imagine. And that's because they are so
[6:55] big. Um, they are
[6:57] basically puffed up by the
[7:01] energy coming from this radiation. Uh,
[7:03] but because they're so big, their surfaces,
[7:07] uh, are relatively cool. And so
[7:10] what you see is an object in the infrared.
[7:13] Uh, if you're looking out for a dark matter
[7:16] star or what you would see
[7:20] if they existed.
[7:21] Andrew Dunkley: Yeah, I get it.
[7:23] Professor Fred Watson: Um, so that's why that's basically where the
[7:26] energy comes from, the annihilation of dark
[7:28] matter particles. Self annihilation.
[7:31] Um, but yet
[7:33] they're bright, um, because of
[7:36] basically the amount of radiation
[7:39] that they generate with these, uh, uh,
[7:42] annihilation that makes them bright and they
[7:45] get uh, to something like 10
[7:47] billion times more
[7:50] energetic than the sun in terms of the
[7:53] energy that they release. Uh, but as I said,
[7:55] it's infrared radiation. So they're really
[7:58] releasing it, um, in the form of
[8:01] heat.
[8:01] Andrew Dunkley: So in terms of naked eye observation, you
[8:04] can't see a thing.
[8:05] Professor Fred Watson: I think that's right, yes. I mean there would
[8:07] also be. If we're seeing them in the early
[8:09] universe, these things will be very highly
[8:12] redshifted. That means their light will not
[8:15] only be infrared, but it'll be even redder
[8:17] than red infrared, uh, because of the
[8:20] expansion of the universe stretching out the
[8:22] light waves. Um, so, uh, they
[8:25] might be quite difficult, might be quite
[8:27] difficult to detect. However, uh, it's
[8:30] basically, uh, one of the things that the
[8:32] James Webb telescope is looking for. It's
[8:35] looking for any evidence of dark matter
[8:37] stars.
[8:38] Andrew Dunkley: So where a normal star like ours, um,
[8:41] depletes its fuel and then turns into a
[8:44] red giant and then collapses into a white
[8:46] dwarf, a dark matter star
[8:48] annihilates itself.
[8:50] Professor Fred Watson: I think that would be right. I think it would
[8:51] just basically fizzle out
[8:54] Evaporate and fizzle out. Yeah.
[8:56] Andrew Dunkley: Okay.
[8:57] Andrew Dunkley: Wow.
[8:57] Professor Fred Watson: Yeah.
[8:58] Andrew Dunkley: Thank you, Casey. Um, haven't found one yet,
[9:01] but if you do stumble across one, let us
[9:04] know.
[9:05] Professor Fred Watson: Just hand it in, please.
[9:06] Andrew Dunkley: Yes, yes. Just don't forget to put it in a
[9:08] lead box.
[9:10] Professor Fred Watson: That's right.
[9:12] Andrew Dunkley: Thanks for the, the question.
[9:13] Our next question, Fred Watson, comes from
[9:16] Michael. Uh, he said, I understand that. Oh,
[9:18] uh, he says, andrew, I apologise. I still not
[9:20] do not have questions, uh, about dark matter.
[9:23] It's all right, person before you did it. Uh,
[9:26] as I have a firm understanding of how coffee
[9:28] and Coca Cola power my day, uh, I understand
[9:31] that dormant comments have been suggested
[9:33] with a few even confirmed inside the snow
[9:36] line, I'm wondering how many might exist.
[9:39] Seven. There's seven. I have
[9:42] no idea. Uh, and how, uh, a, uh, best
[9:45] guess might be made to arrive at that number.
[9:48] It was my best guess. I'm going. Well here.
[9:51] Professor Fred Watson: Uh, you are, you're guessing.
[9:52] Andrew Dunkley: Well, other than infrared telescopes and
[9:55] cameras looking for low temperature dark
[9:57] objects, what instruments on a smaller
[10:00] satellite might be best for searching for
[10:02] either or both of the Earth Sun Trojan
[10:05] Lagrange points? Uh, that comes from Michael.
[10:08] Now I'm assuming Michael's in Alberta because
[10:11] I'm going off his email address and it had
[10:13] the abbreviation AB And I looked that up and
[10:16] that's the abbreviation for the Province of
[10:19] Alberta, Canada. But I might be wrong and I'm
[10:22] sorry if I'm way off the map,
[10:24] Michael, but thanks, uh, for the question.
[10:27] Okay, um, are there,
[10:30] are there, um, yes.
[10:33] Comets?
[10:33] Professor Fred Watson: Thought to be. So, um, what's a dormant
[10:36] comet? Uh, well, it is,
[10:39] it would be a comet that has,
[10:42] uh, gone past the sun several
[10:45] times in its lifetime. I think that's
[10:47] probably the bottom line. Uh,
[10:50] it's an old comet
[10:53] and uh, because
[10:56] every time a comet gets near the sun,
[10:59] it's basically radiates its uh,
[11:02] gas and dust into space. Uh, the gas
[11:05] turns into a kind of plasma. It's excited by
[11:07] the sun's radiation. Uh, and
[11:10] so you get what we call a gas tail for a
[11:12] comet. And um, you can also get a dust tail
[11:15] because comets are dusty objects with this
[11:18] sort of frozen gas around them. The
[11:21] dust leaks out when the gas blows away.
[11:24] And so you get uh, comets that have two
[11:26] tails. So um,
[11:29] imagine, uh, one of these things that's
[11:32] gone, ah, round the sun several
[11:35] times. And basically
[11:41] it would have a kind of crusty
[11:44] layer to it, an outer layer,
[11:46] uh, which is the dust sort of
[11:49] coagulating on the surface. So the
[11:51] gases has been blowing dust off.
[11:54] But there's still a residual dust layer
[11:57] that might give you this crust
[12:00] around the edge of it. That means that even
[12:03] though it goes near the sun, the sun doesn't
[12:06] penetrate, uh, the sun's radiation and heat
[12:09] don't penetrate the dust. And so it doesn't
[12:11] actually, uh, stir into action. It doesn't
[12:13] start behaving like a comet which is to
[12:15] release its gas and dust.
[12:17] Andrew Dunkley: Okay.
[12:18] Professor Fred Watson: Um, and so, uh, that,
[12:21] uh, you know, that would, that would be a
[12:23] dormant comet once one that's gone to sleep.
[12:26] Um, what might stir it back into
[12:30] action is if you
[12:33] had a dormant comet colliding
[12:36] with something else. Uh, hopefully not the
[12:38] Earth. Uh, but you know, maybe another,
[12:41] another, um, an asteroid or
[12:44] something like that, uh, that might
[12:46] disturb that, that
[12:50] dusty crust on the outside or crusty
[12:53] dust, uh, the sort of crust of the. Over the.
[12:55] I. If you could expose
[12:58] the icy surface to the sun's radiation, then
[13:02] it would basically start giving you what, ah,
[13:05] we would call an active comet as well. Um, I
[13:07] mean the way they are. And this is really the
[13:09] nub of the question, I guess, how do you
[13:11] detect them? Because the problem is,
[13:14] um, if you've got a comet, even though it's
[13:16] made mostly of ice, uh,
[13:19] uh, if it's got this, um, dark
[13:22] crust on the outside of it, there's very
[13:25] little to distinguish that from an asteroid.
[13:28] Um, and so how do you know whether this
[13:31] is a dormant comet or an asteroid?
[13:34] And it's really quite hard to do. Um,
[13:37] there's not that much to choose between them.
[13:39] You will be looking at a kind of thermal
[13:42] signature because, um, asteroids are cold
[13:44] rock. Uh, dormant comets
[13:47] are cold ice with a kind of rocky,
[13:50] sort of dusty, um, rocky layer on the
[13:53] outside. Uh, there's not that much to
[13:56] differentiate between them until you knock
[13:58] some of the dust off and the thing. Thing
[13:59] wakes up.
[14:01] Andrew Dunkley: Yes.
[14:01] Professor Fred Watson: Yeah. Um, so, um,
[14:05] I think, uh, there's scope for us
[14:08] trying to do a survey. But it will be hard
[14:11] to know, uh, whether
[14:14] you've picked a dormant comet or you've got
[14:17] an asteroid. And it may well be that some of
[14:18] the asteroids that we consider to be
[14:20] asteroids are actually dormant comets.
[14:23] Andrew Dunkley: So they're super duper old. I suppose the
[14:25] smoking gun would be. Most of them have got
[14:27] Zimmer frames.
[14:30] Professor Fred Watson: Could be, yep. Um, comet. Zimmer frame.
[14:34] Yes. I like the sound of that.
[14:36] Andrew Dunkley: You never know.
[14:37] Professor Fred Watson: Um,
[14:39] Andrew Dunkley: worth looking for or not. But
[14:41] yeah. Okay, so, um, so
[14:44] they might be out there. When Michael said
[14:47] that, uh, a few have been confirmed in the
[14:49] snow line. What's, what's he
[14:52] Meaning there.
[14:53] Professor Fred Watson: So that means. So the snow line is,
[14:55] um, basically it's on the far side
[14:58] of Mars's orbit. Ye, where, um,
[15:02] water vapour stops being vapour and
[15:05] freezes. It's the, uh, sort
[15:08] of outer side of the
[15:11] Goldilocks zone.
[15:13] Andrew Dunkley: Okay, fair enough. Michael, thanks for the
[15:16] question. Um, that was fascinating. Um,
[15:19] and um, yeah, I suppose one day someone might
[15:22] go, aha, I've found a way. And then
[15:24] we've got the answer. This is Space
[15:27] Nuts, Andrew Dunkley with Professor
[15:29] Fred Watson Watson.
[15:32] Space Nuts. Oh, that was. That
[15:35] was it. That was so short. I'm going to
[15:38] do it again. Space Nuts.
[15:40] Professor Fred Watson: Yeah. He's got a very nice voice, hasn't he?
[15:42] Andrew Dunkley: He has, yes. I can do that on my
[15:44] machine. Hang on. Yeah, wait for
[15:47] it. Uh, not there.
[15:48] Professor Fred Watson: Okay.
[15:48] Andrew Dunkley: Uh, no, not there. Oh, here it is.
[15:51] Space Nuts.
[15:57] Professor Fred Watson: I, um. Yeah, I think you need some, uh,
[16:00] Gaviscon or something.
[16:02] Andrew Dunkley: I can do it with this one.
[16:07] Yeah, I could go on forever.
[16:10] Professor Fred Watson: I know you could,
[16:13] Andrew Dunkley: but I won't. Um, we'll go to it.
[16:15] Andrew Dunkley: Yeah.
[16:15] Professor Fred Watson: Anyway, I'm sure you can use that, uh, in
[16:18] suitable, uh, environments that, um, I
[16:21] mean audio environments that might intrigue
[16:23] our listeners or otherwise, um, confuse
[16:26] them.
[16:26] Andrew Dunkley: Indeed.
[16:28] Our next question comes from Derek.
[16:30] Andrew Dunkley: Hi guys, this is Derek from southern Ontario
[16:33] and Canada. Again, um, just wondering if
[16:36] you could explain the orbital
[16:38] mechanics behind Slingshots. Gravitational
[16:41] slingshots. And uh, I'm trying
[16:44] to understand whether the rotation of
[16:47] the planet has anything to do with that
[16:49] slingshot or if it's just, uh, uh, in
[16:52] terms of how close you get to the planet. Um,
[16:55] if you can elaborate a little bit on that,
[16:57] that would be great. Thank you. Love the
[16:58] podcast. Have a great day.
[17:00] Andrew Dunkley: Thank you, Derek. Uh, it's a good question,
[17:02] uh, and I think we've seen
[17:05] it used, uh, many times for some of these
[17:07] probes that have been sent, um, way out
[17:10] into the solar system because we
[17:13] find it's uh, a much more efficient way of
[17:15] doing things because we haven't got the fuel
[17:17] to send them all the way in under their own
[17:19] steam. That was certainly the case with the
[17:21] Voyagers, uh, and they were two
[17:24] of the best examples of using the gas giants
[17:27] for slingshots, um, but
[17:29] even launching things off our own planet.
[17:32] There's a bit of slingshot effect, isn't
[17:34] there?
[17:35] Professor Fred Watson: Uh, yes, that's right, there is. Um, so,
[17:38] um, it's not just getting to the outer
[17:41] solar system. I think, um, the uh,
[17:43] Bepicolombo, uh, spacecraft which is on
[17:46] its way to Mercury, I think that's had
[17:48] Something like seven slingshots with Venus
[17:51] and the Earth. That's right. Might be
[17:52] exaggerating, but, um, it's had a large
[17:55] number, and that's in order to make
[17:58] its velocity, uh, match the velocity of
[18:01] Mercury, um, which you'd think will be
[18:04] easy as you drop things into the inner solar
[18:06] system, but it's not actually. It's quite
[18:08] hard to do. You've got to kind of catch up
[18:10] with Mercury as it steams around in its orbit
[18:13] because it's going faster than the Earth is
[18:14] in its orbit around the sun. Um,
[18:18] so, um, yes. So it's a very useful tool
[18:21] for exploring the solar system. I think
[18:22] you're about to confirm how many it's had.
[18:25] Andrew Dunkley: I haven't found it yet. I'm usually pretty
[18:27] quick, but I'm not.
[18:28] Professor Fred Watson: You are pretty quick, yeah.
[18:30] Andrew Dunkley: It's proving elusive at the moment, but I'll
[18:33] get it.
[18:33] Professor Fred Watson: I will get. Has had an elusive number
[18:36] of slingshots, uh, uh,
[18:39] but the bottom line is that it's a process
[18:41] that works well and is actually
[18:44] very much a part of the
[18:46] astrodynamicists toolkit when they're
[18:49] actually working out the, um, orbits
[18:52] and um, trajectories of planets.
[18:55] Andrew Dunkley: Exploring the nine slingshots.
[18:58] Professor Fred Watson: Nine slingshots. There you go. Seven was an
[19:01] underestimate.
[19:02] Andrew Dunkley: Yeah. One at Earth, two at Venus, and six at
[19:04] Mercury itself.
[19:06] Professor Fred Watson: Yes. Fantastic. That's what you need to
[19:09] match Mercury's orbital speed. Quite
[19:11] remarkable. So, um, how does it work? Well,
[19:14] it's counterintuitive, isn't it, because you
[19:16] think that a, uh, spacecraft falling in
[19:19] towards a planet, uh, it's going to
[19:22] gain velocity, but then as it leaves the
[19:25] planet, it's going to decelerate and so it
[19:28] would lose velocity. And you might think the
[19:30] two would balance up, but the bottom line is
[19:33] they don't. And it's all about the angle that
[19:35] you come in, uh, when you intercept
[19:38] the planet's orbit. And if you get the
[19:41] angle right, you can have this situation
[19:44] where, uh, without making contact at
[19:46] all, where some of the momentum of the planet
[19:50] is transferred to the spacecra.
[19:53] Um, and so the spacecraft gets
[19:55] a, uh, push in velocity, its velocity
[19:58] increases. The planet doesn't even notice the
[20:01] difference because the spacecraft has so
[20:03] little mass compared with,
[20:06] um, the planet. Um, so it's
[20:08] balancing the momentum.
[20:11] Momentum, of course, is just the mass times
[20:13] the velocity. Uh, and so you've got a very
[20:16] big mass transferring momentum to a very
[20:19] small mass. And, um, that means you get
[20:22] quite a significant velocity kick, uh, in
[20:25] doing that. And so it's not to do
[20:28] with the rotation. Um, so Derek is
[20:32] right to point out that as a query, is it to
[20:35] do with the rotation? The answer is no. So if
[20:37] you had a planet that wasn't rotating at all,
[20:40] uh, you could still do a gravitational
[20:42] slingshot very successfully with it. Oh,
[20:44] okay.
[20:47] Andrew Dunkley: So does the spacecraft, when it's doing
[20:50] this slingshot, actually steal some of
[20:53] the planet's energy?
[20:54] Professor Fred Watson: Yeah.
[20:55] Andrew Dunkley: Is that how it works?
[20:56] Professor Fred Watson: It's stealing momentum, uh,
[20:59] and um, using that to accelerate
[21:02] and sometimes quite dramatically. So the
[21:05] change in the orbital trajectory is really
[21:07] significant. But it's a fantastic tool
[21:10] for exploring the planets.
[21:13] Andrew Dunkley: Yeah, it is until the day we can
[21:16] come up with a new way of,
[21:20] a new form of engine
[21:23] propulsion. That's the word I was wanting.
[21:25] Uh, that um, renders
[21:28] gravitational assist unnecessary.
[21:30] Professor Fred Watson: Yes, that's right. At the moment, we haven't
[21:32] got there yet. No, you're right.
[21:34] Andrew Dunkley: But it might. Yeah, it could be
[21:37] scramjet technology, it could be
[21:40] nuclear power, like fusion engines, things
[21:42] like that. We're a long way from that. But,
[21:45] uh, those are possibilities. Yeah, yeah.
[21:48] Um, who knows? Um,
[21:51] but the more you speed up in space, the more
[21:53] you've got to be careful because there's lots
[21:55] of stuff you can bump into. You don't really
[21:57] want to do that at pace, do you?
[22:00] Professor Fred Watson: You've got to know where all this stuff is.
[22:02] And that's what astronomers are for.
[22:04] Andrew Dunkley: Indeed.
[22:04] Professor Fred Watson: Tell you where it all is.
[22:06] Andrew Dunkley: Uh, thank you, Derek. I hope that covered,
[22:08] uh, your question adequately.
[22:15] Space nuts. What we're going to do
[22:18] now, Fred Watson, is, um, we've got, uh,
[22:21] we've had quite a Canadian influence in, in
[22:24] today's show by the look of it. Uh, this
[22:26] comes um, from Jason in Montreal, in
[22:29] Quebec. And uh, he says, I'm a big fan of the
[22:32] show.
[22:32] I have a question regarding the rapid rise of
[22:34] fully automated smart telescopes
[22:37] and their place in the modern hobby.
[22:40] Uh, on one hand it feels like these devices
[22:43] are, ah, an incredible cost effective
[22:45] gateway. They allow beginners to dive
[22:47] straight into astrophotography and see almost
[22:50] instant results without spending thousands of
[22:52] dollars on complex gear right away.
[22:55] That immediate reward seems to be a fantastic
[22:58] way to spark a lifelong interest in
[23:00] astronomy. On the other hand, there
[23:02] seems to be a, uh, bit of a divide in the
[23:05] community with some traditional
[23:06] astrophotographers viewing them as cheating
[23:10] because the automated software removes so
[23:13] much of the steep learning curve. What
[23:16] are your thoughts on this technological
[23:17] shift? Do you see smart telescopes as a
[23:20] positive tool for opening up the night sky to
[23:23] a broader audience, or do you Feel
[23:26] something valuable is lost when we automate
[23:28] the setup and tracking process.
[23:31] Uh, I actually bought one recently and I've
[23:34] already learned a lot over the past few
[23:36] months. Getting those quick results didn't
[23:38] stop me from wanting to learn more in. In
[23:41] fact, it did the opposite. Uh, it got
[23:44] me watching more astronomy and
[23:45] astrophotography videos than usual, uh, on
[23:48] YouTube and joining Facebook groups to learn
[23:50] from other users. And of course, let me
[23:53] find your podcast. Uh, thank you for the
[23:56] great episodes. Uh, that comes from Jason in
[23:58] Montreal. I'm going to show you something,
[23:59] Fred Watson.
[24:00] Professor Fred Watson: Yep. Let me see.
[24:04] Uh, I've got one.
[24:07] He's got one.
[24:08] Andrew Dunkley: Um, I've got one. And yes, it simplifies
[24:10] everything. It does all the hard work for
[24:12] you, but if you someone who doesn't like
[24:13] doing the hard work, it's a godsend.
[24:17] Yeah, that's my take on it. I'll keep it nice
[24:19] and short. I know a couple of people
[24:22] who've got both. They've got a traditional
[24:23] telescope with the whole kit set
[24:26] up with their computers and the programmes
[24:29] and all the tracking technology.
[24:32] They like to do it the old fashioned way.
[24:34] And, uh, they've also got smart
[24:36] telescopes, um, which
[24:39] do the same thing. But, um, you know,
[24:42] you've got to rob Peter to pay Paul. The
[24:44] efficiency and simplicity of that,
[24:47] uh, also means that your images aren't going
[24:50] to be nearly as good as a
[24:53] traditional telescope. Uh, so
[24:58] it ebbs and flows. There's a cost for
[25:01] the, um, let's not say the word cheating,
[25:04] but there is a cost. Um, uh, but it
[25:07] does make astrophotography
[25:10] immensely affordable for a lot of
[25:13] people.
[25:14] Professor Fred Watson: Yeah. And accessible too. Yes. Um,
[25:17] so, yes, look, um,
[25:20] I think Jason sort of answered his own
[25:22] question in exactly the way I would. Uh,
[25:25] that, uh, you've got
[25:28] the two aspects of it. It's a
[25:31] brilliant way of getting
[25:34] into astrophotography,
[25:37] um, almost painlessly, um,
[25:42] on a very good level too.
[25:45] Uh, and if you then wanted to do
[25:48] more, if you wanted to go for a bigger
[25:50] telescope and do your image processing
[25:53] in a more, um,
[25:56] perhaps a more precise way that's,
[25:59] uh, still open to you, I think, as a tool
[26:02] for getting people involved in astronomy.
[26:04] I think they're absolutely fabulous. I don't
[26:07] have one myself. Uh, I'm glad you've got one
[26:09] one, Andrew, because I've seen some of the
[26:11] results from that and they are very
[26:12] impressive. Uh, I've got a number of other
[26:15] friends who've got them as well, who are
[26:16] themselves professional astronomers.
[26:20] Andrew Dunkley: There's a photo I took the Other night of the
[26:21] M8.
[26:22] Professor Fred Watson: Yeah. There you go. And it's lovely.
[26:25] Colour balance. That's pretty well what you'd
[26:28] expect to see from a David Malin image.
[26:30] And that's what's like.
[26:32] Andrew Dunkley: David Malan was a pioneer in this stuff.
[26:34] Professor Fred Watson: He did.
[26:35] Andrew Dunkley: Now you can do it from your lounge room.
[26:37] Professor Fred Watson: Yes. With. You can literally with your mobile
[26:39] phone. On your m. Mobile phone,
[26:43] Telescope outside. Um, yeah. I think
[26:46] it's fantastic. I'm very, uh,
[26:49] much old school. I love pottering around with
[26:51] a telescope with nothing more than an
[26:53] eyepiece. I've never really ventured into
[26:54] astrophotography. The nearest thing I've got
[26:57] to that has been a lot of aurora
[26:59] photography. Uh, um, which I
[27:02] love and is now also a lot more accessible
[27:05] just with a smartphone. Uh, so I don't
[27:08] carry around. Found all the kit I used to.
[27:09] When we go up to the Arctic, uh, to look for
[27:12] the aurora, just take my smartphone.
[27:15] Um, but you're right. Um,
[27:19] I think, as I said, I think Jason's answered
[27:21] it perfectly. It's obviously
[27:23] stimulated him to go further. Uh, he loves
[27:26] what he's got and he's finding out more. Uh,
[27:29] best of all, he found space nuts. Yes, nice.
[27:31] But, um. Uh,
[27:34] I would not be somebody who
[27:37] would frown upon these devices and
[27:40] saying, in my day we did not
[27:43] have this sort of thing. You know, we had to
[27:45] do it properly. We had to understand what was
[27:47] going on. Well, you can still do it
[27:50] and understand what's going on, uh, with
[27:53] your smart telescope. Well, what's. Sorry, go
[27:56] ahead.
[27:56] Andrew Dunkley: On mine, when I pick a target, it then gives
[27:59] me an audio briefing on what the target is,
[28:02] who found it, when it was found.
[28:05] Professor Fred Watson: That is fabulous.
[28:06] Andrew Dunkley: It is amazing.
[28:10] Good stuff.
[28:10] Professor Fred Watson: It's an astronomy class as well.
[28:13] Um, I think I'm right in saying that
[28:16] the first of these smart telescopes was a
[28:19] Unihedron. I think, uh, that was probably
[28:22] six or seven years ago when I saw the first
[28:25] one of those and I was very impressed with
[28:27] it. But what I was going to say was that they
[28:29] have now come down in price to be,
[28:33] um, really quite affordable.
[28:35] Andrew Dunkley: Yeah.
[28:35] Professor Fred Watson: And it's not beyond the realms of possibility
[28:37] that one day there might be one in the Watson
[28:39] household. Although I do like things that are
[28:42] made of brass. And do you look through one
[28:44] end and see how they.
[28:45] Andrew Dunkley: There are a mass of them out there and quite
[28:47] a few are, uh, well under a thousand dollars.
[28:51] Professor Fred Watson: Yes.
[28:52] Andrew Dunkley: So, you know, that makes
[28:55] a pretty wide target audience.
[28:56] The other thing mine does is you can click on
[28:59] the map on your phone and you can see where
[29:01] other uh, people are that are using
[29:04] the same gear as you.
[29:06] Professor Fred Watson: Interesting.
[29:07] Andrew Dunkley: I'm not sure, I'm not sure that goes down
[29:09] with the privacy laws.
[29:10] Professor Fred Watson: But anyway, uh, I was going to say is there a
[29:11] privacy infringement there? Maybe, yeah.
[29:14] Andrew Dunkley: I've got um, satellite navigation in the car
[29:16] that does the same thing. It shows you other
[29:18] users of that particular device but um,
[29:22] they've um, curtailed it in Australia so it
[29:24] only shows you where they were like 10
[29:26] minutes ago.
[29:27] Professor Fred Watson: Okay.
[29:28] Andrew Dunkley: Which is pointless. Just turn it off.
[29:30] Professor Fred Watson: Yes, it is of a waste.
[29:32] Andrew Dunkley: Yeah. Uh, well, you know, we live in nanny
[29:35] state New South Wales, so you've um,
[29:38] everything's on the table for uh, some sort
[29:40] of scrutiny. Probably me now after saying
[29:43] that. But yeah, Jason, look, I'm a big fan
[29:46] and you are too. And uh,
[29:49] I don't think it does spoil the tradition,
[29:52] uh, or the traditional approach to um,
[29:54] astrophotography because vinyl um,
[29:57] records have come back, back. So you know,
[30:01] you can't write anything off.
[30:03] Yeah, but I wanted that question
[30:05] to um, I wanted you to hear
[30:08] that question Fred Watson, because I know
[30:10] you've got a long history in um, in
[30:12] telescopes, you've written books about them
[30:14] and um, this is, this is the next big thing,
[30:17] I suppose.
[30:19] Professor Fred Watson: Yeah, yeah.
[30:20] Andrew Dunkley: While we're talking about it, um, when you
[30:22] were away last, um, Jonty
[30:24] Horner grabbed a couple of astrophotographers
[30:27] and we did a special on astrophotography
[30:31] which I'm not sure if Huw's released it yet,
[30:33] but I think he's still working on how to get
[30:36] that out there. It's quite a, I think it's an
[30:38] hour long special on
[30:40] astrophotography and the techniques and how
[30:43] they did it and what you can do. So if you
[30:45] really want to get into the nuts and bolts of
[30:47] astrophotography, have a look for that one.
[30:50] Um, I'm not sure it's been released yet. Yet.
[30:52] Um, it took some pretty heavy editing because
[30:55] there were four people on it. So it was okay,
[30:57] it was a big show. But uh, yeah, that one
[31:00] will be available soon, if not already.
[31:04] Uh, and thanks for all your questions. Please
[31:06] keep them coming at our, ah, website,
[31:08] spacenutspodcast.com or spacenuts
[31:10] IO and click on the Little AMA tab at the
[31:13] top and send us your text or audio questions.
[31:16] If you're sending us an audio question,
[31:17] please remember to tell us where you're from
[31:20] and your name.
[31:21] Andrew Dunkley: Name.
[31:21] Andrew Dunkley: Um, it doesn't do that by itself. Uh,
[31:24] although I know sometimes people forget to
[31:26] tell us their name on where they're from on
[31:28] text as well. Um, but that's
[31:30] okay. Um, it's not mandatory, but, uh,
[31:33] it just helps us to know where everybody's
[31:36] at. Fred Watson, we're done. Thanks very
[31:38] much.
[31:39] Professor Fred Watson: Oh, thank you, Andrew. Good fun and great to
[31:42] hear from the listeners as well. Especially,
[31:44] you know, when we get questions that, uh,
[31:46] cover everything from, from dark matter,
[31:49] stars and dormant comets to the latest in
[31:51] telescope technology. Where else can you hear
[31:54] about all that?
[31:54] Andrew Dunkley: Uh, exactly.
[31:55] Professor Fred Watson: Right.
[31:56] Andrew Dunkley: Yeah. All right. Thanks, Fred Watson. See you
[31:58] soon.
[31:59] Professor Fred Watson: Yeah. Cheers. Cheers.
[32:00] Andrew Dunkley: For now, Professor Fred Watson Watson,
[32:01] astronomer at large, and thanks to Huw in the
[32:03] studio, couldn't be with us today because he
[32:05] bought a smart telescope. He's
[32:07] not smart enough to use it. Uh, and from me,
[32:09] Andrew Dunkley, thanks for your company.
[32:12] We'll catch you on the next episode of Space
[32:14] Nuts. Bye bye. Space Nuts.
[32:16] You've been listening to the Space Nick Nuts
[32:18] podcast, available at
[32:21] Apple Podcasts, Spotify,
[32:23] iHeartRadio or your favourite podcast
[32:26] player. You can also stream on demand at
[32:28] bytes.
[32:29] Professor Fred Watson: Com. This has been another quality podcast
[32:32] production from Bytes. Com. Um,

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