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Galactic Revelations, Cometary Wonders & Moon Mysteries: #487 - First Edition of 2025 · Space Nuts: Astronomy Insights & Cosmic Discoveries

• 0:00
  Speaker 1: Hello again, thanks for joining us. This is Space Nuts.
• 0:03
  Speaker 1: My name is Andrew Dunkley. Welcome to our first edition
• 0:06
  Speaker 1: of twenty twenty five coming up.
• 0:09
  Speaker 2: Oh boy, it is jam packed.
• 0:11
  Speaker 1: Weick a lot of catching up to do, some really
• 0:13
  Speaker 1: interesting things. One of the biggest this might be one
• 0:15
  Speaker 1: of the biggest stories of the year already a new
• 0:18
  Speaker 1: paper suggesting the universe has no dark matter and isn't
• 0:22
  Speaker 1: expanding like we think, so that'll tip the whole thing
• 0:26
  Speaker 1: upside down. We're also going to look at a comet
• 0:29
  Speaker 1: that is in our skies at the moment, Comets C
• 0:32
  Speaker 1: twenty twenty four, G three Atlas. So we'll talk about
• 0:36
  Speaker 1: that and don't be a Karen Kiss and tell what's
• 0:39
  Speaker 1: that mean. We'll tell you shortly on this edition of
• 0:42
  Speaker 1: Space Nuts.
• 0:43
  Speaker 3: Fifteen seconds guidance in Channel ten nine ignition Squench Space
• 0:50
  Speaker 3: Nuts Guy or three two.
• 0:55
  Speaker 1: One Space Nuts as when I report it. Neil's good
• 1:00
  Speaker 1: and it feels real good to be back in the
• 1:03
  Speaker 1: chair with Professor Fred Wat's an astronomer at large. Hello Fred,
• 1:06
  Speaker 1: Hello Andrew, how are you doing?
• 1:08
  Speaker 2: Mind doing well? It's good to be back.
• 1:12
  Speaker 1: We had a nice break just very quickly Judy and
• 1:15
  Speaker 1: I went to India, Sri Lanka, Thailand, Malaysia, Singapore.
• 1:18
  Speaker 2: And then back home.
• 1:19
  Speaker 1: And then we had to go to a wedding on
• 1:22
  Speaker 1: New Year's Day, believe it or not, down in the
• 1:24
  Speaker 1: snowy mountains. So we've had a very eventful break.
• 1:27
  Speaker 4: What about you, Oh well, yes, I had a full
• 1:31
  Speaker 4: break as well, because seven members of my UK family
• 1:35
  Speaker 4: descended on us. Not all of them stayed with us,
• 1:40
  Speaker 4: but most of them did because I had a significant
• 1:43
  Speaker 4: birthday in December and so they all came to help.
• 1:45
  Speaker 2: Me celebrate eight hundreds of real milestone.
• 1:48
  Speaker 4: Absolutely, it does begin with an E, but it's not
• 1:52
  Speaker 4: eight hundred and it's not eight either.
• 1:56
  Speaker 2: Eighteen that's it. It's nearer to that.
• 2:00
  Speaker 1: Just can't imagine being stuck in a room with that
• 2:02
  Speaker 1: many poems all at once. But anyway, you know.
• 2:07
  Speaker 4: They started fighting among themselves as as usual, but actually
• 2:12
  Speaker 4: compared with the way the Ossies fought among themselves, there
• 2:14
  Speaker 4: were pretty tame.
• 2:15
  Speaker 2: I have to say. Yeah, well that happens a lot.
• 2:18
  Speaker 2: Christmas brings that out in estuffes. Yeah, that was absolutely
• 2:21
  Speaker 2: Now I.
• 2:22
  Speaker 1: Have a little bit of a surprise for our audience.
• 2:26
  Speaker 1: Moving forward, we have another guest with us at the moment,
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  Speaker 1: he is Professor John T.
• 2:31
  Speaker 2: Horner.
• 2:32
  Speaker 1: He's the professor of Astrophysics at the University of Southern Queensland.
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  Speaker 2: Johnty, welcome, Thank you for having me. It's good to
• 2:39
  Speaker 2: be here.
• 2:41
  Speaker 1: It's good that you decided to join us, because we
• 2:43
  Speaker 1: thought you'd say no.
• 2:43
  Speaker 2: But anyway, the reason you're on.
• 2:47
  Speaker 1: Board because Fred and I have basically run out of
• 2:50
  Speaker 1: time to do catch up episodes for when both of
• 2:53
  Speaker 1: us are going to be away over the coming months,
• 2:56
  Speaker 1: and so this is technically Fred's only episode for the
• 3:00
  Speaker 1: next month or so and you're going to fill in
• 3:04
  Speaker 1: for him over that time frame.
• 3:06
  Speaker 2: So we're really pleased about that. Can you tell us
• 3:09
  Speaker 2: a little bit about.
• 3:09
  Speaker 1: Yourself, you know, professor of estro physics.
• 3:13
  Speaker 2: Very exciting, happy to do so. I mean you probably
• 3:15
  Speaker 2: pick up from the accent that I've got a bit
• 3:17
  Speaker 2: of a shared heritage with Fred, which I'm sure is
• 3:19
  Speaker 2: the only reason you invited me on. It's to maintain
• 3:21
  Speaker 2: the Yorkshire connection. I grew up in the North of
• 3:25
  Speaker 2: England back in the eighties really and got hooked by
• 3:29
  Speaker 2: astronomy very young. Thanks Sir Patrick Moore, and I seem
• 3:33
  Speaker 2: to be expanding in a similar way to him as well,
• 3:35
  Speaker 2: so I'm clearly mimicking his share and join my local
• 3:39
  Speaker 2: astronomy society, which is a West the olkso Astronomy Society
• 3:42
  Speaker 2: when I was about eight years old, and I now
• 3:45
  Speaker 2: get to be their president. Actually, even though I'm in absentia,
• 3:47
  Speaker 2: which is really kind of a lovely touching thing. You know,
• 3:50
  Speaker 2: some young kid that came through the society went to
• 3:53
  Speaker 2: talks from professional astronomers all the time, and basically that
• 3:56
  Speaker 2: let me stay hooked through being a teenager and meant
• 3:59
  Speaker 2: that I have the ammunition in the world with all
• 4:02
  Speaker 2: I guess coming from a well salesio economic area, you know,
• 4:05
  Speaker 2: not the best part of the world to grow up
• 4:07
  Speaker 2: in at that time. Thanks to Magufacturre milk Snatcher, I
• 4:11
  Speaker 2: still have the opportunity to head off to you and
• 4:14
  Speaker 2: to get to study what I want to do, and
• 4:15
  Speaker 2: that's allowed me to have a reasonably entertaining and challenging
• 4:19
  Speaker 2: at time's career and move around the world. Wrapped up
• 4:22
  Speaker 2: in Australia in about twenty ten and I've been here
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  Speaker 2: ever since. So despite the accent, I am officially Australian.
• 4:28
  Speaker 2: I just quite found again. So well, that's kind of
• 4:31
  Speaker 2: the potted history.
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  Speaker 1: We're so drilled to have you, and people will get
• 4:36
  Speaker 1: to know you over the coming week, So welcome aboard,
• 4:38
  Speaker 1: and we're going to have a lot of fun today
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  Speaker 1: talking about these topics, and we're going to start with
• 4:45
  Speaker 1: probably a big one in regard to this new paper
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  Speaker 1: suggesting the universe has no dark energy and isn't expanding
• 4:55
  Speaker 1: like we think.
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  Speaker 2: Your thoughts on this thread.
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  Speaker 4: Yeah, it's entertaining. It's something that I think is going
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  Speaker 4: to cause not a consternation by any means, but certainly
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  Speaker 4: give cosmologists, the people who look at the history and
• 5:17
  Speaker 4: evolution of the universe as a whole, perhaps reason to
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  Speaker 4: pause and say, Okay, maybe this is a time to
• 5:24
  Speaker 4: have a look at the paradigm under which we're working.
• 5:27
  Speaker 4: And in fact the research that we're talking about, which
• 5:30
  Speaker 4: has been done by a group actually all of them
• 5:34
  Speaker 4: are at the University of Canterbury in New Zealand. So
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  Speaker 4: it's the Kiwi's who stolen a march on us with this.
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  Speaker 4: Their paper in Monthly Notices of the Royal Astronomical Society
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  Speaker 4: is entitled Supernova Evidence for Foundational Change to cosmological models
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  Speaker 4: and what they're basically saying is that we now have
• 5:56
  Speaker 4: such a big collection of super and over data, and
• 6:01
  Speaker 4: these are stars, as you know, that explode at the
• 6:05
  Speaker 4: ends of their lives. They explode with a specific brightness.
• 6:10
  Speaker 4: This is the trick to it. They become standard candles
• 6:13
  Speaker 4: because they all reach the same peak brightness, and that
• 6:16
  Speaker 4: allows them to give us a direct measurement of the
• 6:19
  Speaker 4: geometry of the universe, basically their distance. And when you
• 6:23
  Speaker 4: do that with the latest data, it turns out that
• 6:28
  Speaker 4: the dark energy model, which is kind of getting a
• 6:33
  Speaker 4: bit creaky because we've always thought dark energy are springing
• 6:37
  Speaker 4: us of space, might be constant. There's new evidence that
• 6:39
  Speaker 4: suggests that it's not, but that model might really need
• 6:44
  Speaker 4: to be taken apart for a rethink. And the rethink
• 6:47
  Speaker 4: that they're proposing is a model that is being called
• 6:55
  Speaker 4: I've got the word time share in my mind, but
• 6:57
  Speaker 4: it's actually timescape, which suggests that the reason why we
• 7:02
  Speaker 4: think we see dark energy, and remember that was discovered
• 7:05
  Speaker 4: back in nineteen ninety eight, the reason why we think
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  Speaker 4: we see dark energy is that the universe is far
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  Speaker 4: from homogeneous. It's not the same in all directions. It's
• 7:14
  Speaker 4: got thick bits and thin bits in terms of the
• 7:16
  Speaker 4: amount of matter that it contains. And the problem with
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  Speaker 4: all our cosmological modeling is the first premise that we
• 7:24
  Speaker 4: start from, the first foundational fact ooid that we take,
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  Speaker 4: is that the universe is the same in all directions.
• 7:31
  Speaker 4: It's isentropic and uniform, and that is not the case.
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  Speaker 4: We know that because we look out there and we
• 7:37
  Speaker 4: see galaxies in some places and not in others, So
• 7:40
  Speaker 4: we know that the universe is highly inhomogeneous. And what
• 7:43
  Speaker 4: these people are saying is, perhaps that is the bigger
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  Speaker 4: effect that is manifesting itself in what we think we're
• 7:51
  Speaker 4: seeing as an accelerated expansion of the universe caused by
• 7:55
  Speaker 4: dark energy, whereas in reality that's not the case. The
• 7:58
  Speaker 4: universe perhaps is not accelerating in its expansion, but what
• 8:04
  Speaker 4: we can see makes us think it is. So the
• 8:06
  Speaker 4: more measurements that we can make, the more likely we
• 8:09
  Speaker 4: are to be able to pick between one model and another.
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  Speaker 1: So are they suggesting this is some kind of optical
• 8:16
  Speaker 1: illusion in.
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  Speaker 4: A sense, yes, that's right, Well, all universe optical illusion
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  Speaker 4: in the you know, we see these things dotted around,
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  Speaker 4: and we've got to be very careful as to how
• 8:27
  Speaker 4: we interpret that as a three dimensional entity, and that's
• 8:31
  Speaker 4: always the problem. My take on it, if you'll forgive me,
• 8:35
  Speaker 4: and I'd love to hear what John Ty thinks about
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  Speaker 4: this work as well. My take on it is that
• 8:40
  Speaker 4: there is a lot of evidence not just from the
• 8:43
  Speaker 4: super and Over observations, but from the geometry of the
• 8:46
  Speaker 4: universe as a whole. When we look at the way
• 8:48
  Speaker 4: galaxies form this kind of honeycomb of material, almost like
• 8:53
  Speaker 4: a foam of galaxies. When you analyze that and look
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  Speaker 4: at the characteristic distances between galaxy and things of that sort,
• 9:01
  Speaker 4: you can really work out what the geometry of the
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  Speaker 4: universe is like in some detail, and that allows you
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  Speaker 4: to tease out the constituent components, including the contribution of
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  Speaker 4: normal matter which is only about a five percent, constitution
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  Speaker 4: of dark matter which is something like twenty five percent,
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  Speaker 4: and this mysterious thing called dark energy, which is seventy percent.
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  Speaker 4: There's Jordy agreeing with everything I'm saying.
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  Speaker 1: He's yeah, wait, he couldn't wait to them back, couldn't wait.
• 9:32
  Speaker 4: No, It's yeah, sorry about that, all right, Jordy.
• 9:36
  Speaker 1: It's okay, So yeah, not confusing Jordie with John Ty.
• 9:41
  Speaker 1: Which is an email and I apologially Jordan nearly.
• 9:44
  Speaker 4: Got called Johnty, I have to say, and that's what
• 9:47
  Speaker 4: they're enough for you, john Ty, Johnny.
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  Speaker 2: What's your take on this?
• 9:51
  Speaker 1: And I do remember reading in one of her emails
• 9:54
  Speaker 1: when we discussed this.
• 9:55
  Speaker 2: Topic that it gave you a headache. Well, I think
• 9:58
  Speaker 2: most of these things do, because we're trying to visue
• 10:00
  Speaker 2: things that are the very limits of our understanding. And
• 10:03
  Speaker 2: I always find it amazing that we're having this podcast
• 10:06
  Speaker 2: here in all this technology we've developed, with this incredible
• 10:09
  Speaker 2: wealth of understanding how the universe that has all been
• 10:12
  Speaker 2: developed by about two kilograms of squishy stuff in people's heads,
• 10:15
  Speaker 2: And it's amazing that two quos are squishy carbon can
• 10:18
  Speaker 2: work out what the universe is like. But what I
• 10:21
  Speaker 2: love about this is it's a really nice reminder of
• 10:24
  Speaker 2: how science actually works. So you kind of get the
• 10:27
  Speaker 2: impression at school that science has just done undusted, and
• 10:29
  Speaker 2: here's a theory and that's it. But what we're actually
• 10:31
  Speaker 2: doing is this kind of literative process where in astronomy
• 10:35
  Speaker 2: we're not an experimental science. We're an observational science, which
• 10:38
  Speaker 2: is a bit of a subtlety, but what it means
• 10:40
  Speaker 2: is we're looking out of the universe like detectives. We're
• 10:43
  Speaker 2: gathering all these clues and then we try and piece
• 10:45
  Speaker 2: them together into a narrative of how things work. And
• 10:49
  Speaker 2: what makes that narrative a theory is that you can
• 10:51
  Speaker 2: use it to make predictions. If this is correct, then
• 10:54
  Speaker 2: you will see this, then you'll see the other. And
• 10:56
  Speaker 2: sometimes people make explicit predictions, like with the next generation
• 11:00
  Speaker 2: of telescopes, you need to look for this, and this
• 11:02
  Speaker 2: is a really good test. Other times it's a bit
• 11:04
  Speaker 2: more implicit, because it's just saying this is how things behave.
• 11:08
  Speaker 2: And typically those theories, those explanations do an exceptionally good
• 11:12
  Speaker 2: job of explaining everything we already see and going a
• 11:16
  Speaker 2: little bit beyond it. But there's this really long history
• 11:19
  Speaker 2: of us hitting a wall where suddenly we've reached beyond
• 11:23
  Speaker 2: the point where the theory works because we just didn't
• 11:26
  Speaker 2: have enough data. So the theory was a good explanation,
• 11:28
  Speaker 2: but it's not the final answer, and then you get
• 11:31
  Speaker 2: the observationals that show the theory isn't quite right, and
• 11:35
  Speaker 2: you go back and new bachelors of theories come, and
• 11:37
  Speaker 2: sometimes they're just refinement or an improvement, which is what
• 11:39
  Speaker 2: this is doing. Essentially, it's saying we can no longer
• 11:42
  Speaker 2: assume the universe is howmo genius. You've got to take
• 11:45
  Speaker 2: account of the papchoness. There's a few different models that
• 11:48
  Speaker 2: try and do that in different ways. They'll predict different things.
• 11:52
  Speaker 2: We can look at that in the future. Sometimes it
• 11:55
  Speaker 2: knocks a theory over and you start again from scratch.
• 11:57
  Speaker 2: And this is what we're seeing. We've seen science happening
• 12:00
  Speaker 2: before our very eyes here, and it's because what we're
• 12:02
  Speaker 2: looking at it's the hardest ever things to measure, the
• 12:06
  Speaker 2: most challenging observations, really pushing the boundaries of what we know.
• 12:10
  Speaker 2: And so as we get more detailed answers, you are
• 12:13
  Speaker 2: going to hit a point where the simpler theory doesn't work.
• 12:15
  Speaker 2: And I mean it makes my head hurt to call
• 12:17
  Speaker 2: the curb cogmology the simple version because it really really isn't.
• 12:23
  Speaker 2: But it's a steady improvement and we've seen it in
• 12:25
  Speaker 2: the past. I use Newton's gravitation in all the research
• 12:28
  Speaker 2: work I do all the simulations, even though it's wrong.
• 12:32
  Speaker 2: It's wrong because you need to do general relativity to
• 12:36
  Speaker 2: improve on it. That's, you know, if we were doing
• 12:38
  Speaker 2: the podcast. One hundred and twenty years ago, that would
• 12:40
  Speaker 2: have been the great revelation Newton was wrong. Here's Einstein.
• 12:44
  Speaker 2: But Newton's model was good enough that it's easier for
• 12:47
  Speaker 2: my simulations to use it, and the differences are so
• 12:51
  Speaker 2: small we can ignore them. That was one hundred and
• 12:53
  Speaker 2: twenty years ago. This is the equivalent kind of thing
• 12:55
  Speaker 2: going on now. This is right at the forefront, and
• 12:58
  Speaker 2: it's brilliant to see how all these new surveys that
• 13:01
  Speaker 2: will put together best off the stuff twenty years ago
• 13:04
  Speaker 2: and now pushing the limits of where that may or
• 13:06
  Speaker 2: may not work, allowing to take that next step. Yeah.
• 13:09
  Speaker 1: Would it be fair to say that challenging what we
• 13:13
  Speaker 1: perceive to be the current reality is the way we
• 13:17
  Speaker 1: can improve the potential outcomes or the potential changes in
• 13:23
  Speaker 1: the way we look at cosmology or the universe as
• 13:26
  Speaker 1: a whole. If we didn't challenge these things, there'd be
• 13:30
  Speaker 1: no progress.
• 13:31
  Speaker 2: Would that be a fair point? Yeah? Yeah, absolutely so.
• 13:36
  Speaker 4: It's you know, essentially, what we're trying to do here,
• 13:41
  Speaker 4: or the authors of this paper, is lift the lid
• 13:43
  Speaker 4: on not the elephant in the room, in the sense
• 13:46
  Speaker 4: that you know, we think there's something definitely drastically wrong
• 13:50
  Speaker 4: with dark energy, because it's still very much the paradigm
• 13:53
  Speaker 4: by which astronomers work. But lifting the lid on maybe complacency.
• 13:58
  Speaker 4: So it is challenging our eye years and it will.
• 14:02
  Speaker 4: It will produce new results. It may even produce a
• 14:05
  Speaker 4: paper that says, no way the dark energy model fits
• 14:08
  Speaker 4: the data better than the time skate model, especially when
• 14:15
  Speaker 4: there is new data, and actually those data already exist,
• 14:18
  Speaker 4: it's just that they've been fed into the mix yet,
• 14:20
  Speaker 4: so there might be challenges to the new model. Not
• 14:25
  Speaker 4: very far down the track. I kind of hope though,
• 14:27
  Speaker 4: that this sort of thing actually starts to gain a
• 14:32
  Speaker 4: little bit of traction, and that we might see some
• 14:35
  Speaker 4: glimmer of hope in understanding what we have hitherto thought
• 14:38
  Speaker 4: of as dark energy, because it's been one of the
• 14:40
  Speaker 4: biggest puzzles faced by astrophysicists.
• 14:44
  Speaker 2: Yes, that's kind of what this whole paper is doing. Actually,
• 14:47
  Speaker 2: so the idea behind this is two or three different
• 14:50
  Speaker 2: models what proposed in the last ten or fifteen years,
• 14:53
  Speaker 2: and what this paper's doing in sane Now we have
• 14:55
  Speaker 2: all this observational data. We've got enough data to compare
• 14:58
  Speaker 2: the models and run a statistical test to see which
• 15:01
  Speaker 2: fits better, essentially, and they find that the Timescape one
• 15:06
  Speaker 2: fits a little bit better for this sample than dark Energy,
• 15:09
  Speaker 2: but not enough to be definitive yet. And what's interesting
• 15:13
  Speaker 2: is there's this fantastic thing called the Dark Energy Survey,
• 15:15
  Speaker 2: which I think tomorrow day this sound at UQ has led.
• 15:18
  Speaker 2: But it's this incredible global project that I know about
• 15:22
  Speaker 2: because of the spinoffs in soulsism astronomy that I've heard about,
• 15:25
  Speaker 2: which is an even bigger data set, and I suspect
• 15:27
  Speaker 2: the next set with this is to say, look the
• 15:29
  Speaker 2: test with the data set we use here, sure that
• 15:32
  Speaker 2: this is a worthwhile test to do. Now let's use
• 15:34
  Speaker 2: an even bigger data set so I could easily see
• 15:37
  Speaker 2: you're talking about this again in twelve months, tund saying,
• 15:39
  Speaker 2: remember that team that said Timescape was interesting, They've got
• 15:42
  Speaker 2: a new one out. It's a sequel and it's really.
• 15:45
  Speaker 1: Yeah, yeah, it could be really exparting down the track,
• 15:48
  Speaker 1: and we obviously there's gonna be a lot of peer
• 15:51
  Speaker 1: review or a lot of discussion, a lot of debate.
• 15:54
  Speaker 1: Some will debankers, some will say, well, actually you know,
• 15:56
  Speaker 1: they're onder something we might Yeah, who knows where this
• 15:58
  Speaker 1: will lead, but we'll watch with great interest. This is
• 16:02
  Speaker 1: space nuts. You can follow up that story on the
• 16:05
  Speaker 1: conversation dot com. This is Space Nuts Andrew Dunkley with
• 16:08
  Speaker 1: Fred and Johndy Horner and glad to have your company. Okay,
• 16:15
  Speaker 1: we check your space nuts, right, Johnny, Yeah to you.
• 16:21
  Speaker 1: And just before we started, you showed us some fabulous
• 16:25
  Speaker 1: images of this comet. C twenty twenty four G three Atlas.
• 16:29
  Speaker 1: Is that the right title for it?
• 16:31
  Speaker 2: Like, if I get that right, it is? Yeah, And
• 16:34
  Speaker 2: naming conventions for comics are a little bit like barcodes.
• 16:37
  Speaker 2: So you've got two parts. The Atlas parties who discovered it,
• 16:41
  Speaker 2: and that's the Atlas survey. The rest of it is
• 16:43
  Speaker 2: a unique identifier that tells you when it was found.
• 16:46
  Speaker 2: So the C tells you that this is a comet
• 16:48
  Speaker 2: that is not a periodic comet. It's the first time
• 16:50
  Speaker 2: we've seen it. If it was a periodic comet like
• 16:52
  Speaker 2: comet Hallett and Berp, and it might even have a
• 16:55
  Speaker 2: number before it. And then the twenty twenty four G
• 16:58
  Speaker 2: three tells you when it was found, So it was
• 17:01
  Speaker 2: discovered in twenty twenty four. The letter tells you which
• 17:05
  Speaker 2: fortnight of the year it was found in so air
• 17:07
  Speaker 2: would be the first fortnight in January be the second,
• 17:10
  Speaker 2: and so on, and then three tells it was the
• 17:12
  Speaker 2: third object in that fortnight. So nice, I'm straightforward, and
• 17:17
  Speaker 2: it rolls off the tongue. I mean, it's easier than
• 17:18
  Speaker 2: touching shan Atlas, which was last year. Now, this comet
• 17:22
  Speaker 2: was found, and people got moderately excited. Got moderately excited
• 17:28
  Speaker 2: because it was very faint when it was found, which
• 17:30
  Speaker 2: suggests that it might be intrinsically relatively small as icy
• 17:35
  Speaker 2: object goes. But when they worked out it's all a bit.
• 17:38
  Speaker 2: They found that it was going to get within a
• 17:40
  Speaker 2: tenth of the distance between the Earth and the Sun
• 17:42
  Speaker 2: off the Sun, so it's going to get really close
• 17:44
  Speaker 2: to the Sun. And all of the things being equal,
• 17:47
  Speaker 2: the closer cometary nucleus gets to the Sun, the more
• 17:49
  Speaker 2: active it gets, and therefore the more spectacle of the
• 17:52
  Speaker 2: comet gets. So that's an indication that this comic could
• 17:55
  Speaker 2: get very very bright around perihelium closest to the Sun,
• 17:58
  Speaker 2: which is literally while we're recording this podcast, it's around now.
• 18:03
  Speaker 2: The reason everybody's been tentative about it is being quite
• 18:06
  Speaker 2: a small object. Small things that get close to the
• 18:08
  Speaker 2: Sun tend not to survive. They tend to fall apart, disintegrate,
• 18:12
  Speaker 2: and so with this thing, people have been far more cautious.
• 18:15
  Speaker 2: And I'm used to with comments. Actually I'm used to
• 18:17
  Speaker 2: people hyping them and me having to play the voice
• 18:19
  Speaker 2: of reason. With this one, people have been really cautious
• 18:22
  Speaker 2: because it might not survive. But now that it's that
• 18:25
  Speaker 2: it's closest to the Sun, it's going really well and
• 18:28
  Speaker 2: it is surviving. I mean that doesn't mean that in
• 18:30
  Speaker 2: two days, sim it won't disintegrate, So caution. Their comets
• 18:33
  Speaker 2: are like cats, they have tails that do whatever they want.
• 18:36
  Speaker 2: But it's looking promising. At the minute. It's as nearly
• 18:40
  Speaker 2: as bright as the planet Venus, but you can't see
• 18:43
  Speaker 2: it sits within five degrees of the Sun. That's as
• 18:45
  Speaker 2: we record this. But in the next few days it's
• 18:48
  Speaker 2: going to start to move away from the Sun in
• 18:50
  Speaker 2: the sky very low on the western horizon. Apologies to
• 18:53
  Speaker 2: people in the northern hemisphere that this is going to
• 18:55
  Speaker 2: be one which we're going to have a much better
• 18:57
  Speaker 2: view down south just because of the orient of the
• 19:00
  Speaker 2: comet's abit. It's diving very seeply south below the plane
• 19:03
  Speaker 2: of the solar system, so as it moves away from
• 19:05
  Speaker 2: the Sun, it's moving in a southerly direction. What all
• 19:08
  Speaker 2: that means is that Thursday, Friday, Saturday, Sunday, So that Thursday,
• 19:13
  Speaker 2: the sixteenth of January, through the weekend, maybe into next week,
• 19:17
  Speaker 2: there is a chance we could have a reasonably bright comet,
• 19:20
  Speaker 2: very low on the western horizon after sunset, probably a
• 19:24
  Speaker 2: little bit brighter than Comet tour Chinchha Atlas was, but
• 19:28
  Speaker 2: a little bit harder to see. It's a bit more
• 19:30
  Speaker 2: lost in the Sun's glare, fading day by day as
• 19:33
  Speaker 2: it gets higher above the horizon. So on Thursday, for
• 19:37
  Speaker 2: me here to wonder in southeast Queensland, it'll said about
• 19:39
  Speaker 2: forty five minutes after the sun. On Friday, it'll said
• 19:43
  Speaker 2: about an hour after the sun on Saturday about an
• 19:45
  Speaker 2: hour and a quarter. So you get this feel it's
• 19:46
  Speaker 2: moving away from the sun low on the western horizon.
• 19:50
  Speaker 2: I'm going to get out there and try and photograph it,
• 19:52
  Speaker 2: and there are actually people getting photos of it in
• 19:54
  Speaker 2: broad daylight at the minute. But thet there is don't
• 19:58
  Speaker 2: do that unless you really know what you're doing. Beare
• 20:00
  Speaker 2: it's a very good way of damaging your camera, your eyesight,
• 20:02
  Speaker 2: and your wallet, and it could be very very good.
• 20:06
  Speaker 1: They've described this as a once in one hundred and
• 20:09
  Speaker 1: sixty thousand year comet. I also believe it's of old
• 20:15
  Speaker 1: cloud origin.
• 20:16
  Speaker 2: I mean that what does that mean? Basically, it means
• 20:20
  Speaker 2: that people are throwing a lazoo around something that astronoms
• 20:25
  Speaker 2: probably wouldn't mention. So comets move on these really elongated
• 20:29
  Speaker 2: orbits around the Sun. And when a comet's trapped on
• 20:32
  Speaker 2: an orbit that's relatively short period, you know, in tens
• 20:35
  Speaker 2: or hundreds or even a few thousand years, it's not
• 20:38
  Speaker 2: getting so far from the Sun that anything else is
• 20:40
  Speaker 2: going to stir it up other than the planets in
• 20:42
  Speaker 2: the inner soil system. So comet Halley is roughly seventy
• 20:44
  Speaker 2: six years, and it comes back when you get to
• 20:46
  Speaker 2: orbital periods of around one hundred thousand years or so,
• 20:49
  Speaker 2: or even more than that. You're getting far enough from
• 20:52
  Speaker 2: the Sun that you get perturbed by passing stars, by
• 20:56
  Speaker 2: the tidal effects of the galaxy. Stuff like that. Saying
• 21:00
  Speaker 2: that the things on one hundred and sixty thousand year
• 21:02
  Speaker 2: orbit doesn't mean that it will be back in one
• 21:05
  Speaker 2: hundred and sixty thousand years, because when it gets furthest
• 21:07
  Speaker 2: from the Sun, it will be nudged around and will
• 21:09
  Speaker 2: probably not coming on quite the same orbit. The reason
• 21:13
  Speaker 2: that gets thrown around, though, is that it's currently one
• 21:15
  Speaker 2: hundred and sixty thousand a year orbit, so therefore it
• 21:18
  Speaker 2: wasn't seen at any point in the last one hundred
• 21:20
  Speaker 2: and sixty thousand years. It's a little specious. What it
• 21:24
  Speaker 2: did give astronomers a bit of faith for, though, is
• 21:27
  Speaker 2: that this comet has probably been past the Sun at
• 21:29
  Speaker 2: least once before. Because that orbit is slightly tightly bound.
• 21:35
  Speaker 2: That gives a little bit more confidence that it would
• 21:37
  Speaker 2: survive perihelium. So the comets that break up are either
• 21:40
  Speaker 2: really small fragments of a bigger comet and they're too
• 21:43
  Speaker 2: small to survive. All comets coming through for the very
• 21:46
  Speaker 2: first time have a tendency to break apart more often.
• 21:50
  Speaker 2: So the media stories use that number because it's a
• 21:53
  Speaker 2: big number and it makes it sound exciting. It is
• 21:56
  Speaker 2: not the best comt you'll see in the next one
• 21:58
  Speaker 2: hundred and sixty thousand years. It's pop stably the best
• 22:00
  Speaker 2: comet of this year, but we don't know untill the
• 22:02
  Speaker 2: years over yet, but having that orbital period that is
• 22:07
  Speaker 2: indicating it's been through before the give astronomers a little bit
• 22:09
  Speaker 2: of faith that it might survive. And at the minute
• 22:12
  Speaker 2: it's looking good. There's some glorious images out online from
• 22:15
  Speaker 2: the Solar Helius Ferry Cobservatory SOHO, which points at the Sun,
• 22:19
  Speaker 2: has a little thing in the middle to block the
• 22:20
  Speaker 2: sun out so it can look at solar eruptions coronal
• 22:24
  Speaker 2: mass ejections, and this commet's in the field of view
• 22:26
  Speaker 2: at the minute, and it's the third brightest comet that
• 22:29
  Speaker 2: SOHO has ever seen. It's brighter than trichinshan Atlas was
• 22:31
  Speaker 2: at the minute. The only two that were better was
• 22:34
  Speaker 2: Comet McNaught in early two thousand and seven and Comet
• 22:38
  Speaker 2: ice On in twenty twelve. So it's in a steamed company.
• 22:42
  Speaker 2: It could be really good and well worth a look,
• 22:44
  Speaker 2: and you will see some awesome photos. I can almost
• 22:46
  Speaker 2: guarantee that, Gosh.
• 22:48
  Speaker 1: I'm going to have to get out there with my
• 22:49
  Speaker 1: telescope and see if I can have a crack at it.
• 22:52
  Speaker 1: We've talked about comments a lot, and we got pretty excited.
• 22:58
  Speaker 2: Like last year in.
• 23:00
  Speaker 1: The comet made the news and we couldn't see it
• 23:03
  Speaker 1: because it was cloudy in Sydney, it was cloudy here.
• 23:06
  Speaker 1: I never got one chance to see it. I'm very
• 23:10
  Speaker 1: hopeful about this one.
• 23:12
  Speaker 4: Well, the great thing about this one, Andrew, is that
• 23:13
  Speaker 4: you're not going to have to get up at three
• 23:15
  Speaker 4: o'clock in the morning, as Johnty did to photograph the
• 23:18
  Speaker 4: last one. So yeah, so I'm sure that fingers will
• 23:25
  Speaker 4: be crossed. Sadly mine won't be because days in two
• 23:28
  Speaker 4: days time, I'll be very well up in the northern Hemisphere,
• 23:32
  Speaker 4: in the Arctic Circle in fact, so that's going to
• 23:35
  Speaker 4: take me well away from night sky viewing of this comet.
• 23:38
  Speaker 4: In the evening sky.
• 23:39
  Speaker 1: Maybe when you take off you could just take your
• 23:41
  Speaker 1: telescope and shove it out the window of the plane.
• 23:44
  Speaker 2: I'll just think, I think, what time you fly. If
• 23:47
  Speaker 2: you're taking off in the early evening, you might get
• 23:50
  Speaker 2: to see it from the plane window, and that's a
• 23:52
  Speaker 2: good way of being above the clowns it is.
• 23:54
  Speaker 4: Indeed, Yeah, it's an afternoon flight. John t up to
• 23:58
  Speaker 4: Bangkok and then from there up to stock Comb.
• 24:01
  Speaker 2: So just to be on the western side of the aircraft.
• 24:06
  Speaker 4: My seat is already picked so that I will be
• 24:09
  Speaker 4: next to my wife.
• 24:11
  Speaker 1: You probably need to be looking at her. Yes, indeed, Yeah,
• 24:17
  Speaker 1: it's very exciting. So something to keep an eye out for.
• 24:20
  Speaker 2: And Johnny just quickly if people want.
• 24:23
  Speaker 1: To have a go at saying this best time, best way.
• 24:28
  Speaker 2: The further south you are in the world, the better.
• 24:31
  Speaker 2: Actually I think about where I am. Really, the nearer
• 24:34
  Speaker 2: you are to the equator, the most deeply things set,
• 24:37
  Speaker 2: and so the higher above the horizon, they are a
• 24:39
  Speaker 2: given amount of time before the set. So if it's
• 24:41
  Speaker 2: thirteen minutes before something sets and you're at the pole,
• 24:44
  Speaker 2: it's pretty much on the horizon already. If you're on
• 24:46
  Speaker 2: the equator, it's setting vertically. But have a play around
• 24:50
  Speaker 2: with one of the wonderful free planetarium programs. I often
• 24:53
  Speaker 2: use Stilarium because that's a free one. You can just
• 24:56
  Speaker 2: open in a browser window, set your location and awhere
• 24:59
  Speaker 2: you go. And also what I did earlier on because
• 25:02
  Speaker 2: I'm looking at trying to get some photos Sursday Friday's
• 25:04
  Speaker 2: happy if the weather holds out, is actually hop onto
• 25:07
  Speaker 2: Google Maps, have a look for a place around you,
• 25:10
  Speaker 2: because you can drop that little peg man in and
• 25:12
  Speaker 2: have a look what the horizon's like just south of
• 25:14
  Speaker 2: west and there you can find somewhere with the lowest
• 25:16
  Speaker 2: western horizon possible, because it's going to be quite low
• 25:20
  Speaker 2: to the horizon, and if you can't see it with
• 25:22
  Speaker 2: the naked eye, mob a camera, especially if you've got
• 25:25
  Speaker 2: a DSLR type camera, bang it on a tripod roughly
• 25:28
  Speaker 2: where it should be in play around with the exposure
• 25:30
  Speaker 2: times because the images are shown. Before we started recording,
• 25:33
  Speaker 2: I could just see the comet with the naked eye,
• 25:35
  Speaker 2: but it was really obvious through the back of the camera,
• 25:38
  Speaker 2: and it was really obvious in the lens, so that
• 25:41
  Speaker 2: comet I could see it with the naked eye, and
• 25:43
  Speaker 2: it's like, yeah, wow, I can see it. Brilliant. But
• 25:45
  Speaker 2: the photos came out better than my view was.
• 25:48
  Speaker 1: Right, and get out of town, get somewhere dark.
• 25:52
  Speaker 2: Dark's a bit less relevant when you're still so close
• 25:54
  Speaker 2: to sunset. I mean, we're talking about observing here during
• 25:57
  Speaker 2: twilight at least. Even if you go a week from now,
• 26:01
  Speaker 2: it's still only setting at about eight pm, so it's
• 26:04
  Speaker 2: only an hour and a bit after sunset, and by
• 26:05
  Speaker 2: then it will be feding relatively quickly. If it goes
• 26:08
  Speaker 2: really well, it might be visible with an eked eye
• 26:10
  Speaker 2: for about a fortnite. But that's tenuously but basically find
• 26:14
  Speaker 2: somewhere with a low western horizon slightly south of west.
• 26:17
  Speaker 2: Actually lower the better, because if the streets in the way,
• 26:20
  Speaker 2: our buildings in the way, our people in the way,
• 26:22
  Speaker 2: they're going to get in the way of the commet.
• 26:24
  Speaker 2: So ideally want the western horizon to be as low
• 26:26
  Speaker 2: as possible.
• 26:27
  Speaker 1: Yeah, okay, well we've got plenty of flat earth around
• 26:31
  Speaker 1: this part of the world. Well use a different terminology
• 26:35
  Speaker 1: any flat ground. So yeah, where we are in the northwest,
• 26:40
  Speaker 1: it's probably or the central West. It's probably a great
• 26:43
  Speaker 1: place to make some observations. Lots of stories online space
• 26:48
  Speaker 1: dot com. But yeah, just do a search for comet
• 26:51
  Speaker 1: see twenty twenty four G three, and yeah, you won't
• 26:54
  Speaker 1: be disappointed. There's a space that It's Andrew Dunkley here
• 26:57
  Speaker 1: with Professor Fred Watson and Professor John D. Horner Murder.
• 27:04
  Speaker 2: Spacemuds.
• 27:06
  Speaker 1: Our next story takes us to the outer Solar System.
• 27:10
  Speaker 1: I kind of introduced this as don't be a Karen
• 27:13
  Speaker 1: kiss and tell this is actually an interesting story about
• 27:17
  Speaker 1: how Pluto got its.
• 27:18
  Speaker 2: Moon, and you know, we talk about how Earth.
• 27:22
  Speaker 1: Got its Moon with that massive collision with theear. Now
• 27:26
  Speaker 1: they're starting to think something different happened with the Moon,
• 27:31
  Speaker 1: Carron and Pluto. So take it away, whoever wants to
• 27:35
  Speaker 1: pick this one up first.
• 27:36
  Speaker 4: I think this is definitely John Tis because he's a
• 27:39
  Speaker 4: planetary scientist, so cannot you go get.
• 27:42
  Speaker 2: So we've got kind of broadly three types of moon
• 27:46
  Speaker 2: in the Solar System. We've got what we call the
• 27:48
  Speaker 2: regular supltes, which you see around the giant plummets, and
• 27:51
  Speaker 2: that's io you're a pagnomy Clister type. The thinking about
• 27:55
  Speaker 2: them is their form around their planets. Like the planet's
• 27:58
  Speaker 2: farmed around the Sun, you get a disc of material.
• 28:00
  Speaker 2: These things are creating that disk, and that's why they're
• 28:02
  Speaker 2: pretty much in the plenty of the equator of those planets,
• 28:05
  Speaker 2: and they look like miniplanetary systems essentially. You've then got
• 28:09
  Speaker 2: what are called the irregular satellites, which are things typically
• 28:12
  Speaker 2: again around the giant planets, that are way way out
• 28:15
  Speaker 2: as much as twenty thirty million kilometers from the planet,
• 28:18
  Speaker 2: moving on really bizarre orbits, really eccentric, really inclined, and
• 28:22
  Speaker 2: typically small icy objects. And then we understand because they
• 28:25
  Speaker 2: were captured it's really straightforward, that's how you form them.
• 28:28
  Speaker 2: They didn't form where they are, they were grabbed. Then
• 28:31
  Speaker 2: you've got the oddities, which are the things that don't
• 28:34
  Speaker 2: fit either of those models, and they're the Moon, their neptunes, Moon, Triton,
• 28:39
  Speaker 2: and a number of the satellite systems around smaller objects
• 28:42
  Speaker 2: Pluto and Karam being kind of the really prime obvious example,
• 28:48
  Speaker 2: And those ones didn't form in either of the two
• 28:50
  Speaker 2: kind of standard ways. They have to be formed somewhere different,
• 28:54
  Speaker 2: and it seems to be that collisions are part of
• 28:57
  Speaker 2: that story. And the real key point here is that
• 29:00
  Speaker 2: for the Earth and the Moon, for Pluto and Caron,
• 29:03
  Speaker 2: the mass of the Moon compared to the mass of
• 29:05
  Speaker 2: the planet is really, really, really big. So for the
• 29:08
  Speaker 2: regular satellites all their mass together, and it's still less
• 29:12
  Speaker 2: than one ten thousandth of the mass of their planet.
• 29:15
  Speaker 2: The irregular satellites are even less. But the Moon is
• 29:18
  Speaker 2: an eighty first of the mass of the Earth, Caron
• 29:21
  Speaker 2: is a sixth of the mass of Pluto, and that
• 29:23
  Speaker 2: just doesn't work with a disc. That doesn't make sense. Equally,
• 29:27
  Speaker 2: capturing them gravitationally doesn't work, So you need the dissipative
• 29:31
  Speaker 2: foss You need something to slow them down. Otherwise they
• 29:34
  Speaker 2: just fly by, get perturbed, and escape again. You need
• 29:37
  Speaker 2: something to put the brakes on. Added to that, you've
• 29:40
  Speaker 2: got the similarities and the differences between the Moon and
• 29:43
  Speaker 2: the object that hurts it. And we knew this since
• 29:46
  Speaker 2: Apollo astronauts brought samples back. Our Moon is almost identical
• 29:51
  Speaker 2: in composition to the Earth, but it's lacking in heavy
• 29:54
  Speaker 2: elements like iron and nickel, and it's overly rich in
• 29:58
  Speaker 2: the light stuff that makes up the Earth's c and
• 30:00
  Speaker 2: that led people in the eighties to come up with
• 30:02
  Speaker 2: the Big Smash idea that the Earth was in a
• 30:05
  Speaker 2: collision with something, and this was after it was differentiated,
• 30:09
  Speaker 2: so all the heavy suffers in the middle, all the
• 30:11
  Speaker 2: light suffers in the crust, and that splashed off and
• 30:14
  Speaker 2: formed the Moon. And so you get a moon that
• 30:15
  Speaker 2: is formed from the same material as the Earth. It's
• 30:18
  Speaker 2: really big, but doesn't have all the iron and nickel.
• 30:22
  Speaker 2: Then when it comes to Pluto, you've got a very
• 30:24
  Speaker 2: similar looking system. You've got a very big moon compared
• 30:26
  Speaker 2: to the planet really close in, so it doesn't look
• 30:29
  Speaker 2: like a capture scenario. And that led to a lot
• 30:32
  Speaker 2: of models through the nineties coming out with a story
• 30:35
  Speaker 2: that Pluto and Karen and also the little moons Nixon, Hydra,
• 30:39
  Speaker 2: Cabaret and sticks and they formed in a giant collision
• 30:44
  Speaker 2: just the same as our moon formed around the Earth.
• 30:46
  Speaker 2: There was a big splash, and you get this satellite
• 30:49
  Speaker 2: system with one big one and a few little bits,
• 30:52
  Speaker 2: and that works really well. That is a perfectly valid explanation.
• 30:55
  Speaker 2: But the new model is slightly different, and it only
• 30:58
  Speaker 2: really works because when you're that far from the Sun,
• 31:00
  Speaker 2: the speed's are lower, so that means you can get
• 31:03
  Speaker 2: gentler collisions. Everything goes around slower the further you are
• 31:06
  Speaker 2: from the Sun. And so this new modeling has said,
• 31:10
  Speaker 2: let's have a look at whether you need it to
• 31:12
  Speaker 2: be a catastrophic collision. Run a load of simulations essentially
• 31:15
  Speaker 2: to see what are the scenarios you can get. And
• 31:19
  Speaker 2: they included in this fact that Pluto and Karen will
• 31:22
  Speaker 2: be physically strong objects. They're not blobs of liquid water.
• 31:26
  Speaker 2: They're solid material that has an inherent strength to it.
• 31:29
  Speaker 2: And they found a set of scenarios within that where
• 31:31
  Speaker 2: you can get a gentle enough collision that Pluto on
• 31:35
  Speaker 2: the thing hitting it that becomes caron collide and semimerge,
• 31:39
  Speaker 2: giving you an object a bit like a snowman with
• 31:41
  Speaker 2: a small bulge and a big bulge but never fully emerge.
• 31:44
  Speaker 2: But that collision dissipates energy. You have a collision that
• 31:48
  Speaker 2: like absorbs and they bounce off each other, but the
• 31:52
  Speaker 2: speed has been slowed down because the collision happened. Essentially,
• 31:55
  Speaker 2: you've got cushioning for want of a better word. That
• 31:59
  Speaker 2: means that Karen doesn't move away from Pluto quickly enough
• 32:03
  Speaker 2: to escape, but instead gets tracked. So you get this
• 32:06
  Speaker 2: collisional capture, and that can set up the system as
• 32:09
  Speaker 2: it looks in a bit of the debris that goes
• 32:11
  Speaker 2: offward form those are the moons, and it seems equally
• 32:14
  Speaker 2: valid to the more catastrophic collision version. But what I
• 32:19
  Speaker 2: really like about it is there's a very clear prediction
• 32:22
  Speaker 2: you can make from this, which is that if you
• 32:25
  Speaker 2: have the catastrophic collision type model like the Earth and Moon,
• 32:28
  Speaker 2: then Pluto and Karen will essentially be made of the
• 32:31
  Speaker 2: same stuff. They'll be compositionally identical, maybe with a little
• 32:34
  Speaker 2: bit of a difference because of the differentiation of Pluto.
• 32:37
  Speaker 2: You might get Karen being a little bit under dense
• 32:39
  Speaker 2: and Pluto being denser. With this model, you've got two
• 32:42
  Speaker 2: discrete objects that formed separately and remained fairly discreete. There
• 32:48
  Speaker 2: remain separate objects with a little bit of mixing, which
• 32:51
  Speaker 2: means that if there were any compositional differences when they're formed,
• 32:55
  Speaker 2: they should still have them. Now, we can't test this
• 32:58
  Speaker 2: at them, and we need to go there and land
• 32:59
  Speaker 2: on them and drill them and do sample. But it's
• 33:02
  Speaker 2: another of those examples we talked about it with the
• 33:04
  Speaker 2: cosmology earlier on where theories make predictions that allow you
• 33:08
  Speaker 2: to test them and rule between them. And the big
• 33:10
  Speaker 2: test of this compared to the other model is the compositions.
• 33:14
  Speaker 2: It's the density, it's the stuff that we can in
• 33:16
  Speaker 2: theory in the future check and it's really important because
• 33:20
  Speaker 2: one of the big problems with our understanding of the
• 33:23
  Speaker 2: objects beyond nature and the transsept union objects, of which
• 33:26
  Speaker 2: Pluto is just one of the biggest, is that there's
• 33:28
  Speaker 2: actually quite a few of these binaries that have very
• 33:31
  Speaker 2: similar masses out there, so this might not be an
• 33:34
  Speaker 2: isolated event. And the better we can understand those mechanics,
• 33:37
  Speaker 2: the better a handle we have on planet formation, moon formation,
• 33:41
  Speaker 2: and also these smaller objects. So it's really fascinating and
• 33:44
  Speaker 2: for me, it's one that is setting up future investigations,
• 33:49
  Speaker 2: probably sets the scene for new horizons match mark two
• 33:52
  Speaker 2: in twenty years, thirty year sam and the technology is
• 33:55
  Speaker 2: a bit better where we can actually go there and
• 33:57
  Speaker 2: put a lander down and do some sampling and actually
• 33:59
  Speaker 2: test this exciting. Yeah, it's so.
• 34:02
  Speaker 1: It was more of a scrape rather than a crash,
• 34:05
  Speaker 1: similar to the way my wife parks a car.
• 34:10
  Speaker 2: But this was really quick.
• 34:11
  Speaker 1: When you talk about the age of the Solar System,
• 34:13
  Speaker 1: the age of the universe, with you know, millions billions
• 34:16
  Speaker 1: of years, this was a really quick encounter. It's like
• 34:20
  Speaker 1: ten to fifteen hours of contact and then they were apart.
• 34:25
  Speaker 2: Again.
• 34:25
  Speaker 1: That's why they're calling it a kiss.
• 34:27
  Speaker 2: I suppose it is. And I mean that timescale sounds
• 34:31
  Speaker 2: surprisingly short, but in the scheme of an impact, that's
• 34:34
  Speaker 2: actually surprisingly long because if you think about the collision
• 34:37
  Speaker 2: between the Earth and the Moon, if the moon's coming in, well,
• 34:40
  Speaker 2: if fear's coming in at the slowest possible speed, you
• 34:44
  Speaker 2: can come in and hit the Earth without being gravitationally bound.
• 34:47
  Speaker 2: It's traveling at ten kilometers a second. The Earth is
• 34:51
  Speaker 2: twelve thousand kilometers across, so that's twelve hundred seconds for
• 34:55
  Speaker 2: the Moon for the thea to go from one side
• 34:56
  Speaker 2: of the Earth to the other. Twelve thousand seconds is
• 35:00
  Speaker 2: what two hundred minutes in a bit hours. Pluto is
• 35:05
  Speaker 2: much smaller than the Earth, so ten hours here is
• 35:07
  Speaker 2: indicative of that slower speed. The only way you can
• 35:11
  Speaker 2: stay in contact for ten hours is been moving much slower,
• 35:14
  Speaker 2: and you just couldn't do that speed in the inner
• 35:16
  Speaker 2: Solar system. So it's a long speed for a collision,
• 35:18
  Speaker 2: but it's a short time in terms of the edge
• 35:20
  Speaker 2: of the Solar system.
• 35:22
  Speaker 1: That's fascinating any thoughts for it, only.
• 35:26
  Speaker 4: That you know, sometimes we probably would have had collisions
• 35:30
  Speaker 4: between objects which are even more gentle, so that without
• 35:35
  Speaker 4: demolishing each other, they do stick together. And I'm thinking
• 35:38
  Speaker 4: of Aracoth, the object that was observed by New Horizons
• 35:42
  Speaker 4: after the Pluto encounter in twenty fifteen. Arakov is not
• 35:47
  Speaker 4: actually two blobs. It's two pancakes stuck together edgewise. And
• 35:53
  Speaker 4: so maybe that was a kiss that turned into a
• 35:57
  Speaker 4: rather longer embrace, because it's clearly still like.
• 36:00
  Speaker 2: And there's quite a few examples of that through the
• 36:03
  Speaker 2: Celsius eat. How another one which the Japanese sent hiboust
• 36:08
  Speaker 2: that's not what's called a contact by mean, there's quite
• 36:10
  Speaker 2: a few of them around where things have spiraled in,
• 36:13
  Speaker 2: but they've done it so gently that they're just balanced
• 36:15
  Speaker 2: against each other. And these objects are small enough that
• 36:18
  Speaker 2: their mutual attraction isn't strong enough to overcome their physical strength.
• 36:23
  Speaker 2: So if you put the Earth and Venus in physical
• 36:25
  Speaker 2: contact with each other, we wouldn't be recording this podcast.
• 36:28
  Speaker 2: But they eventually kind of smushed together. Yeah, but if
• 36:31
  Speaker 2: they're small enough, the physical strengths enough to resist, and
• 36:34
  Speaker 2: you get these contact bindaries.
• 36:36
  Speaker 1: Fascinating, all right, If you'd like to read about that story,
• 36:39
  Speaker 1: you can also find that on space dot Com. We're
• 36:43
  Speaker 1: just a bit of finish, but we probably have enough
• 36:47
  Speaker 1: time to just go very quickly over what will be
• 36:49
  Speaker 1: the best of the best things to see astronomically speaking
• 36:54
  Speaker 1: in twenty twenty five. Any thoughts, Go for.
• 36:58
  Speaker 4: It, John Ty, I'll do this. I'll do space launchers,
• 37:00
  Speaker 4: you do the astronomy.
• 37:03
  Speaker 2: There's a few things that are good to watch now.
• 37:05
  Speaker 2: Always like the things that you can look at without
• 37:07
  Speaker 2: needing specialist equipment. So things like eclipses and meetia showers.
• 37:11
  Speaker 2: This year is absolutely terrible for eclipses of the Sun.
• 37:15
  Speaker 2: There's two very very poor partial eclipses, one of which
• 37:18
  Speaker 2: you'll only see if you're in far northeastern Canada, the
• 37:21
  Speaker 2: other for which you need to go to Antarctica, and
• 37:23
  Speaker 2: they're going to be unimpressive anyway. But we've got two
• 37:26
  Speaker 2: really good total lunar eclipses, the first of which comes
• 37:29
  Speaker 2: at the end of March, mid March, actually fourteenth of March,
• 37:33
  Speaker 2: and that's going to be really good for people in
• 37:35
  Speaker 2: the Americas. You're going to get a proper blood moon,
• 37:38
  Speaker 2: as has become kind of common parlance, back in the
• 37:40
  Speaker 2: middle of the night you see the full eclipse. For
• 37:42
  Speaker 2: us here in Australia, we get a really good one
• 37:45
  Speaker 2: unfortunately before dawn, so yeah, grumble grumble about that. But
• 37:48
  Speaker 2: that's on the eighth of September, and that'll be a
• 37:51
  Speaker 2: really good one with more than an hour and a
• 37:53
  Speaker 2: half of totality, so the moon will be blood red
• 37:55
  Speaker 2: for an hour and a half, which is kind of cool.
• 37:58
  Speaker 2: We've also got meatia active as always we've got for
• 38:02
  Speaker 2: us here in the Southern Hemisphere. The eat aquarians are
• 38:05
  Speaker 2: our second best shower of the year. Northern hemisphere gets
• 38:08
  Speaker 2: better ones, but for a zet aquarieds are our second
• 38:10
  Speaker 2: best and they're good, particularly in the first week of May,
• 38:14
  Speaker 2: and again they're get up before dawn to see them, unfortunately,
• 38:17
  Speaker 2: but it's good time to go camping as the weather
• 38:19
  Speaker 2: cools down in our autumn. The Geminids in December are
• 38:22
  Speaker 2: the best shower of the year every year. They're awesome.
• 38:25
  Speaker 2: I love them. They're brilliant from the Northern hemisphere, but
• 38:28
  Speaker 2: they're also good for the southern hemispheres. Northern hemisphere gets
• 38:31
  Speaker 2: them a bit better. They peak on the thirteenth and
• 38:34
  Speaker 2: fourteenth of December. This year, the moon's out of the way,
• 38:37
  Speaker 2: so it's perfect and like last year where the blind
• 38:39
  Speaker 2: site was in the way and we had all this
• 38:40
  Speaker 2: natural light pollution and it was a bit disappointing. Yeah,
• 38:44
  Speaker 2: this year they'll be really good. So they're really my
• 38:46
  Speaker 2: highlights and a lovely way to finish the year with
• 38:48
  Speaker 2: the geminis.
• 38:50
  Speaker 1: Excellent, Rija Marty.
• 38:51
  Speaker 4: They're my birthday meteors because they peak on my birthday.
• 38:56
  Speaker 4: Now drifting off, Yeah, just you know, the things to
• 39:00
  Speaker 4: watch for this year are going to be star it's
• 39:03
  Speaker 4: going to be Starship Starship, Starship Starship. We are expecting
• 39:08
  Speaker 4: the seventh test launch of Starship anytime now, possibly tomorrow,
• 39:13
  Speaker 4: compared with where we're recording at the moment, so by
• 39:15
  Speaker 4: the time this recording goes to air, it might have
• 39:17
  Speaker 4: happened the seventh test flight, which will once again, we hope,
• 39:21
  Speaker 4: bring the Falcon Super Heavy back to its chopstick landing
• 39:27
  Speaker 4: down there at Bockachica and the other space I like
• 39:31
  Speaker 4: to look out for, perhaps is the eventual return of
• 39:35
  Speaker 4: Sunny Williams and Butch Wilmore, who've been stuck up on
• 39:38
  Speaker 4: the International Space Station since June last year, because I
• 39:43
  Speaker 4: think their return has now been pushed another month further
• 39:47
  Speaker 4: down the track. I think it's no earlier than the
• 39:49
  Speaker 4: twenty fifth of March was the last thing I read, which,
• 39:53
  Speaker 4: considering they expected to be at the International Space Station
• 39:56
  Speaker 4: for a week, is pretty good going.
• 39:58
  Speaker 2: Really. Ye that's the thing.
• 40:01
  Speaker 1: You never know what you're in for when you get
• 40:02
  Speaker 1: up the International Space Station. But yeah, I'm sure he'll
• 40:06
  Speaker 1: be really happy to get home eventually.
• 40:09
  Speaker 2: All Right.
• 40:10
  Speaker 1: That just about wraps it up for this edition of
• 40:12
  Speaker 1: Space Nuts. Don't forget to visit us online at our website,
• 40:15
  Speaker 1: Space Nuts podcast dot com or space Nuts dot io.
• 40:18
  Speaker 1: Don't forget our shop. We've got to post Christmas sale.
• 40:21
  Speaker 1: Everything's the same price as it was before Christmas, so yes,
• 40:26
  Speaker 1: have a look at that, and don't forget our social
• 40:29
  Speaker 1: media platforms as well. And our thanks to Professor Fred Watson,
• 40:33
  Speaker 1: who will be around for one more episode, not just
• 40:36
  Speaker 1: this one. We'll do the Q and A episode with
• 40:38
  Speaker 1: him soon, but then he'll be off up round Finnland
• 40:43
  Speaker 1: here or somewhere like that, and Johnny will be sitting
• 40:47
  Speaker 1: in his chair for a few weeks. So Professor Fred
• 40:50
  Speaker 1: Watson and Professor Johnny Horner, thank you so much as always.
• 40:53
  Speaker 2: Great pleasure.
• 40:54
  Speaker 4: Andrew, keep up the good work.
• 40:57
  Speaker 2: I never have.
• 40:58
  Speaker 1: All right, thank you. We'll catch you on the next episode.
• 41:01
  Speaker 1: This is Space Nuts and from me Andrew Dunkley. Oh,
• 41:04
  Speaker 1: by the way, Hugh in the studio is here today.
• 41:06
  Speaker 1: Hello here, What where have you been for the last
• 41:08
  Speaker 1: six months? It's good to have you along and guess
• 41:11
  Speaker 1: what he did? Nothing and from me Andrew Dunkley, thanks
• 41:14
  Speaker 1: for your company. We'll see you on the very next
• 41:15
  Speaker 1: episode of Space Nuts.
• 41:17
  Speaker 2: Bye.
• 41:17
  Speaker 1: Byepacenuts. You'll be listening to the Space Nuts podcast.
• 41:23
  Speaker 2: Available at Apple Podcasts, Spotify, iHeartRadio, or your favorite podcast player.
• 41:29
  Speaker 1: You can also stream on demand at guides dot com.
• 41:32
  Speaker 4: This has been another quality podcast production from nights dot com.