The Supermassive Podcast - 49: The End of the World

Episode Date: January 30, 2024

The Supermassive Podcast is back for 2024 and putting the "happy" in Happy New Year! What could be a cheerier start to the year than an episode about the End of the World… Astronomically speaking!? From supernova explosions, to super volcanoes, Izzie Clarke, Dr Becky Smethurst and Dr Robert Massey are running through the checklist of big bad things that put our planet at risk. Special thanks goes to Professor Chris Impey from the University of Arizona and author of How It Ends, and Dr Mike Cassidy from the University of Birmingham. Things we promised we'd put in the show notes:  NASA worksheet - https://spacemath.gsfc.nasa.gov/earth/10Page5.pdf Recent Betelgeuse paper - Saio et al. (2023; Betelgeuse in carbon fusion stage) - https://arxiv.org/pdf/2306.00287.pdf  Don't forget to leave us a review, send in your questions ,or share your astrophotography using [e-mail] or find us on Instagram @SupermassivePod.  The Supermassive Podcast is a Boffin Media production for The Royal Astronomical Society. The producers are Izzie Clarke and Richard Hollingham. 

Is that how you spell existential? It is. I was like, existential? Exist-ential. Anyway. Spirits might get hit by a big rock. That's another thing to keep you up at night. The universe is all about reduce, reuse, recycle, right?

Is the end of the world worth panicking about? Hello and welcome to the Supermassive podcast from the Royal Astronomical Society with me, science journalist Izzy Clark and astrophysicist Dr Becky Smithers. We're back for 2024 and putting the happy in Happy New Year because what could be a cheerier start to the year than an episode about the end of the world, at least astronomically speaking, anyway? It's been on our radar for so long and this is the month to do it, apparently. January. So from supernova explosions to super volcanoes, we're running through the checklist of the big bad things that put our planet at risk.

And could mean the end of everything as we know it i mean just perfect really you know like who doesn't want an existential crisis in january and as always robert massey the deputy director of the royal astronomical society is here too So this episode is looking at the natural workings of the world, not us pesky humans. But I think this question from listener Sarah M.H. sums it up perfectly. Robert, is the end of the world worth panicking about? Oh, no, not for me. Not for most days. I think not for most people. And you know, you shouldn't lose sleep over all these existential threats immediately you know we're not talking about this but honestly i worry a lot more about what humanity does to itself than than threats from space most days and you know global conflicts global heating all those things very very immediate threats but that's

not to say we should ignore the risks of things from space and and actually the ras in the part of work we've done has looked at that too. Things like whether a space weather event could knock out power grids and satellites and all that sort of stuff is a very real risk. It's not something, again, you should just sleep about, but we just do need to think about it. You know, if a transformer burns out, it's a power transformer,

it's really expensive to replace. So those sort of things we should think about. And it's really important too to understand where that population of near-Earth objects for that, you know, that infamous asteroid impact to where they actually are. So, but, you know, most of the time

I get a pretty good night's sleep without worrying too much about these things. Yeah, me too. I don't really sleep over this stuff. So cheers, Robert. We'll catch up with you later in the show for some more questions and some stargazing. So if something from space

could end our little blue-green planet, what could that be? I spoke with Chris Impey, Professor of Astronomy at the University of Arizona and author of How It Ends. I mean, the one that people have been reading about and think about is the fact that the Earth might get hit by a big rock, asteroid, comet, meteor. And if it's big enough, it is the end of the world. So that's the one that people worry about a little because it's a random thing. You can't predict when this is going to happen. All you can say is on average how long it's going to take

for the big things to come our way. And so how big would an asteroid have to be for it to be an existential threat? Yeah, sort of half a kilometer, kilometer, something like that. The things are traveling at tens of thousands of miles an hour. So the kinetic energy is phenomenal. It depends on where it hits. A big thing hitting the ocean will send, this is scary to think about, sort of 100 meter tidal waves circling the planet.

And since most of the population lives in coastal areas, that's probably the way you're going to go. If it hits the land, it depends a bit on where it hits, it's going to obliterate the poor country it lands on. But it's also going to throw up so much dirt and dust and toxic stuff into the sky that it'll dim the sunlight. And then the downstream thing that's, apart from the initial impact and the blast wave and so on, if you survive that because you're on the other side of the world or something, the darkening effect on the sun will sort of break the food chain apart. So all the photosynthetic life forms will die, the microbial food chain, and at some point will run out of food sources. What is the likelihood of any of this

happening? So statistically, it's inevitable. And there's basically a power law or a logarithmic distribution of the size of things that are floating around in space. So there are many more small bits of rock than there are big bits of rock. Well, that's good news. It means the small things land all the time and the big things very rarely. And you can put numbers on it. So, you know, there's interstellar dust that's raining down on the Earth, like 500 tons a year. And that's pretty innocuous because it's just dust. When you get up to something about 100 meters in size, then you're talking regional damage. So Tunguska 100 years ago happened in Siberia. There were hardly anyone lived there. It's possible nobody even died, but it flattened, you know, 1000 square kilometers of forest and shockwaves were felt

far, far away. So that's at the level of one a century or one every few centuries. And then if you step up to a kilometer, you're talking about million year timescales. So quite a long time. And then 10 kilometers is the, is where all, that's all she wrote. I mean, that's the one where there's no doubt about it. That's, that's a sort of lifeying event. And those only happen every 50 to 100 million years. So very, very rare. Is it possible that an asteroid could ever be so big that it does obviously destroy life, but in itself, it actually destroys an entire planet? planet? No, I think they're never going to be planet destroying because asteroids are, they're much smaller than the moon and they're much, much smaller than the earth. So the earth as a planet is sturdy enough that it wouldn't get broken apart. Now, you know, you go back way into

history and there was apparently the early earth, the sort of baby earth collided with a Mars sized object and that's what led to the Moon. So that was almost an Earth-destroying event very soon after formation. But there are no big things out there to hit us at this point. Yeah. And so how do we study this? How do we better understand what's out there and also trajectories of asteroids and actually if they are coming our way? Right. So that's the good news about this, even though it's a clear possible danger. You only need networks of one meter, fairly small telescopes to track this stuff. And NASA was tasked by the American government

to find everything bigger than 250 meters by a few years ago. And they've pretty much done that. So there are lists of the objects that could potentially hit us. There's a website that tracks them. And it also uses the data of their orbit to project a threat level. And it's on a thing called the Torino scale. And most of them are color-coded green, which means their odds of hitting us are infinitesimally small. Okay. And so basically, you know, people are looking at this. And when it's very far away, even the prediction of whether it might or might not hit us is uncertain because you get slight difference in trajectory and it would hit, miss us anyway. So almost always when something seems to be coming our way, when you hit it with the computers and calculate a better orbit or trajectory, you say, oh, well, it's missing.

Because space is big and the space junk is small. So on average, it's just not going to hit us. There's pretty good technology. It's not even a very advanced rocket science. To find an object that might be coming to hit us, you would, because you're seeing it so far off, you would have time. It's not like a movie scenario where the clock is counting down 24 hours, 10 hours, five hours. You're going to have months,

and maybe even years. Plenty of time to send a mission out to it when it's still a million or millions of miles away. So the clever thing to do is to hit it on the side and deflect it. And you don't have to blow it apart or do anything Dr. Strangelove about it. Amazing. Okay, so at least we've got solutions in that scenario.

What are some of the other astronomical risks? Well, other risks are associated with massive stars at the end of their lives. So supernovae, and then there's a very dramatic stellar cataclysm called a gamma ray burst, which is much rarer. Supernova is not an unusual event. Stars that are a few more times massive than the sun will die that way. And it's a violent explosion where a single star can brighten as much as a galaxy, sends out a lot of high energy radiation, neutrinos, all sorts of things. And we see supernova remnants in the sky. Hubble and others take pictures of beautiful things,

the Crab Nebula. That was a supernova that went off a millennium ago, and it leaves this beautiful glowing gas. Well, that's about 1,000 light years away. The problem comes if the supernova is less than, say, 10 or 20 light years away. And then that supernova and the blast wave and the radiation is probably going to toast the upper atmosphere. It'll destroy the ozone layer, and that will spike mutation rates on the Earth and damage any life that's on the surface of the Earth because our protective blanket will be taken away.

And the blast wave itself, if it's only 10 light years away, that could literally cause a big problem. And again, how do we study that? And what is the likelihood of that happening? So there's sort of good news and bad news. The good news is we know how stars work and we know how they die. So we can say what type of star, what massive star will die as a supernova. And so we can look in the neighborhood of the sun where most stars are little puny red dwarfs that are not going to die that way. They're pretty innocuous. Stars like the sun are not going to die that way. So they're innocuous. So you can look for the

fairly rare massive stars that will die that way in the solar neighborhood. And you can, you know, you can identify them. And so that's the good news. And they're not that many of them. And so statistically, they're just not going to be that close to us. However, there are a handful that are within 50 light years, say. There are none within 10, but there are some in the danger zone. And then the bad news is, even though we have good models and theories of how stars work and how they die, they're not super precise on the end of life. So we can't look at a star right now that we know is near the end of its life, maybe because it's starting to fuse heavier elements, which is the last crescendo of fusion before the supernova event, we just can't measure the time to death of a star with any precision. I mean, maybe we can at a precision of 10 or 10,000 or 100,000 years,

but that's not very helpful. But we have seen indirect evidence of the supernova impact on life on Earth where it's not so close that it's catastrophic. This is a little controversial, but what was when supernovae go off, they create radioactive heavy elements in the blast wave. And so there's this very interesting situation where there was a mini extinction of all the large land mammals that's well documented, especially in the Northern Hemisphere in North America and Canada about 2 million years ago. And if you go into the rock record, you find a spike in the concentration of supernova radioactive elements

dating to 2 million years ago. So there's this very interesting indirect evidence that a supernova, not super close, but maybe 100 light years away or 50 light years away. And then you mentioned gamma ray bursts as well so if this is a new term for anyone what is that exactly so a gamma ray burst is associated with a place a time when a very massive star implodes to form a black hole and the energy generated in that implosion event sends beams of radiation out of the polar axis because the black hole is spinning and the star was spinning that created it.

And this very intense gamma radiation comes out into beams or jets on the polar axes. And these are extraordinarily energetic events. They outshine individual galaxies, one event by a factor of 100 or 1,000, so incredibly. And the bad news there is if the beam is pointing to you. So there's bad news in this because if the gamma ray burst is now within 1,000 light years, so that's pretty far away, and the beam and the jet and the radiation is so damaging that that will truly torch the biosphere. That would be end of life on Earth if you happen to be in the way of that jet and the radiation is so damaging that that will truly torch the biosphere. That would be an end of life on Earth if you happen to be in the way of that jet and that beam. The good news is

the gamma ray bursts themselves are very rare events, and most orientations won't have the beam pointing at you. You'd have to be very unlucky that one of these rare stellar cataclysms happens within a thousand light years, and you happen to be sitting in the path of that jet that's quite focused. And so people work out what are the odds of it, and therefore how often does it happen? And that's in the similar category to the huge impacts on Earth. About once every hundred million years with a gamma ray burst might affect the Earth. I think it's worth noting that astronomers are generally very optimistic people, even though they know there's all this bad stuff out there. And the universe is going to end too. If you really want to lose sleep over something that you shouldn't, you could worry

about the accelerating universe and the ripping apart of space time billions of years from now. Oh, goody. Nice one. Thank you, I think, to Chris Impeyy and way back in November 2021 we have done an episode on the end of the universe if you would like some context to those potential sleepless nights okay so Becky let's bring this a little closer to home we've talked about solar flares before these sort of high energy burps from the sun how dangerous could they be yeah i mean this is something that people have been talking about a lot lately because we've got the peak of solar activity next year in sort of 2025 you know it's a 22 year cycle and so in the peaks we see a lot more of these burps of high energy particles in the sun which then impact our atmosphere now obviously that causes a lot of

beautiful northern and southern lights which i feel like is what everyone's actually talking about sort of online when it comes to the peak it's like yeah now's the time tiktok is like sending me things like now's the time to go on that like stargazing astronomy holiday you've been planning i'm like okay well maybe i will happily but obviously there also is this risk of a solar flare geomagnetic storm but whatever you want to call it which you know if they were a lot stronger would mean you know a lot of charged particles moving around our atmosphere beyond just producing the aurora now moving charged particles means you create a magnetic field if you remember sort of physics 101 from sort of high school and that can interact with all of our electrical systems and so there's quite a

big risk if you have a solar flare not a sort of like direct to life like a sort of an asteroid impact or a supernova or gamma ray burst like chris was talking about but sort of like indirectly because there's a risk to the electricity grid to satellite communications i like to say that like these big solar for i like to say that these like big solar storms these solar flares they spark fires and fry wires basically good great yeah so as robert was saying earlier like transformers burning out electricity grids just completely taken out essentially um so you're looking more at like a huge monetary impact right you know you need to

fix your entire electricity grid in every single country right you know the i think you then have to think about the knock-on effect that has on people's lives taking the electric out and how much that would cost to repair and how many people are going to be out of electricity for so long that we i mean we all rely on it right like yeah lives would be affected completely we'd have to change everything so if there's another solar storm like the carrington event that robert mentioned before which was you know from back in 1859 strongest ever recorded right you had aurora as far south as like hawaii and like people in australia were like oh look southern lights you know they got very far around uh sort of towards the equator um the monetary impact of that kind of level of storm today has been estimated to be up to three trillion dollars

in the u.s alone oh so yeah that's not worldwide that's just in the u.s okay wow uh you know because this is where that was the the estimate was done kind of thing. So it would be big. And I think it would be more of a societal impact than sort of a direct risk to life. But obviously those kind of impacts then do knock on. And, you know, you do then have a risk to life indirectly from it. Yeah.

Okay, that makes total sense. And is there any way that we can predict solar flares or better prepare for them in any way no they're kind of like earthquakes in that respect right they're very hard to predict there are some possible clues so you know like flashes from the sun's surface are sort of akin to like the ground rumbling a few days before an earthquake and people thinking, oh, is something going to happen here? But again, like that doesn't necessarily tell you

something is going to happen at all. You know, these sort of tremors that you get before earthquakes. So no predictions on when exactly they'd happen beyond like the fact that we know the sun is in a more active stage in its cycle right now but also you know they could happen at any time the good news is that we might get a tiny bit of warning because in a flare you get both radiation so high energy lights and then the charged particles so the light will be traveling at the speed of light it'll take eight minutes to get to us that's the time it takes to travel between the earth and the sun,

if you are light. And then after that, the charged particles will be behind that because they'll be traveling a little bit slower depending on how much energy was in the burst, but they won't be traveling at the speed of light. So you could have a few hours, you could have a day between, you know, the radiation and the charged particles. So because of that, you start hearing people talk about like having a resilient electrical grid, you know, making electrical grids like resilient against these kind of solar flares, you know, protections that you could put in place if you did have some warning. The problem is we can't test those without a solar flare. So we don't know if we do actually have a resilient grid or not.

It's just wait and see, I guess. We hope. I hope we have. Yeah. Okay. I wanted to come in for a sec, which is this has happened in 1989. There was an event in March 1989. So what, 25 years ago, nearly in Quebec.

25? 25 years ago. Yeah. No. They're more like 35. Yes. Sorry, better do that again. I was like, I'm not 25 and I was born after this.

Yeah, all right. It just feels like 25 years. Yeah, sure. Right, okay, starting that one again. I was just going to add that 35 years ago in March 1989, there was a blackout of this type in Quebec and global disruption to communications. So it has happened already. And yes, we recovered from it.

It took about nine hours to get electricity back up and running again. But there is a real effect. It does happen. And power operators already have to be very aware. So from what we've covered so far, which is getting hit by a big rock, supernova, gamma ray bursts and solar flares. Becky, what do you think is the riskiest? I love how cheerful you sound here, isn't it? It's fantastic.

Is it A? Who wants to be a millionaire? This is why disaster movies do so well, right? Because everyone's just like so momently curious about like, which one is it? Yeah. I think, to be fair, I think most likely or riskiest right there's two different questions right like i definitely wouldn't want to get hit by a gamma ray burst that sounds horrific i don't i'd prefer not to go that way thank you um but it's very very unlikely so not that risky um i'd say most likely is the asteroid scenario or perhaps even comet on a very like elongated orbit like in the film don't look up do you remember this like yeah yeah it's

far on the edge of the solar system which is why we hadn't found it yet and it starts coming in towards us and we get like six months warning you know it's all i could think about when i was talking to chris i was like well yeah um the good news is though in that scenario like we are putting the majority like all of our efforts is going into this like asteroid scenario because we know that it is a big risk as chris said that there's lots of telescopes that are just constantly searching the sky for things that move to find more asteroids but also we've had nasa's dart mission as well i'm sure we've done a podcast on in the past that if you remember it crashed into an asteroid essentially just this little cube of metal that just went pew yeah you

know and essentially the idea was to transfer energy to the asteroid to try and see if you could you know take i think it was take energy away from it because it crashed in the opposite direction and so if you take energy away from it you slow it down slightly which means it ends up missing earth in its orbit right it just instead of impacting it just yeah just close close pass basically just nudge it slightly um so i think it's just great that we're testing that you know that there are these plans in place that don't involve you know sending people who drill for a living onto an asteroid or trying to send a nuke like warhead down there or trying to mine it at the last minute like a dollocup um if anyone got all those references great yes that's really it's as much exciting um but i think yeah it's it's great that we're

testing it and also it's fairly cheap in the grand scheme of things to just send a little cube and smash it into an asteroid yeah i mean even having a rocket traveling alongside it right that would be enough to pull it or move it from its trajectory anyway so you mean sort of like with its nose out on the asteroid and just firing its boosters or no but even when i was speaking to chris he was saying even if you're just traveling if you had a rocket traveling alongside it the interaction from that is enough of the interaction of the gravity between that to also move it's like a what they call a gravity tractor so we have options so yeah this is where we don't lose sleep at night right because everything else

is so unlikely it's not worth worrying about and the asteroid stuff like we're on it guys you know we've gotcha okay so far we've explored the existential risks from space but we can't forget about some of the processes here on earth that could cause problems super volcano because me as a 10 year old is he right right now is so happy because i watched far too many of the Discovery Channel documentaries about Yellowstone and like the island of La Palma collapsing into the sea and causing this massive big tidal wave across the Atlantic. And I'm just I'm so happy that we've got someone on the podcast to like talk about this and answer all the questions that I was just like desperate to ask as a 10 year old. I mean, maybe we should have set you to do this interview. We would have been there for days.

I gave you this gift, it's fine. So how much of a threat could super volcanoes be? I spoke with Mike Cassidy, an associate professor at the University of Birmingham and research affiliate at what I think is probably the most interesting name ever, the Centre for the Study of Existential Risk. the Centre for the Study of Existential Risk. I mean, brilliant. So my first question to him was, what actually is a supervolcano? It's a term that was coined by the BBC, actually, by journalists and not necessarily scientists, but it's been adopted by scientists now, essentially. A supervolcano is a volcano that's had at least one super eruption.

So a super eruption is well-defined within our science, and that's an eruption that can emit a thousand cubic kilometers of material, kind of lava rock. So this is hard to visualize, but I'll have a go. So if you were to cover the whole of the US, United States in 10 centimetres of ash, that would be about 1000 cubic kilometres. So we're talking about a huge amount of material ejected. Oh my gosh, that's, that's a lot. Okay, right. So then you've mentioned super eruptions. So is that sort of does what it says on the tin a massive eruption of types is there a scale to that yeah there is a scale i mean i should say also that not every eruption from a super volcano is going to be a super eruption mostly for the famous volcanoes that you might have heard of before yellowstone etc usually a lot of the eruptions will be fairly small and that's partly

why i don't like the term super volcano or super eruption is because actually you can have global consequences without being in this top category. So I should explain the, I can explain the categories. We have really large eruptions and very small eruptions. And it goes from a scale, which is logarithmic from one to eight. And this is called the volcano explosivity index. So once you start getting above 6, you know, 6 is your cracker toes in 1883, very large. Then you get to 10 times more magma erupted, and that's magnitude 7. And then 10 times more again is your super eruption, magnitude 8.

And we saw that in Tambor in 1815, where we had an eruption in Indonesia halfway across the world. And in the following years in the UK, our agriculture decreased by something like 75%. So these have global consequences. Oh my gosh, break it down for me. So what are the risks from super eruptions? What could potentially happen? So it's not just super eruptions, actually, but even kind of potentially smaller magnitude eruptions can have huge impacts on our societies. So this could be through these large flows, what are called pyroclastic flows. These are kind of avalanches of dense, ash-rich, gas-rich blocks the size of cars that

run down slopes and into oceans at kind of hundreds of miles per hour sometimes. These can have huge impacts to destroy infrastructure and people and their livelihoods. And we can also have kind of the production of tsunamis, which can be obviously very widespread, as we know, through collapses of the volcanic system. But on a global stage as well, we have these gases that get emitted into the upper atmosphere, particularly sulfur dioxide. And it reacts with the water in the stratosphere, the upper atmosphere, to form sulfur particles, sulfuric acid essentially. And that acts as kind of tiny little mirrors that reflect solar radiation back into space. And that has an effect of cooling down the earth and reduces our rainfall and affects our climate systems. And is that quite localized or does that actually have a global impact? Yeah, so that has a global impact. Those

aerosols, they get circulated by upper atmosphere winds right across the world. They have a huge global impact and can decrease temperatures by up to sort of one to three degrees, we think. So if you think about global warming at the moment, it's increasing temperature of 0.3 degrees per decade. What we're talking about here is something like one or two degrees cooling, but within the stretch of sort of six months or so. Oh, wow. That's really quick. OK. And last in maybe five to 10 years. Oh, my gosh. OK. So a very long time. And so when we talk about like mass extinctions, have we seen that? You know,

what level of magnitude are we talking about for a mass extinction? Yeah, so mass extinctions, they're often associated with volcanic eruptions, but not necessarily these explosive eruptions that we see every 17,000 years or so, they're more associated with kind of a greater order of magnitude outpourings of lava, essentially, on continent scale. This includes the largest mass extinction that we know about, the end Permian mass extinction. And that occurred 250 million years ago. And that was caused by eruptions in Siberia that produced so much lava and so much carbon dioxide gas. And as we now know very well from global warming, this produced a really large global warming impact 250 million years ago. And this killed something like 96% of all marine life and 70% of terrestrial life.

So we're talking about something, you know, really catastrophic here. These are relatively infrequent every 30 million years or so. Okay. Are we at a point that should an eruption be on its way? Can we predict when that might happen? Well, it's tricky. Oh, good. It's not the answer you're wanting, I'm sorry. To be honest with you, we haven't identified all the volcanoes that are responsible, that we think are responsible for some of these really large eruptions that we've seen in the climate records, in the ice records,

for instance. And I should say, actually, that the risk of these global climatic risks are quite similar, quite equivalent in impact to some of the risks that we might be seeing from a planetary object like an asteroid. But they're hundreds of times higher for a given amount of impact. But despite this, there's no sort of global body for global volcanic threats. But we can monitor things like deformation of the volcano, so where the volcano swells before it erupts sometimes. We can measure that from space. And now we have our kind of satellite capability in this respect to measure temperature on Earth, where the ground might be heating up, to measure gases that are coming out.

That's increasing all the time. So that's great. Developing our seismic networks so we can try and measure the earthquakes before would be great but one problem also that we have is that we've never measured a large eruption with modern instrumentation and so if we are looking to how we prepare for eruptions or after eruptions what change would you like to see? How would you like to see that better monitored? Yes, I would like to see us trying to understand which volcanoes are producing these large magnitude eruptions in the past. I would like to see greater amount of

monitoring that's going on. And I'd like to see much more sort of global preparedness on that scale. Because I think we can mitigate a lot of these impacts that we've been talking about. But it does require this global cooperation, a global body potentially, that's in there. And that's able to kind of really respond when these things kick off. And this is something that we're planning to do is planning to launch a non-profit in this area called Volcano Aid. And that will aim to advocate and try to respond and plan for these kind of larger events so that we can drive policy in this area. So if there's an eruption in a certain area, and you know, we want countries to be nice to each other to not start banning their exports, but actually try to be collaborative

and try to have early action so we can mitigate a lot of the disastrous effects. Thank you to Mike Cassidy. Just all of my 10-year-old questions. Yeah, was that up to scratch? Yeah. Do we approve? Yes, I approve. 10-year-old me approves.

This is the Supermassive podcast from the royal astronomical society with me astrophysicist dr becky smethurst and science journalist izzy clark i think we've had quite a lot of people watching uh those disaster movies so let's get on to these questions robert can you come in on this too um david poto has emailed us a question about an era that's known as the late heavy bombardment so this is about 4.1 to 3.8 billion years ago and he says love the podcast in sci-fi they depict this era as asteroids hitting the earth continuously in reality how often did earth get hit? It's a great question, David, and you're absolutely right about the film depictions. It was never going to be anything quite that violent. For reference, the late heavy bombardment is this time when we think there was an end spike in the number of things impacting the planets and moons and so on.

The sort of rubble left over from the formation of the planets crashing into there. And it did last 300 million years. So you might get the impression from films that there's this constant rain of material coming down because it wouldn't be quite like that. So the best source I found for this, looking around, I found various papers, but one of the best sources I found was there was a NASA school worksheet with the simple point of this is how long it lasted, this is how many craters

of this size there are on Earth. And long it lasted this is how many craters of this size there are on earth and so if you take that number of craters and you look at the average over time you can see what the average interval between impacts was and it turns out that i mean it talks about small craters and describes them as 20 kilometers right which i don't think is very small in my book but nonetheless 20 000 small craters over 300 million years you're looking at 15 000 years of average in time between those impacts so it wouldn't be I don't think well the earth wasn't remotely habitable at that time but even if you're on the surface you wouldn't be seeing events like

that every day or anything like that I think when you'd be seeing smaller ones more often and then the larger impacts it would have been obviously a longer interval still so it's whether or not when we talk about a rapid pelting of the planets like that you don't imagine these sort of shotguns blasting away to the planets it's nothing like that it's it's a lot of impacts compared with today many many more compared with today and if we were living in that epoch we there would have every reason to worry about existential threats but it was still you know it wasn't happening all the time it was a relatively calm solar system okay i think you've just made a lot of science teachers very happy robert they're like where can i get this

yeah they need to get this just for simple maths yeah we should put it in the description or something yeah yeah definitely send it to me i'll put it in there um okay becky anna l on instagram asks if the world was destroyed would all elements redistribute back into the universe and then star planet formation restarts yeah definitely um the universe is all about reduce reuse recycle right it's the same as when the sun dies all the atoms that currently make up the planet and us are going to be distributed back across space and then you know you get this very slow collapse back down into the next generation you know star and planet system you know it's where we came from you know there was a star here before us that will have made all of the atoms that we're made of in that star's core before it died and went supernova and some

might say you know this podcast has been a bit morbid so far but i quite like thinking about where the atoms that make me up might end up one day, right? Like, could I end up powering a star like in a few billion years? Or could I be part of another super volcano on a new planet? I mean, what an aspiration. What an aspiration, exactly. Like, you could be, you could end up in some future life, you know, as well on a completely different planet that exists a billion years into the the future so the possibilities are just wonderful and i and i feel like that's what you should lie awake thinking about at night you know oh my gosh they need to redo the film don't look up and you should be the pr person for just covering the finder

well you just think about it okay um robert joseph elton wants to know are we all going to die when beetlejuice goes supernova i hear it soon so i think robert there needs to be some clarification on some rumors going around about beetlejuice please sure and then they're not new i mean this is a great example actually of reduce reuse reduced reuse cycle because we recycle elements and stars when stars go supernova. But it's really timely also, not just because the topic of the episode, because February is a really good time to see Beetlejuice. The star, by the way, not the Tim Burton film. But if you look in the night sky this time of year.

You can do both. You can do both. Absolutely, there's nothing to stop you looking at the sky and going and watching the film afterwards totally agree up in the night sky in february early evening orion's really prominent and beetlejuice in the northern hemisphere is the top left star in the southern hemisphere the bottom right star very easy to spot somewhat reddish tint and it's about 700 light years away it's at least 14 times as massive as the sun so pretty big star and and size-wise it's huge as well it's you know seven it varies in size but 700 to a thousand times as

big as the sun which for reference would easily be enough to swallow all the planets out to mars and probably beyond and it's about a hundred thousand times as luminous as the sun and that means it's one of those stars that is indeed going to explode one day as a supernova and then you know that will happen when the fuel runs out gravity collapses the core there's a shock wave a whole burst of neutrinos the whole star rips itself to bits and you might also remember and this is i think a lot of where the rumors have come from that about three or four years ago it dimmed down very dramatically and there was a real lot of interest people looking at saying it hasn't been this faint in a long time, maybe in more than a century. Is it about to explode?

And it's possible that that was a result of some material coming off of the star. It might also have been some big star spots on the surface that made it look temporarily a bit dimmer. But it didn't explode, quite obviously, at least not as far as we know. In our time frame, everyone was always like, it could have gone. And you're like, yes, we know. Indeed, know indeed indeed expecting follow-up yeah yeah you're right if it did though it would be really really bright for us on earth probably i was finding another paper on this amazing stuff it would be as bright as a first quarter moon so really really brilliant at night absolutely bright enough to cast shadows and they would be weird because they'd be pin sharp because the moon and the sun are not point sources so you get slightly fuzzy shadows but just

imagine that and it would be visible in daylight for up to a year so you'd go out during the day and if Orion was above the horizon there would be the star shining at you during the day something we haven't seen anything like that in more than 400 years because that's the time when a really bright supernova last happened in our galaxy at least that we were able to see but the other evidence on this is it might have anything up to a hundred thousand years before it actually does explode so when people say oh it might be tomorrow well maybe but that would probably mean our models of understanding the evolution of stars are wrong and the good news is it's far enough away that it almost certainly wouldn't cause us

any real harm on Earth. It would have to be about 20 times closer for that to be a risk, really quite close to the Earth within a few tens of light years. And then the problem would be that you'd get not just the very brilliant light and this blazing object in the sky,

but also some radiation coming off it as well. But far enough away, we don't really have to worry about it. So that is not a an imminent existential threat to the earth or even life on it well yeah we i will add to that so i think some of the excitement over beetlejuice came from a paper last year as well that came out where people looked at the pulsations of beetlejuice over the past like 50 60 years that we have observations a bit of and from that modeled, the interior.

And this paper, I can't remember who it was written by. Izzy will put it in the description of the podcast. But it was, they essentially said that from that model to give you those pulsations, the amount of carbon that you must have in Betelgeuse's core, which is like one of the late stages of Betelgeuse's life, suggests it's only got between 10 and 100 years left to live. Which I think is where a lot of the excitement came from but again like it that rests on so

many dominoes of our understanding of what goes on in the inside of stars that yes it's really exciting to think it could be in our lifetimes or in the next century but also it's still like well we're relying on a lot of these things so it still could be a few thousand hundred thousand years i think you can safely say we'll do an episode on it if it does oh 100 i'm like not leaving my garden if the yeah yeah exactly i'm not coming into wednesday we'll all record from our gardens just like so um okay so becky assuming the worst case scenario, RobWeb82 asks, do you think it's feasible that humans will ever be able to settle on another world? I think if it's a solar system world, like, I think then it's feasible. I think if we had to, and we were forced to make this very long list of all of the things that we had to problem solve to be able to live

on another planet say mars or perhaps one of like saturn's moons or something like that i think you know with enough money and enough minds and enough energy thrown at that big long list we could do it you know if there was the motivation that was going to force us to do it we could do it you know we just figure out how to house people and provide water and with life support we just work on it very long maybe if not for the whole of the earth's population maybe a fraction of it which is another problem um but i think if we're talking about outside the solar system like another like an exoplanet or something then i think under our current knowledge of physics and biology like we're it's completely infeasible like we just can't travel to another planet in a short enough span of time yeah you know outside of the solar system so i think you know we're a

lot further away from say passengers you know the film with like chris pratt and jennifer lawrence that scenario of like freezing people and sending them on a very long journey to another planet and we're a lot closer to like the red rising series of books you know by pierce brown where they have actually colonized the solar system if you will so yes and no rob basically right i mean it's interesting because i i made a document i mean this was ages ago but i made a documentary on on whether we could inhabit another planet and that is a real risk though the the the center of the existential risk look at is if you do have a space connolly somewhere who do you choose who goes and that in itself is just such a huge issue to overcome so and that is a story for

another time that is also not my problem to worry about that's another thing to keep you up at night you're welcome but if you want to send in any questions for a future episode, then please do so. You can email podcast at ras.ac.uk or find us on Instagram at supermassivepod. We do read them all. So thank you very much if you do send them in. So as usual, let's finish with some stargazing. What can we see in the night sky this month, Robert? And hopefully it's not a big old asteroid making its way to us.

Not that I know of, not that anybody's told me but you know no no i don't think so um so look february is a really nice month for looking at the sky because all the bright winter stars orion is still very very dominant and a bit earlier in the evening as well so you can go out you know you don't have to go out at midnight to see you can get that bit earlier and it's really lovely sight uh and i think last time i talked about all these wonderful star clusters you can pick up and you know know, in an audio podcast, you can't describe exactly where they are. But if you look in the constellations, respectively, of Orion, Gemini to the top left above it with Messier 35, Auriga above it with 36, 37, 38, and even the not very bright, but quite nicely sounding

constellation, Monoceros the Unicorn has a cluster in it. And there is also one under Sirius, which I think is a Messier 41, which is a nice one to mention because Sirius itself is the brightest star in the night sky. And, you know, unexpected supernovae aside, it's always a nice thing to see. Now, in the solar system, so thinking about planets, we're actually entering something of a fallow period, an unusual time in March and April when there won't be very many planets around that are visible at all so Jupiter's still really good at the moment and it'll be there in the evening sky for a bit longer so you know as ever do pick up a pair of binoculars and look at that but if you've been seeing Venus in the morning sky February is pretty much your last chance to do that it's going to slide behind the sun from our perspective so it'll be out of view until really quite a lot later in the

year saturn's going to disappear in the evening sky and by april there won't be very many around at all but there is a bright ish comet to look out for called ponds brooks and that's a bit like halley it takes 71 years to orbit the sun it's really not very well known at all it's in the evening sky right now it's moving near the bright star denner which you'll be familiar with if you know the summer triangle. But this time of year, that's low in the west after dark. And if you look around the 9th of February in New Moon or in early March, if you're listening to this later on, then those are some of the best times to spot it. The quirk about it is that it does go through these weird outbursts every so often, and even quite recently. And it has this nickname, the Devil Comet, And it has this nickname, the devil comet,

because it has this weird horn-like appearance in photographs. There's nothing demonic about it. It's just a comet. So it might just surprise us. And in early March, it might just be visible to the naked eye. So do take a look out for that. And then finally, there's a nice event for astrophotographers that I just found this morning preparing for this recording. And on the evening of 16th of February,

the first quarter moon, which is when it's half illuminated, will go right next to the Pleiades cluster and just under the southern bit of it. So if you've got a pair of binoculars, that's going to be a really nice sight. And if you're an astrophotographer, it's a really nice thing to play around with

and try and photograph as well. It's always a bit of a challenge to photograph the bright moon and stars next to it, but I know people manage all these wonderful stacking techniques. So please, if you do that, take those pictures, tag us on Twitter and Instagram and Blue Sky and Threads and so on and show us what you're doing. I mean, we've had some really lovely astrophotography images sent in over the Christmas break. Yeah, just keep them coming because I'll post some of them on Instagram.

They're lovely. It's a nice little joy, isn't it, in the inbox? because I'll post some of them on Instagram. They're lovely. And it's a nice little joy, isn't it, in the inbox? You're just like, oh, how pretty. I lose so much time looking at everyone's pictures like, no, no, no,

I'm not going to do my work. What's everyone else up to? So good, so good. Right, well, I think that's it for this month. We'll be back with our first bonus episode of 2024 in a few weeks' time.

And then after that, we'll have an episode for you all about quakes oh quakes exciting contact us if you try some astronomy at home like izzy said it's at supermassivepod on instagram or you can email your questions to podcast.ras.ac.uk and keep an eye on that social media too because you can actually like izzy you put like a shout out a few days before we record don't you like this is what we're doing the episode on if you've got a specific question on this you know drop us a line here also like people are putting questions in the little spotify reviews now as well right it's so nice people are sending in questions and they're leaving reviews

as well so if you want to review or send us questions that's another way to do it yeah so i guess apple podcast whatever platform you listen on, if it has reviews, chuck a question in there. We'll probably see it too. But until next time, everybody, happy stargazing.