The Supermassive Podcast - 41: BONUS - Why do Gas Giants exist?

Episode Date: June 13, 2023

Can JWST see galaxies at different life stages? What is a "former" constellation?  And why do we see Jupiter in monochrome? This month, Izzie Clarke, Dr Becky Smethurst and Dr Robert Massey take on your questions from The Supermassive Mailbox. Want to support The Supermassive Podcast? Why not buy our book The Year In Space - https://geni.us/jNcrw The Supermassive Podcast from the Royal Astronomical Society is a Boffin Media Production. The producers are Izzie Clarke and Richard Hollingham.

Hello and welcome to another bonus episode of the Supermassive podcast from the Royal Astronomical Society. With me, science journalist Izzy Clark, astrophysicist Dr. Becky Smethurst, and deputy director of the Royal Astronomical Society, Dr. Robert Massey. We had some drama this month because we were locked out of the supermassive mailbox but luckily we just got it back just in time for this bonus also is he this is just written in my script i didn't know this what happened we went from a forwarding address to an actual email address but i did not have the password to the actual email address i was like I haven't had any emails in a while does everyone hate us and then realized like it had been changed over and then I opened up the inbox and everyone had

sent in their messages and I was I had a lovely morning of just going through about a month's worth of emails like oh yay we are loved for. And also we now have questions to answer as well. Yes. So let's get into that pile of questions that we now are a month behind. And we've had two great questions from Todd Young. And as he is the first priest, I think, to have ever emailed us, I'm going to play the producer card and I'm going to allow both. Todd says, I discovered your podcast a few months ago and have been binge listening. I have two questions I haven't heard addressed. In one episode, Robert mentioned a former constellation.

How do you get a former constellation? And number two was with JWST looking back into the ancient universe and with the universe expanding, what are the possibilities that we are seeing the same galaxies at different places and stages in their lives thanks for the always interesting content so robert let's start with the former constellation how can you get a former constellation how can you get a form yeah that sort of implies somehow the stars have moved around or disappeared and it's not like the constellations are just things that we impose as a way of structuring the sky.

So they differ depending on where you are in the world. They're obviously different systems were set up by different civilizations, different peoples. Now, the Western canon pretty much dominates now in international terms, perhaps unsurprisingly. And they were standardized in 1922 by the International Astronomical Union. So there are now 88 constellations remaining.

And they are a combination of the ancient Greek ones with Latin names. But of course, the Greeks couldn't see the Southern Hemisphere. So there are many others as well that were typically designated by telescopic observers who worked down in the Southern Hemisphere. And so they built up these names. And apparently decided oh there's two bright stars i will join them and they will be telescopium exactly exactly right but before that standardization people quite commonly gave names to them and one of the best

examples is quadrans muralis which is the mural quadrant so the kind of navigation device thing for measuring angles and that's between the constellation of boetes the herdsman in the spring sky and ursa major the plow and the associated stuff around it and it no longer exists because it was standardized out of existence but but uh it does name a meteor shell we still have the quadrantids in january which is named for that constellation which no longer exists so there are quite a few of those and yes if you look on old maps some of the some of which are in the ras library you will see constellations that are no longer and also that's just a reminder to be like make your own constellations up guys if you don't recognize anything just to be like what do i see amazing and becky can you explain the jwst and looking at galaxies and different life stages I like to think it's like

oh there's the terrible twos and that's it well that is I usually use that analogy right when we when we use telescopes to look sort of back as far as with JWST so what I mean by that is that light takes time to travel to us so we're seeing the universe at different stages in its life and that's the same for galaxies as well. So we see galaxies nearby, we see galaxies far away. The nearby ones are probably 13 billion years old, the distant ones are half a billion or a billion years old. And so what it's like is like looking at the human population, right? You can't in one instant look and see a single human age, right, throughout their entire lifetime.

But you can look at the entire human population and be like, okay, I can see how a baby becomes, you know, an 80 year old, a 90 year old and evolves to become that. So that is really what we do when we're looking at galaxies. We cannot see the same galaxy at different life stages in the same way that in one observation, you can't see a human at all.

It's different life stages. Light same way that in one observation, you can't see a human at all. It's different life stages. Light takes time to travel to us. So we just get that one snapshot and the expansion is not happening faster than light. So it's not like, you know, we, a galaxy moves within the expansion and we end up seeing it twice.

Unfortunately, that's really not what happens here. Okay. Thanks. And Robert, can you help with this one from kyle murphy he says hello from america my question is if space is always just above absolute zero why do gas giants like jupiter exist wouldn't the gas condense into a solid in the cold vacuum of space i hope all is well i love the podcast like massively thank thank you for that girl uh yeah i mean the answer is that yes space away from you know

it's very hard to define completely empty space because no space is absolutely empty it's always got very very tenuous material in it but someone else is going to send another question about that anyway that's someone else is going to say they are about that. Yeah. Anyway, that's for the future. Someone else is going to say, they are indeed. That's fine. But we'll come to that one in Jupiter. It's not a perfect vacuum. Exactly.

So, yeah, it's not a perfect vacuum. But you've got local concentrations of matter. They're pooled together. And this is akin to the way stars form. When stars form, you've got mass collapsing in under the influence of gravity and heating up as a result until, you know, it gets to the point where it's hot enough to fire nuclear reactions now that doesn't quite happen in Jupiter's case but that contraction of matter heats the internal core of course the earth's core as well is hot you know all of these local heating processes offset that now it is a good question to say why doesn't gas condense into a solid in the cold vacuum of space and it certainly would be cold

enough in certain circumstances but you have to remember that it's often quite diffuse it's not connected together you've got by terrestrial standards really quite isolated atoms and molecules and if you look at say a typical dark nebula if you look at say the horse head nebula the famous one that looks like it indeed a horse's head in orion the temperature in there might only be as low as 10 degrees above absolute zero, but it's molecular hydrogen and other things that are just widely separated. They're not going to come together to form a solid in the same way that they would if you had it on the Earth. Okay. Okay. And Becky, Nick Corn on Twitter asked, it's often said there's a black hole at the centre of the galaxy. How close to the actual centre and why?

black hole at the center of the galaxy how close to the actual center and why so i'm gonna take this is um the center of every galaxy is tends to always say um and for all galaxies i'd say it's center ish um because our favorite uh scientific unit among astronomy friends it's like yeah i'll take that um and that's because um black holes they do tend to slosh around a little bit um so you you can have mergers of two galaxies you know we often say you know in a merger of two galaxies no two stars will collide just because space is so big and stars are so far apart the black holes though because they are the heaviest thing they will sort of sink to the center to the center of that gravitational sort of well of the galaxy um and eventually they will sort of you know orbit around each other and slowly spiral in and merge as well. Now, because of that, that means there's lots of gravitational forces involved. And if you

can have a merger of two black, two supermassive black holes at the center as well, you could obviously have a lot of leftover like momentum and stuff, which is why they tend to slosh around. And we see this in simulations as well. When we do galaxy simulations, we see that they're not always in the center. They are sort of just like, it is the best word is sloshing. I can't give you another word, Izzy, is they slosh around, right?

It's a slightly frightening thought there, Becca. You know, black holes just sloshing around. Yeah, well, yeah, a little bit. Yes. I mean, it's not a huge amount. And you might think, oh, why would they slosh in the center? Because surely all the stars in the galaxies are orbiting around these black holes as well. But really, they're orbiting around that center of mass, that gravitational center of the galaxy.

A black hole in the center is not like the sun in the solar system. If you remove the sun, you've removed 99% of the solar system's mass, and all the planets would just fly off. The black hole's mass is less than a percent of the galaxy's mass. So even though it is super massive and it is the heaviest thing, it's still not the main driving force like the sun is. So this is why they tend to slosh, and that doesn't affect the galaxy. So we say center-ish, but if you've got a very calm very left alone galaxy then yes the black hole will sink to that center of mass of the rest of the galaxy as well just through you know gravitational physics as for why they're at the center i don't know um it's the astrophysics chicken or the egg right what came first the galaxy of stars one of them went supernova made

a black hole that grew to become the biggest thing became the black hole the center or did a cloud of gas in the early universe collapse down into a black hole and a galaxy of stars formed around it um we just don't know yet it's maybe something we're hoping jdbst can help solve fingers crossed fingers crossed okay thank you and robert christopher Gotch has been in touch. He says, good morning. As a child of the 80s, I spent many an evening as an eight-year-old huddled under the blankets, pouring over Sir Patrick Moore's A Guide to the Solar System with a torch. The book showed wonderful images of the planets in glorious technicolor.

My question is this. Why, as a grown man in his 40s, when I observe Jupiter through my 90mm refractor, do I see this in monochrome? Is it me? It's not you, Christopher. No, it's not you. Really? I see things in colour. You're telling me you see things in colour.

Well, all right. Eagle-eyed Becky. No, I'm joking, I'm joking, I'm joking. No, it's not you. It's basically down to the fact that the eye is not sensitive to colour at low light levels. So you've got the two different parts of it, the cones that are the ones that detect the colour and all the glorious stuff we see during the day. And when it gets dark, the rods take over and they're monochromatic. So we tend to, unless we've got very bright objects, we tend to end up seeing them much more monochromatic than

digital images and so on and even for the photographs that you saw in those books in the 80s have if you look at with a larger telescope the colours can become a bit more obvious so that they're still subtle but for example Saturn will look quite obviously yellow Mars is fairly easy to see a sort of salmon pink colour not deep red necessarily but usually at least at that level and Jupiter the same you know you do start to see a sort of salmon pink colour, not deep red necessarily, but usually at least at that level. And Jupiter, the same, you know, you do start to see a bit of colour in it, but you need a larger telescope, you need to gather that much more light. Nebulae as well, you know, if you look at things like the Orion Nebulae, you'd think from the images it's brilliantly red and green and blue and all those fabulous colours. Actually, they're very, very

subtle. A small telescope, it will just look like a glow of light. But again, a bigger one, a medium-sized, large reflector, I guess the sort of big Dobsonians that amateur astronomers build, you can start to see colours in that under dark skies. But they are subtle. And it's just down to the way that biology works that it's better for us to be able to see faint things at night without worrying too much about their colour. Right, so when Christopher says, is it me?

Yes, it is you, Christopher. Yes, it's him and all of us. Except Becky. I was joking. Bionic Becky. No, but you can't see this, you know, when you look. I will. You can see this when you go to bed at night, right? You turn the light off and you open your eyes and you

can't see colour in your bedroom anymore. Yeah. And Becky, there's also a PS here that you are going to love okay ps are there any taylor swift inspired astronomical objects for my daughter i hasten to add for my daughter yeah sure uh no i've had hilarious thing i have thought about this before obviously and that is and that is because on one of two hotels this album she makes a lot of space references like rar albums she makes a lot of space references like

rarer than the glimmer of a comet in the sky or I love you to the moon and Saturn kind of thing so I was like I wonder if the reverse is true that there is

Swift references in space rather than space references in Taylor Swift so there's Comet Swift Tuttle we'll take it right which is responsible

for the Perseid's meteor shower right that's the best meteor shower of the year. And I looked into that. It's actually named for an astronomer, Lewis Swift. As far as I can tell, there's no relation to Taylor Swift. I did look, though.

I have to admit. He's also got asteroid 5035 Swift and a lunar crater called Swift, named after them as well. Sometimes it's incorrectly called Graham, that lunar crater as well, apparently. I don't know why. If there's any Taylor Swift fans out there, they're the only ones going to get this joke, but we need to get t-shirts printed with no, it's Graham on it instead. Literally 1% of the audience is going to get that, but I don't care. And then there's the Swift Observatory. Oh, of course. Of course.

Yeah. So this is a telescope that detects um like it's multi wavelengths so it's gamma rays x-rays but it's really looking for gamma ray bursts and the reason it's called the swift observatory is because of how swiftly it reacts when a gamma ray burst goes off which is what you really want for a gamma ray burst you want like oh there's one there quick move look you know over there it can very swiftly like slew to another part of the sky and and and look at the gamma ray burst that's that's going off so i like the fact that there is you know swift yeah all over the sky i mean becky you have an asteroid named after you surely if you get an opportunity to name another one it could just be if it's not happened already that could be my moment that finally gets me i was gonna say anything to meet taylor swift i've named it on me just like you know be best friends

can i come to a concert i love you right well thank you everyone for the questions do keep coming. You can email them to podcast at ras.ac.uk, tweet at Royal Astro Sock, and we're also on Instagram at SupermassivePod. We'll be back next time with a full episode on the history of astronomy, which is something I love looking at. Sort of, you don't really realise

how much we never understood until recently and how much work's gone into sort of just things we now take for granted. It's awesome. Really excited for that episode. But until then, everybody, happy stargazing.