Galactic Revelations, Cometary Wonders & Moon Mysteries: #487 - First Edition of 2025

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