Why isn't Pluto a planet?

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And Dr Robert Massey, the deputy director for the Royal Astronomical Society, will take on listener questions later on in the show. So Becky, you get the opening question this time. How did you feel when Pluto went from being a planet to a dwarf planet? I mean, I was a little bit sad like everybody, right? I think we can't help but anthropomorphise these things. We're like, I'm so sorry, Pluto. I don't like change. And yeah, I was still one of the generations that grew up being like, there's nine planets and what do you do now to all your mnemonics now that Pluto's not at the end and all this kind of thing. But I think, you know, these feelings are slightly irrational because they are not just inanimate objects, you know. And the IAU, the International Astronomical Union, they were trying to tidy up all these designations of objects that we have in the solar system. The number of bodies that we knew about was growing as we detected more and more things beyond the orbit of Neptune and also big things in the asteroid belt as well, like Ceres. And it was sort of just getting a little bit messy to be like, well, those are planets because we knew about those for ages, those aren't planets because we just discovered them and they're a bit fun. Sorry, there's no more room. Yeah, you know, it was either we had nine planets or we had, you know, like a growing list, which the mnemonics also wouldn't have been able to cope with, I guess. But some of those things even were bigger than Pluto as well. We have to remember that when Eris was discovered and it was bigger than Pluto, people were like, isn't that 10 planets in the solar system? Yeah, so I think I was sad, but at the same time, I understood the reasoning behind why you would want to define a planet more clearly. Yeah. Well, then we all agree with the definition. It was come up with, I don't know. But yeah, I think it's funny how the internet is still mad about this though. So hopefully we can put to bed without interviewing Alan about why this was necessary in the case. Exactly, we will. And he was actually in the room where it happened when there was the vote. So we'll get to that later on in the show. But you will still find Pluto out in the depths of our solar system, whether it is, you know, as a dwarf planet. And Professor Alan Simmons from Queens University of Belfast studies, comets and asteroids in our local slice of space. And he explained why Pluto is unique to other objects in our solar system. Well, first of all, when it was discovered in 1930, it was the furthest object known from the sun in much further out than the planet Neptune, which was the record holder up until that point. It was then realized that it had this really strange orbit. Most of the major planets in our solar system, they're all fairly circular with the possible exception of Mars, which is slightly elliptical. But this was incredibly elliptical in the sense that it actually crosses the orbit of Neptune. But it's great because it's in what we call a gravitational resonance. That means it goes around the sun twice for exactly every three times Neptune orbits the sun. And that means although their orbits cross, they can never hit each other. So it's been like that for literally billions of years. Even though you say that, I still feel that element of jeopardy of like, but what if, but no, we'll trust the numbers. Yeah. Now, the next thing that made it special and somewhat unique and it's still kind of unique is that about almost 50 years after its discovery in 1930, in 1977, a moon was discovered orbiting Pluto called Charon. And Charon is huge compared to Pluto. It's about half the size of Pluto. So it makes it the biggest moon relative to its kind of planetary size. And it's so big that we have no parents that we have in the solar system. I mean, all of its Earth is only about the quarter of the size of our planet. Amazing. And so can you put it into perspective? Like how, well, I was going to say how big, but probably how small is Pluto? Well, when Pluto was discovered, it's expected it would be about the size of the Earth. And over time, estimates of the size got smaller and smaller and smaller. So it's got a diameter of about 2,400 kilometres. So it really is a small body, but that doesn't make it any more less interesting. You know, it just means it's really tricky to study with telescopes here in the inner solar system around Earth. Yeah, absolutely. So let's talk about some of those interesting features. What are some of those surprising or unexpected features discovered on Pluto? What's it like? Well, if you're standing on the surface of Pluto, the first thing to realise is that it's not only very cold. It's very dark because you're so far away from the sun. You get hundreds of times less light during the day on Pluto than you do here on Earth because it's so far from the sun. Now, you'll also probably be standing on ice rather than rock, although we believe there is rock on the surface of Pluto. And you'll be in an atmosphere. This is one of the big surprises that came out in the 1980s when scientists using the technical stellar occultations from Earth watching Pluto pass in front of a star. So they didn't just cut on and off really quickly, but this starlight gradually faded away and came back again, which is the signature of an atmosphere. Now, it's not a very thick atmosphere, but there's an atmosphere nonetheless. And it wasn't known, however, if this was a permanent atmosphere or initially or whether or not it was being generated by volcanoes or something like that on the surface. What we did know is that it's so cold out there on Pluto that because we were studying it near the point in its orbit where it's closest to the sun and therefore warmest, when it receded in its orbit out to its furthest point from the sun, it was possible that it would get so cold. The atmosphere would literally freeze out and dissipate and freeze out onto the surface in kind of a wonderful, frosty crystalline layer, only to be then heated and regenerated as gas the next time it comes around the sun. And that's crazy, right? We used to have things having an atmosphere, not having an atmosphere, not just having an atmosphere every now and again once per orbit. From Earth, we can study the ices on the surface of Pluto through spectroscopy. And it's been known for decades that there's carbon monoxide and methane ice on the surface. And that's because it's very cold. You know, it's out there on the edge of our planetary system. So we're looking at a temperature of perhaps minus 220 degrees centigrade and low heat. Really, it really is quite chilly. It just reminds me that every time I listen to people talk about Pluto, you read up about Pluto, and you're like, it is a bit mad. It's just like ridiculous. So there was this probe that went to visit Pluto and it has helped us understand it more. So can you tell us about the New Horizons probe? What was it? When did it go and visit? And how has that changed our understanding of Pluto? Yeah, New Horizons was an amazing mission from NASA. One of the smallest but fastest interplanetary spacecraft that's ever been built. It was launched in 2005 and by using Jupiter's gravity en route, it basically only took 10 years to get there. So it took a decade, but that's pretty fast compared to most other spacecraft. And in 2015, it flew through the Pluto system. Now, I say the Pluto system because in the run up to New Horizons getting there, the Pluto and its moon Charon had been studied by the Hubble Space Telescope. And over the years, they'd found another four small moons with the Hubble Space Telescope. So they knew they had a system of Pluto plus five moons to study as they barreled through the Pluto system. And when they got there, because this was on the edge of the solar system, we really didn't know what to expect. And what New Horizons found was an amazing small world in its own right. With all kinds of features that you could not see clearly or detected all from Earth. So for example, one side of the Pluto is dominated by a huge glacier made of nitrogen ice. And you can actually see how it's flowed across the surface over time. There's also surprisingly a great difference in ages between different parts of Pluto. Now, we date ages on objects like Pluto by counting craters because there's small asteroids and comets out there that on occasion will hit these objects. And the more craters you have on a surface, that must mean it must have been around for longer. So it's older. Now, there are some regions of Pluto which look like they're about four billion years old. I know they're dated back towards the beginning of the solar system. But there are some which have hardly any craters at all, particularly around these glaciers, which tell us that those features are perhaps only a few million years old. And so we've got a picture now of a world where some parts of it are very old, but others are very dynamic. The other thing we find, for example, are mountains. But interestingly enough, they're not like the mountains here on Earth, where some of these mountains and indeed smaller hills we saw are mostly made of ice. And they're made of water ice and methane ice, which is of a smaller density. So they're lighter than the nitrogen ice they're sitting on. So you can actually think of these as small, it's kind of floating icy mountains that are floating on the ice below them, which is just crazy. It is. It's so bonkers. So is there any evidence to suggest that Pluto could harbor or support any form of life? It's really cold. And although the ingredients for life are there, there's a lot of light elements. There's water ice. There's carbon-based molecules. It's just too cold and too frigid to support any kind of life. And it's even difficult to think of a kind of life that we don't know right now that could survive there. But you're underneath the recent modeling of Pluto implies that there may be it may be warm enough beneath the surface for that water to exist in the liquid state. But we still don't understand whether or not it might be in a kind of a subsurface ocean or whether it's just water permeating through rocks underneath because we know there's rock involved in the composition of Pluto as well. So it's pretty uncertain at the moment, I'd say. And at this point, maybe I could throw up the usual astronomers' crime saying, we need another spacecraft to go out there. Thank you to Alan Fitzsimmons and we'll hear all about why Pluto was demoted in just a moment. So, Becky, how many dwarf planets are in the Kuiper Belt? We always have this discussion. And are they all quite similar? So technically, there are five dwarf planets in the Kuiper Belt. So you've got Pluto, Orcus, Hamaea, Kwaowa, Sean wanted to say, and Maki Maki, which I have pronounced make, make on this podcast before and Robert's gone. Maki Maki. Maki Maki. But in terms of you just how many objects are there in the Kuiper Belt in total? Like it's how long is a piece of string, right? Because it's like the asteroid belt. It's just rubble of all sizes, right? And just going down to the smallest specks of dust even. So the line between what is a dwarf planet and what is just lump of asteroid rock is also kind of grey, like the line between planet and dwarf planet as we'll hear in a minute. So the thing that sort of takes objects from being dwarf planets and from the five that we recognize to being just asteroid is something called hydrostatic equilibrium. Equilibrium, everything balanced, right? It's this idea that you've got strong enough gravity because your object is heavy enough so that you would round it. Yeah. So it's not going to be just some lumpy potato like you get with a lot of asteroids. It's going to look like a round thing. Yeah. Like we are used to picturing planets and moons and things like this. The problem is there's no definitive mass, like mass cut off, like some threshold you can define of like this many, you know, trillions of kilograms where all of a sudden there's this clear line that something becomes round and becomes a dwarf planet. So for example, there is an object called salatia that if it had a typical asteroid composition of the things that we would expect asteroids to be made of the same elements, molecules, things like that same rock, then it wouldn't be in hydrostatic equilibrium. Well, if it had a less than typical asteroid composition, maybe some heavier elements, things like that, then it would be in hydrostatic equilibrium and therefore it would be round and classed as a dwarf planet. So we're not entirely sure where salatia falls. So this is why I said technically there is five but like, No question mom. Good piece of it. Yeah. Exactly. Yeah. I mean, like, and when we look at salatia, we know it has a moon as well, right? So in that sense, you think of it being like, you know, like Pluto and Sharon and like a, like almost like a binary planet dwarf planet system, you know? So it's a really intriguing object, salatia. And I think, you know, if people can, I think they'll try and, you know, drill down on what it actually looks like. Is it round? Because obviously what we get is just sort of a fuzzy blob of light from it, given that it's so far away. And I think those are my favorite kind of objects. Yeah. You know, sometimes I think I've built those ones on that boundary. Yeah, yeah, yeah, yeah. And I wouldn't be surprised if we had more of those popping up very soon, thanks to the Vera Rubin Observatory. I know. Oh, gosh. So, to put it in a point of recording, we've had some of the first images and it just, I was reading a BBC article and it said, literally one of the first paragraphs, if there is a ninth planet, we will find out within the year. Yeah. And I was just like, oh, wow. Goodness me. Yeah. And to put into context why, right, that Rubin, in its like seven days of commissioning data, it doesn't work. It detected 2,000 new asteroids. In just seven days. None of those are anything to worry about, first of all. But that is more asteroid. Sorry, my god was like, that's so exciting. Not to fear. Yeah. No, no fear. But yeah, 2,000 new asteroids is more asteroids than have been discovered in the past 200 years. Oh my goodness me. Yeah. I mean, mostly those are in the asteroid belt because they're the easy targets that found very clearly. But you know, these little things, this is what I'm saying, like, you can get down to the little things. But if there are big things further away, they're going to be as detectable as well with Rubin because it has such a massive, what we call field of view. Yeah. You know, when you like, you point your phone camera and you can switch to like the wide lens versus, you know, the 0.5, the 1, the 3, right? This one is just like, you just keep going out with Rubin and it can look at this massive patch of sky at once. And it can move really fast as well. So it covers this huge area very quickly. And so seeing things move is like what Rubin is just going to be like excelling at. And it's not over exaggerating the fact that me and my colleagues have been waiting for this observatory to come online for, I mean, I've been waiting for 10 years. Yeah. For a lot longer as well. Right. We have been anticipating this for so long. And I, it's almost like when JDBOS tealonged as well, I kind of can't believe we're finally here. Yeah. And seeing that day to the other day and hearing that number of 2000 asteroids. I just, yeah. Yeah. I hit the roof. I hit the roof. My, my, the ship has sailed, but I'm like, should a PhD? This would be an exciting time to do a PhD. But anyway, we move, we'll move on. Let's talk about New Horizons. Like, do you have any favorite discoveries from New Horizons? Ooh, that one's a bit difficult because there were so many. I actually saw Pluto. I know the whole episode is about you, but it's, I don't think my favorite discovery was a Pluto discovery. There was a lot, but I think it was actually, did you remember the little snowman, Aracoff? Yes. It was called Odomotul and the name was changed. But if you remember, so after the flyby of Pluto that New Horizons did, I think it was 2015, that was, the trajectory of New Horizons was just shifted slightly. So that, you know, as it just continued to sail past Pluto, because, you know, it didn't break. And he just went, yep, and kept going into the cove belt. They changed it ever so slightly. So they were actually do a flyby of one of these trans-Neptunian objects, as we call them in the cove belt. In this case, Aracoff. And the closest approach, it was about 3,500 kilometers from its surface, and it was on the 1st of January, 2019. So if you remember on New Year's Day, we've got the images and pictures. The little snowman. And it was a snowman, and it was in winter because it revealed that it was essentially what we call this contact binary asteroid, where you've had two smaller asteroids come together. But instead of sort of colliding and breaking apart and just being very almost like messy in a collision, it was a very slow collision, so much that they just kind of like stuck together and became one thing. And they're probably slowly maybe going to become, you know, one sort of more rounded asteroid, who knows. Over time. Yeah, but all they might say is this weird snowman. It's the best way to describe it. If you're picturing, literally putting a head of a snowman onto the body of a snowman, that is what this thing looks like. And it was such an amazing surprise at the time. I remember people being like, what? You know, it wasn't like it was picked because we knew that it was a contact binary. It was just a complete surprise. And it was just one of the things that was, oh, that's going to be close to where New Horizons is currently heading. And we should shift it ever so slightly so that it comes close enough. So it's led to so much more science in terms of understanding how our solar system came together, how planets form, how asteroids form, how do all planets form as well to become these larger objects, these collisions between these bits of rubble don't have to necessarily be destructive or violent. They can be gentle leading to these snowmen. Wake up. I'm that thing you just remembered. Huh? The invoice payments I need to chase, but it's too A.N. You didn't catch up on cash flow, so cash flow is catching up with you. Zero helps you transform financial uncertainty into cash flow clarity. 81% of customers agree. Zero online invoice payments help them get paid on time. That's quite a lot. So search Zero with an X and supercharge your business with a free trial. Conditions apply. Now back to sleep. In 2006, the International Astronomical Union, a.k.a. the IAU, reclassified Pluto as a dwarf planet. And as we've already talked about, I don't think some of us have forgiven them yet. Read it. Anyway, Alan Fitzsimmons was part of that vote and explained to me why Pluto was reclassified. Well, it's really because of an oversight. An oversight on the behalf of astronomers because we'd never formally defined what a planet is. And you might say, well, it's like a cat, you know it when you see it. But that's not quite true, right? So historically, the planets were the planets out in the Saturn that have been identified by the ancient astronomers without telescopes. But since then, we'd had Uranus and Neptune and Pluto. And we've got other objects out there. And in particular, in 2005, another object was found even further out than Pluto called Eris. And Eris is almost exactly the same size as Pluto, literally within about 50 kilometers. It's actually slightly more massive. And we know that because it's got a small moon orbiting it. That's been seen from the Hubble Space Telescope, another ground-based telescopes. So if Pluto is a planet, it's Eris a planet. And what about the objects that are slightly smaller out there, like how may I which has rings around it and a couple of moons? And it's kind of this weird rugby ball shape and mucky mucky and all kinds of objects. How many planets do you want in the solar system? That's the question. But it really was the discovery of Eris in 2005 that convinced the astronomical community through the International Astronomical Union that, yeah, we're going to have to decide what's a planet and what isn't a planet. If something isn't a planet, what is it? Okay, so let's go through that. What is the criteria for being a planet and how does Pluto fall short? Right. Okay. So after a lot of discussion and debates, there's three criteria you need to call something a planet in our solar system. First of all, it's got a little bit of sun. And that's important because Jupiter's moon, Ganymede, is larger than the planet Mercury, but it doesn't orbit the sun. It's not orbit Jupiter. So by definition, Ganymede is a moon of Jupiter and not a planet. Okay. So the first one. Got that. Yep. The second thing is that, well, technically it's got to have enough mass to obtain hydrostatic equilibrium. And basically what you're saying is that it's got to be big enough that its own self-gravity can overcome all the internal forces to mould it into a sphere. Why planets, when we think of planets, are balls and not just irregular objects like the much smaller asteroids and comets that orbit our sun. So it's got to have enough gravity that it will mould it into a ball, basically, or pretty close to a ball. And Pluto matches those first two criteria. But the third criteria, and this is the one that's kind of remained most, well, there's been a lot of discussion about it over the years, is the third criteria is that it has cleared its orbit of other things, which means that about that distance from the sun or around that distance from the sun. That object's gravity is big enough that there's no other stable orbits at about that distance. And that's where Pluto falls down because we have a huge number now, hundreds of other objects that aren't only in the same distance as Pluto from the sun. They're in the same three to two resonance with the planet Neptune. We call them Plutinos, colloquially, because they're kind of nice. They're smaller versions of Pluto. But there's a lot of them out there. Pluto's mass isn't big enough to actually disturb their orbits enough so that they disappear. And so you can't have a stable orbit around that distance if you're going to be a planet. And that's where Pluto falls down. I see. Okay. Although I do think Neptune and the Plutinos could be an excellent band name, but I'll be fine. So I think the thing here, and I think this is a question that we get quite a lot though, is like, why is it that a dwarf planet though can still have moons? That doesn't make it what we classify as a planet. So can you just cover that if you can? Okay, sure. Well, what's important is actually the orbit about the sun. Now, to be honest, if you're big enough and you're bringing something small close enough, almost anything could be a moon or sort of be a planet in that definition. No, I mean, okay, I don't think I could be a planet. I don't need quite that much. But for example, let's go to the Earth. Now the Earth we call a planet, and it is surrounded by objects called near Earth asteroids. But those orbits aren't stable. They only last in their orbits somewhere between an average 10 to 20 million years, and either they hit the Earth very rarely, or they hit the sun more frequently, or they'll be ejected to another part of the solar system. But if we look at those tens of thousands of near Earth asteroids, about 15% of them have little moons next to them. Something as small as a kilometer across or so can have its own even smaller moon. So having a moon certainly can't mean that you are called a planet. Yeah. And so you were at that vote when Pluto was reclassified. So what was that like? Well, it's pretty interesting. It came at the end of this two week long meeting in Prague in 2006. It's a general assembly of the International Astronomical Union, and there were a few thousand people there, although only a few hundred took part in the vote because it was held on the last day of the meeting in the end, and all people were kind of leaving at that stage, I think. But it was kind of interesting because there had already been one idea of what the definition of a planet should be in the first week, and really, very few people actually liked it. So it kind of threw that out. And then we came up with this second one. In fact, there was a couple of Eurogrind astronomers who proposed this previously. They said, this might be a good definition of a planet. And the more we thought about it, we thought, yeah, okay, that this kind of works. And what worked about it was that, you know, it would mean that Pluto wasn't officially a planet anymore, but the meeting as a whole came up with this new category of objects called dwarf planets. Everybody felt that kind of, that's a pretty good compromise. The important point is this. As you discover more things in science, you've got to reassess what you call stuff, how we categorize stuff, and how you understand what's going on out there. And there will be these revisions. And when you do that, then sometimes things like Pluto will be put into a different box from what it was there before. But it doesn't change anything about Pluto itself. It's a fascinating world. Absolutely. And, I mean, the science, it adds up, it makes sense, but still people feel that connection and like justice for Pluto. So why do you think the public is still so emotionally attached to Pluto as that, you know, ninth planet? Well, I think it's a function of time. Because everybody, or most people now, including myself, grew up knowing there were nine planets. And if you were a science geek like me and Paul, Paul and you are as well, you learned the order of the planets at school going out. My very easy method just feeds up naming and then nothing. Yeah, that's it. That's it. So so I think people grew up with nine planets and suddenly in the news, they read that. Oh, no, scientists have decided there's a plan. Yeah, because what gives them the right to do that is the idea. But you know, it's because they don't realize that there are many other objects out there. And there are these other dwarf planets. We now have five planets in the solar system. And so when people ask me why that we have nine planets in the solar system anymore, well, I said, well, the choice isn't nine. We've got eight. Or do you want 13? Yeah, and it's probably going to be 20 or 30 when as new discoveries roll in and we categorize more dwarf planets out there. How many planets do you want? Thank you to Alan Fitzsimmons, Professor of Astronomy at Queen's University of Belfast. This is the Supermassive Podcast from the Royal Astronomical Society with me, astrophysicist Dr Becky Smithhurst and science journalist Izzy Clark. It's me. So before we get on to our Pluto questions, as we're one of the world's most popular astronomy podcasts, I don't mind tweeting our own horn on that front. I think I think this is a real tone shift. We can't really not mention the significant proposed cuts in the NASA science budget. Robert, Becky, let's have both of your thoughts on this. Robert, these come from the White House. What would they mean if they were approved by Congress? Well, I mean, they just look really big and really awful. I mean, it's not just NASA. It's cuts to a lot of science programs in the US across the board. And many of us here, you know, in other countries in the UK in particular, we're just honestly shocked by what's being suggested. It's been described as an extinction level event for some aspects of US science. So to give you some numbers, NASA as a whole, the proposal is a 20% cut. But for the science program, that's a 47% cut. And if you look at the individual proposals, astrophysics cut by two thirds, you know, heliophysics, so physics the sun cut by 50% planetary science down by a third. The Mars sample return mission, you know, we've got the perseverance rover that's been dutifully basically putting samples in canisters to return them to Earth. So cancelling that whole thing seems crazy.哎哎哎哎哎哎哎哎哎哎哎哎哎哎 It's a lot. It is a kick. It is a huge kick. Yeah, it's kicking the teeth. There have been rumours for a long time. Now we've had like a proper huge 400-odd page document detailing every single thing that's going to be cut, not just for NASA, but also for the National Science Foundation in the US as well. And like, I think a lot of us will read that say the Nancy Grace Roman Space Telescope would go the same way. So I know we talk about JWST as being the follow-up to Hubble. But actually, it's the Roman Telescope that's the follow-up to Hubble. The JWST is infrared. Yes. It's not quite the same as Hubble. Hubble is going to die at some point. The Nancy Grace Roman Telescope is pretty much built. It's going through a load of testing and everything. And we all thought with this budget that it would just get completely cut. It hasn't been cut, thankfully, but again, it's been told that like, I think the budget cut is huge on it in terms of like, I think it's sort of like in the 80, 90% number. I can't remember the number itself, top of my head. We can look it up, but like it's huge. And basically, it's just kind of like, figure out how to do this on a two-string budget now. And you know, this whole episode is about Pluto. It's been 10 years. In July, it'll be 10 years since New Horizons first took proper images of Pluto and transformed what we thought Pluto was and what it looked like. Now New Horizons is one of the missions that the White House wants to cut as well. Yes. It's painfully extensive. Yeah. Well, I think the thing about New Horizons that gets me and then also, do you remember a Cyrus Rex that went to the asteroid and collected it? I mean, we literally talked about it in one of our recent episodes. Yeah. Yeah. So that had also, in the same way to New Horizons, it was like, well, it's still out there. It's still flying through space. We just give it a little nudge and it'll visit, you know, somewhere else. And that was the plan for New Horizons. It was the plan for a Cyrus. And they've renamed it Apex. Because it's going to Apophis, which is the asteroid that'll come really close to Earth in 2029, I think it is. So those missions were like, they were on their way. And now NASA have gone, no, funding completely cut. So like you were saying, like these missions are in space. So what does that mean to cut the funding? Well, it means there'll be no funding for the deep space network to collect, you know, the signals back from those missions that they will send back to Earth. There'll be no funding for people to then, you know, grab that data and analyze it and put it out to the world and make it available for the scientists. So basically those missions are just going to fly past those objects and we'll just not know what they found, which is insane. It's just, it is sad. I'm sat here just like sort of rubbing my forehead in disbelief because, OK, yes, it's all of this science that could be and is technically actually happening right now that we would just leave by the wayside. It's also the legacy of space exploration, you know, if God are to go. I mean, that is such an iconic part of spaceflight history. And then it's also the people, the collaborative effort, the possibilities of discovery and that collective effort, that international collective effort that again is, it's just really sad. I think that's what I like to say. It's just, it's so frustrating. It's remarkable. It's the US, you know, seeming happy to give up its decades of leadership in this area, you know, and it does have big ramifications for us too, because the European Space Agency has relied on a collaboration with NASA for so many of its projects over the years. And we have to, you know, the UK specifically. So there's things like the gravitational wave observatory, LISA, the Another Venus Mission and Vision, new Athena X-ray to observatory. These are things that really depend on US input. And without that, it's going to be a real challenge. And, you know, I guess if it happens, then what many of us are just hoping and it will be difficult is that Europe, including the UK, and it works on building its own capacity that we have our own kind of space sovereignty. But it is, it would be still for all that be really gut wrenching if the US is no longer a reliable partner. And I, I just really hope that the Congress sees sense and throws out the package and says, no, you're not doing this, you know, nobody, you know, we're in the real world. We know there are cuts, they're fairly often to budget, so they get trimmed. And sometimes if you're lucky, they grow, but, you know, quite a lot of the time they're trimmed. But to do it on this scale, it's just crazy. And it'll be really, really damaging. So I just hope it doesn't happen. So do we know what the proposed timeline is? I think it plays out over the year. So as I understand it, you know, this all goes through the Congress, presumably over a period of months. And then there is a slight risk that if they haven't made a decision by the end of the year, the president, the administration can act to a certain extent on their own under some obscure legislation or a obscure process that was last used in the early 1970s about them being able to determine the budget now. But I hope that we don't get to that. I hope that Congress just says, no, you're not doing this. You know, it's much too important to just decimate these amazing things that we we've got to have these things that if nothing else, offer us some hope in the world, if they, you know, all those amazing wider impacts of science, the inspiration that comes from space and astronomy, let's just not let's not destroy that. Yeah. I think it's time to cheer things up with some questions from our listeners. We should say again, this isn't approved by Congress yet. It still has to go through Congress. There is opposition on both sides of the political spectrum in the US. So this isn't a guarantee yet. And you can also make your voice heard as well with petitions and writing to your members of Congress and picking up the phone and speaking to them if you're in the US as well. And you don't want to see this happen. Yeah, absolutely. OK, Robert, let's start things with this question from Lewis Donaldson on Instagram. He asks, with photos, odd orbit, is there risk of collisions with Neptune or influence from its gravity? Yeah. So if you look down on the solar system from the north, so imagine you're high above the north pole of the earth and the north pole of the sun and so on, then the orbits of Neptune and Pluto do indeed appear to cross. And from 1979 to 1999, Pluto was actually closer to the sun than the outermost ice giant, so it was a bit closer in. But this is a 2D map, right? So because the orbits of the two worlds are actually at very different inclinations, they're tilted compared with each other. And that means they never really come close at all. So Pluto is simply never that close to Neptune. And the planet Neptune and the dwarf planet Pluto are actually also in a two to three resonance where Pluto completes three orbits for every two, two orbits, rather, for every three that Neptune does. And that interaction as well stops them from ever getting closer than a couple of billion kilometers. Now, that's a very big decision to give you an idea. The earth is 150 million kilometers in the sun. So, you know, you think they're close together, they're really, really not. And the outer solar system is on a big scale. So there is basically no prospect because of that resonance and because the tilt's the orbit that they will ever come close. OK, thanks, Robert. And Becky, Brian Ross has posted in the Supermassive Club and he was the first one to do so. So perhaps on the back to him. Yeah, exactly. And he says, if Pluto were a second moon of the earth, what would be the most interesting difference considering its chemical makeup? Would it still retain its atmosphere or would it be way too warm? And what would its furthest stable orbit be? Thanks, Yal. And he says that you have to do it in America, and I hope that was up to standard. It doesn't work in a northern accent. You're like, thanks, Yal. It doesn't work the same. It doesn't work the same. Anyway, yeah, great question, Brian. I think a fun fact that always blows people's minds if they haven't really come across this before is that our moon is actually six times heavier than Pluto and twice the diameter of it. So in terms of if you were going to move Pluto to where the moon is, it does on sky view, it would look a lot smaller than the moon does now in the sky if it was at the same distance. Now, in the rest of my answer to this question, I am going to assume that Pluto is a captured moon rather than forming in situ around the earth. I'm a record scientist. I state my assumptions up front. Yes, we will allow that. Carry on. That would mean that Pluto would keep its current composition because obviously things that form on the outskirts of the solar system versus on the inskirts of the solar system, on the inside of the solar system. It's not even a word on the inskirt. Towards the inside of the solar system have very different compositions for the fact that you just have like, you know, the different materials, you know, separating out because of the solar wind, throwing things, lighter things out to the far reaches and keeping heavier things further in, etc, etc. But assuming it was captured rather than having formed there around earth, that would mean Pluto would keep its current composition, meaning I can now say that it would look a different color to the moon as well. If you were going to put it in the moon's orbit, right? It would look that sort of yellowish kind of color that we associate with Pluto from the New Horizons images, you know? Now, given that it would be much closer to the sun than where it was now, it most likely would lose its atmosphere, Brian. So yeah, it doesn't have a magnetic field, right? That's the thing that protects like earth, for example, from all the high energy radiation from the sun. It basically diverts all of that radiation, most of the radiation anyway, so that we, our atmosphere at least isn't affected. What that would mean is that essentially all that high energy and radiation would hit into Pluto's atmosphere and it would give the molecules of the atmosphere energy and then they would escape the pull of Pluto's gravity, right? We've seen this with Mars already. Mars doesn't have a magnetic field. It has a very, very thin atmosphere. Now, we think it may have had a thicker atmosphere in the past, given all of the geological history on Mars. And if you think about it like Mars is 46 times heavier than Pluto, right? So if it happened on Mars, it's gonna happen on Pluto. That's also closer to the sun than Mars would be if it was, you know, in the moon's orbit. In terms of like what could Pluto's like stable orbit be around the earth and how far away it could be? It's actually not really got anything to do with Pluto, which is always a weird thing when you realize that it only makes sense when you look at the maths and you realize it cancels out on both sides like Pluto's mass. But it's all to do with like the earth's sun system really, because basically what you're asking by saying what's the furthest out stable orbit it could have is basically when does the sun's gravity start to have more of an effect than the earth's gravity? And so essentially that's the same whatever kind of massive thing you've got. And it's around about 1.5 million kilometers away from earth. So just over four times the moon distance. Amazing. Thanks Becky. And Robert Polish nerd asks, Kuiper belt objects could be dragged into the inner solar system. Could that happen to Pluto? Yeah, this is talking really about something that happened early in the life of the solar system. So the prevailing idea is that Neptune in particular and Uranus a bit really helped shape the Kuiper belt because it moved outwards early in the solar system as a result of the gravitational influence of Jupiter and Saturn. You know, the Kuiper belt is the bit that's got Pluto, but also all these other bodies, these leftover small icy bodies that are sort of basically de facto comets. If they do get nudged in towards the sun, then some of them become comets because they heat up and all the ice is become gas and so on. But anyway, in that time, Neptune was moving through that region where all these icy chunks were or planetesimals. A lot of those were then sent in towards the sun. This is all billions of years ago, but that process is essentially over now. And Pluto and those other objects are mostly pretty stable. So it is possible that something, well, you know, you can speculate about some hidden planet nine out there or something that's disrupting things, but there's still really rather tentative evidence for that. But it's possible that some passing star could nudge them. That, you know, every so often, every tens, hundreds of thousands of years, stars come a bit closer to the sun, not drastically close, but a bit closer. Maybe that would nudge it. But I think it's one thing to do that with the Oort cloud, which is a lot further out. That's the region where long period comets are, where the ones that take thousands of years to go around the sun. Those things are, you know, it's a light year away from the sun, much closer in. It's going to be a lot rarer that a star comes that close. So I don't think it's very likely for a very long time. So the cook about, yeah, it's essentially stable and Pluto is is quite safe for now. OK, good. Becky, we've had this question on Instagram, which says, how are the glaciers composed mostly of nitrogen ice? Is that the low pressure? Oh, what's it's more to do with the extreme cold than the pressure necessarily. So Pluto is around about a toasty 40 Kelvin, so it's about minus 233 degrees Celsius. Might need a jumper, just mine. Mine may be. Minus 387 Fahrenheit, if you must. These temperatures nitrogen behaves essentially like water does on earth. So I mean, Pluto's atmosphere is mostly nitrogen. First of all, it's like 90 percent nitrogen. The other 10 percent or so is methane, you know, some trace of the things. But it's so cold that what happens is that the nitrogen in the atmosphere can condense on the surface of Pluto. It freezes out of the atmosphere, essentially. Now, it is the low pressure in the atmosphere that allows that process to then be cyclical. So it can go from solid and then back to a gas again as things change on the planet. So that's how you end up with sort of I hesitate to use the word seasonal, because obviously here on earth, the buildup of a glacier is seasonal. It melts a little bit in the summer. And then as long as you get more snow in the winter, it will it will continue, it will eventually form the glacier. Right. So I hesitate to use the word seasonal, but let's think of it as a cyclical nature. And then once you have your nitrogen ice on the surface, nitrogen ice is a lot softer than water ice. So it flows actually a lot more easily than water ice does. And I know it's weird to think of water ice flowing, but it's literally just like the pressure of the fact that you've got so much ice there, just like crushing down, right, is what causes glaciers to flow. But that means that on Pluto, you can very easily get a glass of solid nitrogen ice that forms. So, yeah, that stands as that question. And I'm sure we've triggered so many Americans by calling them glaciers all the way through rather than glaciers. Let me hold it. What are they talking about? I can't attempt to do any more American accidents. I'm going to insult so many people. I'm so sorry. So thank you to everyone who did send in their questions. It's we just love reading them all and keep sending them in for a future episode. You can email podcast at rs.ac.uk, send them on Instagram at supermassivepod or put them on the forum in the supermassive club. I honestly, I love reading those questions. It's been fun, hasn't it? Yeah. We do read them. We are there. We're lurking. I'm lurking. You'll see me respond to the occasional ones. I'm in there. Anyway, so, Robert, shall we finish with some stargazing? What can we see in the night sky this month? Well, I mean, we're still in the summer in the Northern Hemisphere. And if you're as far north as we are in the UK, it still doesn't get properly dark at the start of July, but that starts to change at the end of the month. So, you know, you start to enjoy longer evenings again. Assuming that's what you like rather longer days. I'm personally happy with both. But but it is also the time when the kind of classical constellations of summer start to be visible, a more convenient point in the evening, at least. So you've got the summer triangle, which is just not a constellation, but made up of three bright stars, Denne, Vega and Alto. And there's very, very standout. It's a really good signpost for that region of the sky. They are respectively in the constellations of Cygnus, Lyra and Aquila. So the Swan, the lyre, which is a kind of harp and the Aquila, the eagle. And the milk, the nice thing about those is the Milky Way runs down through Cygnus and Aquila. So you see those bright stars and if you haven't got a moon in the sky and you're somewhere dark and, you know, always say this, if you're on holiday or somewhere, then it's a good place to look for them. You're looking at the inside plane of the galaxy, the inside view of the galaxy. So you've got a rich Milky Way running across the sky, full of clouds of dust and bright nebulae and star clusters. And really just amazing visitors. So if you have a pair of binoculars, pick them up, look at it. There's also one binary cell, one double star, rather, you can see called albirio, that's in Cygnus. Just look that up. That's a lovely blue and yellow combination. And it's even better, though, if you're further south, if you're down in the Mediterranean, because all of that is a bit higher up and you get Sagittarius and Scorpius lower down, higher in the sky. That's very much the richest part of the Milky Way. Absolutely stunning. Now, for planets, we're still slightly in a bit of a famine season. Yeah. Yeah, Mars is just about in the evening sky in Leo, but now really, really small and getting very hard to spot. So if you look at the telescope, you see a tiny, tiny disc, you won't see any detail. Venus is nice in the morning sky, but that doesn't mean getting up at dawn, which at this time of year is rather early, you know, half three in the morning or something like that over in the east. Got to give us phase getting smaller as it goes away from the earth, but more of it is being lit up as it changes its orientation. Don't expect to deep see much detail of that. Some very skilled observers see little hints of cloud markings. And then Jupiter is emerging as well. That'll be lower down, but, you know, it's so bright that it's obvious. And there are also two meteor showers that might add a few shooting stars each night. I'm not going to overstate it, but it's my add a little bit of background. The Alpha Capricorn, it's they reach a peak at the end of the month on 30th and the Southern Delta Aquarium, which are best viewed from the Southern Hemisphere, they peak on the same night. And so you might see a few more meteors in the background as a result. Around that time, there'll be some moonlight. So, you know, don't expect anything too dramatic. It's just that nice thing to add to it. If you're up really late or conversely up really early, you might see them. And finally, look, we're still at solar maximum. So do you keep an eye out for possible displays? The Northern Lights, the Aurora, because I saw one a few weeks ago, even the time we're recording this, you know, back in June, I saw there was one near where I live in Sussex and that's unusual for them to be that far south. I didn't see that one. You know, I can't keep all of these things. I just get the alerts on my phone and I have to make a decision. It's three in the morning, whether to get up. But, you know, do have a look. And also, if you're up late in the evening sky, do look live these beautiful Noctilucent clouds, these displays that are good this time of year. 80 colloquement is up and they're completely ethereal and they're quite unlike where the lower down. And I know I plug those things all the time. I love that. They aren't great. No, always, always, because I love them and we get so many nice pictures sent to us and I just think there's something they are. They're so ethereal and they they're just beautiful to see. And also, can we I would love to shout a couple of people from the Supermassive Club, because we've had some amazing photos in the Stargazing Forum. So we've had one sent in from Michael Stone of M81 and M82, these galaxies. And it was taken in his back, well, he says backyard with about 10 hours of data in this photo and you can see the spirals of these galaxies. They're amazing. And there's one that's just like really zoomed in as well. And I just thank you so much for those and also to Phil Banting as well for sharing his photo and Brian Ross as well. And there's one from Pirate Numbers. And it's a picture of the ISS transiting the sun. And so it's just like these little the little dots of the ISS just going across. It's amazing. Brilliant. So yeah, they're so great. There are these wonderful prediction sites that tell you when that's going to happen. And it's only over a very narrow strip of the Earth's surface. I guess people are just driving to those to find them. It's it's quite incredible. So yeah, hopefully with their permission, I'll be able to share them on Instagram. I'm lucky you need to do this, is he too? Surely there's a case for a podcast adventure. That's it for this month. And we'll be back next time with a very special episode recorded from the UK Space Conference with some actual astronauts. There's going to be another astronaut special. I'm so excited. Make more astronaut friends. And I'm so jealous because I can't go. I know. I'll just hold a couple cut out of you next. It's like Becky is here. She won't say much because she is made from cardboard. But anyway, yeah, and pick me up to all your new astronaut friends. Yeah, absolutely. And there will be another bonus episode on its way. And also to say on the 10th of July, we will also be at the National Astronomy Meeting. It's going to be a live Q&A. So if you're in the Durham area that evening on the 10th of July and would like to come down, then please do. We'll see you there. And it's not just the podcast that's going to be hitting the Durham area as well because of the National Astronomy Meeting. There's always a public astronomy talk that goes with it as well. So check out the talk from Professor Isabel Hook on supernovae, advanced telescopes in the search for dark energy as well. That's on Monday, the 7th of July. Contact us if you try some astronomy at home. It's at SupermassivePod on Instagram or you can email your questions to podcast.ras.ac.uk and we'll try and cover them in a future episode. Until next time, everybody, though, happy stargazing. Psst. Wake up. I'm that thing you just remembered. Huh? The invoice payments I need to chase, but it's 2 AM. You didn't catch up on cash flow, so cash flow is catching up with you. Zero helps you transform financial uncertainty into cash flow clarity. 81% of customers agree. Zero online invoice payments help them get paid on time. Hmm, that's quite a lot. So search Zero with an X and supercharge your business with a free trial. Conditions apply. Now back to sleep. When life gets hectic, energy ups and downs are all you need. If you're seeking energy reassurance, Eonnext can help. From smart tech that helps you take control of your energy future to always staying below the price cap with NexPledge. We're here for whatev' is next. 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