The Supermassive Podcast - 33: Q&A - The Year in Space

Episode Date: September 30, 2022

It's been an exciting time for space exploration, so Izzie and Dr Becky celebrate the year in space.... co-incidentally the title of The Supermassive Podcast's book which is out in October. How do plants grow in the ISS? Has JWST changed ideas about cosmology? And when will we get a home gravitational wave detector? The honourable Izzie Clarke, Dr Becky Smethurst, Dr Robert Massey, and (his excellency) space and science journalist Richard Hollingham take on your questions. Pre-order our upcoming book The Year In Space for a run down of the most exciting space news and a look to the year ahead: https://geni.us/jNcrw Listen to Space Boffins: https://www.thenakedscientists.com/podcasts/astronomy-podcasts/space-boffins/apollo-remastered Listen to Gardeners of the Galaxy: https://gardenersofthegalaxy.podbean.com/ Bookclub: The Year in Space - The Supermassive Podcast (that's us!)  Apollo Remastered - Andy Saunders  Star Names: Their Lore and Meaning - Richard Hinckley Allen A Responsibility to Awe - Rebecca Elson  A Brief History of Black Holes - Dr Becky Smethurst

It's the size of a squash quartz and it could be the brightest object in the night sky excluding the moon. But I am looking forward to the home gravitational wave detector to push the boundary back a bit. All the planets are indeed moving away from the sun very, very slowly. Hello and welcome to the Supermassive podcast from the Royal Astronomical Society with me, science journalist Izzy Clark and astrophysicist Dr Becky Smethurst. This month we're celebrating the year in space, coincidentally.

The title of our book which is out next month Izzy, like can you believe it's already here? I'm so excited, oh my god. Me too, yeah. But in all honesty, it's just been a really exciting year for space exploration as well. Yeah, plus the emails were piling up and we just needed to do something about it. That's the story of everybody's life.

So Becky and Robert are here as usual, but I've also decided to give our editor, Richard Hollingham, a microphone for this episode too. Hello. He disembodied voice. So I asked this in January and I enjoyed it so much that I want to do it again. So everyone, to start things off, what is your favourite space fact from this year that you can bring to the table? I don't know if mine's a fact necessarily but it's just a

statement that we can now say that it's true that a year ago would have just blown my mind like the idea that jwst is now finding galaxies at redshift 20 like the fact that i can say that is insane so we're talking about redshift we're talking essentially about how you know far the light has traveled essentially so how much it's been redshifted through the universe as the universe is expanded so the bigger the number the further distant the galaxy is and you know last year you might have said oh redshift 9 that's so high now we're like redshift 12 12, 15, maybe even 20. It's just insane.

The scientific term of being way, way far away. Yes, they're very far away. Robert, what about you? Well, mine's definitely JWST-ish as well. I mean, Frankie, the fact the thing launched successfully, deployed successfully is unbelievable. I mean, that is true i mean you know apart from my anxiety levels being a little high around the launch around the deployment all

of those things now it's just fantastic and amazing amazing amazing achievement uh in the very last week there's been i don't know again it's not necessarily a fact but it's particularly interesting to me because when i did my phd which was back in the early 1990s i looked we looked at these forming planetary systems in the Orion Nebula given the name Proplids for protoplanetary disks and they were observed with Hubble at that time and now JWST has done the same and it's just the images out in the last week you can see the kind of environment where the sun and the planets formed which I think is just fantastic and it's obviously particularly interesting to me but I do recommend you look

at the images if you haven't checked them out yet. Nice. And Richard, you gave us pineapple cake last time. What have you got for us this time? I've got a fact of the second. So it's the 45th anniversary just past of the launch of Voyager 1 and Voyager 2. And right now, their distance from Earth, so the distance from Earth of Voyager 1, is 14,672,936,483 miles. Wow.

Can I have that in kilometres as well? Oh, yeah, I can. Hang on. Well, it's changed. It's changed since I gave it to you in miles. But in kilometres, it's 23,613,810,000 and it's now 427. And by the time this podcast goes out, this will be completely irrelevant.

It'll be an inaccurate fact yeah it's already an inaccurate fact we love it when you said a fact of the second i thought you meant i was like oh we're gonna learn something about seconds like as in the minute of time i was like is it some anniversary of the definition of a second in si units no no calm down okay well that's my silly question done so we should probably get to the proper ones. So, Robert, can you start off with this one? As we said, the year began with the launch of the James Webb Space Telescope. And, you know, we are still not bored of talking about it.

And it seems that our listeners aren't either because we've had quite a few questions. So Fernando has emailed to ask, since JWST can look further back in time with its infrared lens it made me consider what if you could look back extremely far back in time so much so that you could look back to the origin of the universe what is the limit to how far telescopes can see and could you hypothetically look at the start of the Big Bang? Yeah, well, that is a good question, Fernando. And with, I mean, we shouldn't underestimate how far back JWST is looking. It's looking very, very far back, back to just 100 million years or so after the Big Bang. That's more or less the prediction that's being made for that, for when

the very first stars and galaxies formed. Now, so we get light from those, but it's very red-shifted, so we need an infrared telescope like JWST to detect them. And the absolute limit for that kind of radiation, so for photons, which is packets of electromagnetic radiation like light, infrared, radio waves, X-rays, gamma rays, that stuff, the limit is the cosmic microwave background, which is the time when the universe became transparent so all the photons and so on all the basically infrared heat was scattered at that

point it's a bit like looking at the surface of clouds and you know you can't see into the clouds but you can see the light from the clouds coming down to the ground which i have to say sitting here in my uh study at home looking at a very gray sky seems like a very appropriate analogy you know i can only see probably about a mile above my head so we don't get to see inside them that well with that technique but you could use things like gravitational waves to sort of look in quotation marks even further back and try and detect the disturbances that were going on in the universe even earlier back so before about 380,000 years after the big bang and there is a team at the stephen hawking center for theoretical cosmology in cambridge they're working on this and they

because those waves would be very high frequency they'd have short wavelength you'd have to somehow come up with very small detect and very very sensitive detectors which we don't have yet the detectors of gravitational wave are enormous i mean they're they're kilometers long and they have to be because you're measuring a tiny tiny disturbance in space time but the idea of that team which i quite like is that they could have something that could fit in your kitchen now i think we're quite a long way from having you know home gravitational wave detectors but i guarantee that if anybody comes up with an affordable one i will consider it and it will be on my christmas list i'm back i was just about say, I'll put that on mine as well, just for fun.

Can you imagine conversations like, but the microwave needs to go on the kitchen bench, Becky. No, no, not right up top. Exactly, and instead we've got the gravitational wave detector. So anyway, so that would get us back towards the Big Bang. How close you can get to that is then another question. You then get much more complicated ideas. And I guess we sort of simulate it.

We try and simulate it with things like the Large Hadron Collider, where we smash particles together to simulate those kind of conditions. But the energies you need get higher and higher, and it gets harder and harder. So we can go at least theoretically further back than JWST and those telescopes that look at the cosmic microwave background, the satellites that did that. It just gets harder. But I am looking forward to the home gravitational wave detector

to push the boundary back a bit. Yeah, well, I think we all are. And Becky, we have this question from young good postingman Brown, who's tweeted to ask, has JWST changed ideas about cosmology with its early data? So somewhat in a way, yes,

but not significantly in the way that some of you might have seen claimed online. So I mean, there's a huge amount of misinformation online right now about many a topic, but specifically about JWST as well. There's lots of pseudoscience articles claiming, for example, that JWST has somehow disproved the Big Bang theory, which is obviously, you know, sort of the foundation of cosmology, essentially. So this sort of origins of the universe, but that is not the case at all, right? Especially because these articles are sort of written as the Big Bang never happened. But the Big Bang theory is basically the explanation for the entire 13.8 billion years of the past universe's history

which we know happened because well we're here we can see it yeah um what jwst has revealed is that there are disc galaxies so sort of spiral galaxies with these features that are flat at much higher red shifts so at further distances away from us and therefore earlier in the universe because light takes time to travel to us so for the distance something is we're seeing it at a younger age in the universe so we can see those now at higher distances but we can also see these smaller galaxies as well at these higher distances or earlier times in the universe's history and that's not a surprise because for hubble they're just fuzzy blobs right and we think they're fuzzy blobs and with jdwst you can finally resolve them into the

shape that there are but of course our models are based on what observations we have we literally that's what the simulations in theory all do is try and match observations so they match the observations we had which was with hubble which showed fuzzy blobs then rather than disk galaxies now with jdwst yeah we're gonna have to tweak some of the models that in cosmology explain the evolution of the universe to give us smaller galaxies and more disk galaxies forming earlier on than we currently have them now. that you know the underlying things of modern cosmology like you know the expansion of the universe or the fraction of dark matter and dark energy in the universe change in any way like they're not affected at all by these results from jdbc yet anywhere i mean if they were we'd be shouting the loudest from the rooftops because we'd be so excited by the fact that it was um it was sort of showing that and i think that's always how you can tell if something's a conspiracy theory online because they're like scientists are hiding this incredible

result and it's like um no it's not what we do i'd be out there with my party propers you know yeah are you uh are you keeping your nobel prize quiet yeah she's lying to us everyone okay uh thanks becky and so richard this next question is from sam and it's a little different for us i mean no need to be alarmed everyone but it's a biology question astrobiology astro it comes under our in front of it it was fine but i think we should let richard handle this one hello my name's Sam and I'm 15 years old. I recently learned about tropisms in biology, the influences on plant growth. And I was wondering how the lack or change in gravity

would affect the growth and direction of roots of a plant on the ISS or orbiting a planet. And how would gravity or light influence a plant on the moon or Mars with the possibility of cultivation on permanent bases? Great question, Sam. I should explain, I have a degree in biology, which is why I've been handed this question. We just palm everything else like, oh, I'm not sure, Richard. We're all biology. So, trophisms, trophisms are great.

So there's phototrophism, which is almost like senses for plants. So phototrophism is the way plants lean towards light, seek out light. And you see that with trees and plants maybe in your garden. There's chemotrophism, which is a reaction to chemicals. Hydrotrophism, reaction to water. Love this one. Traumatrophism. Guess what that is, everyone?

Something I talk about with our therapists and then the response to gravity which is either gravitrophism which is what we learned uh when i was at university or uh it's also called geotrophism so response to gravity so obviously you want the the roots to grow down and the shoots to grow up. But it was a major concern with space and with humans living in space. Well, what would happen to plants, particularly in microgravity on the space station? Now, there have been experiments for a good amount of time, really since the 1970s, in a serious way. And gravity is really not the limiting factor. So plants do tend to just point towards the light

it affects the roots a little bit but they grow pretty much okay the big limiter particularly in microgravity is the soil or what you grow the plants in you've got to make some sort of artificial soil and then you've got the problem in microgravity that water tends to bubble. And then you can actually drown the plants. The plants end up being drowned if you don't get that medium right. So that's really what's going to happen and what's happening now on the space station. And according to NASA, they have now successfully grown three types of lettuce, kale and flowers. I mean, kale of all the plants you're going to grow all the things you've got to be pretty desperate to crave kale which nuts a hipster decided to grow kale on the international

they're like i want my kale caesar salad on the iss can i just recommend though another podcast um which has nothing to do with us but there's one called uh which is just the best name there's a podcast by someone called emma doughty and it's called gardeners of the galaxy podcast oh my god it's so good uh because it goes into all this in some detail of the challenge of growing plants in space so i would say and coming back to sam's question when you're looking at growing plants on on the moon or mars assuming you've got the you know the right conditions in terms of oxygen and water shouldn't be a problem the big limit is going to be getting that soil right and stopping contamination okay so that's a good biology degree finally paid off yes

okay well thanks for sorting that one out richard so robert we've had this question from simon whittaker via his son and this is based on something that we talked about earlier in the year with our gas giants episode so can you help with this he says and I apologize good day from Sydney loved it thank you I was committed to my role um firstly thanks for the podcast it's so good I do have a question though from one of the podcasts my son asked me this and I don't have an answer I mean that is what we're here for. If the moon was formed following a collision of an object with Earth and all the debris coalesced into the moon,

why will the rings of Saturn disappear in the future instead of forming a single or maybe multiple satellites? I think this is a great question. Did my precious Saturn's rings disappear? It is a great question. Did my precious Saturn's rings disappear? It is a great question. So for the moon, the specific way in which it formed, we think is that something big, something the size of Mars, which was given the name Theia,

hit what you might think of as the proto-Earth, so the Earth before it became like the planet we have today. And that was a cataclysmic collision very early on in the solar system so you can be reassured that these these kind of collisions just can't happen now you haven't got the same stuff around but some of that you know a lot of that debris would have been chucked out into space entirely you know massively energetic collision and quite a lot of it would have fallen back to the proto-earth and only a bit would have coalesced to form the moon and the moon only has about an 81st the

mass of the earth whereas you know the mass of the impactor would have been about a tenth of the mass of the earth so you can see quite a lot didn't go on to form the moon and also the moon was outside what something called the roche limit and this comes to saturn too so the roche limit is the point at which a satellite generally something as big as satellite if it goes within that limit and by satellite i mean i mean natural satellite moons it goes within that limit it gets pulled apart by the differential gravitational field of the planet it's orbiting or star two and what you're looking at if you imagine that one side of the the moon has a stronger gravitational field the other side you get a differential force it gets stretched and broken up so there's a limit

to how close a moon can be before it's pulled apart and the moon was strong enough to overcome that and it was far enough out in the case of saturn though what we think happened is that you had small asteroids and comets getting too close to the planet being pulled apart because they were inside the roche limit and then creating the rings and there's a really interesting debate going on as to how long they've been around you know the Cassini mission back in the 1990s and 2000s and actually it only finished a few years ago but that assumed that they were fairly recently formed that they weren't that dark and you know they estimated the mass to be about the same as one of Saturn's moons Mimas which is the

Death Star the Death Star moon yes the most it's the most reminiscently Death Star moon you can imagine. But now there's a debate saying, well, actually, it might be a bit higher, the rings might be a bit older. But whatever, they are sort of disappearing slowly because some of the dust, the inner ring debris is moving into Saturn's atmosphere and slowly drifting down. So over a period of time, they will disappear.

We just don't know how long that is. So hopefully, I mean, they'll be around long around long enough i think that everybody listening to this podcast can rest assured that saturn's moons will still be there and if they're not there then it's a conspiracy theory obviously we're keeping quiet but i'm joking about that quite clearly saturn's rings are still there i saw them two nights ago i think they're there tonight okay so no need to worry too much becky you're okay no no i mean it's just i mean it's still cool that they're younger than the dinosaurs it's like my favorite i hope that doesn't go away if if people like find they're older because i i just want to keep saying that like if dinosaurs had a telescope they wouldn't have seen saturn's rings well yeah

and the lower limit is 10 million years old which is you know if it was a few million years old we'd be thinking oh the very first humans had they had, wouldn't that be able to see them? But yeah, there seems to be this ongoing debate, you know, including people in the UK, like Michelle Doherty, who's a brilliant Cassini scientist. She was on a paper discussing the different hypotheses for the origins. So, yeah, so don't quite know. But yeah, I like you. I like to think they're young and recent and stuff is going on in the solar system. are like you I like to think they're young and recent and stuff is going on in the solar system so as it's a book special I think it's only appropriate that we do book club so what's everyone been reading recently what your recommendations um who wants to go first well I don't know if I can class this as reading. Oh, yes.

I know exactly what you're going to say. So I'm going to go. I got a copy of Apollo Remastered by Andy Saunders, which is this great big giant coffee table book of remastered imagery from the Apollo missions. And oh my days, like it's so beautiful like to the point where like I've had people come over and I've just lost them for half an hour because they've just started opening this book and I've been like I'm gonna give you that time to enjoy this because it's just

fabulous it's so immersive and so crisp and clear and yeah i just recommend it for anyone a great christmas present you know if you want that really like chunky well it's definitely on my list and i could see richard is there like i have something to say about this so we interviewed the author andy saunders on the space bouffins podcast. He's fascinating. He's gone back to the original images from the Apollo missions and also taken frames from the films that were on

the spacecraft. I think they're some of the most vivid of those images. Seeing the astronauts sort of go about their daily lives in this tiny, cramped Apollo spacecraft, particularly during the apollo 13 mission where it was all going wrong and they just look bored for the most part but we've never seen that before we've just got this impression of apollo 13 i think from the movie more than we

have from the seeing the real astronauts in the spacecraft looking a bit bored and miserable and then i mean the most extraordinary one for me yeah yeah, it's a marvellous book, is, again, we haven't seen this before, Neil Armstrong's face on the moon. Actually seeing his face on the moon, because he took all the pictures. So there's loads of pictures of Buzz Aldrin on the moon, hardly any apart from reflections of Neil Armstrong on the moon. So actually see his face through the visor on the moon is just extraordinary. It's not a cheap book, but it's a beautiful book. I would absolutely, absolutely recommend it. No, it's, it's superb.

And yeah, and Space Buffins podcast for the Andy Saunders interview. He's very, very interesting. And the amount of work he's put into this, it's just incredible. Oh yeah. And there's a link to that interview in the episode notes, if people want to listen to Space Muffins. Robert. Of course they will. Of course they will.

Sorry. If. When. When you want to listen to Space Muffins. That was such a read. Sorry. Robert, how about you? What are you bringing to the book?

Well, I'm going to listen to Galaxy Gardeners before I listen to Space Mpins, I think. Gardeners of the Galaxy, Robin. I'm one of those people that likes kale. But yeah, what can I say? I'm glad you said that. So did I. I was like, I'm going to stay quiet.

So I'm going to reckon, assuming an old book is okay. I've got one from 1899. Now you might say, why on earth have I come up with this? So even older than me. But the reason is a friend of mine was asking me questions on social media about star names and where they come from. And most of them are Arabic. And then, you know, the Greeks giving names to the constellations. That's the mythology we're used to in the West.

And, of course, there's loads of others around the world as well. And I was looking for the classic book on this and one of the best ones is this star names their law and meaning by richard hinkley allen from 1899 which has been reprinted a lot and it's beautiful actually i read through it and i thought you know i mean it is written in the language of the time it does have some unfortunate descriptions of some parts of the world but the details of it are great and uh you know so for example taurus the constellation that we see in the sky right now, it quotes Virgil, it quotes poetry. When were these golden horns bright Taurus Oaps this year and downward the cross dog star stoops. And then it talks about the names of the different stars in the Pleiades and Hyades clusters.

And that's just one constellation. It goes through the whole sky. it goes through the whole sky so if you're wondering about all those exotics and beautiful sounding names that we give to stars or that we use in this podcast this is a really great guide to describing i'm guessing 1899 though just that little bit too early to make some harry potter percy jackson references to all of the star names it doesn't have those it doesn't have wizard references not that not like well i'm not getting it then i think this has been quite a different book club for us to be honest um because i've got a book of poetry that i want to bring forward so this was given to be by a friend for my birthday um and it's by rebecca elson and it's

called a responsibility to awe and she was an astronomer and was diagnosed with a terminal cancer and so this is a book on her poems which are about the universe but also with an element of time thrown into it as well and it's it's lovely it's one of those lovely books just to dip in and out of I guess similar slightly smaller well very much smaller than the Apollo book. But it's really nice. I thought it was such a thoughtful present. And there's a lovely picture from the Juno mission on the cover as well. And yeah, I think it's a great book. So something a little bit different from our usual stuff. And I feel like we need to mention not only do we have a book, but come on, Becky, let's throw another book into the pile come on i have my book out at the

minute as well a brief history of black holes essentially using the history of who figured stuff out and how did they figure stuff out so that you can understand what we know about black holes today much better and with all the wit and pop culture references that i usually present my stuff with and thrown every taylor throw in there. There is a good three Taylor Swift references in there and there's some of them are very subtle and if anyone can get them all I'll be like yes gold star for you. Gold star for you okay and obviously we're gonna say again the year in space as well when that's out and you fancy dipping in and out or something about this year in space. so shall we get back to

some questions another big thing for the space community this year well and for all of us um was the image of the black hole at the center of our galaxy so becky we've had this question from jesse reese as an aspiring future astrophysicist i love the podcast so much oh thank you um and it makes me think hence hence this question. We know there's evidence for a supermassive black hole in the center of the galaxy. However, could it be that there is a supermassive black hole in the middle of the universe which galaxies orbit around?

I'm not sure whether we know the answer, so I thought I would ask. I love this question. I love it too. It's so amazing. I mean, it's great to hear from an aspiring astrophysicist as well. Like good luck with all your studies and thanks for listening.

So I think before we answer if there's a supermassive black hole at the center of the universe, we need to answer is there even a center of the universe? Which we don't think there is, right? At least from the visible universe that we can see,

which is obviously the universe has only been around for 13.8 billion years. So light has only had that amount of time to travel to us. So there is an edge of the universe almost to what we can see that we call the observable universe. But there is probably a lot beyond that. And so we don't know, you know,

whether the universe is infinite or not infinite, or even if it has a size or a shape or whatever. And from what we can see in terms of the structure, there is no center of the universe. And I think people get a little bit confused when we sort of talk about the Big Bang and expansion of the universe, like the expansion isn't happening

from a point outwards like an explosion. All of space is always expanding. So it's expanding everywhere all at once. There is no center of the universe but if we look at sort of the structure of the universe so when we look out and we map all the positions of the galaxies we end up with the structure that we call the cosmic web it kind of looks like almost like a sponge right you've got all these filaments and voids and big clusters of galaxies lumped together in certain points as well. And when we look at that structure,

we've never been able to find a center, even a gravitational center, where there's something that's heavier than everything else, right? And I guess that's how we probably think about a center, especially if we're thinking about if there's a supermassive black hole there, we're thinking about where's the gravitational driving seat almost, right? And we've never found anything like that in the structure but if we do look for our local area of the universe so the milky way andromeda we're in the local group but the local group is part of a bigger super cluster of galaxies as well that's sort of our little sort of node of this structure of the universe at the center of that is messier 87 and the center of messier 87 is messier 87 super massive black

hole that we got the first image of a black hole from a few years ago so before we had the image of the one at the center of the milky way this year they first released the first big orange donut back in i think it was 2017 of messier 87's black hole so i guess if we're thinking small scale and i use small scale very loosely there as an astrophysicist. Yeah, yeah, fair enough. I guess it's Messier 7's black hole. But if we're thinking about the universe as a whole,

there is no center and there's no supermassive black hole there. Okay, well, thanks for clearing that up, Becky. And so, Robert, you know, next month, we will be talking about planetary defense, given there's this current mission called DART that's aiming to redirect an asteroid. That is not a danger to us. That is not a danger to us.

I keep having to say this. It's a test. It's a test. It's a test. It's a test to see that if one day we really needed to, you know, how do we do that? Could we do it? So it's hopefully done that by the time we release this episode. But Robert, Alex Pimentel fromia has a question about asteroid formation and finally someone has used my official title they say hi dr becky honorable izzy and dr yes thank you that is fully your title now

the honorable is i'm gonna with me as toist Dr. Becky Spethers and science journalist, Honourable Izzy Clark. Thank you very much. That'll be the new introduction to the podcast. Get used to it. Yeah, okay. So Alex has a question about the formation of asteroids.

I understand the solar system condense and coalesce out of a cloud of gas and dust. And I can imagine how the sun, planets and other bodies gradually accreted more and more mass but I can't seem to wrap my brain around how asteroids formed into rocks. Since they don't have enough mass to pull themselves into a sphere, how did they become solid rocks? Is it merely a

result that those dust and gas particles collided at a very high speed Or were they once a part of another larger object that was formed and subsequently smashed apart? Or are they not solid and more like a collection of gravel? That would still pose the question, how did pebbles form? They've thought a lot about this and I really enjoyed that. This keeps them awake at night, doesn't it? It's very good. It's very good. By the way, on Becky's question,

I do like the fact that we're all in some way at the centre of the universe. Yes, the observable universe. We're all special. The observable universe being specific. But it's a great question, actually. And it's, so Alex, and we'll continue to refer to Izzy with that title, obviously. So if you think about the dust that's even in your house, it sticks together fairly easy.

I mean, I don't, you know, most of us, if we look under the sort of less vacuumed bit of our houses, we will find little clumps of dust and they stick together with the electrostatic forces, basically charge forces. That happens in space a bit as well. And they can stick together fairly easily when they're small. But you're right that there is a challenge when they get a bit bigger and there's something called the bouncing barrier, which is where they get sort of pebble sized and if they crash into each other at high speed you know do they just break apart do they bounce off how do they stick together so it turns

out and this is why you know this is an experiment i'd really like to have had fun with that there was some scientists some astronomers used a shot tower in bremen in germany and they fired a container full of glass beads up to the top of this 120 meter high chamber and so it went all the way up and then all the way down presumably it was they were filming it or I'm just thinking what happened to the glass when it hit the bottom again but they filmed that the glass particles in that free fall environment would stick together a bit with millimeter size clumps would stick together under the influence of electrostatic forces so they think that is sort of enough in the right circumstances to overcome some of that

bouncing barrier but it is still a bit of a problem and then once they're big enough of course you're quite right the gravity will pull them together and if you end up with a large enough object big asteroids dwarf planets or full-size planets then you get internal heating and they all coalesce together and melt and so on. But the smaller objects, some of them are a bit like rubble piles. We think they are less coagulated together. So it varies depending on the size of the object. But certainly things like comets can be much more fragile

and we see that with all the missions we've sent to them. That's what they're wondering for the DART mission as well, is when it impacts this asteroid, what is going to happen? Because if it is just a rubble pile, an impact could you know disrupt it more out of cloud of stuff yeah exactly rather than just sort of imparting all this energy to the one piece of it so yeah i'm really excited to see what the dart mission finds and it'll hopefully reveal a bit more about structure of asteroids too but personally i would like to be one of those physicists you know throwing for work throwing containers up 120 meters

just sounds great where's robert oh don't mind him he's just throwing some stuff doing what every kid wants to do do you want to push this button hell yes i do like have you ever have you ever seen how ridiculous on youtube it's these three australian guys that go to this like sort of leaning tower outside of perth and drop stuff for the sake of like it is it is it is like a it's an observatory and like a whole science center where like you know kids and schools can go and do like experiments with gravity but they're like yeah but what if we did all the cool stuff that you never think to do in science yeah yeah you know like remake thor's hammer and drop it on a car and film it so drop it on like a balloon

or like paint canisters that is yeah it's a teacher's dream but it's yeah absolutely so Richard regular listeners the Bath astronomers have sent in a question oh shout out Bath astronomers we love Bath astronomers so Richard and so you do a lot of reporting on spaceflight and satellites. So can you help with this one? And they've asked, is the astronomy community losing the battle with satellite light polluters with the new Starlink getting brighter again as designs change and the launch of Blue Walker 3? So just to explain to anyone who may not have heard about Blue Walker 3. Yeah, I missed this. This is a large satellite from a Texas-based company

called AST Space Mobile. Mobile. Mobile. If you're American, Space Mobile. Space Mobile. I did wonder that, actually. As I got to that word, I was like, are we doing another accent?

No, we're not. But basically, Blue Walker 3 is essentially a massive dish that is going to be a cellular broadband network for mobile phones. It's the size of a squash court and it could be the brightest object in the night sky, excluding the moon. So, you know.

What, there permanently as well? Because when we apply for telescope time, I need dark skies. I need new moon skies to do the science I do. If there's something as bright as the moon in there permanently, that's absolutely going to mess up so much professional astronomy. Hence the question. So Richard and Robert.

Tell me some good news. Richard and Robert, let's start with Richard. What do you think? Well, I've recently been on my BBC impartiality refresher course. So I'm going to give a very balanced answer to this. And then Robert's going to put the perspective, I think, of the astronomy community, which I suspect will be less balanced.

A less balanced answer. So the pros of all these satellites, they are connecting the world. They're filling in the gaps with internet connectivity, with mobile connectivity. I mean, the most famous, of course, is Starlink. They're now getting on about 3,000 Starlink satellites. I was trying to find the exact number earlier, but it kind of changes by the week almost. And you've also got these constellations of satellites,

small satellites for climate change monitoring, forestry monitoring, pollution, agriculture. So they're doing lots of good things. On the downside is the BBC impartiality course kicking in. They're reflecting light, as Becky mentioned. And the other issue is the radio frequencies they're using. So they're blasting the sky with all these different frequencies, which is problematic for radio astronomy. And, you know, from again, this, you know, balanced perspective, there is pretty much open warfare going on within the space agencies, I use the term collectively, between the astronomy community, and the tech community, looking at, you know, the tech community want more of these satellites, because they provide services which benefit people, and the astronomy community, which absolutely does not want these satellites, particularly ones that reflect light. And to be fair, to Starlink, they've painted them darker, a lot of them,

but there are an awful lot of them. When you look at a map of all the Starlink satellites, it's quite terrifying just how many. They are small, but there are a lot of them, and you've got these other constellations like OneWeb, for example. There are a lot of them and you've got these other constellations like OneWeb, for example. So it's a problem. And although radio frequencies are very much regulated at an international level and monitored, there are lots of international agreements on how many satellites you can stick up.

But really, there's no enforcement of it. So, yeah, it's a growing problem. And if I was going to put an opinion on this, I say, yes, the astronomy community is losing the battle at the moment. That's not what I thought you were going to say. I thought you were going to say something a little bit. The astronomy community is... Yes, there's words we can't use on a family podcast. Robert, what do you think about this? Well, this is part of my day job trying to campaign on this.

So I think I'd start by saying, look, nobody wants to say hinder communications. We do accept the idea that remote areas need to be connected, that there are uses for the emergency services and all of those things. But, but, but there are quite a lot of developments in this that are concerning for astronomers and anybody who cares about the appearance of the night sky. And I think the AST satellite is supposed to be, I think, about the brightness of Venus, so probably brighter than the International Space Station is in the sky. And you have to ask, well, if there are multiple satellites like this, how much of an impact that will have on the view that

we have regularly, let alone anything else. And it is then obviously problematic for astronomers trying to image the sky. They have to know when this thing is coming and avoid it but starlink are also now proposing spacex and the starlink system they're now proposing their generation 2 system which will have another 30 000 satellites which will also be bigger and there's currently a filing with the federal communications commission in the u.s which regulates US satellite launches, to discuss this. And whether or not that goes ahead remains to be seen. But my guess is they probably will grant permission. So we're going to have even more of them. And at the high end, by the end of the decade, we could be seeing 100,000, 200,000 satellites like this in these giant constellations. Now, I think in a lot of cases, they're small, you know, they have been darkened,

although then they changed the system on that because making the Starlink satellites darker, the first generation made them hotter, which wasn't a great surprise. Then they put these visors in to shield some of the reflection. And the problem with that was they couldn't then use the laser system to communicate between the satellites. They dropped that idea. And now I understand there's another darkening system being tried out but i really hope that those remain in place because even those are not absolutely adequate you can still see the satellites and i suppose i put the idea that if you go to a very dark sky site and maybe 10 of the things you see in the sky or maybe more

are moving satellites you know what is that is that doing to our cultural heritage, to that view we've enjoyed of the night sky for the whole of the time humanity has been on Earth? So, you know, I do think it's a reasonable point to make that it shouldn't just be satellite operators that get to decide this. And then, yes, there's the impact on astronomy, which will become a bit more expensive, at least as a result. And some things like finding nearer asteroids, for example, are a bit harder because we see those streaks on on images that we have and if you have lots of satellites

moving around which also look like streets it streaks it's a bit harder to disaggregate them and also if you're trying to do things like detect meteors in the sky with all sky cameras you have a similar problem so i do think we should we have to take it seriously and on radio as well there's another issue which is that although richard's right that it's regulated a lot of radio astronomy is outside those regulated bands they're only drawn up in the early 1960s at the very beginning of the science and of course now we want to look across the whole spectrum and we've got around that by putting observatories in very remote places like the square kilometer array city in australia and southern africa but you can't do that it's not remote if there's satellites above you because you see them everywhere on earth so i i would say we're in a difficult stage of the

battle i'm not prepared to accept that we're losing it yet we are discussed it is being discussed at then i say we know i'm not doing that but it is being discussed at the united nations for example and in other fora to try and get a better regulatory framework or at least good practice guidelines in place that hopefully these satellite companies will start to observe and think about the fact that they're not the only community. It's not just about getting mobile phone reception right. I think the issue at the moment is we're essentially relying on astronomy communities, essentially relying on the goodwill of Elon Musk and the other entrepreneurs. I would prefer not to do that, thank you. So that is the big, you know, the international regulation is sadly lacking. I think as well, I'm going to put this out here now, we should do a whole podcast on this.

Sounds good to me. I will rant away, I warn you. Because I could talk for ages on this. It will depress me intensely and I will prepare away I warn you because I could talk for ages it will depress me intensely and I will prepare for that accordingly we'll be measured

get ready for that one everyone okay well obviously still a lot to consider there so we'll circle back to that topic maybe another time

but Becky we've had this question from Ray Gorman and they've said, a recent discoverer of the podcast after trying to find science programs that educate without making me sleepy. I think this one works.

I hope it does. We laugh too much, don't we? Yeah. We keep people on their toes, Izzy. It's fine. I like the word think in there. I think it's qualified, isn't it? It's not emphatic.

Yeah, I know. I think this works. Right, Ray ray if you're asleep wake up we're trying our best here um um they said i do have a question that i was wondering about i know the moon has moved away from earth over time and interacting tidal forces have slowed the earth's rotation down as a result or vice versa as it may be now is the same true for the planets and tidal forces have slowed the earth's rotation down as a result or vice versa as it may be now is the same true for the planets and tidal interactions with the sun are the planets slowly migrating away from the sun in a similar manner if so how long before it's dark at noon and if not then why not love that dark at noon yeah i know i don't want that no no thank you um but yes right all the planets are indeed moving

away from the sun very very slowly um and there is an aspect of tidal interactions but not necessarily between the sun and the planets it's more sort of like the planets and everything else in the solar system so for example like mars and jupiter and saturn and neptune like they all pour on earth ever so slightly and there is sort of that slowing and moving outwards. But the biggest effect is for the fact the sun is losing mass all the time. And I think sometimes we forget about this, right? Is that the sun by, you know, in its core nuclear fusion going on where you have hydrogen, you know, four atoms of hydrogen turned into an atom of helium. And that's what the sort of main energy production in the sun is is that an atom

of helium is slightly lighter than four atoms of hydrogen which is great for us because it means energy is given out in the form of heat and radiation which hooray we can survive on earth because of it um but that does mean it's losing a tiny bit of mass with every single sort of fusion reaction it it that happens like the number is 4.7 million tons a second a second a second okay that's a lot yeah it's insane it's an insane number right so i mean it sounds like a lot but in terms of the entire mass of the sun which is what 10 to the 30 kilograms which is the one with 30 zeros after it it's obviously a drop in the ocean but still it's enough to disrupt that uh sort of orbit of the earth and sort of slowly spiral it outwards so the earth is moving away from the sun because

the sun is essentially getting ever so slightly lighter and that obviously upsets the balance. And it's about 1.5 centimetres per year that the Earth moves away from the sun or 0.000000001% of the Earth-Sun distance. So when I said very slowly, I meant very slowly. So as for Ray's question about when it would be dark at noon that sort of puzzled me a little bit because i was like well how how far away would you have to go for it to be dark at noon because on mars we see images from you know curiosity rover and perseverance rover and everything like that you know on the surface of mars but it's not dark at noon there so you'd

presumably have to go further away than the orbit of mars and i was like well how far away i was like well let's be conservative and say jupiter right because jupiter is pretty far away it's actually 741 million kilometers away from the sun which is a change of 591 million kilometers from where we currently are um and at the speed of 1.5 centimeters per year that would take um 39.4 trillion years which is a little bit longer than the 13.8 billion that the universe has been around for out of curiosity to get to mars's distance it would take five trillion years so right to be honest well let's think about it the sun has only five billion years left of its lifetime so we're not gonna get that far that's what i was literally just about to say i was like

yeah but we need to we need to go back to the sun again because you know yeah let's look at the lifetime there okay so thankfully i don't think it's ever gonna get dark at noon hooray ever for on the earth at least we will only shift in the five billion years the sun's got left for about 75 000 kilometers which is about 0.05 percent of the current earth sun distance okay thanks for clearing that up becky well thank you to everyone who has sent in their questions and robert obviously we have to round things up with what can we see in the night sky this month well in not in the night sky but in the daytime sky on the 25th of october there's actually a partial eclipse of the sun and that's visible from the uk uh quite a lot of europe partial eclipse yes it doesn't have quite the same necessary so yeah it doesn't of course you did

it's not quite as evocative is it yeah so the 25th of october anyway and it's a it's a time when the earth moon and sun are almost exactly in line so you get the Moon blocking out some of the Sun. Now from London it'll be about 15% of the Sun is blocked by the Moon. It starts at 8 minutes past 10 in the morning, maximum eclipse is at 10.59 and it ends at 11.51. If you wanted somewhere in the world where it's much more covered you'd have to go to Siberia where up to about four-fifths of the Sun is covered. But what I should stress in this is that,

firstly, you would think 15% of the sun, oh, it'll be obviously darker. Actually, it won't, because even if it's a beautifully clear sky, your eye is so good at adapting to daylight, you just won't notice any difference. But the other really important point to make, which I cannot stress enough, is that this is not something you should look at and just stare at with your eyes, because it's still incredibly dangerous to sit and look at the sun let alone

say look at it through a telescope without the appropriate filters so if you want to view it I mean firstly do you know hesitate to say do your research online but do good research look at respectable astronomy sites that tell you how to do it safely the guidance is that what you would do is project the sun with a small telescope onto card or binoculars you can do the same with that or you can buy a certified solar filter that goes over the front of your telescope or binoculars not over the eyepiece those are very dangerous they can crack and then they can let the light into your eye and you can get easily get permanent damage to your eyes or you can if you have them and they're in date and they're not damaged and all of those things if you have eclipse glasses if you've seen a solar eclipse fairly recently

then that is another way to do it but whatever you choose to use please be very careful and follow the safety advice another suggestion is if there is an astronomy society in your area they might be running some sort of little event where they set up telescopes properly and safely and you can just go along and look at it that way but it is a nice calendar don't forget all the calendar well the calendar is really yeah it's really difficult with partial that partial ones although i guess it's something we should try to see how it works but yeah little little tiny uh pinholes is a way to do it too but it's it's a bit harder when it's very partial but it does work and there again there's guidance on doing that so apart from that in the night sky uh mars is getting closer to opposition in

december it's getting closer bigger and brighter so do look for that uh love mars should be surely becky's second favorite planet after saturn at least and the earth obviously i do hope so no it's neptune is it neptune someone told me that I was the opposite of Beyonce the other day on Twitter they said that if you wanted me to like it then you should have put a ring on it poor old Mars, what can I say

so Mars is getting closer, bigger and brighter it's really hard to see details on Mars but every couple of years or so when it's close to the Earth is a really good time to do it, so if you've got a decent-ish telescope, now is the time to look at iturn's still there in the evening sky as well beautiful ring system always glorious and jupiter's only just past its very best it's really bright at the moment and it's really obvious in the evening sky as the sun sets it's already pretty high

moves around to the south you know pretty decent view of it right now and it's a really good time to look for not just the weather systems on the planet but also things like when the moons move in front of it so the uh so io for example the innermost moon will move in front of uh jupiter in the evening of the 18th of october and you can see both the moon and its shadow moving across actually fairly easily so if you've never done that that's a really nice thing to look at and then in the sky you know beyond that you've got a meteor shower the orion meteor shower on the 21st 22nd of october worth taking a look for that not vast numbers but some of them can be quite bright and the stars themselves thinking of that star names their law and meaning book

it's a nice time to look out for constellations like pegasus and the big square it shares with andromeda with the galaxy that be that Becky was talking about earlier on this is the time of year to look for the Andromeda galaxy which you know if it was closer to the earth or if it was brighter it would be six times as big as the full moon but because it's relatively faint there's you know although it's the light of a whole galaxy it's it's fairly spread out it's it's faint but you can see it with your eye and it's it's just satisfying to pick up a pair of binoculars and see it as this long... Well, you don't see the spiral arms very easily, but you do see this long fuzz. And to realise you're looking at a system of hundreds of billions of stars.

And then, you know, there are other clusters in the sky as well. Perseus above Andromeda, another part of that whole Greek legend system, has this beautiful double cluster in it too. So a few things to look out for obviously you need maps to find some of these things but i definitely recommend the solar eclipse observed safely definitely recommend the planets and yeah take a look at galaxies and clusters and as it gets colder in the autumn it's it's a nice time to be doing these things oh absolutely so basically just look up as ever as ever yeah exactly enjoy the view like a massive uh thing for having fire pits and everything like chimney is outside right now to sit outside in autumn like you know crack out the

fire pit light a fire such a nice time of year i mean he says looking out of his window at the rain but you know when it's clear and dry it's absolutely stunning let's face it yeah amazing well that's it for this episode and by the next time you'll hear from us, we'll have published our book. So, oh my God. Can you tell we're excited? So yeah, The Year in Space, it's going to be out on the 27th of October. So do consider pre-ordering it if you haven't done already. And I just want to take this moment to say that I actually think it's quite wild that we are the

number one astronomy podcast in the UK and even more so that we have a book so thank you to anyone that has listened supported us sent in questions like we had no idea it would lead us to this point so honestly thank you so much and thank you also to Lindsay lindsey and alex from headline publishing group who have been huge supporters and getting this book off the ground um thank yous all round basically should we tell them what's in the book as well i feel like we haven't actually said well well it's it's basically lots and lots of really interesting articles about the big space stories from this year. So I've written about the launch of JWST and also talking about, you know, 10 years of exploring Mars as well.

I mean, the whole gang's been involved in it. So what else has anyone else? There's stargazing from Robert in there. There's like Ask Dr. Becky sections, right, as well. So if your question that you sent in hasn't been answered in a podcast, it might have been answered in the book instead. Absolutely. And can I just say there is a great guide to how to use a telescope and what to look out for in the night sky you know by month by a month breakdown

the illustrations as well are amazing we've got loads of pictures um just from hubble and james webb i mean we really fought to get, just delay printing so we can get those pictures. So exactly. And for the first time, if I can just interject, for the first time, it has the full interview that I did with Gene Cernan, Last Man on the Moon, which was recorded shortly before he passed away.

So we've got that as well. It's so good to publish it for the first time, have the opportunity to put it all out there for the first time, written as a Q& q a so it's pretty much every word he said in that interview to me and it's absolutely fascinating so i'm gonna call that an exclusive yeah yeah it is i've been holding on to that interview and i've sort of used bits and pieces over the years but it's the first time we can actually put the the whole lot whole lot and i'm going to give a plug for my uh friend greg who's done some of the illustrations really really nicely and thanks greg yeah yeah so he's not going to get much of a mention but he definitely deserves

it for that i'll pick up greg well if you fancy seeing what all the fuss is about then the link to order the book is in our show notes next time we're going to be chatting about planetary defense and the dark mission how the heck do we keep asteroids from colliding with our planet and not end up in some hollywood disaster movie style thing where it breaks into two pieces and once again anyway we don't want that we'll find out in that next month's episode but until then happy stargazing