Space Nuts 246 Show Notes
Astronomy, Science, Space, and Stuff.
Space Nuts Episode 246 with Professor Fred Watson & Andrew Dunkley
● Fred’s road trip to Adelaide, South Australia. So, what was he doing there?
● The significance of the magnetic fields of the Black Hole M87.
● There’s been a new echo received from exo-asteroid Borisov….but what does it mean? Fred explains
● Audience questions…from a listener in New Zealand (do other planets have magnetic poles? and another in Sweden (how to photograph very distant objects?). Fred has answers for both.
● Thank you for your participation…you make the show.
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Space Nuts 246 AI Transcript
[00:00:00] VoiceOver: [00:00:00] 15 seconds. Guidance is internal gen nine ignition sequence
to nurse as the magic
Andrew: [00:00:14] word. It feels good. Hello, once again, thank you for joining us on the space nuts podcast. Andrew Dunkley here with. So our good friend, professor Fred Watson astronomer at large. Hello, Fred.
Fred: [00:00:26] Hi, Andrew. How are you doing to be your good friend?
Andrew: [00:00:31] Now I'm honored that you are my good friend.
No, it's good to see
Fred: [00:00:35] you again. Hope you're well, yep. All good. Excellent. Now
Andrew: [00:00:38] on today's program, we are going to be looking at lots of stuff, which is what we do on the space and that's podcast, astronomy, space, science and stuff. Um, we're going to talk about your little trip down to Adelaide shortly, which, uh, is, uh, very exciting.
There's something happening down there. Uh, we got to find out about the [00:01:00] magnetic fields of, um, M 87, uh, the black hole and, um, uh, an echo, another echo from the XO asteroid known as Borisov, which we talked about only recently, but this was, um, the second such XO asteroid that pass through. Of course the space Doogie was the first , which is no longer a Doogie.
It's a. but, um, we, we explained that last week, uh, some audience questions as well about, uh, whether or not other planets have magnetic poles. Now I've never even considered the possibility. So there you have it. We'll look into that and how to photograph distant objects, photon rates. Um, whether or not dogs and cats can live together in harmony, we're going to cover it all this week on this space, nuts podcast.
Uh, but first Fred, let's talk about your little Sojourn to the city of Adelaide, the city of churches in South Australia. Yeah, where there is going to be. Um, [00:02:00] the Australian space discovery center is that this officially opened yet, or is it still in them? It is. Isn't it? Uh,
Fred: [00:02:06] no, no. So it was launched. It's a space thing.
So it was launched, but in fact, it's not open to the public for about another month. It's a little bit more of that, the test, that test running it with, I think, you know, groups, booked groups and things of that sort, just to make sure everything works out all right. And all the displays hang, um, you know, they all hold up, uh, with the, uh, the public, um, with all due respect, the public can be quite rough on exhibition things.
You know, it's a, it's a tough gig for an, an exhibitor. Um, but the story is that, uh, Well, first of all, the story starts with the Australian space agency, which came into being a bit more than I think it's two years ago now. Um, but then they got their headquarters, which are in Adelaide. Um, about a year ago, they moved into what used to be a hospital.
[00:03:00] Uh, and it's a repurposed building. It's called lot 14. Uh, it has lots of high tech. Um, you know, organizations within it, including the Australian space agency, um, which set up shop there, as I said about a year ago, uh, my connection is kind of twofold, but, but it's basically because the government department I worked for also overlooks the space agency it's part and parcel of the same, it's the same ministry, that ministerial portfolio.
Um, so, uh, um, we. I know for the past year or so that I've been involved with this. They've been planning an exhibition, a public exhibition, the space discovery center to showcase Australia's place in space. Um, the advertise the way, uh, Australian industry contributes to space, including the moon to Mars, uh, program that NASA has part and parcel of that.
And also to let people know just how much space activities, uh, affect their [00:04:00] day-to-day lives. Uh, nearly everything we do has got a space connection, usually through communication satellites or weather satellites or resources satellites, the whole deal. So many people don't realize that. And that's really the focus of the exhibition.
Um, the exhibition was, was essentially set up, um, under contract by Cuesta. I beg your pardon by quest or con sorry, quest, which is the, the, the national science center. Questa is a. I make of telescope from a long time ago. Um, quest it con um, they, uh, that the national science center and they, uh, responsibility for building the exhibits, uh, question con is also part of the same government department that I'm in.
So it's a little bit incestuous, but it all worked very well. And my involvement was via Questa con because, um, uh, we had. Uh, a working group, uh, to, to look at the kind of exhibits [00:05:00] that you might put together, which would convey the issue of space ethics. It's all about the ethics of space flight. Um, whether we should explore Mars, you know, whether we should put satellite constellations, all of these things, uh, ethical issues, uh, which, uh, focused on in the, in the exhibition.
So I had a bit of, uh, input to that along with a number of, um, other people who were far more. Uh, perhaps professionally involved with ethical issues than I am. My interest is more of a heart, so that was my contribution. So I got an invite to the VIP preview, um, Tuesday night and. Uh, this is that th that was my first trip out of new South Wales in more than a year.
And the first time I've been on a plane for more than a year, uh, it was an interesting experience, but to be honest, being on the aircraft itself was just the same as it always was. Except we all had face masks. Yeah. Quite hard to drink your Qantas coffee with a [00:06:00] face mask on, but they let you take it off.
Andrew: [00:06:03] Yeah. So is the Australian space discovery center, a permanent
Fred: [00:06:07] facilities? It is. It is. Um, but it'll have,
Andrew: [00:06:10] it'll have, um, evolving and change. It will exhibitions within like an art gallery for
Fred: [00:06:16] space, uh, a little bit like that. And in fact, that's a really good point because I am, I happen to know. Um, through Marnie in fact, the, um, uh, the, the, the new manager of the space center, uh, a guy called is a young man.
Brendan, do you, his name is, and he's a really interesting character. And he used to work for money when money was running the Sydney observatory. Uh, so, um, and he's now scored this job and we talked about getting exhibits in, and I'm a little bit interested because, you know, I draw cartoons, which I've been doing for the.
New book. Some of them are space-related, but lovely to have some of my cartoons in there in the exhibition. Um, so it, yes, it is permanent, but evolving. Uh, the, [00:07:00] the one thing I didn't mention was that the day after the preview and that, so this is yesterday. Now the prime minister actually opened it. Um, to gray FunFair.
So that had a high profile. Um, but there is a traveling version of it, Andrew, which is going all around Australia. So quest kind of looking after that, and I bet you anything it comes to Dubbo fairly early in, in
Andrew: [00:07:23] has been here multiple times over the years, and we used to take the kids to the showground, to.
Um, get involved in some of the experiments and, and hi-jinks that they, they got up to do, uh, got up to, and we did actually take the kids to the quest, to con facility in Canberra once and, uh, went around and experienced some of those amazing things that they have on show there. Um, the earthquake machine.
I really enjoyed that. And, uh, yeah, well used to say that Judy and I'll be in Adelaide, in. September Kimbro October. So we're going to go and [00:08:00] you can go and see, definitely
Fred: [00:08:00] have a look at this. You'll love it. You will absolutely love. Yeah, I
Andrew: [00:08:05] know. I will. If I didn't get to go to the one in Hong Kong, I've got a space center there, but it was closed the day we planned to see it.
So, uh, or wasn't open until 1:00 PM and we had to catch a flight to Sydney. So, um, missed out on that one. So. Yeah, I'm really excited to be able to get down there. So it sounds like it's going to be a terrific place. Yep. Wow. Um, all credit to, um, the department and, uh, that, that vaping is the dishwasher.
Fred: [00:08:29] Sorry. Okay. That's all right. So just a word to all of you as it's space nuts, you know, you're going to be able to go and see this and when, when the time comes, make sure you go and catch up with it. Most
Andrew: [00:08:40] definitely. All right. Uh, it's called the Australian space discovery center in Adelaide. All right, moving on Fred let's.
Um, talk about our first, uh, um, interstellar story, if you like, and this is a focus on, um, uh, magnetic fields of the [00:09:00] black hole. Uh, the event horizon telescope has been clipping a BDI on this.
Fred: [00:09:06] Indeed. That's right. Um, I suspect these are actually observations that were made roundabout the same time as the, the black hole picture was constructed.
I'm not clear. Um, in fact, read the paper yet. I've got a link to it, but I've read it. Um, I'm not clear whether these are more recent observations, but it remember the event horizon telescope, it's this conglomeration of eight. Uh, different radio high-frequency radio observatories, uh, which are all in the Western hemisphere until they're all looking at the same, uh, part of the sky.
And they made these incredible observations of Nat seven, the, uh, galaxy about 55 million light years away. Um, it's a galaxy with probably the biggest, uh, central supermassive black hole of any galaxy in our. Vicinity. So it's the [00:10:00] nearest, uh, super-duper, uh, black hole, which is why they chose that because the bigger, the black hole is the bigger the event horizon is.
And that actually seven was black, black holes event. Horizon is about three times bigger than the solar system in diameter. If you, if you. Count the outer solar system as being, um, where Neptune is, uh, it's colossal. And so that makes it an easier target, um, as, as well. And that's why on the 10th of April, 2019, I think it was, um, we saw that great announcement of the first image of the event, horizon of a black.
Cool. But what's now happened is that we've seen something that in many ways, um, puts up another piece in the jigsaw puzzle. Mat seven is known to be what we call an active galaxy, which means it is, uh, it's black hole. It's supermassive black hole. Is is essentially gobbling up stuff around it, very voraciously and [00:11:00] squirting it back out again as these two checks per perpendicular to the disc of material, the accretion disk.
So, um, it's, uh, that's what makes it active. It's relatively quick at the moment. Um, and so that was another reason why it was thought to be a good time to look at it. Um, but th th the, the mechanism for. A swirling disc of material to turn into jets going up and down from a black hole is thought to be strong magnetic fields that it's all, apparently the magnetic fields have got more of a pool than the black hole itself, which sounds a bit comical, but because the magnetic fields are generated by the book and what the scientists have now done is analyze the polarization of the signal that's coming from that.
Bright ring around the event, horizon that kind of donut and polarization. We're all familiar with it from polarizing sunglasses, but it actually, um, In astronomy, uh, when you can study the [00:12:00] polarization, it tells you about the magnetic fields that are present. Um, partly because it does things like align magnetic fields, aligned dust particles, and the alignment of dust particles is something you can measure, uh, with, um, with, with polarization.
So they've done that. Um, and what we're seeing now is the result it was released last week. I think Wednesday, um, uh, late Wednesday night, our time just too late for my ABC radio broadcast, which is always a pain. Um, anyway, the, um, the, the, the, uh, you know, the image shows essentially they've depicted the way the magnetic fields actually spiral around the event horizon, and that kind of fits that.
The puzzle of how these jets of material come out, that the amazing thing, Andrew, um, here's an amazing fact. These jets of material are 5,000 light years long. So they're not just, you know, they're not little things that pop out of the black hole and they're really nearby. So you don't need an event horizon, telescope to see [00:13:00] them.
You can see them with any radio telescope pretty well. Um, but they're generated by the forces from within the black hole. The force is just. I think they're unbelievable. Just unbelievable.
Andrew: [00:13:10] just hard to fathom that kind of power that the enormity of this thing as you described at the beginning is, is, is hard enough to comprehend.
But the, but the awesome power within is. Yeah, it's just, it's beyond me. I just,
Fred: [00:13:28] well, it's been beyond this all really. I mean, you know, we sitting on that jet on the way to Adelaide when it took off, I thought, yeah, this is great. This is power, power personified, but it pales into insignificance and it's the what's going on in a black hole.
Andrew: [00:13:43] And this might seem like a dumb question, but, uh, you know, w w we're still unraveling the mysteries of black holes. We don't understand them, um, sort of piecing information together bit by bit to try and create the big picture, which will ultimately answer our question one day into the [00:14:00] future. But what about magnetic fields?
How well do we understand those?
Fred: [00:14:04] Yeah, I'm actually probably better than. Um, anybody might pick up from our conversations because we don't often talk about them or we're going to talk about them again today, um, in regard to planets, but, uh, yeah, the magnetic fields pervade the universe and they have a very important role.
Um, our galaxy has a magnetic field. We can work that one out, you know, 400 minutes, 200 billion cells or whatever it is. It's got its own magnetic field. Um, and we w you know, we know that, that they are important in many astrophysical processes. Uh, one of my former colleagues here, Brian Gensler, who now is in Canada, I think he runs a Hertzberg Institute in Canada.
Um, his speciality was. Uh, cosmic magnetic fields. And you only got to talk to him for five minutes before you realize that the whole universe, whole universe works on magnetism. And that is actually one of the questions that the square kilometer array radio telescope is being [00:15:00] built for. It it's one of the fundamental questions that it will ask.
This is the one in Western Australia in South Africa. Um, how did the university's magnetic fields coming to being, um, you know, what a, what a great question. And I think, are you still there? What's happened to Google chromo. It's trying to update it. No, it's all right. Sorry. That's something, something funny happened.
Andrew: [00:15:24] Um, yeah. Uh, look, you got to love the way these, these people who create these, these browsers and certainly to faces, uh, don't consider that people are actually working when you want to do the update. We have, uh, there's a bit of sideline chat, but, uh, we w we have a computer at the radio station that we use when.
We haven't got live programs to it. So we run automated programs, but windows windows we'll do an update in the middle of the night. Knock us off the air. It's just,
Fred: [00:15:54] and you can't stop it. No, I know. Well that this is fortunately, um, nothing happened there. It [00:16:00] didn't interrupt the thing. It just another window appeared and you've this lovely face of Andrew had done Claire that was there suddenly was in punk screen, but I've never heard.
I've never heard that
Andrew: [00:16:09] word used to describe my face before.
Fred: [00:16:13] I'm not the, yeah. Anyway, so square kilometer. Uh, one of its quest is how did the, how did the universe get its magnetism? Was it green? What a great thing to ask about. I'm glad I brought it up. I'm glad you did too, because we don't talk about it enough.
Andrew: [00:16:31] as you said, one of our, one of our audience questions is about that very thing. So we'll get into that shortly, but, uh, for now we're going to take a little bit of a breather on the space nuts podcast, episode, episode 246. Thanks for joining us.
Fred: [00:16:47] Okay. We
Andrew: [00:16:49] being with a gov space nuts. Hi, Andrew Dunkley here with professor Fred Watson.
This is space nuts, the podcast and Fred let's move on to our next [00:17:00] topic. Uh, that of, uh, the XO asteroid. Boris solve, which we have talked about a few times. And I think as recently as last week, we, you know, we had a bit of a chat about it. Um, but now they've been, um, sort of crunching the data that they gathered from, from this, which was a sort of, uh, an incidental or almost accidental finding.
But they, they managed to get a lot of data and going through it. And now, now they, uh, they seem to have picked up on some kind of echo.
Fred: [00:17:28] Well, no, that it's an metaphorical echo echo,
Andrew: [00:17:33] right? Yeah, yeah,
Fred: [00:17:35] yeah, yeah, yeah. Sorry about that. I should choose my words more carefully. Excuse me, Andrew. No, but this is a really interesting story.
So it's the first interstellar comets. So Paris off is definitely not an asteroid because. Unlike , which showed evidence that it was out gassing something because it's all a bit changed. Uh, but there was nothing visible and that's, what's led to this [00:18:00] idea that it's a piece of the crossover, uh, an XO Pluto, something like Pluto, but in another solar system and the solid nitrogen is, was broken off.
And that's what we're seeing. The interstellar cabinet, um, bar itself has, was known to be a comment. From the first, because it developed all the features that we see, uh, on comments from the solar system, it developed a coma. This is a cloud of gas, glowing gas around it's around the nucleus, which is the, the flying iceberg part of the comment.
So it developed that it also developed a tail, which is of course, excuse me, Andrew. I've got a frog in my throat here. Probably an interstellar one. The the, the tail comes from, uh, the solar wind, the wind of, uh, radiation and particles coming from the sun that essentially blows the tail out behind the comment in the anti-solar direction, the direction away from the sun.
So it was known from the beginning to be a comment and, um, There, there was some [00:19:00] pretty rapid analysis done on a comment by myself because of course, as soon as you see this glowing tail, you can clap a spectrograph on it and find out what, what elements are in there. What irons is actually of, of, uh, elements and molecules are being given off by the comment.
And there were some unusual things found in that I can't remember the details, but there were some slightly unusual ratios. I have one, uh, uh, you know, one, um, uh, molecule to another, uh, compared with the ones that you find in the solar system, but they weren't unique. They weren't completely different, uh, from what we find in the solar system.
And so that sort of reassured astronomers that they're on the right track, this, the thing is definitely from outside, it's it can't possibly belong to the solar system because of the orbit that it's in. Um, charging through the solar system. Um, but what we've seen now is, um, new information. And this has come from, uh, principally, I [00:20:00] think the very large telescope, uh, part of the European Southern observatory, which, uh, has a mole, was, uh, paints to point out Australian astronomers have a strategic partnership with, so we can use those telescopes and they have telescopes down in Northern Chile.
And, um, some observations that were made, of course the comment is now. Sort of way out. I can't remember where it is, but it's in the outer region of the outer planets. It's much, it stopped out gassing. So it's very hard to observe. So these would have been observations that were made during 19, 19, 1920, when the comment was that it's closest to the sun and was its most active in the sense that it was giving out these plumes of gal.
Um, but using the, uh, the very large telescope. And in particular, an instrument called force two, which is a spectroscopic instrument. It has an additional string to its bow, though, which you might not be surprised to hear what it is. It can measure the polarization as [00:21:00] well as the spectrum of the light that it's looking at.
So there you are, we've talked about polarization in the first story here. It comes again because this polar polar in metric technique. As it's called, uh, let's you look at the structure of dust that's coming off, uh, the, uh, the comment, cause as well as releasing gas, when it comment out gases, there's all clouds of dust come out as well.
And in fact, they developed two separate tails, a plasma tail, and a dusk tail. And so you can look at the dust. And the polarization lets you, as I think I said a few minutes ago, it lets you look at the alignment of dust grains. Um, and it turns out that the, these dust grains are aligned in such a way that the astronomers can deduce.
That this object has never flown near a star. Um, so that's why it's been described as the most [00:22:00] pristine comet ever found it's uh, it's uh, it's um, venturing into the inner solar system, uh, is the first time that it's been near a star and it's, it's actually had these dust grains released, but there's enough of a.
Polar metric signal in the dust, grains, and it's about alignment and things like that. To tell these astronomers that this is the first time it's done that. And that is really quite a big discovery. Um, there is only one other comment and you'll probably remember this cause I do, uh, is back in the 1990s, I think 19.
98 or thereabouts. There's a comic called hair. Hale-Bopp uh, it was very bright. It was, uh, I think it, I think it was the one that stretched halfway across the sky when it was at its brightest. Yes, it was spectacular. That's right now Hale-Bopp had. Similar characteristics in the sense that it was a pristine comment.
And in fact, it wasn't quite as pristine as [00:23:00] Boris off. Uh, but what, uh, what the astronomers are saying is that, uh, hail buck is the most similar comments to borrow SOF and Hale-Bopp is thought to have made only one passage of the sun, uh, before. We saw it if I can put it that way. So it had not been affected by the solar wind and the solar radiation.
And that's what they're saying about calming Boris off. So it turns out, um, that it was a pristine object. Uh, and by that, I mean, It's composition is very similar to the, the cloud of gas and dust that it formed from. This is the, you know, the, the blob of gas and dust that the whole solar system formed from comments are formed in the outer regions of that.
And it's got. Essentially he's completely unaffected by Starlight or star radiation. And then the comments fall into the inner solar system. That's how we're, you know, the familiarity that we have with them, but is thought to have only done that [00:24:00] once. And, um, and Boris off now is thought to have never done it.
So this was the first time it had passed near anywhere near a star. Until it
Andrew: [00:24:08] came into our part of the world and we, we gave it a bit of a dust up. So it's yeah, it
Fred: [00:24:14] it's
Andrew: [00:24:15] high
Fred: [00:24:16] tailing it out of here. I think I'll write that down. That was really good though. I wasn't alive.
Andrew: [00:24:23] Now. You said it's in the outer reaches of the solar system. Now that must mean. Absolutely hurdling along. It's gone that
Fred: [00:24:29] far. That fast. Yeah. I'm sorry. I can't give you exact details of that, but yes, that's the thing. Um, you know, it, it is very high speed and I guess by that I'm talking about 20, 30 kilometers per second.
Um, perhaps even more than that, um, uh, relative to the sun, uh, It's sort of comparable with, um, the speed of new horizons, which was one of the fastest spacecraft ever launched. So yes, it's, it's uh, on [00:25:00] its way. Um, does that mean it will never come
Andrew: [00:25:02] back? Will it, unless somehow. No hurdle off
Fred: [00:25:06] somewhere else.
Yeah. So, um, the technical details are it's in, what's called a hyperbolic orbit. Um, so it remember that the planets move in elliptical orbits because they're closed it, that there are bits that go around the sun. Um, comics are. Usually in what are called parabolic orbits, which means it's like an ellipse, but infinitely long.
Uh, and that's because the cloud, where they come from is so far away that their lips is a very, very long one and it looks like a parabola, but then the next step, this is in the. Series of conic sections that you learn in mathematics. The next one is a hypo, a hyperbola, which is a very open, uh, path, uh, because it's going so fast, it just sideswipes the sun and then it slightly deflected rather than being.
Brought back in a, in an ellipse. That's how, you know, it's it's um, it's interstellar.
Fred: [00:26:13] so yeah. So some comments all in hundreds of thousands of years, I think I'm talking a bright comments.
I think comment ignored, which was. Fabulous in our evening skies in 2007. Uh, I think that's got a period of about a hundred thousand years, which means portaled Rob McNaught, who I saw on the fortnight ago. Uh, he, uh, he's got to wait a long time before it's coming.
Andrew: [00:26:38] Yeah. Yeah. Well, you could just watch reruns of days of our lives and he still probably would.
You probably wouldn't have to watch that twice to catch up.
Fred: [00:26:48] I'm not sure that he's still engaged with things.
Andrew: [00:26:54] I find that show so frustrating.
Andrew: [00:27:03] There we are more news on Barra. Solvan I'm guessing that a as they keep crunching data, we'll find out even more. And, uh, we'll, we'll let you know. Once we have learned it ourselves.
This is the space and that's podcast with Andrew Dunkley and professor Fred Watson space nuts. Welcome back. Thanks for joining us on the space and that's podcast episode 246 with Andrew directly and Fred Watson. And thank you to our patrons who have been financially supporting the podcast. Uh, many of them for quite a while, uh, your support is appreciated.
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The light there. So how I did that, um, anyway, uh, we appreciate the support of our patrons and we're looking for more and more ways to, um, do you know, value add to the podcast through, uh, through our patrons. So we'll be telling you about those sorts of things in the not too distant future. Um, Hugh and I have been discussing some ideas and I like, uh, I like a couple of them very much.
The word adequate came up. Not going to tell you any more about that just yet, but wait for the tee [00:29:00] shirt anyway. Uh, that's where we're at. And thank you again. If you're a supporter of the space that's podcast through Patrion or a cast or super cast or a whatever platform you choose. Yeah, Fred, we're going to take some audience questions.
And first up were off to the, uh, the land of the long white cloud in New Zealand,
Fred: [00:29:25] right. It's Christine from Deneden New Zealand. Um, I'm just wondering how many planets actually have magnetic North and South like earth. And how important is that? There's an Earth-like planet. Also have a magnetic North and South pole, um, really love your podcast, discovered them last year and use them when ever I drove to work, which is half hour either way.
Andrew: [00:29:51] guys. Thank you, Christine. Love the accent. Love the accent and uh, yeah. Thank you for listening. And, um, [00:30:00] obviously Christine, hasn't been listening. Long enough for those New Zealand jobs that I threw in some time ago. So glad I haven't done that lately, but it's all, it's all in. Good humor, Christine.
I promise you. I do have a soft spot for the Cowboys. Of course, being someone who's got a very strong interest in the first world war. Um, everyone knows about the antiques and because we combined with the New Zealand. Uh, soldiers to become the annex, the Australian and New Zealand army Corps, and fought together in world war one.
And yeah, I, I do have a very S um, Strong feeling about that connectivity between our two nations, even though on the sporting field, we hide each other, but now we've got more in common than most other countries, uh, that neighbor each other, huh? Absolutely.
Fred: [00:30:50] Yeah. It's very, very special. It is a really special relationship, which it is.
Andrew: [00:30:56] I Christine's question is, uh, do other planets have [00:31:00] magnetic poles now we've been talking about magnetism a fair bit today and, uh, yeah, it's a really good question. And I've never even thought about it
Fred: [00:31:08] before. And the answer is yes. Uh, well, let's just think about the solar system. Um, the. The planets that have, um, that don't have magnetic fields are numbered by the ones that do.
So, uh, all the gas giants have got really strong magnetic fields. Mars doesn't we do on earth mercury. Does have a surprisingly strong magnetic field given how smaller planet it is. And, um, that actually mercury, is there a really interesting case in point because he also has, and we know, and we know this from, uh, you can measure these things from the orbits of spacecraft around planets.
We know it's got a big iron core, a much bigger iron core than you'd expect. And so one of the. Reasons why we think mercury is [00:32:00] like it is, is that at some time in its early history, it was smashed into, by something else that broke away. Most of the mental or the region outside the core, otherwise it would have been as big as the earth Venus.
Is that right? But yeah. So it's thought to have been smashed up a bit. So what you've got art is a planet with a thin mantle, relatively thin mantle and a big stonking iron core in the middle. When the iron core is of course the secret of magnetic fields. And if you've got something metallic, something Ferris, in fact, or with iron and iron is the most common metal throughout the universe.
Um, that, uh, is going to give you magnetism. Uh, and so it's actually likely that far more planets have magnetic North and South poles like the earth does than the ones that don't the ones that don't are probably relatively few and far between. And so, uh, Christine's other question is how important is that?
Well, [00:33:00] In, in our case, it is very important because it's the magnetic field that shields the earth from the radiation of the sun, the, the, you know, the magnetic particles that could be very harmful and that they're they're radiation. And that's not something you want, uh, with our magnetism. Uh, those, uh, magnetic particles are sort of shifted away.
So they're not bombarding us all the time as they would, for example, on Mars. Um, that's one of the hazards of humans going to Mars because it is like the earth in that it doesn't have a magnetic, a strong magnetic field. So, um, does an Earth-like planet have a magnetic North and South pole? Yes, because if it's a flight, we'll have a, an iron core, the same as ours and we'll get these magnetic poles.
So a great question. And, um, You know, it's one of the things that, uh, in many ways we are yet to this day, discover about the exoplanets there. You know, we now know of more than 4,000 exoplanets, [00:34:00] uh, uh, orbiting other stars. Yeah. If you have enough information on them. Uh, yeah. And some of the observations that we can make do give us this information, then you can get their density, the density of the planet, and that then tells you whether it's a Rocky planet or a gas planet.
Uh, so you've already got hints from that, that there might be magnetism out there. In fact, the gas plant itself make the thick fields as well as it said, the, uh, the magnetic field around Jupiter is by far the strongest in the solar system. So, uh, Very common. Yeah. Uh, seems likely that there's always going to be magnetic, magnetic fields out there.
Andrew: [00:34:38] so are they generally it by different sources? You talked about earth and the iron core and mercury the iron core that, that, um, is that what generates our magnetic field. And if that's the case, what's generating outs, you know what what's generating the magnetic field that encompasses
Fred: [00:34:56] our whole game.
Yeah, that's right. So, [00:35:00] uh, it, it is the own cause that. January it's what's called the dynamo effect. It's basically what goes on in, in a dynamo. Um, dynamos generate currents. Uh, those currents probably flow through the core electrical currents flow through the core of the earth and generate the magnetic field.
It's um, uh, you know, the physics is pretty well understood. I'm not. An expert on that, but I get the general drift of it, but for something like the Galaxy's magnetic field. Yeah. That's a really interesting question. Does it come from the aggregate of all the individual magnetic fields of the stars? And by the way, the sun has a really strong magnetic field as well.
And that's what drives the activity in the sun. Um, Uh, you probably realized that this is the magnetic addition of space nuts. I think we've talked about it in every story so far. This is, this is
Andrew: [00:35:52] how we suck you in.
What the astronomers, who will be using the square kilometer array down the track to look at the magnetic field of the universe to try and work out how it originated now, whether there is some, whether it is still all about, uh, dynamo effects or whether there's some more fundamental underlying mechanism.
Within the, yeah, the early universe. And is
Andrew: [00:36:23] it a highly variable thing? Because Australians will be well aware that we have an Island called magnetic Island because the magnetism there is more significant than it is. In other places. So why would that be? Is that because of the G
Fred: [00:36:36] geology? Yeah, I think so.
I think in the case of magnetic Island and forgive me, I, you know, this is an assumption is no, but I think it's because of high iron content. A lot of hemotype probably in the, in the rocks. Um, I'll check that, but, but yes, so. Uh, the geology does it effect certainly on it, on the earth, it has an effect, but it is a variable thing as you [00:37:00] know, because the pole, the pole at the moment, the North magnetic pole is whizzing across Siberia or, sorry.
Yeah. On its way towards Siberia. Um, so. Something that changes and you can see why that would be given the structure of the earth. You know, I mean, we talk about the core, the inner core, which is solid and the outer core, which is liquid. Those are the iron causing it as a mantle on top. We've got this lovely picture of it, but.
When you look at the natural landscape around it and see how much variation there is in it, just looking, you know, well, I can look out to, to Hills here at, um, uh, Terri cherry Hills, as you might guess. Uh, and, and you, you know, you see that the way the topography varies. So the topography of the mantle and the core are going to be very old.
There'll be blobs of identity, blobs of low density. And if all that slushing around inside, then you're going to get variations in the magnetic field as well. Indeed. There
Andrew: [00:37:57] you go, Christine. Um, yes. [00:38:00] Was the answer to your question, uh, and thank you for, thank you for sending a voice question into us. Let's move on to our next inquisitive.
Fred: [00:38:11] Hello, underwear and friend. Uh, my name is and I'm from Sweden. A couple of nights ago. I captured an image of the Whirlpool galaxy through my telescope. Uh, due to the distance to the galaxy, approximately 25 million light years and not so many photos per time unit hit my camera sensor. So I had to collect about eight hours of data to get a decent final image.
So my first question is how many photos per time unit, when you say hit my camera sources, which is about two and a half square centimeters. And the second question is after traveling 25 million years through space, how is it even possible that the photos don't diffuse and make my image [00:39:00] blurry? Thanks for a great show.
Uh, I've enjoyed all 243
Andrew: [00:39:06] episodes so far. Thank you. Okay. Uh, very, very good to hear from you again. Uh, and I think you mentioned there were pretty technical questions when we were talking about them earlier, Fred, uh, photons per time unit and, uh, diff diffusion of photons over vast distances. They're really fascinating questions, really
Fred: [00:39:29] what they are, and they go to the.
You know, the fundamentals of astronomical observations with telescopes. And I have to say that I used to have all these numbers at my fingertips when I was doing this sort of thing myself, but I've had to look things up, um, because I've got a bit rusty on it. So photons are the subatomic particles that carry.
Light and magnetism, of course, just to get magnetism into this as well. It's the electromagnetic, uh, uh, uh, subatomic particle. Um, and [00:40:00] yes. So from the, you know, when we're, when we're looking in normal daylight or artificial light and seeing things that are going on, uh, you are seeing gazillions of absolutely gazillions of photons.
Um, but astronomers looking at very faint objects, get. Interested in, you know, the smaller numbers of photons. For many years, I used to use an instrument called the IPCs, which is an acronym for the image photon counting system. This was in the 1980s, and it actually was a machine that literally counted individual photons and formed an image with them.
And, and the things I was looking at, I was looking at very faint variable stars, um, in the center of our galaxy. And you could kind of almost see the photons coming in one by one, uh, as, as it built up the, uh, the image. Um, and I had, yeah, I remember having signals that were barely there. It was a tough gig actually to extract [00:41:00] information from them.
So, um, astronomy was dealing. Photons kind of by the handful, which is what orcas getting us. I think, um, I didn't do the calculation for him. And there are so many variables here. The, you know, a galaxy and the Whirlpool galaxy is a beautiful galaxy and I'm sure. Or cause image is stunning, but galaxies are.
You know, they've got a, what we call a surface brightness, the, uh, number of magnitudes per square arch, second magnitude. So the scale that we use to measure brightness, um, and the surface brightness of galaxies is rather typically low. Um, if it's, uh, not that high. And so. That's why it takes eight hours to, to form an, an image.
Um, cause you're just getting bundles of photons from each arc. Second one I'm going to do is just, um, for orcas benefit, uh, there is a lot on the web that you can discover about this. Um, and th there is a. Really pretty technical page. That's aimed at professional [00:42:00] astronomers. Uh, it comes from it's on the Harvard university website.
Um, it's actually CFA, which is the center for astrophysics. So that's web.cfa.harvard.edu, EDU. Uh, I won't give you the full reference, but, um, I noticed that the two names attached to this. Uh, HTML, uh, uh, fabric content, hooker, Dan fabric, and, uh, John hooker, two very, very big names in the world of astronomy, but it's a website called absolute magnitude, sorry, astronomical magnitude systems.
And it goes through the whole definition. Of how we define this scale of brightness that we use. Uh, but there is, um, a section which is called photon flux and it's, uh, it is quite complicated and you've got to spend a bit of time to figure out what's going on. Cause it converts magnitudes via Jan scales, which are a unit that are more often used in radio astronomy, but they're a photon, a flux unit.
Uh, and you, you, you can, you can end up by working out how many [00:43:00] photons you're receiving. And let me just give you one example, um, which is. How many, um, what are called V band photons. Now these are photons in the visible band of the spectrum. So rather than the blue or red region, it's the greenish region of the spectrum.
How many V band photons are incident per second on an area of one square meter at the top of the atmosphere? In other words, you're neglecting the atmosphere from this from a V equals 23.90 star. Now that is a very, very faint star, 23rd magnitude. It's nearly 24th. Magnitude is the limits of observability for a, for a big telescope.
For, for me to telescope. You're talking now though, about a one meter telescope. You've got a one square meter aperture. That's the, you know, the diamond, the collecting area of the telescope. And the answer is. 2.4, two photons per second. So, you know, you're talking tiny, tiny numbers. This is a faint object, [00:44:00] but they are still there.
You can count them, you know, if you've got photon counting devices, um, it's a really interesting topic. I won't go into any more detail, but, um, okay. Hey, check it out on the web. There's a few websites where people discuss this kind of thing. And, um, you, you will find you, you will get some idea of how many photons were, was coming to you, uh, to your camera sensor when you took your image of the Whirlpool galaxy and all those other questions, um, why they don't diffuse that that's right.
Yeah. So, and that's because, um, In the vacuum of space, there's nothing to diffuse them, essentially, these streams of photons. So what you've got, if you imagine that the galaxy itself, this beautiful looking object, every part of that galaxy is squirting photons out and they travel, you know, the travel. Um, in, in all directions, but each one only goes in one direction and that's the one that you pick up, uh, in your [00:45:00] telescope if it's pointing the right way and they, they don't start diffusing until they hit the us atmosphere.
And that's the problem with the atmosphere. They do exactly what Orca is talking about, uh, of, uh, you know, the last 10 kilometers of their journey to travel 25 million years. No diffusion whatsoever hit the atmosphere and then all bets are off. If you've got, unless you've got really good atmospheric conditions, which is why you build telescopes on mountaintops.
So yeah, it look, they're great questions and it's good to think about things in the photon regime because that's really what professional astronomers are, uh, focused on. If I can put it that way.
Andrew: [00:45:40] Yes, indeed. And, uh, we've talked about subatomic particles and their various roles before, and that's one of the great mysteries they're trying to unravel, um, whether or not there's, there's some kind of subatomic particle that, uh, that carries, uh, some of the more mysterious things that we're trying to learn about like dark [00:46:00] energy, uh, dark matter.
Uh, who knows what else is out there that we haven't yet discovered, as we mentioned last week, that, um, again, could be attributable to yet to be discovered subatomic particles. So
Fred: [00:46:11] it's,
Andrew: [00:46:12] uh, fascinating world. I'm pretty sure they'll unravel at one day. They're afraid. Um, I'm very confident. We learned so much so fast these days that it's only a matter of time before someone has a, uh, you know, a brainwave idea and goes, Oh, I can't check the.
That's what dark matter is dry peanut butter.
Fred: [00:46:35] That's what it is. There you go. Look, you might have something there. Andrew. I'd check that out.
Andrew: [00:46:43] Could be. All right. Uh, thanks again for your questions today. Really appreciate it. And of course, if you do want to send us an audio question, you can do that via our website, uh, space notes, podcast.com and click on the AMA link.
And you can, um, you can, uh, [00:47:00] record your questionnaire or you can send it. Yeah. As a text question via email interface. Now we do have a whole bunch of text questions that have been sent to us, but they were, they were compiled on a spreadsheet that we can't read because for some reason it's formatted itself into one line.
So the question is, hi, Andrew. And Fred really loved the PO. And the rest of it's over there, over there, over there
Fred: [00:47:22] next door.
Andrew: [00:47:24] So w we haven't figured out yet how to decipher that. So, um, if you have sent us text questions, we haven't ignored them. We just can't read more than the hello. I'm Sarah and I'm from Santana and that's about it, uh, or whatever, but, uh, we'll, we'll try and get to them because you, you certainly deserve a hearing as much as anybody else.
So leave that one with us. Uh, we'll get back to you in a life. Second or two maybe longer. Um, but anyway, uh, thanks again for your support of the space and that's podcast. Uh, I think that brings us to an end or something I [00:48:00] haven't mentioned for a long time is the space in that shop on our, um, on our website.
Um, while you're looking at recording your question, just click on the shop. Button as well, and have a look at about our vast array of product, our t-shirts, our polo shirts, our mugs, our caps, our cups. You might like to get yourself something special as a space, nuts listener. And yeah, you could wear that proudly down the street.
What they hell's a space nut might. Well, it's a new, it's a new form of pistachio. You should know. Um, but anyway, we'll leave it there. Thank you for it as always. Great to talk to
Fred: [00:48:36] you. Good to talk to you, Andrew as well. And, uh, yeah. Keep, keep up the good work. I think we, um, w we, we explored many, many different aspects of the universe from, from pistachios to magnetic fields.
We do it or NT.
Andrew: [00:48:49] Yes. There's. I wouldn't think there'd be too many other. Podcasts that combine those two things into the one subject matter. All right.
Andrew: [00:49:02] Watson astronomer at large part of the team here, the vast team of three that put together the space in that podcast.
Hello to you in the studio and from me, Andrew Dunkley. Thanks again. We'll talk to you again next week. Bye-bye
Fred: [00:49:16] to the spice nuts
Andrew: [00:49:17] podcast,
Fred: [00:49:20] Apple podcasts, Google podcasts, Spotify. I have radio. Oh, your favorite podcast player. You can also stream on demand at
Andrew: [00:49:29] Gladstone. This has been another quality podcast
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